content: package com.termux.view;
  
  import android.annotation.SuppressLint;
  import android.annotation.TargetApi;
  import android.app.Activity;
  import android.content.ClipData;
  import android.content.ClipboardManager;
  import android.content.Context;
  import android.graphics.Canvas;
  import android.graphics.Typeface;
  import android.os.Build;
  import android.os.Handler;
  import android.os.Looper;
  import android.os.SystemClock;
  import android.text.Editable;
  import android.text.InputType;
  import android.text.TextUtils;
  import android.util.AttributeSet;
  import android.view.ActionMode;
  import android.view.HapticFeedbackConstants;
  import android.view.InputDevice;
  import android.view.KeyCharacterMap;
  import android.view.KeyEvent;
  import android.view.Menu;
  import android.view.MotionEvent;
  import android.view.View;
  import android.view.ViewConfiguration;
  import android.view.ViewTreeObserver;
  import android.view.accessibility.AccessibilityManager;
  import android.view.autofill.AutofillValue;
  import android.view.inputmethod.BaseInputConnection;
  import android.view.inputmethod.EditorInfo;
  import android.view.inputmethod.InputConnection;
  import android.widget.Scroller;
  
  import androidx.annotation.Nullable;
  import androidx.annotation.RequiresApi;
  
  import com.termux.terminal.KeyHandler;
  import com.termux.terminal.TerminalEmulator;
  import com.termux.terminal.TerminalSession;
  import com.termux.view.textselection.TextSelectionCursorController;
  
  /** View displaying and interacting with a {@link TerminalSession}. */
  public final class TerminalView extends View {
  
      /** Log terminal view key and IME events. */
      private static boolean TERMINAL_VIEW_KEY_LOGGING_ENABLED = false;
  
      /** The currently displayed terminal session, whose emulator is {@link #mEmulator}. */
      public TerminalSession mTermSession;
      /** Our terminal emulator whose session is {@link #mTermSession}. */
      public TerminalEmulator mEmulator;
  
      public TerminalRenderer mRenderer;
  
      public TerminalViewClient mClient;
  
      private TextSelectionCursorController mTextSelectionCursorController;
  
      private Handler mTerminalCursorBlinkerHandler;
      private TerminalCursorBlinkerRunnable mTerminalCursorBlinkerRunnable;
      private int mTerminalCursorBlinkerRate;
      private boolean mCursorInvisibleIgnoreOnce;
      public static final int TERMINAL_CURSOR_BLINK_RATE_MIN = 100;
      public static final int TERMINAL_CURSOR_BLINK_RATE_MAX = 2000;
  
      /** The top row of text to display. Ranges from -activeTranscriptRows to 0. */
      int mTopRow;
      int[] mDefaultSelectors = new int[]{-1,-1,-1,-1};
  
      float mScaleFactor = 1.f;
      final GestureAndScaleRecognizer mGestureRecognizer;
  
      /** Keep track of where mouse touch event started which we report as mouse scroll. */
      private int mMouseScrollStartX = -1, mMouseScrollStartY = -1;
      /** Keep track of the time when a touch event leading to sending mouse scroll events started. */
      private long mMouseStartDownTime = -1;
  
      final Scroller mScroller;
  
      /** What was left in from scrolling movement. */
      float mScrollRemainder;
  
      /** If non-zero, this is the last unicode code point received if that was a combining character. */
      int mCombiningAccent;
  
      private final boolean mAccessibilityEnabled;
  
      /** The {@link KeyEvent} is generated from a virtual keyboard, like manually with the {@link KeyEvent#KeyEvent(int, int)} constructor. */
      public final static int KEY_EVENT_SOURCE_VIRTUAL_KEYBOARD = KeyCharacterMap.VIRTUAL_KEYBOARD; // -1
  
      /** The {@link KeyEvent} is generated from a non-physical device, like if 0 value is returned by {@link KeyEvent#getDeviceId()}. */
      public final static int KEY_EVENT_SOURCE_SOFT_KEYBOARD = 0;
  
      private static final String LOG_TAG = "TerminalView";
  
      public TerminalView(Context context, AttributeSet attributes) { // NO_UCD (unused code)
          super(context, attributes);
          mGestureRecognizer = new GestureAndScaleRecognizer(context, new GestureAndScaleRecognizer.Listener() {
  
              boolean scrolledWithFinger;
  
              @Override
              public boolean onUp(MotionEvent event) {
                  mScrollRemainder = 0.0f;
                  if (mEmulator != null && mEmulator.isMouseTrackingActive() && !event.isFromSource(InputDevice.SOURCE_MOUSE) && !isSelectingText() && !scrolledWithFinger) {
                      // Quick event processing when mouse tracking is active - do not wait for check of double tapping
                      // for zooming.
                      sendMouseEventCode(event, TerminalEmulator.MOUSE_LEFT_BUTTON, true);
                      sendMouseEventCode(event, TerminalEmulator.MOUSE_LEFT_BUTTON, false);
                      return true;
                  }
                  scrolledWithFinger = false;
                  return false;
              }
  
              @Override
              public boolean onSingleTapUp(MotionEvent event) {
                  if (mEmulator == null) return true;
  
                  if (isSelectingText()) {
                      stopTextSelectionMode();
                      return true;
                  }
                  requestFocus();
                  mClient.onSingleTapUp(event);
                  return true;
              }
  
              @Override
              public boolean onScroll(MotionEvent e, float distanceX, float distanceY) {
                  if (mEmulator == null) return true;
                  if (mEmulator.isMouseTrackingActive() && e.isFromSource(InputDevice.SOURCE_MOUSE)) {
                      // If moving with mouse pointer while pressing button, report that instead of scroll.
                      // This means that we never report moving with button press-events for touch input,
                      // since we cannot just start sending these events without a starting press event,
                      // which we do not do for touch input, only mouse in onTouchEvent().
                      sendMouseEventCode(e, TerminalEmulator.MOUSE_LEFT_BUTTON_MOVED, true);
                  } else {
                      scrolledWithFinger = true;
                      distanceY += mScrollRemainder;
                      int deltaRows = (int) (distanceY / mRenderer.mFontLineSpacing);
                      mScrollRemainder = distanceY - deltaRows * mRenderer.mFontLineSpacing;
                      doScroll(e, deltaRows);
                  }
                  return true;
              }
  
              @Override
              public boolean onScale(float focusX, float focusY, float scale) {
                  if (mEmulator == null || isSelectingText()) return true;
                  mScaleFactor *= scale;
                  mScaleFactor = mClient.onScale(mScaleFactor);
                  return true;
              }
  
              @Override
              public boolean onFling(final MotionEvent e2, float velocityX, float velocityY) {
                  if (mEmulator == null) return true;
                  // Do not start scrolling until last fling has been taken care of:
                  if (!mScroller.isFinished()) return true;
  
                  final boolean mouseTrackingAtStartOfFling = mEmulator.isMouseTrackingActive();
                  float SCALE = 0.25f;
                  if (mouseTrackingAtStartOfFling) {
                      mScroller.fling(0, 0, 0, -(int) (velocityY * SCALE), 0, 0, -mEmulator.mRows / 2, mEmulator.mRows / 2);
                  } else {
                      mScroller.fling(0, mTopRow, 0, -(int) (velocityY * SCALE), 0, 0, -mEmulator.getScreen().getActiveTranscriptRows(), 0);
                  }
  
                  post(new Runnable() {
                      private int mLastY = 0;
  
