如何預覽相機

Question

我使用該示例從相機獲取預覽：

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;

import android.app.Activity;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.TextureView;
import android.widget.FrameLayout;
import android.view.TextureView;
import android.widget.ImageView;
import android.graphics.Bitmap;
import android.graphics.ImageFormat;
import android.graphics.PixelFormat;
import android.graphics.SurfaceTexture;


public class MainActivity extends Activity implements
TextureView.SurfaceTextureListener, Camera.PreviewCallback {

    static {
        System.loadLibrary("JNIProcessor");
    }

    private final String TAG="LiveFeature";

    private Camera mCamera;
    private byte[] mVideoSource;

    private TextureView mTextureView;

    private String[] ResolutionList;
    private Menu AppMenu;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_live_feature);


        mTextureView.setSurfaceTextureListener(this);
    }

    @Override
    public void onSurfaceTextureSizeChanged(SurfaceTexture pSurface,
            int pWidth, int pHeight) {
        // Ignored
    }

    @Override
    public void onSurfaceTextureUpdated(SurfaceTexture pSurface) {
        // Ignored
    }

    @Override
    public void onPreviewFrame(byte[] pData, Camera pCamera) {
    }
}

似乎不建議使用Camera.PreviewCallback，我應該使用android.hardware.camera2。 問題是我找不到預覽回調函數來獲取原始數據字節。 我只想從相機中抓取幀而不將其渲染到表面中並將其放入JNI函數中。

Answer 1

這些步驟以獲得預覽：

• 在清單文件（Manifest.permission.CAMERA）中添加相機權限

• 使用以下方法獲取相機實例：

   public static Camera getCameraInstance() { Camera c = null; try { c = Camera.open(); // attempt to get a Camera instance } catch (Exception e) { Log.e(TAG, e.getMessage()); // Camera is not available (in use or does not exist) } return c; // returns null if camera is unavailable } 

• 創建一個擴展SurfaceView的類，並讓該類實現SurfaceHolder.Callback並將其Camera實例傳遞到其構造函數中。 使用getHolder()獲取構造函數中的getHolder()

• 在方法“ surfaceCreated”中，設置預覽顯示並開始預覽

  public void surfaceCreated(SurfaceHolder holder) { try { mCameraSource.start(holder); mCamera.setPreviewDisplay(mHolder); setWillNotDraw(false); } catch (Exception e) { Log.d(TAG, "Error setting camera preview: " + e.getMessage()); } }

• 停止預覽並釋放不再需要的相機

  mCamera.stopPreview(); mCamera.release();