Android之Canvas DrawText

Android之Canvas DrawText

Android之Canvas DrawText

  String str = "Hello";

  int len = str.getBytes().length;
  int w = len * 16;
  int h = 32;
  Bitmap strBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.RGB_565);
  Canvas c = new Canvas(strBitmap);
  Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
  paint.setTextSize(35);
  Typeface tf = Typeface.createFromAsset(getAssets(), "caiyun");
  paint.setTypeface(tf);
  paint.setColor(0xFFFFFFFF);
  paint.setTextAlign(Align.LEFT);

  FontMetrics fm = paint.getFontMetrics();
  c.drawText(str, 0, h + fm.top - fm.ascent, paint);
  c.save();

其中 c.drawText(str, 0, h + fm.top - fm.ascent, paint);

是在指定位置开始输出文字，而其中“h + fm.top - fm.ascent”就是这里面的关键，h相当与一个参照（我这里是要把文字写到一个bitmap上，所以h就是bitmap的基准），fm.top - fm.ascent是开始输出文字的baseline,不太明白的请看 Canvas.drawText的说明：Draw the text, with origin at (x,y), using the specified paint. The origin is interpreted based on the Align setting in the paint. Parameters:

text The text to be drawn

x The x-coordinate of the origin of the text being drawn

y The y-coordinate of the origin of the text being drawn

paint The paint used for the text (e.g. color, size, style)

这个origin就是文字baseline基线的坐标。

另外关于Typeface，比较遗憾是不太明白如何设置其他中文字体，比如宋体，楷体之类的，Typeface.createFromAsset(getAssets(), "caiyun");