Android ApiDemos樣本解析(81):Graphics->Text Align

前面例子Android ApiDemos樣本解析(68):Graphics->MeasureText 介紹了如何取的所繪製文字串的尺寸（寬度和高度），文字的預設對齊為靠左對齊，本例介紹了其它幾種對齊：Left, Center ,Right 以及如何沿任意曲線繪製文字。

Paint的getTextWidths 方法取得字串中每個字元的寬度：

[java] 
private float[] buildTextPositions(String text, 
 float y, Paint paint) { 
 float[] widths = new float1; 
 // initially get the widths for each char  
 int n = paint.getTextWidths(text, widths); 
 // now popuplate the array,  
 //interleaving spaces for the Y values  
 float[] pos = new float[n * 2]; 
 float accumulatedX = 0; 
 for (int i = 0; i < n; i++) { 
 pos[i*2 + 0] = accumulatedX; 
 pos[i*2 + 1] = y; 
 accumulatedX += widths[i]; 
 } 
 return pos; 
} 

private float[] buildTextPositions(String text,
 float y, Paint paint) {
 float[] widths = new float1;
 // initially get the widths for each char
 int n = paint.getTextWidths(text, widths);
 // now popuplate the array,
 //interleaving spaces for the Y values
 float[] pos = new float[n * 2];
 float accumulatedX = 0;
 for (int i = 0; i < n; i++) {
 pos[i*2 + 0] = accumulatedX;
 pos[i*2 + 1] = y;
 accumulatedX += widths[i];
 }
 return pos;
}然後使用三種不同對齊繪製文字：Left，Center，Right：

[java] 
p.setTextAlign(Paint.Align.LEFT); 
... 
p.setTextAlign(Paint.Align.CENTER); 
... 
p.setTextAlign(Paint.Align.RIGHT); 
canvas.drawText(TEXT_R, x, y, p); 

p.setTextAlign(Paint.Align.LEFT);
...
p.setTextAlign(Paint.Align.CENTER);
...
p.setTextAlign(Paint.Align.RIGHT);
canvas.drawText(TEXT_R, x, y, p);建立一條路徑makePath

[java] 
private static void makePath(Path p) { 
 p.moveTo(10, 0); 
 p.cubicTo(100, -50, 200, 50, 300, 0); 
} 

private static void makePath(Path p) {
 p.moveTo(10, 0);
 p.cubicTo(100, -50, 200, 50, 300, 0);
}然後沿這條路徑，也以三種不同對齊沿Path繪製文字：

[java] 
p.setTextAlign(Paint.Align.LEFT); 
... 
p.setTextAlign(Paint.Align.CENTER); 
... 
p.setTextAlign(Paint.Align.RIGHT); 
canvas.drawPath(mPath, mPathPaint); www.2cto.com
canvas.drawTextOnPath(TEXTONPATH, mPath, 0, 0, p); 

p.setTextAlign(Paint.Align.LEFT);
...
p.setTextAlign(Paint.Align.CENTER);
...
p.setTextAlign(Paint.Align.RIGHT);
canvas.drawPath(mPath, mPathPaint);
canvas.drawTextOnPath(TEXTONPATH, mPath, 0, 0, p);

 

作者：mapdigit