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, 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);
}
}
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, x, y, w, 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, 100, 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;
}
}
原文地址：http://blog.csdn.net/u013369232/article/details/45392409
