Android默认是没有高斯模糊效果的,Android默认是含有半透明效果的Dialog。但是iOS上的弹出曾是可以只是高斯模糊效果的。自从苹果引入了高斯模糊,这个模糊的玻璃效果就变得是分流行。但是很不幸的是Android系统本身并没有提供这种API。
其实原则上讲,Android是不推荐使用高斯模糊的,因为实现高斯模糊其实是比较耗资源的。但是非要实现也是有办法的。

下边实现含有高斯模糊效果的Dialog

整体思想:
1,将Dialog设置为全屏,(把布局的根RootView可以设置为居中不全屏,达到效果上Dialog的效果)
2,获取到Activity 的缓存背景图(类似于截屏的原理)。然后将这个图片进行高斯模糊的处理。
3,将处理后的图片设置Dialog的背景。

将Activity 的缓存普进行高斯模糊处理,并去除图片状态栏的高度

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private void setBlurBg() {
//设置高斯模糊
decorView = mActivity.getWindow().getDecorView();
new Thread(new Runnable() {
@Override
public void run() {
try {
decorView.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_LOW);
decorView.setDrawingCacheEnabled(true);
decorView.buildDrawingCache();
Bitmap drawingCache = decorView.getDrawingCache();
//将Activity 的缓存图片,去掉状态栏,状态栏的高度就是25dp
Bitmap bitmap1 = Bitmap.createBitmap(drawingCache, 0, DisplayUtil.dipToPixels(mActivity, 25), drawingCache.getWidth(), drawingCache.getHeight() - DisplayUtil.dipToPixels(mActivity, 25));
final Bitmap bitmap = BlurFilterUtil.boxBlurFilterBmp(bitmap1);
Canvas canvas = new Canvas(bitmap);
canvas.drawARGB(220,255,255,255);//让图片绘制的更加白
mActivity.runOnUiThread(new Runnable() {
@Override
public void run() {
mRootView.setBackgroundDrawable(new BitmapDrawable(bitmap));
}
});
if(!drawingCache.isRecycled() && drawingCache != null){
drawingCache.isRecycled();
drawingCache = null;
}
if(!bitmap1.isRecycled() && bitmap1 != null){
bitmap1.isRecycled();
bitmap1 = null;
}
if(!bitmap.isRecycled() && bitmap != null){
bitmap.isRecycled();
bitmap1 = null;
}
} catch (Exception e) {
e.printStackTrace();
}
}
}).start();
}

高斯模糊的处理工具类。高斯模糊处理可以去看一下开源的库

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public class BlurFilterUtil {
// 以下代码均是高斯模糊代码
public static Bitmap boxBlurFilterBmp(Bitmap bmp) {
if(bmp == null || bmp.isRecycled()){
return null;
}
float hRadius = 7;
float vRadius = 7;
int iterations = 3;
int width = bmp.getWidth();
int height = bmp.getHeight();
int[] inPixels = new int[width * height];
int[] outPixels = new int[width * height];
bmp.getPixels(inPixels, 0, width, 0, 0, width, height);
for (int i = 0; i < iterations; i++) {
blur(inPixels, outPixels, width, height, hRadius);
blur(outPixels, inPixels, height, width, vRadius);
}
blurFractional(inPixels, outPixels, width, height, hRadius);
blurFractional(outPixels, inPixels, height, width, vRadius);
Bitmap bitmap = Bitmap.createBitmap(width, height,
Bitmap.Config.ARGB_8888);
bitmap.setPixels(inPixels, 0, width, 0, 0, width, height);
Bitmap bitmap1 = Bitmap.createBitmap(bitmap, 5, 5,
bitmap.getWidth() - 15, bitmap.getHeight() - 5);
if (!bitmap.isRecycled()) {
bitmap.recycle();
}
if (!bmp.isRecycled()) {
bmp.recycle();
}
return bitmap1;
}

private static void blur(int[] in, int[] out, int width, int height,
float radius) {
int widthMinus1 = width - 1;
int r = (int) radius;
int tableSize = 2 * r + 1;
int divide[] = new int[256 * tableSize];

for (int i = 0; i < 256 * tableSize; i++)
divide[i] = i / tableSize;

int inIndex = 0;

for (int y = 0; y < height; y++) {
int outIndex = y;
int ta = 0, tr = 0, tg = 0, tb = 0;

for (int i = -r; i <= r; i++) {
int rgb = in[inIndex + clamp(i, 0, width - 1)];
ta += (rgb >> 24) & 0xff;
tr += (rgb >> 16) & 0xff;
tg += (rgb >> 8) & 0xff;
tb += rgb & 0xff;
}

for (int x = 0; x < width; x++) {
out[outIndex] = (divide[ta] << 24) | (divide[tr] << 16)
| (divide[tg] << 8) | divide[tb];
int i1 = x + r + 1;
if (i1 > widthMinus1)
i1 = widthMinus1;
int i2 = x - r;
if (i2 < 0)
i2 = 0;
int rgb1 = in[inIndex + i1];
int rgb2 = in[inIndex + i2];

ta += ((rgb1 >> 24) & 0xff) - ((rgb2 >> 24) & 0xff);
tr += ((rgb1 & 0xff0000) - (rgb2 & 0xff0000)) >> 16;
tg += ((rgb1 & 0xff00) - (rgb2 & 0xff00)) >> 8;
tb += (rgb1 & 0xff) - (rgb2 & 0xff);
outIndex += height;
}
inIndex += width;
}
}

private static void blurFractional(int[] in, int[] out, int width,
int height, float radius) {
radius -= (int) radius;
float f = 1.0f / (1 + 2 * radius);
int inIndex = 0;
for (int y = 0; y < height; y++) {
int outIndex = y;
out[outIndex] = in[0];
outIndex += height;
for (int x = 1; x < width - 1; x++) {
int i = inIndex + x;
int rgb1 = in[i - 1];
int rgb2 = in[i];
int rgb3 = in[i + 1];

int a1 = (rgb1 >> 24) & 0xff;
int r1 = (rgb1 >> 16) & 0xff;
int g1 = (rgb1 >> 8) & 0xff;
int b1 = rgb1 & 0xff;
int a2 = (rgb2 >> 24) & 0xff;
int r2 = (rgb2 >> 16) & 0xff;
int g2 = (rgb2 >> 8) & 0xff;
int b2 = rgb2 & 0xff;
int a3 = (rgb3 >> 24) & 0xff;
int r3 = (rgb3 >> 16) & 0xff;
int g3 = (rgb3 >> 8) & 0xff;
int b3 = rgb3 & 0xff;
a1 = a2 + (int) ((a1 + a3) * radius);
r1 = r2 + (int) ((r1 + r3) * radius);
g1 = g2 + (int) ((g1 + g3) * radius);
b1 = b2 + (int) ((b1 + b3) * radius);
a1 *= f;
r1 *= f;
g1 *= f;
b1 *= f;
out[outIndex] = (a1 << 24) | (r1 << 16) | (g1 << 8) | b1;
outIndex += height;
}
out[outIndex] = in[width - 1];
inIndex += width;
}
}
private static int clamp(int x, int a, int b) {
return (x < a) ? a : (x > b) ? b : x;
}
}