Android高斯模糊（无需任何三方框架）的实现思路，Android多种截图方式
16lz
2021-01-26
产品设计要求：当操作APP需要登录权限时，弹出登录界面，要求登录界面的背景是上一个界面的透明、模糊、阴影效果，就像iOS8下拉通知栏的背景效果。最终效果如下图：
最初的想法，是想搞个模糊、透明的图片当作登录界面的背景。后来发现这种想法不切合实际。于是就找到了高斯模糊的这一图像处理技巧。
Android系统本身自带高斯模糊的功能，但是要求系统版本在11以上，然后有个厉害的家伙重写了一个支持低版本的类库。但是这两种方法我都没采纳，根据前人的经验直接用一个不算复杂的算法实现。
主界面跳转登录界面的高斯模糊实现步骤：
MainActivity–>LoginActivity
跳转登录界面
这里用到了Android注解框架androidannotations，https://github.com/excilys/androidannotations
LoginActivity_.intent(activity).start();主界面截图
// 从activity堆栈里面获取MainActivity，自己定义AppBase实现Bitmap bitmap = BitmapUtil.shotActivity(activities.get(activities.size() - 2));// 参考下面的设置背景图片代码片段blur(bitmap, vContent);BitmapUtil代码：
/** * 截取可见屏幕，包括状态栏 */ public static Bitmap shotScreen(Activity activity) { View view = activity.getWindow().getDecorView(); Display display = activity.getWindowManager().getDefaultDisplay(); view.layout(0, 0, display.getWidth(), display.getHeight()); // 允许当前窗口保存缓存信息，这样getDrawingCache()方法才会返回一个Bitmap view.setDrawingCacheEnabled(true); return Bitmap.createBitmap(view.getDrawingCache()); } /** * 截取可见屏幕，不包括状态栏 */ public static Bitmap shotActivity(Activity activity) { View view = activity.getWindow().getDecorView(); Rect frame = new Rect(); view.getWindowVisibleDisplayFrame(frame); view.setDrawingCacheEnabled(true); view.destroyDrawingCache();// 更新cache return Bitmap.createBitmap(view.getDrawingCache(), 0, frame.top, frame.width(), frame.height()); } /** * 截取view的根层可见屏幕部分的视图 */ public static Bitmap getRootViewBitmap(View view) { return shotViewBitmap(view.getRootView()); } /** * 截取可见屏幕部分的view视图 */ public static Bitmap shotViewBitmap(View v) { v.clearFocus(); v.setPressed(false); Bitmap bmp = null; try { v.layout(0, 0, v.getWidth(), v.getHeight()); // 允许当前窗口保存缓存信息，这样getDrawingCache()方法才会返回一个Bitmap v.setDrawingCacheEnabled(true); v.buildDrawingCache(); bmp = Bitmap.createBitmap(v.getDrawingCache()); } catch (Exception e) { e.printStackTrace(); } return bmp; } /** * 获取view的完整视图图片（即使没有显示出来的部分） */ public static Bitmap convertBitmap(View view){ return convertViewToBitmap(view, view.getWidth(), view.getHeight()); } /** * 通过计算的方法宽高后，获取view的完整视图图片（即使没有显示出来的部分） */ public static Bitmap convertMeasureBitmap(View view){ view.measure(View.MeasureSpec.makeMeasureSpec(view.getWidth(), View.MeasureSpec.EXACTLY), View.MeasureSpec.makeMeasureSpec(view.getHeight(), View.MeasureSpec.AT_MOST)); return convertViewToBitmap(view, view.getMeasuredWidth(), view.getMeasuredHeight()); } /** * convert view to bitmap according to with and height */ public static Bitmap convertViewToBitmap(View view, int width, int height){ Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); view.draw(new Canvas(bitmap)); return bitmap; }图片高斯模糊算法
package com.witspring.tool;import android.graphics.Bitmap;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); }}设置背景图片
private void blur(Bitmap bkg, View view) { float radius = 2; float scaleFactor = 8; 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); // 参考上面的图片高斯模糊算法 overlay = FastBlur.doBlur(overlay, (int) radius, true); view.setBackgroundDrawable(new BitmapDrawable(getResources(), overlay)); }更多相关文章
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