安卓相机2 api 触摸对焦示例

嗨，我正在使用 camera2basic 示例来实现我的 camera2 应用程序。我找不到任何好的例子来实现触摸到使用 camera2 api 对焦。目前，我用于触摸焦点的代码是这样的：

    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
    }
}

但问题是它显示出奇怪的行为，在自动闪光灯开启的情况下，它会无限次地重复自动对焦序列，而且它似乎没有聚焦在触摸区域。我试过改变

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

自：

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

这停止了重复的自动对焦序列，但它仍然没有对焦于触摸区域，闪光灯只是闪烁不到一秒钟，而不是正常的对焦序列。请帮助我解决这个问题或指导我到一个工作触摸焦点的例子。谢谢

您的问题是设置 AF 区域的控件。

计算要设置焦点的区域
停止当前会话mPreviewSession.stopRepeating()
启动自动对焦触发!!

3.1. 安全开始使自动对焦区域空闲

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);

捕获一次以应用您的设置

检查是否支持 AF 和 AE 区域如果支持，则应用此区域

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);
}

再次拍摄一次以设置焦点

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

在mCaptureCallback里面你应该取消自动对焦触发器，但文档说 AF 触发器在某些设备中可能为空，所以我确实喜欢

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);

最后一件事是 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

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