logo标签列表

Android相机2 API触摸对焦示例？

androidautofocusandroid-camera2camera2
9

你好，我正在使用camera2basic示例来实现我的相机应用。我找不到任何好的例子来使用camera2 api实现触摸对焦。目前我用于触摸对焦的代码如下：

    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
    }
}

但问题在于它表现出了奇怪的行为。自动闪光开启后，它会无限次重复自动对焦序列，并且似乎无法聚焦到触摸区域。我尝试更改设置，但是依然无济于事。

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

to:

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

这个操作可以停止重复自动对焦，但是它仍然无法对焦于触摸区域，闪光灯只会闪烁不到一秒钟而不是正常的对焦序列。请帮我解决这个问题或指导我一个有效的触控对焦示例。谢谢。

1
有人解决了吗？ - Shailendra Madda
请看一下，我已经更新了我的回答。 - Jasurbek
1个回答
10

您的问题是设置AF区域的控制。

  1. 计算您想要设置焦点的区域
  2. 停止当前会话 mPreviewSession.stopRepeating()
  3. 开始AF触发!!!

3.1. 安全地开始使AF区域处于IDLE状态

3.2. 然后开始AF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. Capture once to apply your settings

  2. Check if AF and AE regions are supported or not is supported If supported then apply this region

    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. Again capture once to set the focus

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

  4. inside mCaptureCallback you should cancel AF trigger, but the documentation says AF trigger can be null in some device so I did like

    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. The last things is mPreviewCaptureSession.setRepeatingRequest(mCaptureRequestBuilder.build(), null, mBackgroundHandler);

编辑

以下是可行的示例：

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;

}

希望这有所帮助。 享受编码。
关于第一点：计算您要设置焦点的区域，您指的是这个区域（一个矩形对吧？）必须在camera2坐标空间中对吗？有没有一个好的示例来说明如何实现呢？ - dnhyde
如何重新启用CONTROL_AF_MODE_CONTINUOUS_PICTURE功能，而不是通过触摸触发？ - undefined
网页内容由stack overflow 提供, 点击上面的
可以查看英文原文，
原文链接