Multiscreen Support in android : Camera preview is stretched in Samsung Galaxy s4 mini issue android

问题

This is my Preview class to take a picture : it's working perfectly with many devices but Android Samsung Galaxy S4 shows me bad result => the problem that the image is stretched when preview.

You can see the image below :

Here is my code :

class Preview extends ViewGroup implements SurfaceHolder.Callback {
private final String TAG = "Preview";
SurfaceView mSurfaceView;
SurfaceHolder mHolder;
Camera.Size mPreviewSize;
List<Camera.Size> mSupportedPreviewSizes;
Camera mCamera;

Preview(Context context, SurfaceView sv) {
    super(context);
    mSurfaceView = sv;
    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();

        // get Camera parameters
        Camera.Parameters params = mCamera.getParameters();

        List<String> focusModes = params.getSupportedFocusModes();



        try {
                    if (focusModes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)) {
                        params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);

                    } else  if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
                        params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
                    }
                    else if (focusModes.contains(Camera.Parameters.FOCUS_MODE_INFINITY)) {
                        params.setFocusMode(Camera.Parameters.FOCUS_MODE_INFINITY);
                    }
            mCamera.setParameters(params);
                }
                catch (Exception e) {
                }
    }
}

@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 && getChildCount() > 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 > height * previewWidth) {
            final int scaledChildWidth = previewWidth * height / previewHeight;
            child.layout((width - scaledChildWidth) / 2, 0,
                    (width + scaledChildWidth) / 2, height);
        } else {
            final int scaledChildHeight = previewHeight * width / previewWidth;
            child.layout(0, (height - scaledChildHeight) / 2,
                    width, (height + scaledChildHeight) / 2);
        }
    }
}

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);
        }
    } 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 Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int w, int h) {
    final double ASPECT_TOLERANCE = 0.1;
    double targetRatio = (double) w / h;
    if (sizes == null) return null;

    Camera.Size optimalSize = null;
    double minDiff = Double.MAX_VALUE;

    int targetHeight = h;

    // Try to find an size match aspect ratio and size
    for (Camera.Size size : sizes) {
        double ratio = (double) size.width / size.height;
        if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
        if (Math.abs(size.height - targetHeight) < 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 (Camera.Size size : sizes) {
            if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }
    }
    return optimalSize;
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    if(mCamera != null) {
        if (mPreviewSize!=null){
            Camera.Parameters parameters = mCamera.getParameters();

            parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
            requestLayout();

            mCamera.setParameters(parameters);
            mCamera.startPreview();
        }

    }
}

}

I want to keep image support Multiscreen in android after preview.

回答1:

To not have a stretched image or preview , you should choose a previewSize that keep the same ratio as the screen of the phone. Then , you should set it before launching and starting the camera. Try this code :

public void setCamera(Camera camera, int screenW, int screenH) {

    //screenW ==> screen width of the phone in Pixels
    //screenH ==> screen height of the phone in Pixels

    mCamera = camera;
    if (mCamera != null) {
        mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes();
        if (mSupportedPreviewSizes != null) {
            mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, screenW
                    , screenH);
        }
        requestLayout();

        // get Camera parameters
        Camera.Parameters params = mCamera.getParameters();

        if (mPreviewSize != null)
            params.setPreviewSize(mPreviewSize.width, mPreviewSize.height);

        List<String> focusModes = params.getSupportedFocusModes();


        try {
            if (focusModes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)) {
                params.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);

            } else if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
                params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
            } else if (focusModes.contains(Camera.Parameters.FOCUS_MODE_INFINITY)) {
                params.setFocusMode(Camera.Parameters.FOCUS_MODE_INFINITY);
            }
            mCamera.setParameters(params);

            Log.i(TAG, " getPreviewSize " + mCamera.getParameters().getPreviewSize().width + " X "
                    + mCamera.getParameters().getPreviewSize().height);

            Log.i(TAG, " getPictureSize " + mCamera.getParameters().getPictureSize().width + " X "
                    + mCamera.getParameters().getPictureSize().height);

        } catch (Exception e) {
        }
    }
}

来源：https://stackoverflow.com/questions/42690797/multiscreen-support-in-android-camera-preview-is-stretched-in-samsung-galaxy-s