很久以前就想自己實現一下仿微信圖片載入的那種策略了，先載入一張模糊的圖片，然後再載入清晰大圖，今天研究了一下，不過要是Glide支援進度條顯示就好了，不得不說Glide很強大，
不囉嗦了，直接上程式碼了。
首先看看高斯模糊到底怎麼實現，你問我我也不會(^__^) 嘻嘻……，直接附上網上的演算法：

package com.cisetech.dialogdemo;

import android.graphics.Bitmap;

/**
 * Author:Yqy
 * Date:2016-09-29
 * Desc:
 * Company:cisetech
 */
public class FastBlur
 
 {
    public static Bitmap doBlur(Bitmap sentBitmap, int radius, boolean canReuseInBitmap) {

        // Stack Blur v1.0 from
        // http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html
        //
        // Java Author: Mario Klingemann <mario at quasimondo.com>
        // http://incubator.quasimondo.com
 

        // created Feburary 29, 2004
        // Android port : Yahel Bouaziz <yahel at kayenko.com>
        // http://www.kayenko.com
        // ported april 5th, 2012

        // This is a compromise between Gaussian Blur and Box blur
        // It creates much better looking blurs than Box Blur, but is
        // 7x faster than my Gaussian Blur implementation.
 

        //
        // I called it Stack Blur because this describes best how this
        // filter works internally: it creates a kind of moving stack
        // of colors whilst scanning through the image. Thereby it
        // just has to add one new block of color to the right side
        // of the stack and remove the leftmost color. The remaining
        // colors on the topmost layer of the stack are either added on
        // or reduced by one, depending on if they are on the right or
        // on the left side of the stack.
        //
        // If you are using this algorithm in your code please add
        // the following line:
        //
        // Stack Blur Algorithm by Mario Klingemann <[email protected]>

        Bitmap bitmap;
        if (canReuseInBitmap) {
            bitmap = sentBitmap;
        } else {
            bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
        }

        if (radius < 1) {
            return (null);
        }

        int w = bitmap.getWidth();
        int h = bitmap.getHeight();

        int[] pix = new int[w * h];
        bitmap.getPixels(pix, 0, w, 0, 0, w, h);

        int wm = w - 1;
        int hm = h - 1;
        int wh = w * h;
        int div = radius + radius + 1;

        int r[] = new int[wh];
        int g[] = new int[wh];
        int b[] = new int[wh];
        int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
        int vmin[] = new int[Math.max(w, h)];

        int divsum = (div + 1) >> 1;
        divsum *= divsum;
        int dv[] = new int[256 * divsum];
        for (i = 0; i < 256 * divsum; i++) {
            dv[i] = (i / divsum);
        }

        yw = yi = 0;

        int[][] stack = new int[div][3];
        int stackpointer;
        int stackstart;
        int[] sir;
        int rbs;
        int r1 = radius + 1;
        int routsum, goutsum, boutsum;
        int rinsum, ginsum, binsum;

        for (y = 0; y < h; y++) {
            rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
            for (i = -radius; i <= radius; i++) {
                p = pix[yi + Math.min(wm, Math.max(i, 0))];
                sir = stack[i + radius];
                sir[0] = (p & 0xff0000) >> 16;
                sir[1] = (p & 0x00ff00) >> 8;
                sir[2] = (p & 0x0000ff);
                rbs = r1 - Math.abs(i);
                rsum += sir[0] * rbs;
                gsum += sir[1] * rbs;
                bsum += sir[2] * rbs;
                if (i > 0) {
                    rinsum += sir[0];
                    ginsum += sir[1];
                    binsum += sir[2];
                } else {
                    routsum += sir[0];
                    goutsum += sir[1];
                    boutsum += sir[2];
                }
            }
            stackpointer = radius;

            for (x = 0; x < w; x++) {

                r[yi] = dv[rsum];
                g[yi] = dv[gsum];
                b[yi] = dv[bsum];

                rsum -= routsum;
                gsum -= goutsum;
                bsum -= boutsum;

                stackstart = stackpointer - radius + div;
                sir = stack[stackstart % div];

                routsum -= sir[0];
                goutsum -= sir[1];
                boutsum -= sir[2];

                if (y == 0) {
                    vmin[x] = Math.min(x + radius + 1, wm);
                }
                p = pix[yw + vmin[x]];

                sir[0] = (p & 0xff0000) >> 16;
                sir[1] = (p & 0x00ff00) >> 8;
                sir[2] = (p & 0x0000ff);

                rinsum += sir[0];
                ginsum += sir[1];
                binsum += sir[2];

                rsum += rinsum;
                gsum += ginsum;
                bsum += binsum;

                stackpointer = (stackpointer + 1) % div;
                sir = stack[(stackpointer) % div];

                routsum += sir[0];
                goutsum += sir[1];
                boutsum += sir[2];

                rinsum -= sir[0];
                ginsum -= sir[1];
                binsum -= sir[2];

                yi++;
            }
            yw += w;
        }
        for (x = 0; x < w; x++) {
            rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
            yp = -radius * w;
            for (i = -radius; i <= radius; i++) {
                yi = Math.max(0, yp) + x;

                sir = stack[i + radius];

                sir[0] = r[yi];
                sir[1] = g[yi];
                sir[2] = b[yi];

                rbs = r1 - Math.abs(i);

                rsum += r[yi] * rbs;
                gsum += g[yi] * rbs;
                bsum += b[yi] * rbs;

                if (i > 0) {
                    rinsum += sir[0];
                    ginsum += sir[1];
                    binsum += sir[2];
                } else {
                    routsum += sir[0];
                    goutsum += sir[1];
                    boutsum += sir[2];
                }

