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POAndroid SurfaceView conflict between CameraPreview and GoogleMaps API v2 View
 

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  1. POAndroid SurfaceView conflict between CameraPreview and GoogleMaps API v2 View
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    <p>My application has a set of tabs hosting FragmentActivity's. Some of these tabs contain a GoogleMaps Api v2 Support MapFragment and/or MapView and another single one is a QR scanner.</p> <p>The problem I am facing is that if you are currently viewing a SupportMapFragment or MapView on one tab, and then switch to the Scanner tab, the SurfaceView is still taken over by the previous SupportMapFragment / MapView (unless of course the Fragment/View is removed prior to selecting the Scanner tab). This was not a problem until trying to incorporate GoogleMaps Api v2, over v1, due to the SurfaceView use.</p> <p>I'm not entirely sure how to address this problem, I am thinking something along the lines of "clearing" the SurfaceView when the Scanner tab is selected and the CameraPreview is started? And achieve this using a canvas somehow? But I do not have a lot of knowledge on the SurfaceView class.</p> <p>Attached is my "CameraPreview" class which is used to handle the Android Camera on the Scanner tab. The GoogleMaps api v2 class is just the basic setup provided by Google, nothing special.</p> <p>Thank you for your time and help.</p> <pre><code>class CameraPreview extends ViewGroup implements SurfaceHolder.Callback { private final String TAG = "CameraPreview"; SurfaceView mSurfaceView; SurfaceHolder mHolder; Size mPreviewSize; List&lt;Size&gt; mSupportedPreviewSizes; Camera mCamera; PreviewCallback mPreviewCallback; AutoFocusCallback mAutoFocusCallback; CameraPreview(Context context, PreviewCallback previewCallback, AutoFocusCallback autoFocusCb) { super(context); mPreviewCallback = previewCallback; mAutoFocusCallback = autoFocusCb; mSurfaceView = new SurfaceView(context); addView(mSurfaceView); // Install a SurfaceHolder.Callback so we get notified when the // underlying surface is created and destroyed. mHolder = mSurfaceView.getHolder(); mHolder.addCallback(this); mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); } public void setCamera(Camera camera) { mCamera = camera; if (mCamera != null) { mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes(); requestLayout(); } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { // We purposely disregard child measurements because act as a // wrapper to a SurfaceView that centers the camera preview instead // of stretching it. final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec); final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec); setMeasuredDimension(width, height); if (mSupportedPreviewSizes != null) { mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height); } } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { if (changed &amp;&amp; getChildCount() &gt; 0) { final View child = getChildAt(0); final int width = r - l; final int height = b - t; int previewWidth = width; int previewHeight = height; if (mPreviewSize != null) { previewWidth = mPreviewSize.width; previewHeight = mPreviewSize.height; } // Center the child SurfaceView within the parent. if (width * previewHeight &gt; height * previewWidth) { final int scaledChildWidth = previewWidth * height / previewHeight; child.layout(0, 0, width, height); } else { final int scaledChildHeight = previewHeight * width / previewWidth; child.layout(0, 0, width,height); } } } public void surfaceCreated(SurfaceHolder holder) { // The Surface has been created, acquire the camera and tell it where // to draw. try { if (mCamera != null) { mCamera.setPreviewDisplay(holder); mCamera.setDisplayOrientation(90); } } catch (IOException exception) { Log.e(TAG, "IOException caused by setPreviewDisplay()", exception); } } public void surfaceDestroyed(SurfaceHolder holder) { // Surface will be destroyed when we return, so stop the preview. if (mCamera != null) { mCamera.stopPreview(); } } private Size getOptimalPreviewSize(List&lt;Size&gt; sizes, int w, int h) { final double ASPECT_TOLERANCE = 0.1; double targetRatio = (double) w / h; if (sizes == null) return null; Size optimalSize = null; double minDiff = Double.MAX_VALUE; int targetHeight = h; // Try to find an size match aspect ratio and size for (Size size : sizes) { double ratio = (double) size.width / size.height; if (Math.abs(ratio - targetRatio) &gt; ASPECT_TOLERANCE) continue; if (Math.abs(size.height - targetHeight) &lt; minDiff) { optimalSize = size; minDiff = Math.abs(size.height - targetHeight); } } // Cannot find the one match the aspect ratio, ignore the requirement if (optimalSize == null) { minDiff = Double.MAX_VALUE; for (Size size : sizes) { if (Math.abs(size.height - targetHeight) &lt; minDiff) { optimalSize = size; minDiff = Math.abs(size.height - targetHeight); } } } return optimalSize; } public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { if (holder.getSurface() == null){ // preview surface does not exist return; } // Now that the size is known, set up the camera parameters and begin // the preview. if(mCamera!=null){ Camera.Parameters parameters = mCamera.getParameters(); parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height); requestLayout(); mCamera.setParameters(parameters); mCamera.setPreviewCallback(mPreviewCallback); mCamera.startPreview(); mCamera.autoFocus(mAutoFocusCallback); } } } </code></pre>
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    1. CO"My application has a set of tabs hosting FragmentActivity's" -- using activities in tabs has been deprecated for over two years. "I'm not entirely sure how to address this problem" -- switching to a non-obsolete tab model, such as `ViewPager` and `PagerTabStrip`, may help. While I have not tried two distinct `SurfaceView` uses, you can certainly host multiple Maps V2 fragments in a `ViewPager`. You are also welcome to try action bar tabs or `FragmentTabHost`, as replacement for activities-in-tabs.
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      1. USCommonsWare
    2. CO@CommonsWare: Thank you for your input. I did actually originally have the apps tabs setup through use of fragments only, but wanted a separate fragment backstack for each tab, and recently refactored to TabActivity to accommodate this. FragmentTabHost looks like it will also provide this separate backstack so I will look into it further. Cheers.
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      1. USTheo Cartwright
    3. COYou wouldn't happen to have an example of this "Multiple Maps V2 fragments in a ViewPager" would you?
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      1. USTheo Cartwright
 

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