在 Android 中使用 RenderScript 更加模糊

Question

对于我的项目，我想使用模糊背景。当我使用以下方法时，它会模糊我的背景，但它对我来说不够模糊，我想做更多模糊的背景。我将半径设置为其最大值25.有人可以帮帮我吗？

private static final float BITMAP_SCALE = 0.9f;
private static final float BLUR_RADIUS = 25.0f;

public static Bitmap blur(Context context, Bitmap image) {
    int width = Math.round(image.getWidth() * BITMAP_SCALE);
    int height = Math.round(image.getHeight() * BITMAP_SCALE);

    Bitmap inputBitmap = Bitmap.createScaledBitmap(image, width, height, false);
    Bitmap outputBitmap = Bitmap.createBitmap(inputBitmap);

    RenderScript rs = RenderScript.create(context);
    ScriptIntrinsicBlur theIntrinsic = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
    Allocation tmpIn = Allocation.createFromBitmap(rs, inputBitmap);
    Allocation tmpOut = Allocation.createFromBitmap(rs, outputBitmap);
    theIntrinsic.setRadius(BLUR_RADIUS);
    theIntrinsic.setInput(tmpIn);
    theIntrinsic.forEach(tmpOut);
    tmpOut.copyTo(outputBitmap);

    return outputBitmap;


}

Answer 1

如果使用 25 的模糊半径仍然不够，一种廉价的模糊方法是先缩小背景图像的大小，然后再放大。

private static final float BITMAP_SCALE = 0.9f;
private static final float RESIZE_SCALE = 1.f/5.f;
private static RenderScript rs;

public static Bitmap blur(Context context, Bitmap image) {
    int width = Math.round(image.getWidth() * BITMAP_SCALE);
    int height = Math.round(image.getHeight() * BITMAP_SCALE);

    Bitmap inputBitmap = Bitmap.createScaledBitmap(image, width, height, false);
    Bitmap outputBitmap = Bitmap.createBitmap(inputBitmap);

    if (rs == null) {
        // Creating a RS context is expensive, better reuse it.
        rs = RenderScript.create(context);
    }
    Allocation tmpIn = Allocation.createFromBitmap(rs, inputBitmap);
    Allocation tmpOut = Allocation.createFromBitmap(rs, outputBitmap);

    Type t = Type.createXY(mRS, tmpIn.getElement(), width*RESIZE_SCALE, height*RESIZE_SCALE);
    Allocation tmpScratch = Allocation.createTyped(rs, t);

    ScriptIntrinsicResize theIntrinsic = ScriptIntrinsicResize.create(rs);
    // Resize the original img down.
    theIntrinsic.setInput(tmpIn);
    theIntrinsic.forEach_bicubic(tmpScratch);
    // Resize smaller img up.
    theIntrinsic.setInput(tmpScratch);
    theIntrinsic.forEach_bicubic(tmpOut);
    tmpOut.copyTo(outputBitmap);

    return outputBitmap;
}