我已经创建了自己的自定义 SurfaceView，它可以自己正常工作，但是当我尝试将两个放在TabWidget中的单独选项卡上时，无论选择哪个选项卡，都只会显示一个，并且它始终是 SurfaceView 在应用程序启动。
为了说明问题，我创建了可以编译以显示问题的示例代码。
下面的SurfaceView，叫做SurfaceViewCircle，只是简单的创建一个位图，默认画一个蓝色的圆圈，然后显示出来。有一个公共方法changeColour()，它将改变位图中的圆圈颜色。
其次，我创建了一个 XML 布局，它只包含一个 SurfaceViewCircle 实例。
在 Activity 类中，我创建了一个 TabWidget 和主机等。然后我将上述 XML 膨胀两次，但在一个实例中，我将 SurfaceViewCircle 的颜色更改为红色。一旦应用程序运行，无论我选择哪个选项卡，红色圆圈总是显示，除了当应用程序退出并显示蓝色圆圈时的简短实例。
谁能指出我在使用 SurfaceView 时是否遗漏了一步？
这是活动代码：
public class TestActivity extends Activity {
/** Called when the activity is first created. */
private TabHost mTabHost;
private Context mTabHostContext;
private View surfaceView1, surfaceView2;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/*
* Setup tabs
*/
setContentView(R.layout.maintabs);
setupTabHost(); //Prepares the TabHost from code rather than XML;
mTabHost.getTabWidget().setDividerDrawable(R.drawable.tab_divider); //Sets a thin dividing line
mTabHostContext = mTabHost.getContext();
surfaceView1 = LayoutInflater.from(mTabHostContext).inflate(R.layout.surfaceviewindependent, null);
SurfaceViewCircle s = (SurfaceViewCircle)surfaceView1.findViewById(R.id.circle1);
/*
* Change the colour to red
*/
s.changeColour(getResources().getColor(R.color.red_square));
/*
* Create a second layout containing SurfaceViewCircle but leave circle as default blue.
*/
surfaceView2 = LayoutInflater.from(mTabHostContext).inflate(R.layout.surfaceviewindependent, null);
setupTab(surfaceView1,"SurfaceView1");
setupTab(surfaceView2,"SurfaceView2");
}
private void setupTabHost() {
mTabHost = (TabHost) findViewById(android.R.id.tabhost);
mTabHost.setup();
}
private void setupTab(final View view, final String tag) {
View tabview = createTabView(mTabHost.getContext(), tag); // This creates a view to be used in the TAB only
/* this creates the tab content AND applies the TAB created in the previous step in one go */
TabSpec setContent = mTabHost.newTabSpec(tag).setIndicator(tabview).setContent(new TabContentFactory() {
public View createTabContent(String tag) {return view;}
});
mTabHost.addTab(setContent);
}
private static View createTabView(final Context context, final String text) {
View view = LayoutInflater.from(context).inflate(R.layout.tabs_bg, null);
TextView tv = (TextView) view.findViewById(R.id.tabsText);
tv.setText(text);
return view;
}
}
这是我的自定义 SurfaceView：
public class SurfaceViewCircle extends SurfaceView implements SurfaceHolder.Callback{
private Paint paint, circlePaint;
private Bitmap bitmap = null;
private int w;
private int h;
private int colour = 0;
private Resources r = null;
private _Thread t = null;
private boolean surfaceIsCreated;
public SurfaceViewCircle(Context context) {
super(context);
initialise();
}
public SurfaceViewCircle(Context context, AttributeSet attrs) {
super(context, attrs);
initialise();
}
public SurfaceViewCircle(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initialise();
}
private void initialise(){
r = getResources();
getHolder().addCallback(this);
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setFilterBitmap(true);
colour = R.color.blue_square;
circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
circlePaint.setColor(r.getColor(colour));
circlePaint.setStyle(Style.FILL);
circlePaint.setStrokeWidth(0.02f);
t = new _Thread(getHolder());
}
public void changeColour(int colour){
circlePaint.setColor(colour);
if (surfaceIsCreated){
createBitmap();
}
synchronized (t){
t.notify();
}
}
private Bitmap createBitmap(){
Bitmap b = null;
b = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(b);
c.scale((float)w, (float)w); //Scales the background for whatever pixel size
c.drawCircle(0.5f, 0.5f, 0.5f, circlePaint);
//c.drawColor(r.getColor(colour));
return b;
}
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
int width = measure(widthMeasureSpec);
int height = measure(heightMeasureSpec);
int d = Math.min(width, height);
setMeasuredDimension(d,d);
}
private int measure(int measureSpec) {
int result = 0;
// Decode the measurement specifications
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
return specSize;
}
@Override
protected void onSizeChanged(int w, int h, int oldW, int oldH){
super.onSizeChanged(w, h, oldW, oldH);
//synchronized (this){
this.w = Math.min(w, h);
this.h = w;
//}
Bitmap b = createBitmap();
bitmap = b;
Log.i("Square", "onSizeChanged() called.");
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
Log.i("Panel", "surfaceCreated() called.");
t.setRunning(true);
t.start();
surfaceIsCreated = true;
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
Log.i("Square", "surfaceDestroyed() called.");
surfaceIsCreated = false;
boolean retry = true;
synchronized (t){
t.setRunning(false);
t.notify();
}
while (retry) {
try {
t.join();
retry = false;
} catch (InterruptedException e) {
// we will try it again and again...
}
}
}
private class _Thread extends Thread {
private SurfaceHolder _surfaceHolder;
private boolean _run = false;
public _Thread(SurfaceHolder surfaceHolder) {
_surfaceHolder = surfaceHolder;
}
public void setRunning(boolean run) {
_run = run;
}
@Override
public void run() {
Canvas c = null;
while (_run){
try {
c = _surfaceHolder.lockCanvas(null);
synchronized (_surfaceHolder) {
synchronized(bitmap){
c.drawBitmap(bitmap, 0, 0, paint);
}
}
} finally {
// do this in a finally so that if an exception is thrown
// during the above, we don't leave the Surface in an
// inconsistent state
if (c != null) {
_surfaceHolder.unlockCanvasAndPost(c);
}
}
synchronized(this){
try {
wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
}
}
}
}
}
}
maintabs.xml 文件：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@android:id/tabhost" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout android:orientation="vertical"
android:layout_width="fill_parent" android:layout_height="fill_parent">
<TabWidget android:id="@android:id/tabs"
android:layout_width="fill_parent" android:layout_height="wrap_content"
android:layout_marginLeft="0dip" android:layout_marginRight="0dip" />
<FrameLayout android:id="@android:id/tabcontent"
android:layout_width="fill_parent" android:layout_height="fill_parent" />
</LinearLayout>
</TabHost>
</LinearLayout>
和surfaceviewindependent.xml：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<uk.co.androidcontrols.gauges.SurfaceViewCircle
android:id="@+id/circle1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="0.5"
android:layout_margin="1dip">
</uk.co.androidcontrols.gauges.SurfaceViewCircle>
</LinearLayout>
我还注意到其他人在这里遇到了类似的问题。
为糟糕的格式道歉，但代码编辑器几乎不可能用于大代码引号！
附加信息
我尝试使用setVisibility()'inonvisibilityChanged()但最终导致异常：
protected void onVisibilityChanged(View changedView, int visibility){
super.onVisibilityChanged(changedView, visibility);
changedView.setVisibility(visibility);
Log.i("SurfaceViewCircle", "onVisibilityChanged() called.");
}
java.lang.IllegalThreadStateException: Thread already started.
看起来调用changedView.setvisibility()每次都会破坏表面。