package com.kunfei.bookshelf.help;

import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.Bitmap;
import android.os.Build;
import android.renderscript.Allocation;
import android.renderscript.Element;
import android.renderscript.RenderScript;
import android.renderscript.ScriptIntrinsicBlur;

import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
import com.bumptech.glide.load.resource.bitmap.BitmapTransformation;

import java.security.MessageDigest;

import androidx.annotation.NonNull;

public class BlurTransformation extends BitmapTransformation {
    private RenderScript rs;
    private int radius;

    public BlurTransformation(Context context, int radius) {
        super();
        rs = RenderScript.create(context);
        this.radius = radius;
    }

    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
    @Override
    protected Bitmap transform(@NonNull BitmapPool pool, @NonNull Bitmap toTransform, int outWidth, int outHeight) {
        Bitmap blurredBitmap = toTransform.copy(Bitmap.Config.ARGB_8888, true);

        // Allocate memory for Renderscript to work with
        //分配用于渲染脚本的内存
        Allocation input = Allocation.createFromBitmap(rs, blurredBitmap, Allocation.MipmapControl.MIPMAP_FULL, Allocation.USAGE_SHARED);
        Allocation output = Allocation.createTyped(rs, input.getType());

        // Load up an instance of the specific script that we want to use.
        //加载我们想要使用的特定脚本的实例。
        ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
        script.setInput(input);

        // Set the blur radius
        //设置模糊半径
        script.setRadius(radius);

        // Start the ScriptIntrinsicBlur
        //启动 ScriptIntrinsicBlur,
        script.forEach(output);

        // Copy the output to the blurred bitmap
        //将输出复制到模糊的位图
        output.copyTo(blurredBitmap);

        return blurredBitmap;
    }

    @Override
    public void updateDiskCacheKey(@NonNull MessageDigest messageDigest) {
        messageDigest.update("blur transformation".getBytes());
    }
}