Android camera2 api触控焦点的例子？

Question

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以使用camera2 api进行聚焦。目前我用于触控的代码是：

    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，其上的自动闪光不断重复自动对焦序列无限次，而且它似乎并不专注于触摸区域。我试过改变

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

至：

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

这停止了​​重复的自动对焦序列，但它仍然没有聚焦在触摸区域上，闪光灯只闪烁不到一秒而不是正常的对焦序列。请帮我解决这个问题，或者引导我进行工作，以便集中注意力。谢谢

Answer 1

您的问题是设置AF区域控制。

1. 计算要设置焦点的区域
2. 停止当前会议mPreviewSession.stopRepeating()
3. 开始AF触发!!! 3.1。安全地开始使AF区域空闲 3.2。然后启动AF触发器

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

4. 捕获一次以应用您的设置
5. 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);
   }

6. 再次捕获一次以设置焦点 mPreviewCaptureSession.capture(mCaptureRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);
7. 在mCaptureCallback内你应该取消AF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);

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

希望能帮助到你。享受编码