Android全屏摄像头——同时保持摄像头选择比例

Question

我们正在尝试构建类似于Instagram 相机屏幕的东西。即允许用户拍摄square 照片。在执行此操作时，U.i 必须能够让用户在fullScreen 模式下看到相机。我们要强制用户以portrait 模式拍照

获取相机可能的比例

我们正在计算来自camera 的best 比率

   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;
}

使其全屏显示。

public FrameLayout setCameraLayout(int width, int height) {
     float newProportion = (float) width / (float) height;
     // Get the width of the screen
     int screenWidth =     this.customCameraActivity.getWindowManager().getDefaultDisplay()
            .getWidth();
     int screenHeight =    this.customCameraActivity.getWindowManager().getDefaultDisplay()
            .getHeight();
      float screenProportion = (float) screenWidth / (float) screenHeight;
      // Get the SurfaceView layout parameters
      ViewGroup.MarginLayoutParams lp = (ViewGroup.MarginLayoutParams)preview.getLayoutParams();


     if (newProportion > screenProportion) {
        lp.width = screenWidth;
        lp.height = (int) ((float) screenWidth / newProportion);
     } else {
        lp.width = (int) (newProportion * (float) screenHeight);
        lp.height = screenHeight;
    }

    //calculate the amount that takes to make it full screen (in the `height` parameter)
    float propHeight = screenHeight / lp.height;

    //make it full screen(
    lp.width = (int)(lp.width * propHeight);
    lp.height = (int)(lp.height * propHeight);

    frameLayout.setLayoutParams(lp);
    return frameLayout;

}

setCameraLayout 调用者

OnCreate 来自 Activity，然后是 surfaceChanged

 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width,
                           int height) {
    if (getHolder().getSurface() == null) {
        return;
    }
    try {
        cameraManager.getCamera().stopPreview();
    } catch (Exception e) {
        // tried to stop a non-existent preview
    }

    try {
        Camera.Parameters cameraSettings = cameraManager.getCamera().getParameters();

        cameraSettings.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
        this.cameraView.setCameraLayout(mPreviewSize.width, mPreviewSize.height);
        cameraManager.getCamera().setParameters(cameraSettings);
        cameraManager.getCamera().setPreviewDisplay(holder);

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

目标

手机上的全屏相机预览。

问题

现在我们得到了没有失真的预览，它是 GOOD! 并且它具有与 phone 相同的 height 以及也是 GOOD! . 但是！preview 的宽度大于phone width（当然）所以事实证明相机的中心不在手机的中心。我们考虑过的可能解决方案：

1. move 布局左到负位置，使预览中心位于屏幕中心。
2. crop 布局并仅绘制new preview 的中心，phone screens 应该可见

任何想法如何克服这个问题？

非常感谢！ :)

Answer 1

我通过设置 SurfaceView 的重力成功地使预览居中：

FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(wid, hei);
lp.gravity = Gravity.CENTER;
mSv.setLayoutParams(lp);

代码sn-p取自here，有耐心破译的欢迎使用。我想我正在解决类似的问题（预览旋转、扭曲、适合/填充）

祝你好运。

Answer 2

如果我从代码 sn-ps 中理解，每次用户更改方向或旋转相机时，您都会重新实例化相机。有什么理由这样做吗？

为什么不将预览限制为仅纵向并具有可旋转的叠加视图？我很确定其他人（Instagram、Snapchat 等）就是这样做的。如果我能找到它，我将用这个例子进行编辑。