android整合两个bitmap

private Bitmap toConformBitmap(Bitmap background, Bitmap foreground) {
         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, 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;   
    }

private String saveBitmap(Bitmap bitmap) {
        String  imagePath = getApplication().getFilesDir().getAbsolutePath() + "/temp.png";
        
        File file = new File(imagePath);
        if(file.exists()) {
            file.delete();
        }
        try{
            FileOutputStream out = new FileOutputStream(file);
            if(bitmap.compress(Bitmap.CompressFormat.PNG, 100, out)){
                out.flush();
                out.close();
            }     
        } catch (Exception e) { 
            Toast.makeText(this, "保存失败, 1).show();
            e.printStackTrace();
        }
        return imagePath;
    }