                      @Override
                      public void run() {
                          if (mouseTrackingAtStartOfFling != mEmulator.isMouseTrackingActive()) {
                              mScroller.abortAnimation();
                              return;
                          }
                          if (mScroller.isFinished()) return;
                          boolean more = mScroller.computeScrollOffset();
                          int newY = mScroller.getCurrY();
                          int diff = mouseTrackingAtStartOfFling ? (newY - mLastY) : (newY - mTopRow);
                          doScroll(e2, diff);
                          mLastY = newY;
                          if (more) post(this);
                      }
                  });
  
                  return true;
              }
  
              @Override
              public boolean onDown(float x, float y) {
                  // Why is true not returned here?
                  // https://developer.android.com/training/gestures/detector.html#detect-a-subset-of-supported-gestures
                  // Although setting this to true still does not solve the following errors when long pressing in terminal view text area
                  // ViewDragHelper: Ignoring pointerId=0 because ACTION_DOWN was not received for this pointer before ACTION_MOVE
                  // Commenting out the call to mGestureDetector.onTouchEvent(event) in GestureAndScaleRecognizer#onTouchEvent() removes
                  // the error logging, so issue is related to GestureDetector
                  return false;
              }
  
              @Override
              public boolean onDoubleTap(MotionEvent event) {
                  // Do not treat is as a single confirmed tap - it may be followed by zoom.
                  return false;
              }
  
              @Override
              public void onLongPress(MotionEvent event) {
                  if (mGestureRecognizer.isInProgress()) return;
                  if (mClient.onLongPress(event)) return;
                  if (!isSelectingText()) {
                      performHapticFeedback(HapticFeedbackConstants.LONG_PRESS);
                      startTextSelectionMode(event);
                  }
              }
          });
          mScroller = new Scroller(context);
          AccessibilityManager am = (AccessibilityManager) context.getSystemService(Context.ACCESSIBILITY_SERVICE);
          mAccessibilityEnabled = am.isEnabled();
      }
  
  
  
      /**
       * @param client The {@link TerminalViewClient} interface implementation to allow
       *                           for communication between {@link TerminalView} and its client.
       */
      public void setTerminalViewClient(TerminalViewClient client) {
          this.mClient = client;
      }
  
      /**
       * Sets whether terminal view key logging is enabled or not.
       *
       * @param value The boolean value that defines the state.
       */
      public void setIsTerminalViewKeyLoggingEnabled(boolean value) {
          TERMINAL_VIEW_KEY_LOGGING_ENABLED = value;
      }
  
  
  
      /**
       * Attach a {@link TerminalSession} to this view.
       *
       * @param session The {@link TerminalSession} this view will be displaying.
       */
      public boolean attachSession(TerminalSession session) {
          if (session == mTermSession) return false;
          mTopRow = 0;
  
          mTermSession = session;
          mEmulator = null;
          mCombiningAccent = 0;
  
          updateSize();
  
          // Wait with enabling the scrollbar until we have a terminal to get scroll position from.
          setVerticalScrollBarEnabled(true);
  
          return true;
      }
  
      @Override
      public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
          // Ensure that inputType is only set if TerminalView is selected view with the keyboard and
          // an alternate view is not selected, like an EditText. This is necessary if an activity is
          // initially started with the alternate view or if activity is returned to from another app
          // and the alternate view was the one selected the last time.
          if (mClient.isTerminalViewSelected()) {
              if (mClient.shouldEnforceCharBasedInput()) {
                  // Some keyboards seems do not reset the internal state on TYPE_NULL.
                  // Affects mostly Samsung stock keyboards.
                  // https://github.com/termux/termux-app/issues/686
                  // However, this is not a valid value as per AOSP since `InputType.TYPE_CLASS_*` is
                  // not set and it logs a warning:
                  // W/InputAttributes: Unexpected input class: inputType=0x00080090 imeOptions=0x02000000
                  // https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:packages/inputmethods/LatinIME/java/src/com/android/inputmethod/latin/InputAttributes.java;l=79
                  outAttrs.inputType = InputType.TYPE_TEXT_VARIATION_VISIBLE_PASSWORD | InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS;
              } else {
                  // Using InputType.NULL is the most correct input type and avoids issues with other hacks.
                  //
                  // Previous keyboard issues:
                  // https://github.com/termux/termux-packages/issues/25
                  // https://github.com/termux/termux-app/issues/87.
                  // https://github.com/termux/termux-app/issues/126.
                  // https://github.com/termux/termux-app/issues/137 (japanese chars and TYPE_NULL).
                  outAttrs.inputType = InputType.TYPE_NULL;
              }
          } else {
              // Corresponds to android:inputType="text"
              outAttrs.inputType =  InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_NORMAL;
          }
  
          // Note that IME_ACTION_NONE cannot be used as that makes it impossible to input newlines using the on-screen
          // keyboard on Android TV (see https://github.com/termux/termux-app/issues/221).
          outAttrs.imeOptions = EditorInfo.IME_FLAG_NO_FULLSCREEN;
  
          return new BaseInputConnection(this, true) {
  
              @Override
              public boolean finishComposingText() {
                  if (TERMINAL_VIEW_KEY_LOGGING_ENABLED) mClient.logInfo(LOG_TAG, "IME: finishComposingText()");
                  super.finishComposingText();
  
                  sendTextToTerminal(getEditable());
                  getEditable().clear();
                  return true;
              }
  
              @Override
              public boolean commitText(CharSequence text, int newCursorPosition) {
                  if (TERMINAL_VIEW_KEY_LOGGING_ENABLED) {
                      mClient.logInfo(LOG_TAG, "IME: commitText(\"" + text + "\", " + newCursorPosition + ")");
                  }
                  super.commitText(text, newCursorPosition);
  
                  if (mEmulator == null) return true;
  
                  Editable content = getEditable();
                  sendTextToTerminal(content);
                  content.clear();
                  return true;
              }
  
              @Override
              public boolean deleteSurroundingText(int leftLength, int rightLength) {
                  if (TERMINAL_VIEW_KEY_LOGGING_ENABLED) {
                      mClient.logInfo(LOG_TAG, "IME: deleteSurroundingText(" + leftLength + ", " + rightLength + ")");
                  }
                  // The stock Samsung keyboard with 'Auto check spelling' enabled sends leftLength > 1.
                  KeyEvent deleteKey = new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_DEL);
                  for (int i = 0; i < leftLength; i++) sendKeyEvent(deleteKey);
                  return super.deleteSurroundingText(leftLength, rightLength);
              }
  
              void sendTextToTerminal(CharSequence text) {
                  stopTextSelectionMode();
                  final int textLengthInChars = text.length();
                  for (int i = 0; i < textLengthInChars; i++) {
                      char firstChar = text.charAt(i);
                      int codePoint;
                      if (Character.isHighSurrogate(firstChar)) {
                          if (++i < textLengthInChars) {
                              codePoint = Character.toCodePoint(firstChar, text.charAt(i));
                          } else {
                              // At end of string, with no low surrogate following the high:
                              codePoint = TerminalEmulator.UNICODE_REPLACEMENT_CHAR;
                          }
                      } else {
                          codePoint = firstChar;
                      }
  
