接《android SurfaceView初次使用错误解决办法》
我在MainActivity中直接调用这个类的doDraw：
package com.backgammon;
import android.app.Activity;
import android.os.Bundle;
public class MainActivity extends Activity implements Const{
private ChessView chessView;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.chessView = new ChessView(MainActivity.this);
setContentView(this.chessView);
//this.chessView.doDraw();//一运行这个就报错
}
}
一运行，就报错了。
找到别人SurfaceView代码，他们是让SurfaceView实现Rannable接口，自带刷新。于是，我也添加一个Runnable接口：
package com.backgammon;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.SurfaceHolder.Callback;
public class ChessView extends SurfaceView implements SurfaceHolder.Callback,Runnable {
private Paint paint;
private Thread thread;
public ChessView(Context context) {
super(context);
// TODO Auto-generated constructor stub
this.getHolder().addCallback(this);
paint = new Paint();
thread = new Thread(this);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
thread.start();//开启刷新线程
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
paint.setColor(Color.RED);
canvas.drawCircle(40, 40, 40, paint);
}
public void doDraw(){
Canvas canvas = this.getHolder().lockCanvas();
onDraw(canvas);
this.getHolder().unlockCanvasAndPost(canvas);
}
@Override
public void run() {
// TODO Auto-generated method stub
while(true){
this.doDraw();
try {
Thread.sleep(100);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
嘿嘿完全木有问题！然后我开始怀疑是doDraw调用时间不对，于是把开启刷新线程放在构造函数中。
package com.backgammon;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.SurfaceHolder.Callback;
public class ChessView extends SurfaceView implements SurfaceHolder.Callback,Runnable {
private Paint paint;
private Thread thread;
public ChessView(Context context) {
super(context);
// TODO Auto-generated constructor stub
this.getHolder().addCallback(this);
paint = new Paint();
thread = new Thread(this);
thread.start();//在这里启动刷新线程
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
//thread.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
paint.setColor(Color.RED);
canvas.drawCircle(0, 0, 40, paint);
}
public void doDraw(){
Canvas canvas = this.getHolder().lockCanvas();
onDraw(canvas);
this.getHolder().unlockCanvasAndPost(canvas);
}
@Override
public void run() {
// TODO Auto-generated method stub
while(true){
this.doDraw();
try {
Thread.sleep(100);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
果然出现了错误！开来doDraw（）是想在哪里重绘就重绘，但并不是想在什么时候重绘就能重绘的，得在surface Created之后才行。
于是我再在MainActivity中使用doDraw方法：（在判断surface Created之后调用）
package com.backgammon;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity implements Const{
private ChessView chessView;
private class FreshThread extends Thread{
@Override
public void run() {
// TODO Auto-generated method stub
super.run();
while(true){
while(!chessView.ifSurfaceIsCreated()){//等待surface创建
try {
Thread.sleep(100);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
chessView.doDraw();
}
}
}
private FreshThread freshThread = new FreshThread();
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.chessView = new ChessView(MainActivity.this);
setContentView(this.chessView);
freshThread.start();//开启刷新线程
}
}
其中ifSurfaceIsCreated()就是用来判断surface是否已经创建好的方法，修改之后的SurfaceView：
package com.backgammon;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.SurfaceHolder.Callback;
public class ChessView extends SurfaceView implements SurfaceHolder.Callback{
private Paint paint;
private boolean surfaceIsCreated = false;
public ChessView(Context context) {
super(context);
// TODO Auto-generated constructor stub
this.getHolder().addCallback(this);
paint = new Paint();
}
public boolean ifSurfaceIsCreated(){
return this.surfaceIsCreated;
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
this.surfaceIsCreated = true;
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
paint.setColor(Color.RED);
canvas.drawCircle(0, 0, 40, paint);
}
public void doDraw(){
Canvas canvas = this.getHolder().lockCanvas();
onDraw(canvas);
this.getHolder().unlockCanvasAndPost(canvas);
}
}
一运行，OK！
