017-AlbumDetailCoverGaussianBlur.md

#017: 专辑封面高斯模糊实现

#首页

##1. 定义一个工具类实现高斯模糊效果 GaussianBlur.java:

public class GaussianBlur {
public static int DEFAULT_RADIUS = 10;

/**
 * 创建毛玻璃效果
 *
 * @param iv      图片显示的控件嘛
 * @param context 上下文
 */
public static void makeBlur(ImageView iv, Context context) {
    //先拿到控件里显示的内容
    BitmapDrawable drawable = (BitmapDrawable) iv.getDrawable();
    Bitmap bitmap = drawable.getBitmap();
    //开始去转换
    Bitmap blurred = blurRenderScript(bitmap, DEFAULT_RADIUS, context);
    iv.setImageBitmap(blurred); //radius decide blur amount
}


private static Bitmap blurRenderScript(Bitmap smallBitmap, int radius, Context context) {
    //把原图转成ARGB_8888格式
    smallBitmap = RGB565toARGB888(smallBitmap);
    //再创建一张图，同样格式为ARGB_8888
    Bitmap bitmap = Bitmap.createBitmap(smallBitmap.getWidth(), smallBitmap.getHeight(), Bitmap.Config.ARGB_8888);
    //我们的java，效率没有C++的高，其实一般来说，做高斯模糊的话，直接提供类库，然后通过jni去调用，模糊的图片传回来即可。
    //这里借助RenderScript，它是一个高效的计算平台
    RenderScript renderScript = RenderScript.create(context);
    Allocation blurInput = Allocation.createFromBitmap(renderScript, smallBitmap);
    Allocation blurOutput = Allocation.createFromBitmap(renderScript, bitmap);
    ScriptIntrinsicBlur blur = ScriptIntrinsicBlur.create(renderScript, Element.U8_4(renderScript));
    blur.setInput(blurInput);
    //参数范围(0,25)
    blur.setRadius(radius);
    blur.forEach(blurOutput);
    blurOutput.copyTo(bitmap);
    renderScript.destroy();
    return bitmap;
}

private static Bitmap RGB565toARGB888(Bitmap img) {
    int numPixels = img.getWidth() * img.getHeight();
    int [] pixels = new int[numPixels];
    img.getPixels(pixels, 0 , img.getWidth(), 0 , 0 , img.getWidth(), img.getHeight()
    );

    Bitmap result = Bitmap.createBitmap(img.getWidth(), img.getHeight(), Bitmap.Config.ARGB_8888);

    result.setPixels(pixels, 0 , result.getWidth(), 0, 0, result.getWidth(), result.getHeight()
    );
    return  result;
}
}

##2. 专辑封面应用高斯模糊功能

AlbumDetailActivity.java:

@Override
public void onAlbumDataLoaded(Album album) {

if(null != album){
    Picasso.with(this).load(album.getCoverUrlLarge()).into(albumLargeCover, new Callback() {
        @Override
        public void onSuccess() {
            Drawable drawable = albumLargeCover.getDrawable();
            if(null != drawable){
                GaussianBlur.makeBlur(albumLargeCover, AlbumDetailActivity.this);
            }
        }

        @Override
        public void onError() {
            LogUtil.e(TAG, "load picture failed");

        }
    });
    ...
}

##2. 效果图 修改前

修改后