                      // Check onKeyDown() for details.
                      if (mClient.readShiftKey())
                          codePoint = Character.toUpperCase(codePoint);
  
                      boolean ctrlHeld = false;
                      if (codePoint <= 31 && codePoint != 27) {
                          if (codePoint == '\n') {
                              // The AOSP keyboard and descendants seems to send \n as text when the enter key is pressed,
                              // instead of a key event like most other keyboard apps. A terminal expects \r for the enter
                              // key (although when icrnl is enabled this doesn't make a difference - run 'stty -icrnl' to
                              // check the behaviour).
                              codePoint = '\r';
                          }
  
                          // E.g. penti keyboard for ctrl input.
                          ctrlHeld = true;
                          switch (codePoint) {
                              case 31:
                                  codePoint = '_';
                                  break;
                              case 30:
                                  codePoint = '^';
                                  break;
                              case 29:
                                  codePoint = ']';
                                  break;
                              case 28:
                                  codePoint = '\\';
                                  break;
                              default:
                                  codePoint += 96;
                                  break;
                          }
                      }
  
                      inputCodePoint(KEY_EVENT_SOURCE_SOFT_KEYBOARD, codePoint, ctrlHeld, false);
                  }
              }
  
          };
      }
  
      @Override
      protected int computeVerticalScrollRange() {
          return mEmulator == null ? 1 : mEmulator.getScreen().getActiveRows();
      }
  
      @Override
      protected int computeVerticalScrollExtent() {
          return mEmulator == null ? 1 : mEmulator.mRows;
      }
  
      @Override
      protected int computeVerticalScrollOffset() {
          return mEmulator == null ? 1 : mEmulator.getScreen().getActiveRows() + mTopRow - mEmulator.mRows;
      }
  
      public void onScreenUpdated() {
          onScreenUpdated(false);
      }
  
      public void onScreenUpdated(boolean skipScrolling) {
          if (mEmulator == null) return;
  
          int rowsInHistory = mEmulator.getScreen().getActiveTranscriptRows();
          if (mTopRow < -rowsInHistory) mTopRow = -rowsInHistory;
  
          if (isSelectingText() || mEmulator.isAutoScrollDisabled()) {
  
              // Do not scroll when selecting text.
              int rowShift = mEmulator.getScrollCounter();
              if (-mTopRow + rowShift > rowsInHistory) {
                  // .. unless we're hitting the end of history transcript, in which
                  // case we abort text selection and scroll to end.
                  if (isSelectingText())
                      stopTextSelectionMode();
  
                  if (mEmulator.isAutoScrollDisabled()) {
                      mTopRow = -rowsInHistory;
                      skipScrolling = true;
                  }
              } else {
                  skipScrolling = true;
                  mTopRow -= rowShift;
                  decrementYTextSelectionCursors(rowShift);
              }
          }
  
          if (!skipScrolling && mTopRow != 0) {
              // Scroll down if not already there.
              if (mTopRow < -3) {
                  // Awaken scroll bars only if scrolling a noticeable amount
                  // - we do not want visible scroll bars during normal typing
                  // of one row at a time.
                  awakenScrollBars();
              }
              mTopRow = 0;
          }
  
          mEmulator.clearScrollCounter();
  
          invalidate();
          if (mAccessibilityEnabled) setContentDescription(getText());
      }
  
      /** This must be called by the hosting activity in {@link Activity#onContextMenuClosed(Menu)}
       * when context menu for the {@link TerminalView} is started by
       * {@link TextSelectionCursorController#ACTION_MORE} is closed. */
      public void onContextMenuClosed(Menu menu) {
          // Unset the stored text since it shouldn't be used anymore and should be cleared from memory
          unsetStoredSelectedText();
      }
  
      /**
       * Sets the text size, which in turn sets the number of rows and columns.
       *
       * @param textSize the new font size, in density-independent pixels.
       */
      public void setTextSize(int textSize) {
          mRenderer = new TerminalRenderer(textSize, mRenderer == null ? Typeface.MONOSPACE : mRenderer.mTypeface);
          updateSize();
      }
  
      public void setTypeface(Typeface newTypeface) {
          mRenderer = new TerminalRenderer(mRenderer.mTextSize, newTypeface);
          updateSize();
          invalidate();
      }
  
      @Override
      public boolean onCheckIsTextEditor() {
          return true;
      }
  
      @Override
      public boolean isOpaque() {
          return true;
      }
  
      /**
       * Get the zero indexed column and row of the terminal view for the
       * position of the event.
       *
       * @param event The event with the position to get the column and row for.
       * @param relativeToScroll If true the column number will take the scroll
       * position into account. E.g. if scrolled 3 lines up and the event
       * position is in the top left, column will be -3 if relativeToScroll is
       * true and 0 if relativeToScroll is false.
       * @return Array with the column and row.
       */
      public int[] getColumnAndRow(MotionEvent event, boolean relativeToScroll) {
          int column = (int) (event.getX() / mRenderer.mFontWidth);
          int row = (int) ((event.getY() - mRenderer.mFontLineSpacingAndAscent) / mRenderer.mFontLineSpacing);
          if (relativeToScroll) {
              row += mTopRow;
          }
          return new int[] { column, row };
      }
  
      /** Send a single mouse event code to the terminal. */
      void sendMouseEventCode(MotionEvent e, int button, boolean pressed) {
          int[] columnAndRow = getColumnAndRow(e, false);
          int x = columnAndRow[0] + 1;
          int y = columnAndRow[1] + 1;
          if (pressed && (button == TerminalEmulator.MOUSE_WHEELDOWN_BUTTON || button == TerminalEmulator.MOUSE_WHEELUP_BUTTON)) {
              if (mMouseStartDownTime == e.getDownTime()) {
                  x = mMouseScrollStartX;
                  y = mMouseScrollStartY;
              } else {
                  mMouseStartDownTime = e.getDownTime();
                  mMouseScrollStartX = x;
                  mMouseScrollStartY = y;
              }
          }
          mEmulator.sendMouseEvent(button, x, y, pressed);
      }
  
      /** Perform a scroll, either from dragging the screen or by scrolling a mouse wheel. */
      void doScroll(MotionEvent event, int rowsDown) {
          boolean up = rowsDown < 0;
          int amount = Math.abs(rowsDown);
          for (int i = 0; i < amount; i++) {
              if (mEmulator.isMouseTrackingActive()) {
                  sendMouseEventCode(event, up ? TerminalEmulator.MOUSE_WHEELUP_BUTTON : TerminalEmulator.MOUSE_WHEELDOWN_BUTTON, true);
              } else if (mEmulator.isAlternateBufferActive()) {
                  // Send up and down key events for scrolling, which is what some terminals do to make scroll work in
                  // e.g. less, which shifts to the alt screen without mouse handling.
                  handleKeyCode(up ? KeyEvent.KEYCODE_DPAD_UP : KeyEvent.KEYCODE_DPAD_DOWN, 0);
              } else {
                  mTopRow = Math.min(0, Math.max(-(mEmulator.getScreen().getActiveTranscriptRows()), mTopRow + (up ? -1 : 1)));
                  if (!awakenScrollBars()) invalidate();
              }
          }
      }
  
