content: package me.biubiubiu.justifytext.library;
  
  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;
  
  /**
   * @author ccheng
   * @Date 3/18/14
   */
  public class JustifyTextView extends TextView {
  
  	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)) {
  				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';
  		}
  	}
  
  }
  