【轉】6、android圖片特效處理之圖片疊加

這篇將講到圖片特效處理的圖片疊加效果。跟前面同樣是對像素點進行處理，可參照前面的android圖像處理系列之七－－圖片塗鴉，水印－圖片疊加和android圖像處理系列之六－－給圖片添加邊框（下）－圖片疊加兩篇文章，此篇所講的與以前有一點區別。疊加原理是兩張圖片的像素點按透明度疊加，不會進行顏色過濾。疊加圖片能夠是JPG格式，跟前在同樣，最好是放大assets目錄。下面看效果圖：

+=

代碼：

 

/**
     * 圖片效果疊加
     * @param bmp 限制了尺寸大小的Bitmap
     * @return
     */
    private Bitmap overlay(Bitmap bmp)
    {
        long start = System.currentTimeMillis();
        int width = bmp.getWidth();
        int height = bmp.getHeight();
        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
        
        // 對邊框圖片進行縮放
        Bitmap overlay = BitmapFactory.decodeResource(mContext.getResources(), R.drawable.rainbow_overlay);
        int w = overlay.getWidth();
        int h = overlay.getHeight();
        float scaleX = width * 1F / w;
        float scaleY = height * 1F / h;
        Matrix matrix = new Matrix();
        matrix.postScale(scaleX, scaleY);
        
        Bitmap overlayCopy = Bitmap.createBitmap(overlay, 0, 0, w, h, matrix, true);
        
        int pixColor = 0;
        int layColor = 0;
        
        int pixR = 0;
        int pixG = 0;
        int pixB = 0;
        int pixA = 0;
        
        int newR = 0;
        int newG = 0;
        int newB = 0;
        int newA = 0;
        
        int layR = 0;
        int layG = 0;
        int layB = 0;
        int layA = 0;
        
        final float alpha = 0.5F;
        
        int[] srcPixels = new int[width * height];
        int[] layPixels = new int[width * height];
        bmp.getPixels(srcPixels, 0, width, 0, 0, width, height);
        overlayCopy.getPixels(layPixels, 0, width, 0, 0, width, height);
        
        int pos = 0;
        for (int i = 0; i < height; i++)
        {
            for (int k = 0; k < width; k++)
            {
                pos = i * width + k;
                pixColor = srcPixels[pos];
                layColor = layPixels[pos];
                
                pixR = Color.red(pixColor);
                pixG = Color.green(pixColor);
                pixB = Color.blue(pixColor);
                pixA = Color.alpha(pixColor);
                
                layR = Color.red(layColor);
                layG = Color.green(layColor);
                layB = Color.blue(layColor);
                layA = Color.alpha(layColor);
                
                newR = (int) (pixR * alpha + layR * (1 - alpha));
                newG = (int) (pixG * alpha + layG * (1 - alpha));
                newB = (int) (pixB * alpha + layB * (1 - alpha));
                layA = (int) (pixA * alpha + layA * (1 - alpha));
                
                newR = Math.min(255, Math.max(0, newR));
                newG = Math.min(255, Math.max(0, newG));
                newB = Math.min(255, Math.max(0, newB));
                newA = Math.min(255, Math.max(0, layA));
                
                srcPixels[pos] = Color.argb(newA, newR, newG, newB);
            }
        }
        
        bitmap.setPixels(srcPixels, 0, width, 0, 0, width, height);
        long end = System.currentTimeMillis();
        Log.d("may", "overlayAmeliorate used time="+(end - start));
        return bitmap;
    }

疊加的邊框圖片仍是大點比較好，也要控制被疊加圖片大小。alpha變量值能夠根據需求修改，建議仍是大於0.5比較好，否則原圖會看不清楚。