自定义方形相机，如此接近但相机预览错误

Question

我正在做一个需要制作自定义方形相机的项目。我现在正在做一个示例项目，我会上传代码。

游戏计划是打开一个相机预览。在顶部绘制视图以产生它是方形相机的错觉。拍摄全屏图片，最后裁剪图片。

一切似乎都在按计划进行，但是当我最终拍摄照片时，保存在手机中的全屏照片的结果与我拍摄的照片不同。让我举例说明预期结果和最终结果，以向您展示问题所在：

如您所见，当我查看画廊中保存的图片时，我可以看到左侧的桌子以及右侧的部分墙壁，这些部分在我拍照时不在我的相机预览中。

我在我的相机预览类中尝试了各种不同的东西，但目前我正在使用在这篇文章的答案之一中找到的相机预览类：Android Camera Preview Stretched

我目前只发布我的相机预览课程，但如果您需要我的 main/xml 等，我会更愿意将其发布。我觉得我已经搜索了很长时间，但我无法弄清楚发生了什么。谢谢！

公共类 CameraPreview 扩展 SurfaceView 实现 SurfaceHolder.Callback {

private static final String TAG = "CameraPreview";

private Context mContext;
private SurfaceHolder mHolder;
private Camera mCamera;
private List<Camera.Size> mSupportedPreviewSizes;
private Camera.Size mPreviewSize;

public CameraPreview(Context context, Camera camera) {
    super(context);
    mContext = context;
    mCamera = camera;

    // supported preview sizes
    mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes();
    for(Camera.Size str: mSupportedPreviewSizes)
        Log.e(TAG, str.width + "/" + str.height);

    // Install a SurfaceHolder.Callback so we get notified when the
    // underlying surface is created and destroyed.
    mHolder = getHolder();
    mHolder.addCallback(this);
    // deprecated setting, but required on Android versions prior to 3.0
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

public void surfaceCreated(SurfaceHolder holder) {
    // empty. surfaceChanged will take care of stuff
}

public void surfaceDestroyed(SurfaceHolder holder) {
    // empty. Take care of releasing the Camera preview in your activity.
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    Log.e(TAG, "surfaceChanged => w=" + w + ", h=" + h);
    // If your preview can change or rotate, take care of those events here.
    // Make sure to stop the preview before resizing or reformatting it.
    if (mHolder.getSurface() == null){
        // preview surface does not exist
        return;
    }

    // stop preview before making changes
    try {
        mCamera.stopPreview();
    } catch (Exception e){
        // ignore: tried to stop a non-existent preview
    }

    // set preview size and make any resize, rotate or reformatting changes here
    // start preview with new settings
    try {

        Camera.Parameters parameters = mCamera.getParameters();
        parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
        parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
        mCamera.setParameters(parameters);
        mCamera.setDisplayOrientation(90);
        mCamera.setPreviewDisplay(mHolder);
        mCamera.startPreview();

    } catch (Exception e){
        Log.d(TAG, "Error starting camera preview: " + e.getMessage());
    }
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
    final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);

    if (mSupportedPreviewSizes != null) {
        mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height);
    }

    float ratio;
    if(mPreviewSize.height >= mPreviewSize.width)
        ratio = (float) mPreviewSize.height / (float) mPreviewSize.width;
    else
        ratio = (float) mPreviewSize.width / (float) mPreviewSize.height;

//      One of these methods should be used, second method squishes preview slightly
        setMeasuredDimension(width, (int) (width * ratio));
//      setMeasuredDimension((int) (width * ratio), height);

    float camHeight = (int) (width * ratio);
    float newCamHeight;
    float newHeightRatio;

    if (camHeight < height) {
        newHeightRatio = (float) height / (float) mPreviewSize.height;
        newCamHeight = (newHeightRatio * camHeight);
        Log.e(TAG, camHeight + " " + height + " " + mPreviewSize.height + " " + newHeightRatio + " " + newCamHeight);
        setMeasuredDimension((int) (width * newHeightRatio), (int) newCamHeight);
        Log.e(TAG, mPreviewSize.width + " | " + mPreviewSize.height + " | ratio - " + ratio + " | H_ratio - " + newHeightRatio + " | A_width - " + (width * newHeightRatio) + " | A_height - " + newCamHeight);
    } else {
        newCamHeight = camHeight;
        setMeasuredDimension(width, (int) newCamHeight);
        Log.e(TAG, mPreviewSize.width + " | " + mPreviewSize.height + " | ratio - " + ratio + " | A_width - " + (width) + " | A_height - " + newCamHeight);
    }
}

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.height / size.width;
        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;
}

}

Answer 1

class Preview extends ViewGroup implements SurfaceHolder.Callback {
    private final String TAG = "Preview";

