用微博的同学都知道这个效果吧,这篇文章先实现模糊效果,进入、退出动画后面文章分析;
一、说一下实现思路,很简单的:
1、截图:就是获取我们app得截图
获取我们Activity得根view即DecorView,关于DecorView,sdk里面是这么说明的:
Retrieve the top-level window decor view (containing the standard window frame/decorations and the client's content inside of that), which can be added as a window to the window manager.
就是说获取最顶层的window,可以添加到window manager里面;
拿到view之后可以调用view的getDrawingCache方法获取bitmap截图;
2、对图片做高斯模糊;
高斯模糊在Photoshop里面用的比较多,可以用来去痘痘。
大致原理是:对指定像素和其周围像素进行加权平均来得到最终结果,使用高斯分布作为滤波器。
这儿可以了解详细的算法原理:http://www.ruanyifeng.com/blog/2012/11/gaussian_blur.html
二、代码实现:
代码比较简单,我自己加了注释贴出来了:
private void applyBlur() { View view = getWindow().getDecorView(); view.setDrawingCacheEnabled(true); view.buildDrawingCache(true); /** * 获取当前窗口快照,相当于截屏 */ Bitmap bmp1 = view.getDrawingCache(); int height = getOtherHeight(); /** * 除去状态栏和标题栏 */ Bitmap bmp2 = Bitmap.createBitmap(bmp1, 0, height,bmp1.getWidth(), bmp1.getHeight() - height); blur(bmp2, text); } @SuppressLint("NewApi") private void blur(Bitmap bkg, View view) { long startMs = System.currentTimeMillis(); float scaleFactor = 8;//图片缩放比例; float radius = 20;//模糊程度 Bitmap overlay = Bitmap.createBitmap( (int) (view.getMeasuredWidth() / scaleFactor), (int) (view.getMeasuredHeight() / scaleFactor), Bitmap.Config.ARGB_8888); Canvas canvas = new Canvas(overlay); canvas.translate(-view.getLeft() / scaleFactor, -view.getTop()/ scaleFactor); canvas.scale(1 / scaleFactor, 1 / scaleFactor); Paint paint = new Paint(); paint.setFlags(Paint.FILTER_BITMAP_FLAG); canvas.drawBitmap(bkg, 0, 0, paint); overlay = FastBlur.doBlur(overlay, (int) radius, true); view.setBackground(new BitmapDrawable(getResources(), overlay)); /** * 打印高斯模糊处理时间,如果时间大约16ms,用户就能感到到卡顿,时间越长卡顿越明显,如果对模糊完图片要求不高,可是将scaleFactor设置大一些。 */ Log.i("jerome", "blur time:" + (System.currentTimeMillis() - startMs)); } /** * 获取系统状态栏和软件标题栏,部分软件没有标题栏,看自己软件的配置; * @return */ private int getOtherHeight() { Rect frame = new Rect(); getWindow().getDecorView().getWindowVisibleDisplayFrame(frame); int statusBarHeight = frame.top; int contentTop = getWindow().findViewById(Window.ID_ANDROID_CONTENT).getTop(); int titleBarHeight = contentTop - statusBarHeight; return statusBarHeight + titleBarHeight; }
我这里用了外国开源项目中的一个Java算法,地址:https://github.com/paveldudka/blurring
package com.jerome.popdemo; import android.graphics.Bitmap; /** * Created by paveld on 3/6/14. */ public class FastBlur { public static Bitmap doBlur(Bitmap sentBitmap, int radius, boolean canReuseInBitmap) { 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); } }
如果用C/C++实现jni调用,效果会高一些,可以参考:https://github.com/qiujuer/ImageBlurring/blob/master/README-ZH.md
/************************************************* Copyright: Copyright QIUJUER 2013. Author: Qiujuer Date: 2014-04-18 Description:实现图片模糊处理 **************************************************/ #include<malloc.h> #define ABS(a) ((a)<(0)?(-a):(a)) #define MAX(a,b) ((a)>(b)?(a):(b)) #define MIN(a,b) ((a)<(b)?(a):(b)) /************************************************* Function: StackBlur(堆栈模糊) Description: 使用堆栈方式进行图片像素模糊处理 Calls: malloc Table Accessed: NULL Table Updated: NULL Input: 像素点集合,图片宽,图片高,模糊半径 Output: 返回模糊后的像素点集合 Return: 返回模糊后的像素点集合 Others: NULL *************************************************/ static int* StackBlur(int* pix, int w, int h, int radius) { int wm = w - 1; int hm = h - 1; int wh = w * h; int div = radius + radius + 1; int *r = (int *)malloc(wh * sizeof(int)); int *g = (int *)malloc(wh * sizeof(int)); int *b = (int *)malloc(wh * sizeof(int)); int rsum, gsum, bsum, x, y, i, p, yp, yi, yw; int *vmin = (int *)malloc(MAX(w,h) * sizeof(int)); int divsum = (div + 1) >> 1; divsum *= divsum; int *dv = (int *)malloc(256 * divsum * sizeof(int)); for (i = 0; i < 256 * divsum; i++) { dv[i] = (i / divsum); } yw = yi = 0; int(*stack)[3] = (int(*)[3])malloc(div * 3 * sizeof(int)); 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 + (MIN(wm, MAX(i, 0)))]; sir = stack[i + radius]; sir[0] = (p & 0xff0000) >> 16; sir[1] = (p & 0x00ff00) >> 8; sir[2] = (p & 0x0000ff); rbs = r1 - 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] = 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 = MAX(0, yp) + x; sir = stack[i + radius]; sir[0] = r[yi]; sir[1] = g[yi]; sir[2] = b[yi]; rbs = r1 - 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] = 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; } } free(r); free(g); free(b); free(vmin); free(dv); free(stack); return(pix); }
最后来一张屌丝做demo专业效果图: