我想为相机预览有效地进行简单的数字变焦，所以我想我只需将 SurfaceView 的大小调整为大于屏幕即可。其他问题(例如 3813049 )似乎表明这很容易，所以我在下面创建了示例代码，我希望让我在水平方向上只看到一半的图像(因为 SurfaceView 是屏幕的两倍宽)和让图像水平只占据屏幕的一半。但是，运行它(当针对我的 Thunderbolt 和 Android 2.2.1 上的 SDK 版本 4 时)导致能够在水平填充屏幕的同时水平地看到整个图像。 SurfaceView 在垂直方向上表现得像预期的那样(当我使其小于屏幕时)，但 Android 不允许我使 SurfaceView 大于屏幕。

如何实现数码变焦？ (不，我不能使用 Camera.Parameters.setZoom；不仅 Android 1.6 不支持，而且不同的相机支持和实现方式不同)

public class MagnifyTestActivity extends Activity implements SurfaceHolder.Callback {
    private MagnificationView mPreview;
    private SurfaceHolder mHolder;
    private Camera mCamera = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mPreview = new MagnificationView(this);
        setContentView(mPreview);
        mHolder = mPreview.getHolder();
        mHolder.addCallback(this);
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    public class MagnificationView extends SurfaceView {
        public MagnificationView(Context context) {
            super(context);
        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            Display display = getWindowManager().getDefaultDisplay();
            int width = display.getWidth()*2;
            int height = display.getHeight()/2;
            widthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY);
            heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }

    public void surfaceCreated(SurfaceHolder holder) {
        mCamera = Camera.open();
        try {
            mCamera.setPreviewDisplay(holder);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        mCamera.stopPreview();
        mCamera.release();
        mCamera = null;
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        mHolder.setFixedSize(w, h);
        mCamera.startPreview();
    }
}

更新:根据@Pulkit Sethi 的回应，可以垂直拉伸(stretch)/放大 SurfaceView，但不能水平拉伸(stretch)。要垂直放大 SurfaceView，只需将上面的 display.getHeight()/2 替换为 display.getHeight()*2 即可。另请注意，无论是在我的代码中还是在 Pulkit 的代码中，更改宽度都不会产生任何水平放大。

最佳答案

//Activity class

public class CameraActivity extends Activity implements SurfaceListener {

    private static final String TAG = "CameraActivity";

    Camera mCamera;
    CameraPreview mPreview;
    private FrameLayout mCameraPreview;


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

        setContentView(R.layout.activity_camera);

        mCamera = getCameraInstance();
        mPreview = new CameraPreview(this, mCamera);

        mCameraPreview = (FrameLayout) findViewById(R.id.camera_preview);
        mCameraPreview.addView(mPreview);


    }

    @Override
    protected void onPause() {
        super.onPause();

        releaseCamera();
    }

    private Camera getCameraInstance() {
        Camera camera = null;
        try {
            camera = Camera.open();
        } catch (Exception e) {

        }
        return camera;
    }

    private void releaseCamera() {
        if (null != mCamera) {
            mCamera.release();
        }

        mCamera = null;
    }

    @Override
    public void surfaceCreated() {

        //Change these mate
        int width = 1000;
        int height = 1000;
        // Set parent window params
        getWindow().setLayout(width, height);

        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(
                width, height);
        mCameraPreview.setLayoutParams(params);
        mCameraPreview.requestLayout();
    }
}

// Preview class

public class CameraPreview extends SurfaceView implements
        SurfaceHolder.Callback {

    private static final String TAG = "CameraPreview";

    Context mContext;
    Camera mCamera;
    SurfaceHolder mHolder;

    public interface SurfaceListener{
        public void surfaceCreated();
    }
    SurfaceListener listener;


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

        mContext = context;
        listener = (SurfaceListener)mContext;
        mCamera = camera;

        mHolder = getHolder();
        mHolder.addCallback(this);

        // Required prior 3.0 HC
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {

        try {
            mCamera.setPreviewDisplay(holder);

            Parameters params = mCamera.getParameters();
            //Change parameters here
            mCamera.setParameters(params);

            mCamera.startPreview();

            listener.surfaceCreated();

        } catch (Exception e) {
            // TODO: handle exception
        }
    }

    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) {
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.

        Log.i(TAG, "Surface changed called");
        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
        mCamera.setDisplayOrientation(90);

        // start preview with new settings
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();

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

}

//Layout file 
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <FrameLayout
        android:id="@+id/camera_preview"
        android:layout_width="300dp"
        android:layout_height="400dp"
        android:layout_centerHorizontal="true"
        android:paddingTop="10dp" >
    </FrameLayout>

</RelativeLayout>

关于android - 如何使 SurfaceView 大于屏幕？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/6050923/