城乡与住房建设部网站/bt磁力链好用的引擎
如果当View tree很复杂，结构很深的时候， 使用动画的时候会发现即使开了硬件加速还是有些卡，这是因为android系统自带的动画是在UI线程来处理的， 而且每次需要重绘整个View tree，虽然你可以指定重新绘制的区域，不过这样比较麻烦，
SurfaceView中View的绘制不是在UI线程中，所以可以避免上面的问题。我们只要做到SurfaceView背景能够透明就行了。在需要的地方盖一层SurfaceView， 做动画时显示出来。下面是示例代码。
package com.example.myapp;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.PixelFormat;
import android.graphics.Region;
import android.util.AttributeSet;
import android.view.Surface.OutOfResourcesException;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class ZenClockSurface extends SurfaceView implements
SurfaceHolder.Callback {
private DrawClock drawClock;
public ZenClockSurface(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
getHolder().addCallback(this);
}
public ZenClockSurface(Context context) {
super(context);
getHolder().addCallback(this);
}
public ZenClockSurface(Context context, AttributeSet attrs) {
super(context, attrs);
getHolder().addCallback(this);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
drawClock = new DrawClock(getHolder(), getResources());
drawClock.setRunning(true);
drawClock.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
drawClock.setRunning(false);
while (retry) {
try {
drawClock.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
class DrawClock extends Thread {
private boolean runFlag = false;
private SurfaceHolder surfaceHolder;
private Bitmap picture;
private Matrix matrix;
private Paint painter;
public DrawClock(SurfaceHolder surfaceHolder, Resources resources) {
this.surfaceHolder = surfaceHolder;
picture = BitmapFactory.decodeResource(resources,
R.drawable.ic_launcher);
matrix = new Matrix();
this.painter = new Paint();
this.painter.setStyle(Paint.Style.FILL);
this.painter.setAntiAlias(true);
this.painter.setFilterBitmap(true);
}
public void setRunning(boolean run) {
runFlag = run;
}
@Override
public void run() {
Canvas canvas;
while (runFlag) {
matrix.preRotate(1.0f, picture.getWidth() / 2,
picture.getHeight() / 2);
canvas = null;
try {
canvas = surfaceHolder.lockCanvas(null);
synchronized (surfaceHolder) {
float[] f = new float[9];
matrix.getValues(f);
float y = f[Matrix.MTRANS_Y];
matrix.postTranslate(0, 10);
canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR);
canvas.drawBitmap(picture, matrix, this.painter);
float[] f1 = new float[9];
matrix.getValues(f1);
float y1 = f1[Matrix.MTRANS_Y];
if (y1 >= 800) {
matrix.setTranslate(0, 0);
}
}
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
if (canvas != null) {
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}
}
}
调用的activity
package com.example.myapp;
import android.app.Activity;
import android.graphics.PixelFormat;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebView;
import android.widget.LinearLayout;
import android.widget.ScrollView;
public class MyActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ZenClockSurface sfvTrack = (ZenClockSurface)findViewById(R.id.zenClockSurface1);
sfvTrack.setZOrderOnTop(true); // necessary
SurfaceHolder sfhTrack = sfvTrack.getHolder();
sfhTrack.setFormat(PixelFormat.TRANSLUCENT);
WebView webview = (WebView) findViewById(R.id.webview);
webview.getSettings().setJavaScriptEnabled(true);
webview.loadUrl("http://m.vip.com");
}
}
布局。
android:id="@+id/RelativeLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@color/red"
android:orientation="vertical" >
android:id="@+id/zenClockSurface1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"/>
使SurfaceView透明是下面这几句
ZenClockSurface sfvTrack = (ZenClockSurface)findViewById(R.id.zenClockSurface1);
sfvTrack.setZOrderOnTop(true); // necessary
SurfaceHolder sfhTrack = sfvTrack.getHolder();
sfhTrack.setFormat(PixelFormat.TRANSLUCENT);
这句是清屏。
canvas.drawColor(0,android.graphics.PorterDuff.Mode.CLEAR);