ImageView设置背景图片后置灰探究

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直接上代码

public void change(View v) {    Drawable drawAble = img.getBackground();    img.setImageBitmap(toGrayscale(drawableToBitmap(img.getDrawable())));}//置灰 RGB_565会使整个背景都变黑private Bitmap drawableToBitmap(Drawable drawable) {    //Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(),drawable.getIntrinsicHeight(),drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888: Bitmap.Config.RGB_565);    Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(),drawable.getIntrinsicHeight(),Bitmap.Config.ARGB_8888);    Canvas canvas = new Canvas(bitmap);    drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),drawable.getIntrinsicHeight());    drawable.draw(canvas);    return bitmap;}private Bitmap toGrayscale(Bitmap bmpOriginal) {    int width, height;    height = bmpOriginal.getHeight();    width = bmpOriginal.getWidth();    Bitmap bmpGrayscale = Bitmap.createBitmap(width, height,Bitmap.Config.ARGB_8888);    Canvas c = new Canvas(bmpGrayscale);    Paint paint = new Paint();    ColorMatrix cm = new ColorMatrix();    cm.setSaturation(0);    ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);    paint.setColorFilter(f);    c.drawBitmap(bmpOriginal, 0, 0, paint);    return bmpGrayscale;}

混淆的地方

Bitmap.Config.ARGB_8888代表32位ARGB位图
ALPHA_8 代表8位Alpha位图
RGB_565 代表8位RGB位图
ALPHA_8 代表8位Alpha位图

9/25/2015 3:13:56 PM

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