最近做项目有这样的需求: 在activity中启动一个dialog时, 启动的dialog的背景设为启动acitivity的模糊化图片.
实现思路:
1. 截屏, 获取当前activity的界面
2. 将获取的照片进行模糊化
3. 将模糊化的图片设为dialog的背景
1.截屏, 获取当前activity的界面
private Bitmap takeScreenShot(Activity activity) {View view = activity.getWindow().getDecorView();view.setDrawingCacheEnabled(true);view.buildDrawingCache();Bitmap b1 = view.getDrawingCache();// 获取屏幕长和高int width = activity.getResources().getDisplayMetrics().widthPixels;int height = activity.getResources().getDisplayMetrics().heightPixels;Bitmap bmp = Bitmap.createBitmap(b1, 0, 0, width, height);view.destroyDrawingCache();return bmp;}
这里需要注意: 默认dialog是全屏, activity也是全屏没有状态栏. 如果有状态栏需要获取状态栏大小, 在创建图片的时候减去状态栏大小.
2.将获取的图片进行模糊化, 这里的模糊算法, 是从网上查到, 具体是进行高斯模糊. 具体代码在下面的工具类中.
3.设置模糊图片为dialog的背景
//blurBackgroundDrawer为模糊后的背景图片Window window = getWindow();window.setBackgroundDrawable(new BitmapDrawable(mContext.getResources(), blurBackgroundDrawer));
注意: 模糊化图片可能会比较慢, 刚开始测得时候在3 - 4秒之间, 解决办法是将获取到的屏幕进行缩小,然后在进行模糊, 模糊完后, 再将图片放大.
下面是将背景模糊化效果封装成的工具类代码, 使用方法: 只需要将其考到工程中, 在需要模糊化效果的地方调用:
Bitmap bmp = getBlurBackgroundDrawer(activity); 即可.
public class FastBlurUtility {public static Bitmap getBlurBackgroundDrawer(Activity activity) {Bitmap bmp = takeScreenShot(activity);return startBlurBackground(bmp);}private static Bitmap takeScreenShot(Activity activity) {View view = activity.getWindow().getDecorView();view.setDrawingCacheEnabled(true);view.buildDrawingCache();Bitmap b1 = view.getDrawingCache();// 获取屏幕长和高int width = activity.getResources().getDisplayMetrics().widthPixels;int height = activity.getResources().getDisplayMetrics().heightPixels;Bitmap bmp = Bitmap.createBitmap(b1, 0, 0, width, height);view.destroyDrawingCache();return bmp;}private static Bitmap startBlurBackground(Bitmap bkg) {long startMs = System.currentTimeMillis();float radius = 20; //模糊程度Bitmap overlay = fastblur(small(bkg), (int) radius);Log.i("FastBlurUtility", "=====blur time:" + (System.currentTimeMillis() - startMs));return big(overlay);}private static Bitmap big(Bitmap bitmap) {Matrix matrix = new Matrix();matrix.postScale(4f, 4f);Bitmap resizeBmp = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);return resizeBmp;}private static Bitmap small(Bitmap bitmap) {Matrix matrix = new Matrix();matrix.postScale(0.25f, 0.25f);Bitmap resizeBmp = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);return resizeBmp;}private static Bitmap fastblur(Bitmap sentBitmap, int radius) {Bitmap 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++) {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);}}
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