Android camera2自动对焦完成后有什么回调

在Android Camera2中，当自动对焦完成后会触发一个回调函数，该回调函数是OnFocusCompleted()，可以在该回调函数中执行对焦完成后的相关操作。例如，可以在该回调函数中获取对焦区域的坐标和大小，或者通知用户对焦完成等。此外，还可以在该回调函数中设置下一次对焦的参数，以确保拍摄的照片质量更高。

相关问题

android camera2实现自动对焦，点击屏幕后坐标转换后进行对焦

要实现Android Camera2的自动对焦功能，需要使用Camera2 API中的AutoFocus类。首先，在CameraCaptureSession.CaptureCallback的onCaptureCompleted()方法中，您需要检查CaptureResult的CONTROL_AF_STATE是否为FOCUSED_LOCKED或FOCUSING_LOCKED。如果是，则对焦已完成。

在点击屏幕后，您需要将屏幕上的坐标转换为相机预览视图上的坐标，然后使用CameraCharacteristics.SENSOR_INFO_ACTIVE_ARRAY_SIZE属性来计算相应的焦点区域。最后，您可以使用CaptureRequest.CONTROL_AF_REGIONS和CaptureRequest.CONTROL_AF_MODE属性来设置相应的焦点区域和对焦模式。

以下是一个示例代码，可以帮助您实现这个功能：

private void setAutoFocus(int x, int y) {
    try {
        // Convert touch position to focus area
        Rect rect = getCameraFocusRect(x, y);

        // Calculate focus metering area
        MeteringRectangle[] meteringRectangle = new MeteringRectangle[] {
            new MeteringRectangle(rect, MeteringRectangle.METERING_WEIGHT_MAX)
        };

        // Create capture request builder
        CaptureRequest.Builder builder =
            mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);

        // Set focus and metering areas
        builder.set(CaptureRequest.CONTROL_AF_REGIONS, meteringRectangle);
        builder.set(CaptureRequest.CONTROL_AE_REGIONS, meteringRectangle);
        builder.set(CaptureRequest.CONTROL_AF_MODE,
            CaptureRequest.CONTROL_AF_MODE_AUTO);
        builder.set(CaptureRequest.CONTROL_AE_MODE,
            CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);

        // Send capture request
        mCaptureSession.setRepeatingRequest(builder.build(), mCaptureCallback, null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private Rect getCameraFocusRect(int x, int y) {
    // Get active sensor size
    Size sensorSize = mCameraCharacteristics.get(CameraCharacteristics.SENSOR_INFO_ACTIVE_ARRAY_SIZE);

    // Convert screen coordinates to view coordinates
    float viewX = x / (float) mPreviewView.getWidth();
    float viewY = y / (float) mPreviewView.getHeight();

    // Calculate focus rect coordinates
    int rectLeft = (int) ((viewX * sensorSize.width) - 100);
    int rectTop = (int) ((viewY * sensorSize.height) - 100);
    int rectRight = rectLeft + 200;
    int rectBottom = rectTop + 200;

    // Limit focus rect coordinates to sensor size
    rectLeft = Math.max(rectLeft, 0);
    rectTop = Math.max(rectTop, 0);
    rectRight = Math.min(rectRight, sensorSize.width);
    rectBottom = Math.min(rectBottom, sensorSize.height);

    // Create focus rect
    return new Rect(rectLeft, rectTop, rectRight, rectBottom);
}

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

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

        // Check autofocus state
        Integer afState = result.get(CaptureResult.CONTROL_AF_STATE);
        if (afState == null) {
            return;
        }

        switch (afState) {
            case CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED:
            case CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED:
                // Auto-focus has completed
                break;
        }
    }
};

在上面的代码中，我们首先在setAutoFocus()方法中将屏幕上的坐标转换为相机预览视图上的焦点区域。然后，我们使用CaptureRequest.CONTROL_AF_REGIONS和CaptureRequest.CONTROL_AF_MODE属性来设置相应的焦点区域和对焦模式。最后，我们将该捕获请求发送到相机设备并设置回调以接收自动对焦完成事件。

