Android：HTC EVO（Android 2.1 或 2.2）上的相机预览方向

Question

我正在开发一个依赖于相机 API 的 Android 应用程序，使用 HTC EVO 作为我的测试设备。到目前为止，无论我尝试过什么，相机预览看起来正确的唯一时间是在横向模式下（具体来说是 90 度旋转）。在纵向模式（0 度旋转）下，似乎无法正确定位预览。

设备上的默认相机应用程序（用于 HTC Sense）允许任何类型的旋转都没有任何问题，所以我知道没有硬件限制。我什至从 HTC 的开发者site 那里下载了一些源代码，但显然都是 C 内核的东西。

谁能指出我解决这个问题的正确方向？有没有办法在 Android 2.1 或 2.2 中正确旋转预览？

谢谢。

附：这是我正在使用的代码，以防万一……

package spikes.cameraSpike03;

import java.util.List;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.os.Bundle;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;

public class MainActivity extends Activity implements SurfaceHolder.Callback {
 private static final String LOG_TAG = "spikes.cameraSpike03 - MainActivity";

 private Camera _camera;
 private boolean _previewIsRunning = false;

 private SurfaceView _svCameraView;
 private SurfaceHolder _surfaceHolder;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        getWindow().setFormat(PixelFormat.TRANSLUCENT);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

        setContentView(R.layout.main);

        _svCameraView = (SurfaceView)findViewById(R.id.svCameraView);

        _surfaceHolder = _svCameraView.getHolder();
        _surfaceHolder.addCallback(this);
        _surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
  if(_previewIsRunning){
   _camera.stopPreview();
  }

  try{
   Camera.Parameters parameters = _camera.getParameters();

   //Get the optimal preview size so we don't get an exception when setting the parameters 
   List<Size> supportedPreviewSizes = parameters.getSupportedPreviewSizes();
   Size optimalPreviewSize = getOptimalPreviewSize(supportedPreviewSizes, width, height);
   parameters.setPreviewSize(optimalPreviewSize.width, optimalPreviewSize.height);

   _camera.setParameters(parameters);

   _camera.setPreviewDisplay(holder);
  }
  catch(Exception ex){
   ex.printStackTrace();
   Log.e(LOG_TAG, ex.toString());
  }

  _camera.startPreview();
  _previewIsRunning = true;
 }

 @Override
 public void surfaceCreated(SurfaceHolder holder) {
  _camera = Camera.open();
 }

 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
  _camera.stopPreview();
  _previewIsRunning = false;
  _camera.release();
 }

 private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
        final double ASPECT_TOLERANCE = 0.05;
        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;
    }

}

Answer 1

如果适合您的设计，请尝试将 Activity 的方向锁定为水平方向，或者尝试以下操作：

private android.hardware.Camera mCamera;

...

mCamera.setDisplayOrientation(90);
params.setRotation(90);
mCamera.setParameters(params);

但我认为 setDisplayOrientation 可能只有 2.2...