Android camera2 api触摸对焦示例？

Question

您好，我正在使用 camera2basic 示例来实现我的 camera2 应用程序。我找不到任何用 camera2 api 实现触摸对焦的好例子。目前我用于触摸对焦的代码是这样的:

    private void setFocusArea(MotionEvent event) {
    if (mCameraId == null) return;
    CameraManager cm = (CameraManager)getActivity().getSystemService(Context.CAMERA_SERVICE);
    CameraCharacteristics cc = null;
    try {
        cc = cm.getCameraCharacteristics(mCameraId);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }

    int myX = (int)event.getX();
    int myY = (int)event.getY();
    MeteringRectangle focusArea = new MeteringRectangle(myX-100,myY-100,200,200,MeteringRectangle.METERING_WEIGHT_DONT_CARE);
    mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_CANCEL);
    try {
        mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback,
                mBackgroundHandler);
        // After this, the camera will go back to the normal state of preview.
        mState = STATE_PREVIEW;
    } catch (CameraAccessException e){
        // log
    }

    if (isMeteringAreaAESupported(cc)) {
        mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_REGIONS,
                new MeteringRectangle[]{focusArea});
    }
    if (isMeteringAreaAFSupported(cc)) {
        mPreviewRequestBuilder
                .set(CaptureRequest.CONTROL_AF_REGIONS, new MeteringRectangle[]{focusArea});
        mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
                CaptureRequest.CONTROL_AF_MODE_AUTO);
    }
    mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
            CameraMetadata.CONTROL_AF_TRIGGER_START);
    mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER,
            CameraMetadata.CONTROL_AE_PRECAPTURE_TRIGGER_START);
    try {
        mCaptureSession.setRepeatingRequest(mPreviewRequestBuilder.build(), mCaptureCallback,
                mBackgroundHandler);
        mManualFocusEngaged = true;
    } catch (CameraAccessException e) {
        // error handling
    }
}

但问题是它表现出奇怪的行为，自动闪光灯会无限次地重复自动对焦序列，而且它似乎没有对焦在触摸区域上。我试着改变

mCaptureSession.setRepeatingRequest(mPreviewRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);

到:

mCaptureSession.capture(mPreviewRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);

这停止了重复的自动对焦序列，但它仍然没有对焦在触摸区域上，闪光灯只闪烁了不到一秒钟，而不是正常的对焦序列。请帮助我解决这个问题，或者指导我使用工作方式来集中注意力的例子。谢谢

Answer 1

您的问题是设置 AF 区域的控制。

1. 计算出你想设置焦点的区域
2. 停止当前 session mPreviewSession.stopRepeating()
3. 启动自动对焦触发!!!

3.1。安全地开始使 AF 区域 IDLE

3.2。然后启动自动对焦触发

        mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_IDLE);
        mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_START);

1. 捕捉一次以应用您的设置

2. 检查是否支持AF和AE区域如果支持则应用该区域

   if ( isMeteringAreaAESupported()) {
       //System.out.println("AE regions are supported");
       mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AE_REGIONS, new MeteringRectangle[]{focusArea});
   }
   if (  isMeteringAreaAFSupported()) {
       //System.out.println("AF regions are supported");
   
       mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_REGIONS, new MeteringRectangle[]{focusArea});
       mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_AUTO);
   }
   

3. 再次捕捉一次以设置焦点

    mPreviewCaptureSession.capture(mCaptureRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);
   

4. 在 mCaptureCallback 中您应该取消 AF 触发器，但文档说 AF 触发器在某些设备中可以为空，所以我喜欢

   mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_IDLE);
   mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_CANCEL);
   mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, null);
   

5. 最后的事情是 mPreviewCaptureSession.setRepeatingRequest(mCaptureRequestBuilder.build(), null, mBackgroundHandler);

编辑

这是工作示例

private void setFocusArea(int focus_point_x, int focus_point_y) throws CameraAccessException {

if (cameraId == null || mManualFocusEngaged) return;

if (mCameraManager == null){
    mCameraManager = (CameraManager) mContext.getSystemService(Context.CAMERA_SERVICE);
}

MeteringRectangle focusArea = null;

if (mCameraManager != null) {
    if (mCameraCharacteristics == null) {
        mCameraCharacteristics = mCameraManager.getCameraCharacteristics(cameraId);
    }

    final Rect sensorArraySize = mCameraCharacteristics.get(CameraCharacteristics.SENSOR_INFO_ACTIVE_ARRAY_SIZE);

    int y = focus_point_x;
    int x = focus_point_y;

    if (sensorArraySize != null) {
        y = (int)(((float)focus_point_x / currentWidth)  * (float)sensorArraySize.height());
        x = (int)(((float)focus_point_y / currentHeight) * (float)sensorArraySize.width());
    }

    final int halfTouchLength  = 150;
    focusArea = new MeteringRectangle(Math.max(x - halfTouchLength,  0),
            Math.max(y - halfTouchLength, 0),
            halfTouchLength  * 2,
            halfTouchLength * 2,
            MeteringRectangle.METERING_WEIGHT_MAX - 1);
}

CameraCaptureSession.CaptureCallback mCaptureCallback = new CameraCaptureSession.CaptureCallback() {

    @Override
    public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
        super.onCaptureCompleted(session, request, result);

        mManualFocusEngaged = false;

        if (request.getTag().equals(FOCUS_TAG)) { // previously getTag == "Focus_tag"
            //the focus trigger is complete -
            //resume repeating (preview surface will get frames), clear AF trigger
            mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_IDLE);
            mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_CANCEL);
            mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, null);// As documentation says AF_trigger can be null in some device
            try {
                mCurrentCameraCaptureSession.setRepeatingRequest(mCaptureRequestBuilder.build(), null, mBackgroundHandler);
            } catch (CameraAccessException e) {
                // error handling
            }
        }
    }

    @Override
    public void onCaptureFailed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureFailure failure) {
        super.onCaptureFailed(session, request, failure);
        mManualFocusEngaged = false;
    }

};

mCurrentCameraCaptureSession.stopRepeating(); // Destroy current session
mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_IDLE);
mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_START);
mCurrentCameraCaptureSession.capture(mCaptureRequestBuilder.build(), mCaptureCallback, mBackgroundHandler); //Set all settings for once

if ( isMeteringAreaAESupported()) {
    mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AE_REGIONS, new MeteringRectangle[]{focusArea});
}
if ( isMeteringAreaAFSupported()) {
    mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_REGIONS, new MeteringRectangle[]{focusArea});
    mCaptureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_AUTO);
}

mCaptureRequestBuilder.setTag(FOCUS_TAG); //it will be checked inside mCaptureCallback
mCurrentCameraCaptureSession.capture(mCaptureRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);

mManualFocusEngaged = true;
}




   private boolean isMeteringAreaAFSupported() { // AF stands for AutoFocus

    Integer afRegion = mCameraCharacteristics.get(CameraCharacteristics.CONTROL_MAX_REGIONS_AF);
    return afRegion != null && afRegion >= 1;

   }


private boolean isMeteringAreaAESupported() {//AE stands for AutoExposure

    Integer aeState = mCameraCharacteristics.get(CameraCharacteristics.CONTROL_MAX_REGIONS_AE);
    return aeState!=null && aeState >=1;

}

希望对您有所帮助。享受编码