      /** Overriding {@link View#onGenericMotionEvent(MotionEvent)}. */
      @Override
      public boolean onGenericMotionEvent(MotionEvent event) {
          if (mEmulator != null && event.isFromSource(InputDevice.SOURCE_MOUSE) && event.getAction() == MotionEvent.ACTION_SCROLL) {
              // Handle mouse wheel scrolling.
              boolean up = event.getAxisValue(MotionEvent.AXIS_VSCROLL) > 0.0f;
              doScroll(event, up ? -3 : 3);
              return true;
          }
          return false;
      }
  
      @SuppressLint("ClickableViewAccessibility")
      @Override
      @TargetApi(23)
      public boolean onTouchEvent(MotionEvent event) {
          if (mEmulator == null) return true;
          final int action = event.getAction();
  
          if (isSelectingText()) {
              updateFloatingToolbarVisibility(event);
              mGestureRecognizer.onTouchEvent(event);
              return true;
          } else if (event.isFromSource(InputDevice.SOURCE_MOUSE)) {
              if (event.isButtonPressed(MotionEvent.BUTTON_SECONDARY)) {
                  if (action == MotionEvent.ACTION_DOWN) showContextMenu();
                  return true;
              } else if (event.isButtonPressed(MotionEvent.BUTTON_TERTIARY)) {
                  ClipboardManager clipboardManager = (ClipboardManager) getContext().getSystemService(Context.CLIPBOARD_SERVICE);
                  ClipData clipData = clipboardManager.getPrimaryClip();
                  if (clipData != null) {
                      ClipData.Item clipItem = clipData.getItemAt(0);
                      if (clipItem != null) {
                          CharSequence text = clipItem.coerceToText(getContext());
                          if (!TextUtils.isEmpty(text)) mEmulator.paste(text.toString());
                      }
                  }
              } else if (mEmulator.isMouseTrackingActive()) { // BUTTON_PRIMARY.
                  switch (event.getAction()) {
                      case MotionEvent.ACTION_DOWN:
                      case MotionEvent.ACTION_UP:
                          sendMouseEventCode(event, TerminalEmulator.MOUSE_LEFT_BUTTON, event.getAction() == MotionEvent.ACTION_DOWN);
                          break;
                      case MotionEvent.ACTION_MOVE:
                          sendMouseEventCode(event, TerminalEmulator.MOUSE_LEFT_BUTTON_MOVED, true);
                          break;
                  }
              }
          }
  
          mGestureRecognizer.onTouchEvent(event);
          return true;
      }
  
      @Override
      public boolean onKeyPreIme(int keyCode, KeyEvent event) {
          if (TERMINAL_VIEW_KEY_LOGGING_ENABLED)
              mClient.logInfo(LOG_TAG, "onKeyPreIme(keyCode=" + keyCode + ", event=" + event + ")");
          if (keyCode == KeyEvent.KEYCODE_BACK) {
              if (isSelectingText()) {
                  stopTextSelectionMode();
                  return true;
              } else if (mClient.shouldBackButtonBeMappedToEscape()) {
                  // Intercept back button to treat it as escape:
                  switch (event.getAction()) {
                      case KeyEvent.ACTION_DOWN:
                          return onKeyDown(keyCode, event);
                      case KeyEvent.ACTION_UP:
                          return onKeyUp(keyCode, event);
                  }
              }
          } else if (mClient.shouldUseCtrlSpaceWorkaround() &&
                     keyCode == KeyEvent.KEYCODE_SPACE && event.isCtrlPressed()) {
              /* ctrl+space does not work on some ROMs without this workaround.
                 However, this breaks it on devices where it works out of the box. */
              return onKeyDown(keyCode, event);
          }
          return super.onKeyPreIme(keyCode, event);
      }
  
      /**
       * Key presses in software keyboards will generally NOT trigger this listener, although some
       * may elect to do so in some situations. Do not rely on this to catch software key presses.
       * Gboard calls this when shouldEnforceCharBasedInput() is disabled (InputType.TYPE_NULL) instead
       * of calling commitText(), with deviceId=-1. However, Hacker's Keyboard, OpenBoard, LG Keyboard
       * call commitText().
       *
       * This function may also be called directly without android calling it, like by
       * `TerminalExtraKeys` which generates a KeyEvent manually which uses {@link KeyCharacterMap#VIRTUAL_KEYBOARD}
       * as the device (deviceId=-1), as does Gboard. That would normally use mappings defined in
       * `/system/usr/keychars/Virtual.kcm`. You can run `dumpsys input` to find the `KeyCharacterMapFile`
       * used by virtual keyboard or hardware keyboard. Note that virtual keyboard device is not the
       * same as software keyboard, like Gboard, etc. Its a fake device used for generating events and
       * for testing.
       *
       * We handle shift key in `commitText()` to convert codepoint to uppercase case there with a
       * call to {@link Character#toUpperCase(int)}, but here we instead rely on getUnicodeChar() for
       * conversion of keyCode, for both hardware keyboard shift key (via effectiveMetaState) and
       * `mClient.readShiftKey()`, based on value in kcm files.
       * This may result in different behaviour depending on keyboard and android kcm files set for the
       * InputDevice for the event passed to this function. This will likely be an issue for non-english
       * languages since `Virtual.kcm` in english only by default or at least in AOSP. For both hardware
       * shift key (via effectiveMetaState) and `mClient.readShiftKey()`, `getUnicodeChar()` is used
       * for shift specific behaviour which usually is to uppercase.
       *
       * For fn key on hardware keyboard, android checks kcm files for hardware keyboards, which is
       * `Generic.kcm` by default, unless a vendor specific one is defined. The event passed will have
       * {@link KeyEvent#META_FUNCTION_ON} set. If the kcm file only defines a single character or unicode
       * code point `\\uxxxx`, then only one event is passed with that value. However, if kcm defines
       * a `fallback` key for fn or others, like `key DPAD_UP { ... fn: fallback PAGE_UP }`, then
       * android will first pass an event with original key `DPAD_UP` and {@link KeyEvent#META_FUNCTION_ON}
       * set. But this function will not consume it and android will pass another event with `PAGE_UP`
       * and {@link KeyEvent#META_FUNCTION_ON} not set, which will be consumed.
       *
       * Now there are some other issues as well, firstly ctrl and alt flags are not passed to
       * `getUnicodeChar()`, so modified key values in kcm are not used. Secondly, if the kcm file
       * for other modifiers like shift or fn define a non-alphabet, like { fn: '\u0015' } to act as
       * DPAD_LEFT, the `getUnicodeChar()` will correctly return `21` as the code point but action will
       * not happen because the `handleKeyCode()` function that transforms DPAD_LEFT to `\033[D`
       * escape sequence for the terminal to perform the left action would not be called since its
       * called before `getUnicodeChar()` and terminal will instead get `21 0x15 Negative Acknowledgement`.
       * The solution to such issues is calling `getUnicodeChar()` before the call to `handleKeyCode()`
       * if user has defined a custom kcm file, like done in POC mentioned in #2237. Note that
       * Hacker's Keyboard calls `commitText()` so don't test fn/shift with it for this function.
       * https://github.com/termux/termux-app/pull/2237
       * https://github.com/agnostic-apollo/termux-app/blob/terminal-code-point-custom-mapping/terminal-view/src/main/java/com/termux/view/TerminalView.java
       *
       * Key Character Map (kcm) and Key Layout (kl) files info:
       * https://source.android.com/devices/input/key-character-map-files
       * https://source.android.com/devices/input/key-layout-files
       * https://source.android.com/devices/input/keyboard-devices
       * AOSP kcm and kl files:
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/base/data/keyboards
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/base/packages/InputDevices/res/raw
       *
       * KeyCodes:
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/base/core/java/android/view/KeyEvent.java
       * https://cs.android.com/android/platform/superproject/+/master:frameworks/native/include/android/keycodes.h
       *
       * `dumpsys input`:
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/native/services/inputflinger/reader/EventHub.cpp;l=1917
       *
       * Loading of keymap:
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/native/services/inputflinger/reader/EventHub.cpp;l=1644
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/native/libs/input/Keyboard.cpp;l=41
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/native/libs/input/InputDevice.cpp
       * OVERLAY keymaps for hardware keyboards may be combined as well:
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/native/libs/input/KeyCharacterMap.cpp;l=165
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/native/libs/input/KeyCharacterMap.cpp;l=831
       *
       * Parse kcm file:
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/native/libs/input/KeyCharacterMap.cpp;l=727
       * Parse key value:
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/native/libs/input/KeyCharacterMap.cpp;l=981
       *
       * `KeyEvent.getUnicodeChar()`
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/base/core/java/android/view/KeyEvent.java;l=2716
       * https://cs.android.com/android/platform/superproject/+/master:frameworks/base/core/java/android/view/KeyCharacterMap.java;l=368
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/base/core/jni/android_view_KeyCharacterMap.cpp;l=117
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/native/libs/input/KeyCharacterMap.cpp;l=231
       *
       * Keyboard layouts advertised by applications, like for hardware keyboards via #ACTION_QUERY_KEYBOARD_LAYOUTS
       * Config is stored in `/data/system/input-manager-state.xml`
       * https://github.com/ris58h/custom-keyboard-layout
       * Loading from apps:
       * https://cs.android.com/android/platform/superproject/+/master:frameworks/base/services/core/java/com/android/server/input/InputManagerService.java;l=1221
       * Set:
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/base/core/java/android/hardware/input/InputManager.java;l=89
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/base/core/java/android/hardware/input/InputManager.java;l=543
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:packages/apps/Settings/src/com/android/settings/inputmethod/KeyboardLayoutDialogFragment.java;l=167
       * https://cs.android.com/android/platform/superproject/+/master:frameworks/base/services/core/java/com/android/server/input/InputManagerService.java;l=1385
       * https://cs.android.com/android/platform/superproject/+/master:frameworks/base/services/core/java/com/android/server/input/PersistentDataStore.java
       * Get overlay keyboard layout
       * https://cs.android.com/android/platform/superproject/+/master:frameworks/base/services/core/java/com/android/server/input/InputManagerService.java;l=2158
       * https://cs.android.com/android/platform/superproject/+/android-11.0.0_r40:frameworks/base/services/core/jni/com_android_server_input_InputManagerService.cpp;l=616
       */
      @Override
      public boolean onKeyDown(int keyCode, KeyEvent event) {
          if (TERMINAL_VIEW_KEY_LOGGING_ENABLED)
              mClient.logInfo(LOG_TAG, "onKeyDown(keyCode=" + keyCode + ", isSystem()=" + event.isSystem() + ", event=" + event + ")");
          if (mEmulator == null) return true;
          if (isSelectingText()) {
              stopTextSelectionMode();
          }
  