请注意，如果您的相机设备不支持自动对焦，则可能需要手动对焦。

Android camera2实现手动对焦

在Android Camera2 API中实现手动对焦需要以下步骤：

1. 获取CameraManager实例，使用该实例获取可用的相机设备列表。

2. 获取要使用的相机设备的CameraDevice实例。

3. 创建一个CaptureRequest.Builder对象，并将其与相机设备关联。

4. 设置手动对焦模式和对焦区域。

5. 构建CaptureRequest对象。

6. 启动相机预览。

7. 实现一个触摸事件监听器，在用户触摸屏幕时获取焦点坐标，并设置对焦区域。

8. 在触摸事件监听器中调用CaptureRequest.Builder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_START)触发对焦操作。

9. 实现一个CameraCaptureSession.CaptureCallback回调函数，在对焦完成后更新预览界面。

下面是一个简单的实现示例：

private void setupCamera() {
    // 获取相机管理器实例
    CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
    try {
        // 获取可用的相机设备列表
        String[] cameraIds = cameraManager.getCameraIdList();
        for (String cameraId : cameraIds) {
            // 获取相机设备实例
            CameraDevice cameraDevice = cameraManager.openCamera(cameraId, mStateCallback, mBackgroundHandler);
            // 创建一个CaptureRequest.Builder对象，并将其与相机设备关联
            mPreviewRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
            // 设置手动对焦模式和对焦区域
            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_AUTO);
            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_REGIONS, new MeteringRectangle[]{new MeteringRectangle(focusRect, 1000)});
            // 构建CaptureRequest对象
            mPreviewRequest = mPreviewRequestBuilder.build();
            // 启动相机预览
            cameraDevice.createCaptureSession(Arrays.asList(mSurface), mSessionCallback, mBackgroundHandler);
        }
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private void startPreview() {
    try {
        // 设置自动对焦模式
        mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_AUTO);
        // 启动预览
        mCaptureSession.setRepeatingRequest(mPreviewRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private void setFocusArea(float x, float y) {
    // 计算对焦区域
    Rect focusRect = calculateFocusRect(x, y);
    // 设置对焦区域
    mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_REGIONS, new MeteringRectangle[]{new MeteringRectangle(focusRect, 1000)});
    // 触发对焦操作
    mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, CameraMetadata.CONTROL_AF_TRIGGER_START);
    try {
        // 更新预览界面
        mCaptureSession.setRepeatingRequest(mPreviewRequestBuilder.build(), mCaptureCallback, mBackgroundHandler);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private CameraCaptureSession.CaptureCallback mCaptureCallback = new CameraCaptureSession.CaptureCallback() {
    @Override
    public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
        super.onCaptureCompleted(session, request, result);
        // 对焦完成后更新预览界面
        if (request.get(CaptureRequest.CONTROL_AF_TRIGGER) != null && request.get(CaptureRequest.CONTROL_AF_TRIGGER) == CameraMetadata.CONTROL_AF_TRIGGER_START) {
            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER, null);
            mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
            try {
                mCaptureSession.setRepeatingRequest(mPreviewRequestBuilder.build(), null, mBackgroundHandler);
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }
        }
    }
};

private CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
    @Override
    public void onOpened(@NonNull CameraDevice camera) {
        mCameraDevice = camera;
        startPreview();
    }

    @Override
    public void onDisconnected(@NonNull CameraDevice camera) {
        mCameraDevice.close();
        mCameraDevice = null;
    }

    @Override
    public void onError(@NonNull CameraDevice camera, int error) {
        mCameraDevice.close();
        mCameraDevice = null;
    }
};

private CameraCaptureSession.StateCallback mSessionCallback = new CameraCaptureSession.StateCallback() {
    @Override
    public void onConfigured(@NonNull CameraCaptureSession session) {
        mCaptureSession = session;
        try {
            mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback, mBackgroundHandler);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onConfigureFailed(@NonNull CameraCaptureSession session) {
        session.close();
        mCaptureSession = null;
    }
};

在以上代码中，calculateFocusRect()方法用于计算对焦区域，可以根据需要自行实现。