在相机上叠加图像预览

介绍

我有一个自定义相机应用程序，我在其中通过自定义 SurfaceView 显示相机预览。我需要实现的是，从图像资源创建覆盖图像，该图像将显示在cameraPreview 上，例如滤镜。

我一直在不同的主题中搜索这个问题，但我还没有找到适用于我的应用程序的内容。

APPROACH

我一直在尝试使用 onDraw() 方法和其他选项将图像设置为位图，但我还没有实现显示图像。

这是我的代码：

CODE

public class CameraActivity extends Activity implements PictureCallback {

    private Button btnPhoto;
    CameraPreview cameraPreview;

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

        cameraPreview = (CameraPreview) findViewById(R.id.camera_preview);
        btnPhoto = (Button)findViewById(R.id.buttonTakePhoto);

        btnPhoto.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                takePhoto();
            }
        });
    }

    public void takePhoto() {
        cameraPreview.getCamera().takePicture(null, null, this);
    }
    //...
}

_

public class CameraPreview extends FrameLayout implements SurfaceHolder.Callback {

    private SurfaceView surfaceView;
    private Camera camera;

    public CameraPreview(Context context, AttributeSet attrs) {
        super(context, attrs);

        createCamera();

        surfaceView = new SurfaceView(context);
        addView(surfaceView);

        SurfaceHolder holder = surfaceView.getHolder();
        holder.addCallback(this);

        holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        holder.setKeepScreenOn(true);
    }

    private void createCamera() {
        //...
            try {
                this.camera = Camera.open(activeCameraId);
            } catch (Exception e) {
                return;
            }
        //...
    }

    public Camera getCamera() {
        return camera;
    }


    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        //...
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        //...
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        //...
    }
}

_

<com.uax.cameratakephoto.CameraPreview
    android:id="@+id/camera_preview"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_centerInParent="true" />

<Button  //THIS IS THE BUTTON TO TAKE THE PHOTO
    android:id="@+id/buttonTakePhoto"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:layout_centerVertical="true"
    android:background="@android:drawable/ic_menu_camera" />

<ImageView  //THIS IS A SMALL PREVIEW OF THE LAST PHOTO TAKEN
    android:id="@+id/imageView"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true" />

做这样的事情 通过扩展SurfaceView创建相机预览类

public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
    private SurfaceHolder mHolder;
    private Camera mCamera;
    private String TAG = "CameraPreview";

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

        // 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);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, now tell the camera where to draw the
        // preview.
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();
        } catch (IOException e) {
            Log.d(TAG, "Error setting camera preview: " + e.getMessage());
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        try {
            mCamera.stopPreview();
        } catch (Exception e) {
            // ignore: tried to stop a non-existent preview
        }
        mCamera.release();
    }

    @Override
    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.

        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
        StartPreview();
    }

    public void StartPreview() {
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();
        } catch (Exception e) {
            Log.d(TAG, "Error starting camera preview: " + e.getMessage());
        }
    }
}

然后在你的活动中 声明预览对象并初始化相机对象

private CameraPreview preview;

在那之后

   // Create our Preview view and set it as the content of ur activity.
    preview = new CameraPreview(this, camera);

    // Create Frame layout
    FrameLayout previewLayout = new FrameLayout(this);

    // Create camera layout params
    LinearLayout.LayoutParams previewlayoutParams = new LinearLayout.LayoutParams(
    LinearLayout.LayoutParams.WRAP_CONTENT,    LinearLayout.LayoutParams.MATCH_PARENT, Gravity.LEFT);

// Add preview to previewLayout
previewLayout.addView(preview, 0);

Bitmap overlayBitmap = getBitmap();
if (overlayBitmap != null) {
Matrix matrix = new Matrix();
matrix.postRotate(180);

Bitmap rotatedBitmap = Bitmap.createBitmap(overlayBitmap, 0, 0, overlayBitmap.getWidth(),
overlayBitmap.getHeight(), matrix, true);

ImageView oImageView = new ImageView(this);
oImageView.setImageBitmap(rotatedBitmap);
previewLayout.addView(oImageView, 1);
}

// Add previewLayout to main layout
linearLayout.addView(previewLayout, previewlayoutParams);

那是它。