          if (mClient.onKeyDown(keyCode, event, mTermSession)) {
              invalidate();
              return true;
          } else if (event.isSystem() && (!mClient.shouldBackButtonBeMappedToEscape() || keyCode != KeyEvent.KEYCODE_BACK)) {
              return super.onKeyDown(keyCode, event);
          } else if (event.getAction() == KeyEvent.ACTION_MULTIPLE && keyCode == KeyEvent.KEYCODE_UNKNOWN) {
              mTermSession.write(event.getCharacters());
              return true;
          }
  
          final int metaState = event.getMetaState();
          final boolean controlDown = event.isCtrlPressed() || mClient.readControlKey();
          final boolean leftAltDown = (metaState & KeyEvent.META_ALT_LEFT_ON) != 0 || mClient.readAltKey();
          final boolean shiftDown = event.isShiftPressed() || mClient.readShiftKey();
          final boolean rightAltDownFromEvent = (metaState & KeyEvent.META_ALT_RIGHT_ON) != 0;
  
          int keyMod = 0;
          if (controlDown) keyMod |= KeyHandler.KEYMOD_CTRL;
          if (event.isAltPressed() || leftAltDown) keyMod |= KeyHandler.KEYMOD_ALT;
          if (shiftDown) keyMod |= KeyHandler.KEYMOD_SHIFT;
          if (event.isNumLockOn()) keyMod |= KeyHandler.KEYMOD_NUM_LOCK;
          // https://github.com/termux/termux-app/issues/731
          if (!event.isFunctionPressed() && handleKeyCode(keyCode, keyMod)) {
              if (TERMINAL_VIEW_KEY_LOGGING_ENABLED) mClient.logInfo(LOG_TAG, "handleKeyCode() took key event");
              return true;
          }
  
          // Clear Ctrl since we handle that ourselves:
          int bitsToClear = KeyEvent.META_CTRL_MASK;
          if (rightAltDownFromEvent) {
              // Let right Alt/Alt Gr be used to compose characters.
          } else {
              // Use left alt to send to terminal (e.g. Left Alt+B to jump back a word), so remove:
              bitsToClear |= KeyEvent.META_ALT_ON | KeyEvent.META_ALT_LEFT_ON;
          }
          int effectiveMetaState = event.getMetaState() & ~bitsToClear;
  
          if (shiftDown) effectiveMetaState |= KeyEvent.META_SHIFT_ON | KeyEvent.META_SHIFT_LEFT_ON;
          if (mClient.readFnKey()) effectiveMetaState |= KeyEvent.META_FUNCTION_ON;
  
          int result = event.getUnicodeChar(effectiveMetaState);
          if (TERMINAL_VIEW_KEY_LOGGING_ENABLED)
              mClient.logInfo(LOG_TAG, "KeyEvent#getUnicodeChar(" + effectiveMetaState + ") returned: " + result);
          if (result == 0) {
              return false;
          }
  
          int oldCombiningAccent = mCombiningAccent;
          if ((result & KeyCharacterMap.COMBINING_ACCENT) != 0) {
              // If entered combining accent previously, write it out:
              if (mCombiningAccent != 0)
                  inputCodePoint(event.getDeviceId(), mCombiningAccent, controlDown, leftAltDown);
              mCombiningAccent = result & KeyCharacterMap.COMBINING_ACCENT_MASK;
          } else {
              if (mCombiningAccent != 0) {
                  int combinedChar = KeyCharacterMap.getDeadChar(mCombiningAccent, result);
                  if (combinedChar > 0) result = combinedChar;
                  mCombiningAccent = 0;
              }
              inputCodePoint(event.getDeviceId(), result, controlDown, leftAltDown);
          }
  
          if (mCombiningAccent != oldCombiningAccent) invalidate();
  
          return true;
      }
  
      public void inputCodePoint(int eventSource, int codePoint, boolean controlDownFromEvent, boolean leftAltDownFromEvent) {
          if (TERMINAL_VIEW_KEY_LOGGING_ENABLED) {
              mClient.logInfo(LOG_TAG, "inputCodePoint(eventSource=" + eventSource + ", codePoint=" + codePoint + ", controlDownFromEvent=" + controlDownFromEvent + ", leftAltDownFromEvent="
                  + leftAltDownFromEvent + ")");
          }
  
          if (mTermSession == null) return;
  
