Like many others, I am trying to draw 3D objects (using GLSurfaceView) on camera preview (using SurfaceView), along with some buttons placed on top. I actually got a prototype working, but I could not get the onResume working correctly. After a resume, GLSurfaceView stays behind and is not visible anymore. I know that it is working, because I can see the drawing fine if I remove the SurfaceView from the layout.
The target is Nexus One, running stock 2.3.3 ROM.
Here's the layout xml:
<com.example.cameratest.GLPreview
android:id="@+id/cubes"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
<com.example.cameratest.Preview
android:id="@+id/camera"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/buttongroup"
android:orientation="vertical"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_gravity="right" android:gravity="center">
<Button android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center" android:id="@+id/buttonClose"></Button>
<Button android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center" android:id="@+id/buttonMode"></Button>
<Button android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center" android:id="@+id/buttonCameraInfo"></Button>
</LinearLayout>
All of this is wrapped in a <merge> block, but for some reason, I could not include it in the above <code> listing. Preview is the class that extends SurfaceView and implements the camera preview logic.
This works fine when the activity launches. After I launch another activity (for example, by pressing one of the buttons) and finish that activity, the main activity resumes but the 3D objects are not visible anymore.
I found this discussion where it is mentioned that setZOrderMediaOverlay() will help fix this z-ordering issue. Also, the Android document for setZOrderMediaOverlay() says this function should be called "before the surface view's containing window is attached to the window manager". I do not know how I should interpret that statement, so I put debug statements in the code to see the sequence of events. Here's how the GLSurfaceView code looks like:
public class GLPreview extends GLSurfaceView
{
private static final String TAG = "GLPreview";
public GLPreview(Context context, AttributeSet attrs)
{
super(context, attrs);
// this.setZOrderMediaOverlay(true);
}
public void onPause()
{
super.onPause();
Log.d(TAG, "GLPreview: OnPause");
}
public void onResume()
{
// this.setZOrderMediaOverlay(true);
super.onResume();
Log.d(TAG, "GLPreview: OnResume");
}
public void surfaceCreated(SurfaceHolder holder)
{
Log.d(TAG, "GLPreview: surfaceCreated");
super.surfaceCreated(holder);
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h)
{
Log.d(TAG, String.format("GLPreview: surfaceChanged, format=%d, w=%d, h=%d", format, w, h));
super.surfaceChanged(holder, format, w, h);
}
public void surfaceDestroyed(SurfaceHolder holder)
{
Log.d(TAG, "GLPreview: surfaceDestroyed");
super.surfaceDestroyed(holder);
}
protected void onAttachedToWindow()
{
Log.d(TAG, "GLPreview: onAttachedToWindow");
super.onAttachedToWindow();
}
protected void onDetachedFromWindow()
{
Log.d(TAG, "GLPreview: onDetachedFromWindow");
super.onDetachedFromWindow();
}
protected void onWindowVisibilityChanged (int vis)
{
String newVisibility;
switch (vis)
{
case View.GONE:
newVisibility = "GONE";
break;
case View.INVISIBLE:
newVisibility = "INVISIBLE";
break;
case View.VISIBLE:
newVisibility = "VISIBLE";
break;
default:
newVisibility = String.format("Unknown constant %d", vis);
}
Log.d(TAG, String.format("GLPreview: onWindowVisibilityChanged -> %s", newVisibility));
super.onWindowVisibilityChanged(vis);
}
}
Here's the sequence of events when I start the application:
GLPreview: OnResume GLPreview: onAttachedToWindow GLPreview: onWindowVisibilityChanged -> VISIBLE GLPreview: surfaceCreated GLPreview: surfaceChanged, format=1, w=800, h=480
So I assumed that setZOrderMediaOverlay() needs to be called in either onResume() or in the constructor. However, I tried various combinations of setZOrderMediaOverlay() with true or false, in the GLSurfaceView or the SurfaceView classes, but none of it helped with the problem.
I am relatively new when it comes to Android programming. I have come so far but at this point I need some help. If someone who used setZOrderMediaOverlay() successfully in this scenario and got it working with onResume() let me know how this needs to be done.
Thanks a lot in advance!
I have struggled with the same issue for some time, but believe the code below now works. (It continues to work after pausing/ locking regardless of whether the camera is on or off).
Firstly, I haven't got any views etc defined in the layout file - they're created in code. The following is called from the main onCreate() method - Note the setZOrderMediaOverlay() on the augScreen.
I have done nothing special within onPause() or onResume() apart from passing onPause() and onResume() through to the augScreen.
// 1 - Camera Preview
camScreen = new CameraPreview(this);
setContentView(camScreen, new LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
// 2 - 3D object display
augScreen = new AR_SurfaceView(this, getViewRange());
addContentView(augScreen, new LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
augScreen.setZOrderMediaOverlay(true);
// 3 - Permanent overlay
RelativeLayout overlayScreen = new OverlayView(this);
addContentView(overlayScreen, new LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
overlayScreen.setVisibility(View.VISIBLE);
// 4 - UI buttons (toggleable)
uiScreen = new UserInterfaceView(this);
addContentView(uiScreen, new LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));