    SurfaceView mSurfaceView;
    SurfaceHolder mHolder;
    Size mPreviewSize;
    List<Size> mSupportedPreviewSizes;
    Camera mCamera;
    Context context;
    boolean surfaceExists = false;
    boolean isPreview = false;
    static int wid = 0;
    static int hig = 0;
    

    int y = 0;
    private static final double ASPECT_RATIO = 3.0 / 4.0;
    private static final int PICTURE_SIZE_MAX_WIDTH = 1280;
    private static final int PREVIEW_SIZE_MAX_WIDTH = 3264;
    Preview(Context context, SurfaceView sv) {
        super(context);
        this.context=context;
        mSurfaceView = sv;
		mHolder = mSurfaceView.getHolder();
        mHolder.addCallback(this);
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

  @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        
    	int height = MeasureSpec.getSize(heightMeasureSpec);
        int width = MeasureSpec.getSize(widthMeasureSpec);

        if (width > height * ASPECT_RATIO) {
             width = (int) (height * ASPECT_RATIO + .5);
        } else {
            height = (int) (width / ASPECT_RATIO + .5);
        }

        setMeasuredDimension(width, height);
    }
public void determineDisplayOrientation(Camera camera) {
        CameraInfo cameraInfo = new CameraInfo();
        Camera.getCameraInfo(0, cameraInfo);

        Display display = ((WindowManager)context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
        int rotation = display.getRotation(); 
        int degrees  = 0;

        switch (rotation) {
            case Surface.ROTATION_0:
                degrees = 0;
                break;

            case Surface.ROTATION_90:
                degrees = 90;
                break;

            case Surface.ROTATION_180:
                degrees = 180;
                break;

            case Surface.ROTATION_270:
                degrees = 270;
                break;
        }
        int displayOrientation;

        if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
            displayOrientation = (cameraInfo.orientation + degrees) % 360;
            displayOrientation = (360 - displayOrientation) % 360;
        } else {
            displayOrientation = (cameraInfo.orientation - degrees + 360) % 360;
        }

        camera.setDisplayOrientation(displayOrientation);

    }
    @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.
    	try {
  		  if (mCamera != null) {
  	        	mHolder.removeCallback(this);
  	            mCamera.stopPreview();
  	            mCamera.release();
  	        }
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
    }
 private Size getOptimalPreviewSize(List<Size> 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) > 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 (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) {
    	
    	wid = w;
    	hig = h;
    	
    	
    }
     private Camera.Size getBestPreviewSize(int width, int height, Camera.Parameters parameters){
        Camera.Size bestSize = null;
        List<Camera.Size> sizeList = parameters.getSupportedPreviewSizes();
        
        bestSize = sizeList.get(0);
        
        for(int i = 1; i < sizeList.size(); i++){
         if((sizeList.get(i).width * sizeList.get(i).height) >
           (bestSize.width * bestSize.height)){
          bestSize = sizeList.get(i);
         }
        }

        return bestSize;
       }
    
    public void setupCamera(Camera camera,boolean isResolutionHigh) {
 	   mCamera = camera;
    	if (mCamera != null) {
    		determineDisplayOrientation(mCamera); 
    	   Camera.Parameters myParameters = mCamera.getParameters();
    		
    		if(isResolutionHigh){
    	   
      	    Camera.Size myBestSize = getBestPreviewSize(wid, hig, myParameters);
      	   
      	   if(myBestSize != null){
      	    myParameters.setPreviewSize(myBestSize.width, myBestSize.height);
      	    mCamera.setParameters(myParameters);
      	    mCamera.startPreview();
      	    isPreview = true;
      	    
      	   
      	      }
      	   
    		}
    		
    		else{
    			
    			 Size bestPreviewSize = determineBestPreviewSize(myParameters);
    		       Size bestPictureSize = determineBestPictureSize(myParameters);

    		       myParameters.setPreviewSize(bestPreviewSize.width, bestPreviewSize.height);
    		       myParameters.setPictureSize(bestPictureSize.width, bestPictureSize.height);
    		       myParameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);

    		       mCamera.setParameters(myParameters);
    		}
    	}
    }
    private Size determineBestPreviewSize(Camera.Parameters parameters) {
       List<Size> sizes = parameters.getSupportedPreviewSizes();

       return determineBestSize(sizes, PREVIEW_SIZE_MAX_WIDTH);
   }

   private Size determineBestPictureSize(Camera.Parameters parameters) {
       List<Size> sizes = parameters.getSupportedPictureSizes();

       return determineBestSize(sizes, PICTURE_SIZE_MAX_WIDTH);
   }

   protected Size determineBestSize(List<Size> sizes, int widthThreshold) {
       Size bestSize = null;

       for (Size currentSize : sizes) {
           boolean isDesiredRatio = (currentSize.width / 4) == (currentSize.height / 3);
           boolean isBetterSize = (bestSize == null || currentSize.width > bestSize.width);
           boolean isInBounds = currentSize.width <= PICTURE_SIZE_MAX_WIDTH;

           if (isDesiredRatio && isInBounds && isBetterSize) {
               bestSize = currentSize;
           }
       }

       if (bestSize == null) {
          // listener.onCameraError();

           return sizes.get(0);
       }

       return bestSize;
   }
   }
   }

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