          // Ensure cursor is shown when a key is pressed down like long hold on (arrow) keys
          if (mEmulator != null)
              mEmulator.setCursorBlinkState(true);
  
          final boolean controlDown = controlDownFromEvent || mClient.readControlKey();
          final boolean altDown = leftAltDownFromEvent || mClient.readAltKey();
  
          if (mClient.onCodePoint(codePoint, controlDown, mTermSession)) return;
  
          if (controlDown) {
              if (codePoint >= 'a' && codePoint <= 'z') {
                  codePoint = codePoint - 'a' + 1;
              } else if (codePoint >= 'A' && codePoint <= 'Z') {
                  codePoint = codePoint - 'A' + 1;
              } else if (codePoint == ' ' || codePoint == '2') {
                  codePoint = 0;
              } else if (codePoint == '[' || codePoint == '3') {
                  codePoint = 27; // ^[ (Esc)
              } else if (codePoint == '\\' || codePoint == '4') {
                  codePoint = 28;
              } else if (codePoint == ']' || codePoint == '5') {
                  codePoint = 29;
              } else if (codePoint == '^' || codePoint == '6') {
                  codePoint = 30; // control-^
              } else if (codePoint == '_' || codePoint == '7' || codePoint == '/') {
                  // "Ctrl-/ sends 0x1f which is equivalent of Ctrl-_ since the days of VT102"
                  // - http://apple.stackexchange.com/questions/24261/how-do-i-send-c-that-is-control-slash-to-the-terminal
                  codePoint = 31;
              } else if (codePoint == '8') {
                  codePoint = 127; // DEL
              }
          }
  
          if (codePoint > -1) {
              // If not virtual or soft keyboard.
              if (eventSource > KEY_EVENT_SOURCE_SOFT_KEYBOARD) {
                  // Work around bluetooth keyboards sending funny unicode characters instead
                  // of the more normal ones from ASCII that terminal programs expect - the
                  // desire to input the original characters should be low.
                  switch (codePoint) {
                      case 0x02DC: // SMALL TILDE.
                          codePoint = 0x007E; // TILDE (~).
                          break;
                      case 0x02CB: // MODIFIER LETTER GRAVE ACCENT.
                          codePoint = 0x0060; // GRAVE ACCENT (`).
                          break;
                      case 0x02C6: // MODIFIER LETTER CIRCUMFLEX ACCENT.
                          codePoint = 0x005E; // CIRCUMFLEX ACCENT (^).
                          break;
                  }
              }
  
              // If left alt, send escape before the code point to make e.g. Alt+B and Alt+F work in readline:
              mTermSession.writeCodePoint(altDown, codePoint);
          }
      }
  
      /** Input the specified keyCode if applicable and return if the input was consumed. */
      public boolean handleKeyCode(int keyCode, int keyMod) {
          // Ensure cursor is shown when a key is pressed down like long hold on (arrow) keys
          if (mEmulator != null)
              mEmulator.setCursorBlinkState(true);
  
          if (handleKeyCodeAction(keyCode, keyMod))
              return true;
  
          TerminalEmulator term = mTermSession.getEmulator();
          String code = KeyHandler.getCode(keyCode, keyMod, term.isCursorKeysApplicationMode(), term.isKeypadApplicationMode());
          if (code == null) return false;
          mTermSession.write(code);
          return true;
      }
  
      public boolean handleKeyCodeAction(int keyCode, int keyMod) {
          boolean shiftDown = (keyMod & KeyHandler.KEYMOD_SHIFT) != 0;
  
          switch (keyCode) {
              case KeyEvent.KEYCODE_PAGE_UP:
              case KeyEvent.KEYCODE_PAGE_DOWN:
                  // shift+page_up and shift+page_down should scroll scrollback history instead of
                  // scrolling command history or changing pages
                  if (shiftDown) {
                      long time = SystemClock.uptimeMillis();
                      MotionEvent motionEvent = MotionEvent.obtain(time, time, MotionEvent.ACTION_DOWN, 0, 0, 0);
                      doScroll(motionEvent, keyCode == KeyEvent.KEYCODE_PAGE_UP ? -1 : 1);
                      motionEvent.recycle();
                      return true;
                  }
          }
  
         return false;
      }
  
      /**
       * Called when a key is released in the view.
       *
       * @param keyCode The keycode of the key which was released.
       * @param event   A {@link KeyEvent} describing the event.
       * @return Whether the event was handled.
       */
      @Override
      public boolean onKeyUp(int keyCode, KeyEvent event) {
          if (TERMINAL_VIEW_KEY_LOGGING_ENABLED)
              mClient.logInfo(LOG_TAG, "onKeyUp(keyCode=" + keyCode + ", event=" + event + ")");
  
          // Do not return for KEYCODE_BACK and send it to the client since user may be trying
          // to exit the activity.
          if (mEmulator == null && keyCode != KeyEvent.KEYCODE_BACK) return true;
  
          if (mClient.onKeyUp(keyCode, event)) {
              invalidate();
              return true;
          } else if (event.isSystem()) {
              // Let system key events through.
              return super.onKeyUp(keyCode, event);
          }
  
          return true;
      }
  
      /**
       * This is called during layout when the size of this view has changed. If you were just added to the view
       * hierarchy, you're called with the old values of 0.
       */
      @Override
      protected void onSizeChanged(int w, int h, int oldw, int oldh) {
          updateSize();
      }
  
      /** Check if the terminal size in rows and columns should be updated. */
      public void updateSize() {
          int viewWidth = getWidth();
          int viewHeight = getHeight();
          if (viewWidth == 0 || viewHeight == 0 || mTermSession == null) return;
  
          // Set to 80 and 24 if you want to enable vttest.
          int newColumns = Math.max(4, (int) (viewWidth / mRenderer.mFontWidth));
          int newRows = Math.max(4, (viewHeight - mRenderer.mFontLineSpacingAndAscent) / mRenderer.mFontLineSpacing);
  
          if (mEmulator == null || (newColumns != mEmulator.mColumns || newRows != mEmulator.mRows)) {
              mTermSession.updateSize(newColumns, newRows);
              mEmulator = mTermSession.getEmulator();
              mClient.onEmulatorSet();
  
              // Update mTerminalCursorBlinkerRunnable inner class mEmulator on session change
              if (mTerminalCursorBlinkerRunnable != null)
                  mTerminalCursorBlinkerRunnable.setEmulator(mEmulator);
  
              mTopRow = 0;
              scrollTo(0, 0);
              invalidate();
          }
      }
  
      @Override
      protected void onDraw(Canvas canvas) {
          if (mEmulator == null) {
              canvas.drawColor(0XFF000000);
          } else {
              // render the terminal view and highlight any selected text
              int[] sel = mDefaultSelectors;
              if (mTextSelectionCursorController != null) {
                  mTextSelectionCursorController.getSelectors(sel);
              }
  
              mRenderer.render(mEmulator, canvas, mTopRow, sel[0], sel[1], sel[2], sel[3]);
  
