接《android SurfaceView初次使用錯誤解決辦法》
我在MainActivity中直接調用這個類的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();//一運行這個就報錯
}
}
一運行，就報錯了。
找到別人SurfaceView代碼，他們是讓SurfaceView實現Rannable接口，自帶刷新。於是，我也添加一個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();//開啓刷新線程
}
@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();
}
}
}
}
嘿嘿完全木有問題！然後我開始懷疑是doDraw調用時間不對，於是把開啓刷新線程放在構造函數中。
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();//在這裏啓動刷新線程
}
@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();
}
}
}
}
果然出現了錯誤！開來doDraw（）是想在哪裏重繪就重繪，但並不是想在什麼時候重繪就能重繪的，得在surface Created之後才行。
於是我再在MainActivity中使用doDraw方法：（在判斷surface Created之後調用）
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創建
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();//開啓刷新線程
}
}
其中ifSurfaceIsCreated()就是用來判斷surface是否已經創建好的方法，修改之後的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);
}
}
一運行，OK！
