Android使用SurfaceView和Thread绘制
作者：互联网
我想用3个班级把球画到我的屏幕上.我已经阅读了一些关于此的内容,我发现了一个代码片段,可以在一个页面上使用3个类,Playing with graphics in Android
我修改了代码,以便我有一个正在移动的球,并在撞击墙壁时移动方向,如下图所示(这是使用链接中的代码).
现在我喜欢将这些类分成3个不同的页面,因为它们不会让所有东西变得如此拥挤,所有内容都以相同的方式设置.
这是我有的3个班级.
> BallActivity.java
> Ball.java
> BallThread.java
package com.brick.breaker;
import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
public class BallActivity extends Activity {
private Ball ball;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
ball = new Ball(this);
setContentView(ball);
}
@Override
protected void onPause() {
super.onPause();
setContentView(null);
ball = null;
finish();
}
}
package com.brick.breaker;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class Ball extends SurfaceView implements SurfaceHolder.Callback {
private BallThread ballThread = null;
private Bitmap bitmap;
private float x, y;
private float vx, vy;
public Ball(Context context) {
super(context);
bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ball);
x = 50.0f;
y = 50.0f;
vx = 10.0f;
vy = 10.0f;
getHolder().addCallback(this);
ballThread = new BallThread(getHolder(), this);
}
protected void onDraw(Canvas canvas) {
update(canvas);
canvas.drawBitmap(bitmap, x, y, null);
}
public void update(Canvas canvas) {
checkCollisions(canvas);
x += vx;
y += vy;
}
public void checkCollisions(Canvas canvas) {
if(x - vx < 0) {
vx = Math.abs(vx);
} else if(x + vx > canvas.getWidth() - getBitmapWidth()) {
vx = -Math.abs(vx);
}
if(y - vy < 0) {
vy = Math.abs(vy);
} else if(y + vy > canvas.getHeight() - getBitmapHeight()) {
vy = -Math.abs(vy);
}
}
public int getBitmapWidth() {
if(bitmap != null) {
return bitmap.getWidth();
} else {
return 0;
}
}
public int getBitmapHeight() {
if(bitmap != null) {
return bitmap.getHeight();
} else {
return 0;
}
}
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
public void surfaceCreated(SurfaceHolder holder) {
ballThread.setRunnable(true);
ballThread.start();
}
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
ballThread.setRunnable(false);
while(retry) {
try {
ballThread.join();
retry = false;
} catch(InterruptedException ie) {
//Try again and again and again
}
break;
}
ballThread = null;
}
}
package com.brick.breaker;
import android.graphics.Canvas;
import android.view.SurfaceHolder;
public class BallThread extends Thread {
private SurfaceHolder sh;
private Ball ball;
private Canvas canvas;
private boolean run = false;
public BallThread(SurfaceHolder _holder,Ball _ball) {
sh = _holder;
ball = _ball;
}
public void setRunnable(boolean _run) {
run = _run;
}
public void run() {
while(run) {
canvas = null;
try {
canvas = sh.lockCanvas(null);
synchronized(sh) {
ball.onDraw(canvas);
}
} finally {
if(canvas != null) {
sh.unlockCanvasAndPost(canvas);
}
}
}
}
public Canvas getCanvas() {
if(canvas != null) {
return canvas;
} else {
return null;
}
}
}
这是一张显示这些课程结果的图片.
我试图解决这个问题,但由于我对Android开发很新,我以为我可以寻求帮助.
有没有人知道是什么原因造成了这样的球？
代码与链接中的代码几乎相同,我试图尝试找到解决方案,但没有运气.
解决方法:
好吧,正如你在图像上看到的那样,你只画了球.相反,你需要在每次抽球之前重新绘制黑色背景(或任何你想要的).
或者,您可以仅在之前的位置绘制黑色区域,但是当您使用更多对象时,稍后可能会遇到问题.
here’s a nice sample,类似于你所做的
标签：android,surfaceview,ondraw 来源： https://codeday.me/bug/20191001/1838957.html