content: /*
   * Copyright (C) 2006 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package android.text.method;
  
  import android.text.Layout;
  import android.text.Spannable;
  import android.view.MotionEvent;
  import android.view.View;
  import android.widget.TextView;
  
  /**
   * A movement method that interprets movement keys by scrolling the text buffer.
   */
  public class ScrollingMovementMethod extends BaseMovementMethod implements MovementMethod {
      @Override
      protected boolean left(TextView widget, Spannable buffer) {
          return scrollLeft(widget, buffer, 1);
      }
  
      @Override
      protected boolean right(TextView widget, Spannable buffer) {
          return scrollRight(widget, buffer, 1);
      }
  
      @Override
      protected boolean up(TextView widget, Spannable buffer) {
          return scrollUp(widget, buffer, 1);
      }
  
      @Override
      protected boolean down(TextView widget, Spannable buffer) {
          return scrollDown(widget, buffer, 1);
      }
  
      @Override
      protected boolean pageUp(TextView widget, Spannable buffer) {
          return scrollPageUp(widget, buffer);
      }
  
      @Override
      protected boolean pageDown(TextView widget, Spannable buffer) {
          return scrollPageDown(widget, buffer);
      }
  
      @Override
      protected boolean top(TextView widget, Spannable buffer) {
          return scrollTop(widget, buffer);
      }
  
      @Override
      protected boolean bottom(TextView widget, Spannable buffer) {
          return scrollBottom(widget, buffer);
      }
  
      @Override
      protected boolean lineStart(TextView widget, Spannable buffer) {
          return scrollLineStart(widget, buffer);
      }
  
      @Override
      protected boolean lineEnd(TextView widget, Spannable buffer) {
          return scrollLineEnd(widget, buffer);
      }
  
      @Override
      protected boolean home(TextView widget, Spannable buffer) {
          return top(widget, buffer);
      }
  
      @Override
      protected boolean end(TextView widget, Spannable buffer) {
          return bottom(widget, buffer);
      }
  
      @Override
      public boolean onTouchEvent(TextView widget, Spannable buffer, MotionEvent event) {
          return Touch.onTouchEvent(widget, buffer, event);
      }
  
      @Override
      public void onTakeFocus(TextView widget, Spannable text, int dir) {
          Layout layout = widget.getLayout();
  
          if (layout != null && (dir & View.FOCUS_FORWARD) != 0) {
              widget.scrollTo(widget.getScrollX(),
                              layout.getLineTop(0));
          }
          if (layout != null && (dir & View.FOCUS_BACKWARD) != 0) {
              int padding = widget.getTotalPaddingTop() +
                            widget.getTotalPaddingBottom();
              int line = layout.getLineCount() - 1;
  
              widget.scrollTo(widget.getScrollX(),
                              layout.getLineTop(line+1) -
                              (widget.getHeight() - padding));
          }
      }
  
      public static MovementMethod getInstance() {
          if (sInstance == null)
              sInstance = new ScrollingMovementMethod();
  
          return sInstance;
      }
  
      private static ScrollingMovementMethod sInstance;
  }
  