Android进阶篇-Canvas Bitmap

headBgBmp = BitmapFactory.decodeResource(context.getResources(), R.drawable.class_bg_sha1);
headBmp = Bitmap.createBitmap(view.getWidth(),headBgBmp.getHeight(),Config.ARGB_8888);
Canvas canvas2 = new Canvas(headBmp);
Matrix matrix = new Matrix();
float xScale = (float) view.getWidth()/headBgBmp.getWidth();
matrix.setScale(xScale, 1.0f);
canvas2.drawBitmap(headBgBmp, matrix, null);

NinePatchDrawable drawable = (NinePatchDrawable) context.getResources().getDrawable(R.drawable.class_bg_sha2_2);
frameBg = drawableToBitmap(drawable, width, height);

public Bitmap drawableToBitmap(Drawable drawable, int w, int h) {
// 取 drawable 的颜色格式
Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
: Bitmap.Config.RGB_565;
// 建立对应 bitmap
Bitmap bitmap = Bitmap.createBitmap(w, h, config);
// 建立对应 bitmap 的画布
Canvas canvas = new Canvas(bitmap);
drawable.setBounds(0, 0, w, h);
// 把 drawable 内容画到画布中
drawable.draw(canvas);
return bitmap;
}