项目需求：有一个xml文件，记录了一张图片每个元素的位置，大小，样式信息。
通过XmlResourceParser解析xml文件，得到每个元素的属性。
然后使用Paint绘制元素到Canvas上，得到一张Bitmap位图
将位图模糊处理，处理算法的原理(取图片上每个像素点周围的8个点平均值)
模糊算法：
package com.metek.blur;
import android.content.Context;
import android.graphics.Bitmap;
public class BlurUtils {
/**
* Android api 17实现的虚化
* 某些机型上可能会Crash
*
* @param context
* @param sentBitmap
* @param radius 大于1小于等于25
* @return
*/
public static Bitmap fastblur(Context context,Bitmap sentBitmap,int radius) {
if (sentBitmap == null) {
return null;
}
// if (Build.VERSION.SDK_INT > 16) {
// Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(),true);
//
// final RenderScript rs = RenderScript.create(context);
// final Allocation input = Allocation.createFromBitmap(rs,// sentBitmap,Allocation.MipmapControl.MIPMAP_NONE,// Allocation.USAGE_SCRIPT);
// final Allocation output = Allocation.createTyped(rs,// input.getType());
// final ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs,// Element.U8_4(rs));
// script.setRadius(radius /* e.g. 3.f */);
// script.setInput(input);
// script.forEach(output);
// output.copyTo(bitmap);
// return bitmap;
// }
return stackblur(sentBitmap,radius);
}
/**
* 纯Java实现的虚化，适用老版本api，外部只需调fastblur，会自动判断
*
* @param sentBitmap
* @param radius
* @return
*/
private static Bitmap stackblur(Bitmap sentBitmap,int radius) {
Bitmap bitmap = null;
try {
bitmap = sentBitmap.copy(sentBitmap.getConfig(),true);
} catch (OutOfMemoryError e) {
e.printStackTrace();
return sentBitmap;
}
if (radius < 1) {
return (null);
}
int w = bitmap.getWidth();
int h = bitmap.getHeight();
int[] pix = new int[w * h];
bitmap.getPixels(pix,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,h);
return (bitmap);
}
}
package com.metek.blur; import java.io.FileNotFoundException; import java.io.FileOutputStream; import android.content.Context; import android.content.res.XmlResourceParser; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Paint; import android.os.AsyncTask; import android.os.SystemClock; import android.util.DisplayMetrics; /** * 生成天气模糊背景图 * */ public class BlurWeatherImage { private static final String TAG = "BlurWeatherImage"; private Bitmap bitmap = null; private Paint paint; private Canvas canvas; private FileOutputStream out = null; private float wRate; private float hRate; private int width; private int height; private Context context; private static final String IMAGENAME="ani_cloudy_night.png"; public BlurWeatherImage(Context context) { super(); this.context = context; DisplayMetrics dm = context.getResources().getDisplayMetrics(); width = dm.widthPixels; height = dm.heightPixels; bitmap = Bitmap.createBitmap(width,height,Bitmap.Config.ARGB_8888); paint = new Paint(Paint.ANTI_ALIAS_FLAG); canvas = new Canvas(bitmap); wRate = width / 720f; hRate = height / 1280f; } /** 模糊图片 */ public void blurImage() { BulurAsyncTask bat = new BulurAsyncTask(); bat.execute(); } class BulurAsyncTask extends AsyncTask<Void,Void,Void> { protected Void doInBackground(Void... params) { analysisXml(); return null; } protected void onPostExecute(Void result) { super.onPostExecute(result); listener.drawEnd(); } } public void analysisXml() { canvas.drawColor(0xff102d37); XmlResourceParser parser = context.getResources().getXml(R.xml.ani_cloudy_night); try { int event = parser.getEventType(); while (event != XmlResourceParser.END_DOCUMENT) { String tagName = parser.getName(); if (event == XmlResourceParser.START_TAG) { if (tagName.equals("view")) { int x = Integer.parseInt(parser.getAttributeValue(null,"x")); int y = Integer.parseInt(parser.getAttributeValue(null,"y")); int w = Integer.parseInt(parser.getAttributeValue(null,"w")); int h = Integer.parseInt(parser.getAttributeValue(null,"h")); String residname = parser.getAttributeValue(null,"resid"); int resid = context.getResources().getIdentifier(residname.replace("@drawable/",""),"drawable",context.getPackageName()); picture(bitmap,h,resid); SystemClock.sleep(100); } } event = parser.next(); } } catch (Exception e) { e.printStackTrace(); } try { out = context.openFileOutput(IMAGENAME,Context.MODE_PRIVATE); bitmap.compress(Bitmap.CompressFormat.PNG,100,out); out = context.openFileOutput("blur_"+IMAGENAME,Context.MODE_PRIVATE); Bitmap blurBitmap = BlurUtils.fastblur(context,bitmap,80); blurBitmap.compress(Bitmap.CompressFormat.PNG,out); android.util.Log.i(TAG,IMAGENAME + "writer success"); } catch (FileNotFoundException e) { e.printStackTrace(); } } /** * @param x * 元素x坐标 * @param y * 元素y坐标 * @param w * 元素宽度 * @param h * 元素高度 * @param resId * 资源id */ public void picture(Bitmap bitmap,int x,int y,int w,int h,int resId) { Bitmap element = BitmapFactory.decodeResource(context.getResources(),resId); int scaleW = (int) (w * wRate); int scaleH = (int) (h * hRate); Bitmap scaled = Bitmap.createScaledBitmap(element,scaleW,scaleH,false); canvas.drawBitmap(scaled,x * wRate,y * hRate,paint); } private OnDrawListener listener; public interface OnDrawListener { /** 绘图结束 */ public void drawEnd(); } public void setOnDrawListener(OnDrawListener listener) { this.listener = listener; } }原文链接：https://www.f2er.com/xml/296855.html
