Android ApiDemos示例解析(81):Graphics->Text Align

前面例子Android ApiDemos示例解析(68):Graphics->MeasureText 介绍了如何取的所绘制文字串的尺寸（宽度和高度），文字的缺省对齐为左对齐，本例介绍了其它几种对齐方式：Left, Center ,Right 以及如何沿任意曲线绘制文字。

Paint的getTextWidths 方法取得字符串中每个字符的宽度：

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;
}

然后使用三种不同对齐方式绘制文字：Left，Center，Right：

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

创建一条路径makePath

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

然后沿这条路径，也以三种不同对齐方式沿Path绘制文字：

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);