java - 如何在Android中实现双指缩放？

Question

经过对 SO 的一些研究，我找不到使用 android.hardware.camera 实现缩放的方法。我正在使用 SeekBar 但这不是我需要的。有谁知道我在哪里可以找到适用于 Android SKD >= 15 的示例？

在我的 cameraFragment 中，我正在使用 OnSeekBarChangeListener 在 onProgressChanged 方法中，我设置了相机的缩放。

seekbar.setOnSeekBarChangeListener(this); 
.....
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
    try {
        Camera.Parameters params = camera.getParameters();
            params.setZoom(progress);
            currentZoomLevel = progress;
            params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
            camera.setParameters(params);

            //set zoom level value
            try {
                float ratio = ((float) params.getZoomRatios().get(progress)) / 100;
                tvZoomLevel.setText(String.format("%.1fX", ratio));
            } catch (Exception ex) {
                Log.e(TAG, ex.getMessage());
            }
    } catch (Exception ex) {
        Log.e(TAG, ex.getMessage());
    }
}

Answer 1

1.覆盖onTouchEvent(MotionEvent事件)

2.获取相机最大缩放级别param

3.Adjust your pinch zoom into a camera param

    @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);
}

This certain step help you a basic implemention of your requirement.