content: package com.an.trailers.ui.base.custom;
  
  import android.content.Context;
  import android.graphics.Canvas;
  import android.graphics.Paint;
  import android.text.Layout;
  import android.text.StaticLayout;
  import android.text.TextPaint;
  import android.util.AttributeSet;
  import androidx.appcompat.widget.AppCompatTextView;
  
  
  public class JustifyTextView extends AppCompatTextView {
  
      private int mLineY;
      private int mViewWidth;
      public static final String TWO_CHINESE_BLANK = "  ";
  
      public JustifyTextView(Context context, AttributeSet attrs) {
          super(context, attrs);
      }
  
      @Override
      protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
          super.onLayout(changed, left, top, right, bottom);
      }
  
      @Override
      protected void onDraw(Canvas canvas) {
          TextPaint paint = getPaint();
          paint.setColor(getCurrentTextColor());
          paint.drawableState = getDrawableState();
          mViewWidth = getMeasuredWidth();
          String text = getText().toString();
          mLineY = 0;
          mLineY += getTextSize();
          Layout layout = getLayout();
  
          // layout.getLayout()在4.4.3出现NullPointerException
          if (layout == null) {
              return;
          }
  
          Paint.FontMetrics fm = paint.getFontMetrics();
  
          int textHeight = (int) (Math.ceil(fm.descent - fm.ascent));
          textHeight = (int) (textHeight * layout.getSpacingMultiplier() + layout.getSpacingAdd());
  
          for (int i = 0; i < layout.getLineCount(); i++) {
              int lineStart = layout.getLineStart(i);
              int lineEnd = layout.getLineEnd(i);
              float width = StaticLayout.getDesiredWidth(text, lineStart, lineEnd, getPaint());
              String line = text.substring(lineStart, lineEnd);
              if (needScale(line) && i < layout.getLineCount() -1) {
                  drawScaledText(canvas, lineStart, line, width);
              } else {
                  canvas.drawText(line, 0, mLineY, paint);
              }
              mLineY += textHeight;
          }
      }
  
      private void drawScaledText(Canvas canvas, int lineStart, String line, float lineWidth) {
          float x = 0;
          if (isFirstLineOfParagraph(lineStart, line)) {
              String blanks = "  ";
              canvas.drawText(blanks, x, mLineY, getPaint());
              float bw = StaticLayout.getDesiredWidth(blanks, getPaint());
              x += bw;
  
              line = line.substring(3);
          }
  
          int gapCount = line.length() - 1;
          int i = 0;
          if (line.length() > 2 && line.charAt(0) == 12288 && line.charAt(1) == 12288) {
              String substring = line.substring(0, 2);
              float cw = StaticLayout.getDesiredWidth(substring, getPaint());
              canvas.drawText(substring, x, mLineY, getPaint());
              x += cw;
              i += 2;
          }
  
          float d = (mViewWidth - lineWidth) / gapCount;
          for (; i < line.length(); i++) {
              String c = String.valueOf(line.charAt(i));
              float cw = StaticLayout.getDesiredWidth(c, getPaint());
              canvas.drawText(c, x, mLineY, getPaint());
              x += cw + d;
          }
      }
  
      private boolean isFirstLineOfParagraph(int lineStart, String line) {
          return line.length() > 3 && line.charAt(0) == ' ' && line.charAt(1) == ' ';
      }
  
      private boolean needScale(String line) {
          if (line == null || line.length() == 0) {
              return false;
          } else {
              return line.charAt(line.length() - 1) != '\n';
          }
      }
  
  }
  