              // render the text selection handles
              renderTextSelection();
          }
      }
  
      public TerminalSession getCurrentSession() {
          return mTermSession;
      }
  
      private CharSequence getText() {
          return mEmulator.getScreen().getSelectedText(0, mTopRow, mEmulator.mColumns, mTopRow + mEmulator.mRows);
      }
  
      public int getCursorX(float x) {
          return (int) (x / mRenderer.mFontWidth);
      }
  
      public int getCursorY(float y) {
          return (int) (((y - 40) / mRenderer.mFontLineSpacing) + mTopRow);
      }
  
      public int getPointX(int cx) {
          if (cx > mEmulator.mColumns) {
              cx = mEmulator.mColumns;
          }
          return Math.round(cx * mRenderer.mFontWidth);
      }
  
      public int getPointY(int cy) {
          return Math.round((cy - mTopRow) * mRenderer.mFontLineSpacing);
      }
  
      public int getTopRow() {
          return mTopRow;
      }
  
      public void setTopRow(int mTopRow) {
          this.mTopRow = mTopRow;
      }
  
  
  
      /**
       * Define functions required for AutoFill API
       */
      @RequiresApi(api = Build.VERSION_CODES.O)
      @Override
      public void autofill(AutofillValue value) {
          if (value.isText()) {
              mTermSession.write(value.getTextValue().toString());
          }
      }
  
      @RequiresApi(api = Build.VERSION_CODES.O)
      @Override
      public int getAutofillType() {
          return AUTOFILL_TYPE_TEXT;
      }
  
      @RequiresApi(api = Build.VERSION_CODES.O)
      @Override
      public AutofillValue getAutofillValue() {
          return AutofillValue.forText("");
      }
  
  
  
      /**
       * Set terminal cursor blinker rate. It must be between {@link #TERMINAL_CURSOR_BLINK_RATE_MIN}
       * and {@link #TERMINAL_CURSOR_BLINK_RATE_MAX}, otherwise it will be disabled.
       *
       * The {@link #setTerminalCursorBlinkerState(boolean, boolean)} must be called after this
       * for changes to take effect if not disabling.
       *
       * @param blinkRate The value to set.
       * @return Returns {@code true} if setting blinker rate was successfully set, otherwise [@code false}.
       */
      public synchronized boolean setTerminalCursorBlinkerRate(int blinkRate) {
          boolean result;
  
          // If cursor blinking rate is not valid
          if (blinkRate != 0 && (blinkRate < TERMINAL_CURSOR_BLINK_RATE_MIN || blinkRate > TERMINAL_CURSOR_BLINK_RATE_MAX)) {
              mClient.logError(LOG_TAG, "The cursor blink rate must be in between " + TERMINAL_CURSOR_BLINK_RATE_MIN + "-" + TERMINAL_CURSOR_BLINK_RATE_MAX + ": " + blinkRate);
              mTerminalCursorBlinkerRate = 0;
              result = false;
          } else {
              mClient.logVerbose(LOG_TAG, "Setting cursor blinker rate to " + blinkRate);
              mTerminalCursorBlinkerRate = blinkRate;
              result = true;
          }
  
          if (mTerminalCursorBlinkerRate == 0) {
              mClient.logVerbose(LOG_TAG, "Cursor blinker disabled");
              stopTerminalCursorBlinker();
          }
  
          return result;
      }
  
      /**
       * Sets whether cursor blinker should be started or stopped. Cursor blinker will only be
       * started if {@link #mTerminalCursorBlinkerRate} does not equal 0 and is between
       * {@link #TERMINAL_CURSOR_BLINK_RATE_MIN} and {@link #TERMINAL_CURSOR_BLINK_RATE_MAX}.
       *
       * This should be called when the view holding this activity is resumed or stopped so that
       * cursor blinker does not run when activity is not visible. If you call this on onResume()
       * to start cursor blinking, then ensure that {@link #mEmulator} is set, otherwise wait for the
       * {@link TerminalViewClient#onEmulatorSet()} event after calling {@link #attachSession(TerminalSession)}
       * for the first session added in the activity since blinking will not start if {@link #mEmulator}
       * is not set, like if activity is started again after exiting it with double back press. Do not
       * call this directly after {@link #attachSession(TerminalSession)} since {@link #updateSize()}
       * may return without setting {@link #mEmulator} since width/height may be 0. Its called again in
       * {@link #onSizeChanged(int, int, int, int)}. Calling on onResume() if emulator is already set
       * is necessary, since onEmulatorSet() may not be called after activity is started after device
       * display timeout with double tap and not power button.
       *
       * It should also be called on the
       * {@link com.termux.terminal.TerminalSessionClient#onTerminalCursorStateChange(boolean)}
       * callback when cursor is enabled or disabled so that blinker is disabled if cursor is not
       * to be shown. It should also be checked if activity is visible if blinker is to be started
       * before calling this.
       *
       * It should also be called after terminal is reset with {@link TerminalSession#reset()} in case
       * cursor blinker was disabled before reset due to call to
       * {@link com.termux.terminal.TerminalSessionClient#onTerminalCursorStateChange(boolean)}.
       *
       * How cursor blinker starting works is by registering a {@link Runnable} with the looper of
       * the main thread of the app which when run, toggles the cursor blinking state and re-registers
       * itself to be called with the delay set by {@link #mTerminalCursorBlinkerRate}. When cursor
       * blinking needs to be disabled, we just cancel any callbacks registered. We don't run our own
       * "thread" and let the thread for the main looper do the work for us, whose usage is also
       * required to update the UI, since it also handles other calls to update the UI as well based
       * on a queue.
       *
       * Note that when moving cursor in text editors like nano, the cursor state is quickly
       * toggled `-> off -> on`, which would call this very quickly sequentially. So that if cursor
       * is moved 2 or more times quickly, like long hold on arrow keys, it would trigger
       * `-> off -> on -> off -> on -> ...`, and the "on" callback at index 2 is automatically
       * cancelled by next "off" callback at index 3 before getting a chance to be run. For this case
       * we log only if {@link #TERMINAL_VIEW_KEY_LOGGING_ENABLED} is enabled, otherwise would clutter
       * the log. We don't start the blinking with a delay to immediately show cursor in case it was
       * previously not visible.
       *
       * @param start If cursor blinker should be started or stopped.
       * @param startOnlyIfCursorEnabled If set to {@code true}, then it will also be checked if the
       *                                 cursor is even enabled by {@link TerminalEmulator} before
       *                                 starting the cursor blinker.
       */
      public synchronized void setTerminalCursorBlinkerState(boolean start, boolean startOnlyIfCursorEnabled) {
          // Stop any existing cursor blinker callbacks
          stopTerminalCursorBlinker();
  
          if (mEmulator == null) return;
  
          mEmulator.setCursorBlinkingEnabled(false);
  
          if (start) {
              // If cursor blinker is not enabled or is not valid
              if (mTerminalCursorBlinkerRate < TERMINAL_CURSOR_BLINK_RATE_MIN || mTerminalCursorBlinkerRate > TERMINAL_CURSOR_BLINK_RATE_MAX)
                  return;
              // If cursor blinder is to be started only if cursor is enabled
              else if (startOnlyIfCursorEnabled && ! mEmulator.isCursorEnabled()) {
                  if (TERMINAL_VIEW_KEY_LOGGING_ENABLED)
                      mClient.logVerbose(LOG_TAG, "Ignoring call to start cursor blinker since cursor is not enabled");
                  return;
              }
  