                if (i < hm) {
                    yp += w;
                }
            }
            yi = x;
            stackpointer = radius;
            for (y = 0; y < h; y++) {
                // Preserve alpha channel: ( 0xff000000 & pix[yi] )
                pix[yi] = (0xff000000 & pix[yi]) | (dv[rsum] << 16) | (dv[gsum] << 8) | dv[bsum];

                rsum -= routsum;
                gsum -= goutsum;
                bsum -= boutsum;

                stackstart = stackpointer - radius + div;
                sir = stack[stackstart % div];

                routsum -= sir[0];
                goutsum -= sir[1];
                boutsum -= sir[2];

                if (x == 0) {
                    vmin[y] = Math.min(y + r1, hm) * w;
                }
                p = x + vmin[y];

                sir[0] = r[p];
                sir[1] = g[p];
                sir[2] = b[p];

                rinsum += sir[0];
                ginsum += sir[1];
                binsum += sir[2];

                rsum += rinsum;
                gsum += ginsum;
                bsum += binsum;

                stackpointer = (stackpointer + 1) % div;
                sir = stack[stackpointer];

                routsum += sir[0];
                goutsum += sir[1];
                boutsum += sir[2];

                rinsum -= sir[0];
                ginsum -= sir[1];
                binsum -= sir[2];

                yi += w;
            }
        }

        bitmap.setPixels(pix, 0, w, 0, 0, w, h);

        return (bitmap);
    }
}

由於程式碼比較少，我就直接全部貼上了，可以直接拿去研究額。

package com.cisetech.dialogdemo;

import android.app.Dialog;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.WindowManager;
import android.widget.ImageView;
import android.widget.ProgressBar;

import com.bumptech.glide.Glide;
import com.bumptech.glide.load.engine.DiskCacheStrategy;
import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
import com.bumptech.glide.load.resource.bitmap.BitmapTransformation;
import com.bumptech.glide.load.resource.drawable.GlideDrawable;
import com.bumptech.glide.request.RequestListener;
import com.bumptech.glide.request.target.Target;

public class MainActivity extends AppCompatActivity {
    private int screenWidth;
    private ImageView id_iv;
    private ProgressBar pb;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        WindowManager wm=getWindowManager();
        DisplayMetrics outMetrics=new DisplayMetrics();
        wm.getDefaultDisplay().getMetrics(outMetrics);
        screenWidth=outMetrics.widthPixels;
        id_iv= (ImageView) findViewById(R.id.id_iv);
        pb= (ProgressBar) findViewById(R.id.pb);
        Glide.with(this).load("http://img0.bdstatic.com/img/image/shouye/xinshouye/dongman928.jpg")
                .centerCrop()
                .listener(new RequestListener<String, GlideDrawable>() {
            @Override
            public boolean onException(Exception e, String s, Target<GlideDrawable> target, boolean b) {
                return false;
            }

            @Override
            public boolean onResourceReady(final GlideDrawable glideDrawable, String s, Target<GlideDrawable> target, boolean b, boolean b1) {
                Log.e("TAG", "onResourceReady: target-------->"+target );
                Log.e("TAG", "onResourceReady: glideDrawable-------->"+glideDrawable );
                        Glide.with(MainActivity.this).load("http://img0.bdstatic.com/img/image/shouye/xinshouye/dongman928.jpg").
                                centerCrop().placeholder(glideDrawable).
                                diskCacheStrategy(DiskCacheStrategy.NONE).
                                skipMemoryCache(true).dontAnimate().
                                crossFade(1000).
                                listener(new RequestListener<String, GlideDrawable>() {
                                    @Override
                                    public boolean onException(Exception e, String s, Target<GlideDrawable> target, boolean b) {
                                        return false;
                                    }

                                    @Override
                                    public boolean onResourceReady(GlideDrawable glideDrawable, String s, Target<GlideDrawable> target, boolean b, boolean b1) {
                                        pb.setVisibility(View.GONE);
                                        return false;
                                    }
                                }).
                                into(id_iv);
                return false;
            }
        }).
        transform(new MyTransformtion(this)).
                diskCacheStrategy(DiskCacheStrategy.ALL).
                placeholder(new ColorDrawable(Color.BLACK))
                .dontAnimate().into(id_iv);

        //createLoadingDialog(this).show();
    }
    public Dialog createLoadingDialog(Context context) {
        LayoutInflater inflater = LayoutInflater.from(context);
        View v = inflater.inflate(R.layout.wechat_dialog, null);// 得到載入view
        Dialog loadingDialog = new Dialog(context, R.style.loading_dialog);// 建立自定義樣式dialog
        loadingDialog.setCancelable(false);// 不可以用“返回鍵”取消
        loadingDialog.setContentView(v);// 設定佈局
        /**
         * 設定Dialog的寬度為螢幕寬度的61.8%，高度為自適應
         */
        WindowManager.LayoutParams lp = loadingDialog.getWindow().getAttributes();
        lp.width= (int) (screenWidth*0.618f);
        lp.height=lp.WRAP_CONTENT;
        loadingDialog.getWindow().setAttributes(lp);
        return loadingDialog;
    }
    public class MyTransformtion extends BitmapTransformation{

        public MyTransformtion(Context context) {
            super(context);
        }
        @Override
        protected Bitmap transform(BitmapPool bitmapPool, Bitmap bitmap, int i, int i1) {
            Log.e("TAG", "transform: bitmap-------->"+bitmap );
            return FastBlur.doBlur(bitmap,10,true);
        }
        @Override
        public String getId() {
            return "com.cisetech.dialogdemo.MyTransformtion";
        }
    }
}

仿微信進度條可以看我另外一篇部落格Android進階之（Dailog詳解），這裡寫在一個工程裡面了，我就直接貼程式碼了。