使用双指触摸的Android相机预览缩放

Question

我正在尝试在相机预览模式下使用双指触摸手势进行缩放。但我做不到。我已经在 ImageView 上完成了 Zoom 控件，并且工作正常。现在我想在相机预览模式下执行此操作，即当我们启动相机时，我们可以使用双指手势进行缩放。

下面我添加了用于缩放图像的双指手势代码。

@Override
public boolean onTouch(View v, MotionEvent event) {
    // TODO Auto-generated method stub
    ImageView view = (ImageView) v;

    switch (event.getAction() & MotionEvent.ACTION_MASK) {
    case MotionEvent.ACTION_DOWN:
        savedMatrix.set(matrix);
        start.set(event.getX(), event.getY());
        Log.d(TAG, "mode=DRAG");
        mode = DRAG;
        break;
    case MotionEvent.ACTION_POINTER_DOWN:
        oldDist = spacing(event);
        Log.d(TAG, "oldDist=" + oldDist);
        if (oldDist > 10f) {
            savedMatrix.set(matrix);
            midPoint(mid, event);
            mode = ZOOM;
            Log.d(TAG, "mode=ZOOM");
        }
        break;
    case MotionEvent.ACTION_UP:
    case MotionEvent.ACTION_POINTER_UP:
        mode = NONE;
        Log.d(TAG, "mode=NONE");
        break;
    case MotionEvent.ACTION_MOVE:
        if (mode == DRAG) {

            // for draging the image

              matrix.set(savedMatrix); matrix.postTranslate(event.getX() -
              start.x, event.getY() - start.y);

            break;
        } else if (mode == ZOOM) {
            float newDist = spacing(event);
            Log.d(TAG, "newDist=" + newDist);
            if (newDist > 10f) {
                matrix.set(savedMatrix);
                float scale = newDist / oldDist;
                matrix.postScale(scale, scale, mid.x, mid.y);
            }
        }
        break;
    }

    view.setImageMatrix(matrix);
    return true;
}

请指导我如何在相机预览中进行手势缩放控制。至少提供一个教程链接。

谢谢维卡什

Answer 1

这是我在github上找到的解决方案: https://github.com/Betulaphobe/ChatCapsule/blob/8d4f00a7d4c9166aa7ce974670fdf3033a6064f4/chc_application/src/chc/helpers/CameraPreview.java

@Override
public boolean onTouchEvent(MotionEvent event) {
    // Get the pointer ID
    Camera.Parameters params = mCamera.getParameters();
    int action = event.getAction();


    if (event.getPointerCount() > 1) {
        // handle multi-touch events
        if (action == MotionEvent.ACTION_POINTER_DOWN) {
            mDist = getFingerSpacing(event);
        } else if (action == MotionEvent.ACTION_MOVE && params.isZoomSupported()) {
            mCamera.cancelAutoFocus();
            handleZoom(event, params);
        }
    } else {
        // handle single touch events
        if (action == MotionEvent.ACTION_UP) {
            handleFocus(event, params);
        }
    }
    return true;
}

private void handleZoom(MotionEvent event, Camera.Parameters params) {
    int maxZoom = params.getMaxZoom();
    int zoom = params.getZoom();
    float newDist = getFingerSpacing(event);
    if (newDist > mDist) {
        //zoom in
        if (zoom < maxZoom)
            zoom++;
    } else if (newDist < mDist) {
        //zoom out
        if (zoom > 0)
            zoom--;
    }
    mDist = newDist;
    params.setZoom(zoom);
    mCamera.setParameters(params);
}

public void handleFocus(MotionEvent event, Camera.Parameters params) {
    int pointerId = event.getPointerId(0);
    int pointerIndex = event.findPointerIndex(pointerId);
    // Get the pointer's current position
    float x = event.getX(pointerIndex);
    float y = event.getY(pointerIndex);

    List<String> supportedFocusModes = params.getSupportedFocusModes();
    if (supportedFocusModes != null && supportedFocusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
        mCamera.autoFocus(new Camera.AutoFocusCallback() {
            @Override
            public void onAutoFocus(boolean b, Camera camera) {
                // currently set to auto-focus on single touch
            }
        });
    }
}

/** Determine the space between the first two fingers */
private float getFingerSpacing(MotionEvent event) {
    // ...
    float x = event.getX(0) - event.getX(1);
    float y = event.getY(0) - event.getY(1);
    return FloatMath.sqrt(x * x + y * y);
}