              // Start cursor blinker runnable
              if (TERMINAL_VIEW_KEY_LOGGING_ENABLED)
                  mClient.logVerbose(LOG_TAG, "Starting cursor blinker with the blink rate " + mTerminalCursorBlinkerRate);
              if (mTerminalCursorBlinkerHandler == null)
                  mTerminalCursorBlinkerHandler = new Handler(Looper.getMainLooper());
              mTerminalCursorBlinkerRunnable = new TerminalCursorBlinkerRunnable(mEmulator, mTerminalCursorBlinkerRate);
              mEmulator.setCursorBlinkingEnabled(true);
              mTerminalCursorBlinkerRunnable.run();
          }
      }
  
      /**
       * Cancel the terminal cursor blinker callbacks
       */
      private void stopTerminalCursorBlinker() {
          if (mTerminalCursorBlinkerHandler != null && mTerminalCursorBlinkerRunnable != null) {
              if (TERMINAL_VIEW_KEY_LOGGING_ENABLED)
                  mClient.logVerbose(LOG_TAG, "Stopping cursor blinker");
              mTerminalCursorBlinkerHandler.removeCallbacks(mTerminalCursorBlinkerRunnable);
          }
      }
  
      private class TerminalCursorBlinkerRunnable implements Runnable {
  
          private TerminalEmulator mEmulator;
          private final int mBlinkRate;
  
          // Initialize with false so that initial blink state is visible after toggling
          boolean mCursorVisible = false;
  
          public TerminalCursorBlinkerRunnable(TerminalEmulator emulator, int blinkRate) {
              mEmulator = emulator;
              mBlinkRate = blinkRate;
          }
  
          public void setEmulator(TerminalEmulator emulator) {
              mEmulator = emulator;
          }
  
          public void run() {
              try {
                  if (mEmulator != null) {
                      // Toggle the blink state and then invalidate() the view so
                      // that onDraw() is called, which then calls TerminalRenderer.render()
                      // which checks with TerminalEmulator.shouldCursorBeVisible() to decide whether
                      // to draw the cursor or not
                      mCursorVisible = !mCursorVisible;
                      //mClient.logVerbose(LOG_TAG, "Toggling cursor blink state to " + mCursorVisible);
                      mEmulator.setCursorBlinkState(mCursorVisible);
                      invalidate();
                  }
              } finally {
                  // Recall the Runnable after mBlinkRate milliseconds to toggle the blink state
                  mTerminalCursorBlinkerHandler.postDelayed(this, mBlinkRate);
              }
          }
      }
  
  
  
      /**
       * Define functions required for text selection and its handles.
       */
      TextSelectionCursorController getTextSelectionCursorController() {
          if (mTextSelectionCursorController == null) {
              mTextSelectionCursorController = new TextSelectionCursorController(this);
  
              final ViewTreeObserver observer = getViewTreeObserver();
              if (observer != null) {
                  observer.addOnTouchModeChangeListener(mTextSelectionCursorController);
              }
          }
  
          return mTextSelectionCursorController;
      }
  
      private void showTextSelectionCursors(MotionEvent event) {
          getTextSelectionCursorController().show(event);
      }
  
      private boolean hideTextSelectionCursors() {
          return getTextSelectionCursorController().hide();
      }
  
      private void renderTextSelection() {
          if (mTextSelectionCursorController != null)
              mTextSelectionCursorController.render();
      }
  
      public boolean isSelectingText() {
          if (mTextSelectionCursorController != null) {
              return mTextSelectionCursorController.isActive();
          } else {
              return false;
          }
      }
  
      /** Get the currently selected text if selecting. */
      public String getSelectedText() {
          if (isSelectingText() && mTextSelectionCursorController != null)
              return mTextSelectionCursorController.getSelectedText();
          else
              return null;
      }
  
      /** Get the selected text stored before "MORE" button was pressed on the context menu. */
      @Nullable
      public String getStoredSelectedText() {
          return mTextSelectionCursorController != null ? mTextSelectionCursorController.getStoredSelectedText() : null;
      }
  
      /** Unset the selected text stored before "MORE" button was pressed on the context menu. */
      public void unsetStoredSelectedText() {
          if (mTextSelectionCursorController != null) mTextSelectionCursorController.unsetStoredSelectedText();
      }
  
      private ActionMode getTextSelectionActionMode() {
          if (mTextSelectionCursorController != null) {
              return mTextSelectionCursorController.getActionMode();
          } else {
              return null;
          }
      }
  
      public void startTextSelectionMode(MotionEvent event) {
          if (!requestFocus()) {
              return;
          }
  
          showTextSelectionCursors(event);
          mClient.copyModeChanged(isSelectingText());
  
          invalidate();
      }
  
      public void stopTextSelectionMode() {
          if (hideTextSelectionCursors()) {
              mClient.copyModeChanged(isSelectingText());
              invalidate();
          }
      }
  
      private void decrementYTextSelectionCursors(int decrement) {
          if (mTextSelectionCursorController != null) {
              mTextSelectionCursorController.decrementYTextSelectionCursors(decrement);
          }
      }
  
      @Override
      protected void onAttachedToWindow() {
          super.onAttachedToWindow();
  
          if (mTextSelectionCursorController != null) {
              getViewTreeObserver().addOnTouchModeChangeListener(mTextSelectionCursorController);
          }
      }
  
      @Override
      protected void onDetachedFromWindow() {
          super.onDetachedFromWindow();
  
          if (mTextSelectionCursorController != null) {
              // Might solve the following exception
              // android.view.WindowLeaked: Activity com.termux.app.TermuxActivity has leaked window android.widget.PopupWindow
              stopTextSelectionMode();
  
              getViewTreeObserver().removeOnTouchModeChangeListener(mTextSelectionCursorController);
              mTextSelectionCursorController.onDetached();
          }
      }
  
  
  
      /**
       * Define functions required for long hold toolbar.
       */
      private final Runnable mShowFloatingToolbar = new Runnable() {
          @RequiresApi(api = Build.VERSION_CODES.M)
          @Override
          public void run() {
              if (getTextSelectionActionMode() != null) {
                  getTextSelectionActionMode().hide(0);  // hide off.
              }
          }
      };
  
      @RequiresApi(api = Build.VERSION_CODES.M)
      private void showFloatingToolbar() {
          if (getTextSelectionActionMode() != null) {
              int delay = ViewConfiguration.getDoubleTapTimeout();
              postDelayed(mShowFloatingToolbar, delay);
          }
      }
  
      @RequiresApi(api = Build.VERSION_CODES.M)
      void hideFloatingToolbar() {
          if (getTextSelectionActionMode() != null) {
              removeCallbacks(mShowFloatingToolbar);
              getTextSelectionActionMode().hide(-1);
          }
      }
  
      public void updateFloatingToolbarVisibility(MotionEvent event) {
          if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && getTextSelectionActionMode() != null) {
              switch (event.getActionMasked()) {
                  case MotionEvent.ACTION_MOVE:
                      hideFloatingToolbar();
                      break;
                  case MotionEvent.ACTION_UP:  // fall through
                  case MotionEvent.ACTION_CANCEL:
                      showFloatingToolbar();
              }
          }
      }
  
  }
  