Android TextView內容包含中英文時滿行居中，不足一行則左對齊，會出現左右空格不一致。

package com.roya.shandong.view;

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 android.widget.TextView;

/**
* Created by Aphrodite on 2017/8/28.
*/

public class DialogTextView extends TextView {
private float mLineY;
private float mViewWidth;

public DialogTextView(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();
if (null == layout) {
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 (line.equals(“”)) {
break;
}

  if (i < layout.getLineCount() - 1) {
    if (needScale(line)) {
      drawScaledText(canvas, lineStart, line, width);
    } else {
      canvas.drawText(line, 0, mLineY, paint);
    }
  } else {
    canvas.drawText(line, 0, mLineY, paint);
  }
  mLineY += textHeight;
}

}

private void drawScaledText(Canvas canvas, int lineStart, String line, float width) {
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 - width) / 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.length() == 0) {
return false;
} else {
return line.charAt(line.length() - 1) != ‘\n’;
}
}
}

借鑑：https://www.zhihu.com/question/23768161/answer/82424947