相机预览在少量Android设备上展开 [英] Camera Preview Stretched on Few Android Devices

问题描述

我为Android应用程序制作了自定义相机像SnapChat，但相机预览伸展在很少的设备，如（Moto g第二代，一+一），但不是（三星s3，三星s4）。我使用以下参考资料启动。

I am making custom Camera like "SnapChat" for a Android app but camera preview is stretched on Few devices like(Moto g second generation , one+ one) but not on(Samsung s3, Samsung s4). I have use the following reference Camera display / preview in full screen does not maintain aspect ratio - image is skewed, stretched in order to fit on the screen. But this does not help me 100%. I am sharing the screen .

Stretched image on Samsung Moto G second generation is .

Samsung S3 images which does not stretched is Above

private void setPreviewLayout() {
    if (null == mCamera) {
        return;
    }
    Camera.Parameters parameters = null;
    Camera.Size size = null;
    try {
        int screenWidth = (int) getResources().getDisplayMetrics().widthPixels;
        int screenHeight = (int) getResources().getDisplayMetrics().heightPixels;
        parameters = mCamera.getParameters();
        size = getOptimalPreviewSize(mCamera.getParameters().getSupportedPreviewSizes(), screenWidth, screenHeight);
        if (size != null) {

            parameters.setPreviewSize(size.width, size.height);

        }

        parameters.setPictureSize(screenHeight, screenWidth);
        ;
        mCamera.setParameters(parameters);
        if (on && currentCameraId == Camera.CameraInfo.CAMERA_FACING_BACK) {
            parameters.setFlashMode(Camera.Parameters.FLASH_MODE_ON);
        } else {
            parameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
        }
        parameters.setWhiteBalance(Camera.Parameters.WHITE_BALANCE_AUTO);
        parameters.setExposureCompensation(0);
        parameters.setPictureFormat(ImageFormat.JPEG);
        parameters.setJpegQuality(100);
        List<String> focusModes = parameters.getSupportedFocusModes();
        if (focusModes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)) {
            parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
        } else if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
            parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
        }
        mCamera.setParameters(parameters);
        /*
         * camera.setPreviewDisplay(surfaceHolder); camera.startPreview();
         */

    } catch (Exception e) {
        e.printStackTrace();
    }

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

    if (sizes == null)
        return null;

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

    int targetHeight = h;

    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);
        }
    }

    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;
}

解决方案

Using getOptimalPreviewSize() is important, but it does not resolve all stretching on all devices in all layouts. You must be prepared to crop the preview a little bit so that the preview fills the screen without distortion.

There are different techniques to force the size of the surface different from the actual screen size, but this one I find the easiest:

I add the CameraView to my layout:

public class CameraView extends SurfaceView implements SurfaceHolder.Callback {

public CameraView(Context context, AttributeSet attr) {
    super(context, attr);

    // install a SurfaceHolder.Callback so we get notified when the
    // underlying surface is created and destroyed.
    getHolder().addCallback(this);
}

@Override public void surfaceCreated(SurfaceHolder holder) {
    openCamera();
    bCameraInitialized = false;
}

@Override public void surfaceDestroyed(SurfaceHolder holder) {
    camera.release();
}

@Override public void surfaceChanged(SurfaceHolder holder,
        int format, int w, int h) {
        if (bCameraInitialized) {
            // we will get here after we have resized the surface, see below 
            return;
        }
        cameraSetup(w, h);
        bCameraInitialized = true;
}

private void cameraSetup(int w, int h) {
    // set the camera parameters, including the preview size

    FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) getLayoutParams();
    double cameraAspectRatio = ((double)optimalSize.width)/optimalSize.height;

    if (((double)h)/w > cameraAspectRatio) {
        lp.width = (int)(h/cameraAspectRatio+0.5);
        lp.height = h;
    }
    else {
        lp.height = (int)(w*cameraAspectRatio + 0.5);
        lp.width = w;
        lp.topMargin = (h - lp.height)/2;
    }
    lp.gravity = Gravity.CENTER_HORIZONTAL | Gravity.TOP;

    setLayoutParams(lp);
    requestLayout();
}

To emphasize the main idea, I did not include error handling, and I did not show here how the camera is actually started with a secondary Looper.

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