//--合并两张图片 BITMAP

private Bitmap toConformBitmap(Bitmap background, Bitmap foreground) {
    //--合并两张图片
    if( background == null ) {
        return null;
    }
    int bgWidth = background.getWidth();
    int bgHeight = background.getHeight();
    //int fgWidth = foreground.getWidth();
    //int fgHeight = foreground.getHeight();
    //create the new blank bitmap 创建一个新的和SRC长度宽度一样的位图
    Bitmap newbmp = Bitmap.createBitmap(bgWidth, bgHeight, Bitmap.Config.ARGB_8888);
    Canvas cv = new Canvas(newbmp);
    //draw bg into
    cv.drawBitmap(background, 0, 0, null);//在 0，0坐标开始画入bg
    //draw fg into
    cv.drawBitmap(foreground, 0, 0, null);//在 0，0坐标开始画入fg ，可以从任意位置画入
    //save all clip
    cv.save(Canvas.ALL_SAVE_FLAG);//保存
    //store
    cv.restore();//存储
    return newbmp;
}