Android實現圖片的倒影效果

效果以下：

主要代碼以下：

public static Bitmap createReflectedImage(Bitmap originalImage) {
    final int reflectionGap = 4;
    int width = originalImage.getWidth(); 
    int height = originalImage.getHeight();
    Matrix matrix = new Matrix(); 
    matrix.preScale(1, -1);
    Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, 
            height / 2, width, height / 2, matrix, false);
    Bitmap bitmapWithReflection = Bitmap.createBitmap(width, 
            (height + height / 2), Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmapWithReflection);
    canvas.drawBitmap(originalImage, 0, 0, null);
    Paint defaultPaint = new Paint(); 
    canvas.drawRect(0, height, width, height + reflectionGap, defaultPaint);
    canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
    Paint paint = new Paint(); 
    LinearGradient shader = new LinearGradient(0, 
            originalImage.getHeight(), 0, bitmapWithReflection.getHeight() 
                    + reflectionGap, 0×70ffffff, 0×00ffffff, 
            TileMode.MIRROR);
    paint.setShader(shader);
    paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
    canvas.drawRect(0, height, width, bitmapWithReflection.getHeight() 
            + reflectionGap, paint);
    return bitmapWithReflection; 
}

解釋一下：

Matrix matrix = new Matrix(); 
matrix.preScale(1, -1);

實現圖片的反轉，見Android利用Matrix簡單處理圖片。

Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, 
            height / 2, width, height / 2, matrix, false);

建立反轉後的圖片Bitmap對象，圖片高是原圖的一半。

Bitmap bitmapWithReflection = Bitmap.createBitmap(width, 
            (height + height / 2), Config.ARGB_8888);

建立標準的Bitmap對象，寬和原圖一致，高是原圖的1.5倍。

Canvas canvas = new Canvas(bitmapWithReflection);
canvas.drawBitmap(originalImage, 0, 0, null);

建立畫布對象，將原圖畫於畫布，起點是原點位置。

Paint defaultPaint = new Paint(); 
canvas.drawRect(0, height, width, height + reflectionGap, defaultPaint);
canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);

將反轉後的圖片畫到畫布中。

LinearGradient shader = new LinearGradient(0, 
            originalImage.getHeight(), 0, bitmapWithReflection.getHeight() 
                    + reflectionGap, 0×70ffffff, 0×00ffffff,

建立線性漸變LinearGradient 對象。

canvas.drawRect(0, height, width, bitmapWithReflection.getHeight() 
            + reflectionGap, paint);

畫布畫出反轉圖片大小區域，而後把漸變效果加到其中，就出現了圖片的倒影效果。

附件：http://www.oschina.net/code/snippet_157182_8946