目录

对焦(C/C++)

相机框架提供对设备对焦的能力，业务应用可以根据使用场景进行对焦模式和对焦点的设置。

开发步骤

详细的API说明请参考Camera API参考。

  1. 导入NDK接口，导入方法如下。

    // 导入NDK接口头文件
#include "hilog/log.h"
#include "ohcamera/camera.h"
#include "ohcamera/camera_input.h"
#include "ohcamera/capture_session.h"
#include "ohcamera/photo_output.h"
#include "ohcamera/preview_output.h"
#include "ohcamera/video_output.h"
#include "ohcamera/camera_manager.h"

  2. 在CMake脚本中链接相关动态库。

    target_link_libraries(entry PUBLIC libohcamera.so libhilog_ndk.z.so)

  3. 调用OH_CaptureSession_SetFocusMode设置对焦模式。

    Camera_ErrorCode SetFocusMode(Camera_CaptureSession *captureSession, uint32_t mode)
{
    bool isFocusModeSupported = false;
    Camera_FocusMode focusMode = static_cast<Camera_FocusMode>(mode);
    Camera_ErrorCode ret = OH_CaptureSession_IsFocusModeSupported(captureSession, focusMode, &isFocusModeSupported);
    if (&isFocusModeSupported == nullptr || ret != CAMERA_OK) {
        OH_LOG_ERROR(LOG_APP, "IsFocusModeSupported failed.");
        return CAMERA_INVALID_ARGUMENT;
    }

    if (!isFocusModeSupported) {
        OH_LOG_INFO(LOG_APP, "current focusMode(%{public}d) is not supported.", focusMode);
        return CAMERA_OK;
    }

    OH_LOG_INFO(LOG_APP, "OH_CaptureSession_SetFocusMode focusMode(%{public}d).", focusMode);
    ret = OH_CaptureSession_SetFocusMode(captureSession, focusMode);
    if (ret != CAMERA_OK) {
        OH_LOG_ERROR(LOG_APP, "SetFocusMode failed.");
        return CAMERA_INVALID_ARGUMENT;
    }
    return ret;
}

  4. 如果通过OH_CaptureSession_SetFocusMode设置对焦模式为自动对焦模式，支持调用OH_CaptureSession_SetFocusPoint设置对焦点，根据对焦点执行一次自动对焦。

    需要在Session调用OH_CaptureSession_CommitConfig完成配流之后调用。

    Camera_ErrorCode SetFocusPoint(Camera_CaptureSession *captureSession, float x, float y)
{
    Camera_Point focusPoint;
    focusPoint.x = x;
    focusPoint.y = y;
    Camera_ErrorCode ret = OH_CaptureSession_SetFocusPoint(captureSession, focusPoint);
    if (ret != CAMERA_OK) {
        OH_LOG_ERROR(LOG_APP, "SetFocusPoint failed.");
        return CAMERA_INVALID_ARGUMENT;
    }
    return ret;
}

状态监听

在相机应用开发过程中，可以随时监听相机聚焦的状态变化。

通过注册OnFocusStateChange的回调函数获取监听结果，仅当自动对焦模式时，且相机对焦状态发生改变时触发该事件。

void CaptureSessionOnFocusStateChange(Camera_CaptureSession* captureSession, Camera_FocusState focusState)
    {
        OH_LOG_INFO(LOG_APP, "CaptureSession_Callbacks CaptureSessionOnFocusStateChange");
        OH_LOG_INFO(LOG_APP, "CaptureSession focusState = %{public}d", focusState);
        // 为保证对焦功能的用户体验，在自动对焦成功后，可将对焦模式设置为连续自动对焦
        if (focusState == Camera_FocusState::FOCUS_STATE_FOCUSED) {
            Camera_ErrorCode ret = SetFocusMode(captureSession, Camera_FocusMode::FOCUS_MODE_CONTINUOUS_AUTO);
        }
    }

    void CaptureSessionOnError(Camera_CaptureSession* captureSession, Camera_ErrorCode errorCode)
    {
        OH_LOG_INFO(LOG_APP, "CaptureSession_Callbacks CaptureSessionOnError");
        OH_LOG_INFO(LOG_APP, "CaptureSession errorCode = %{public}d", errorCode);
    }

    CaptureSession_Callbacks* GetCaptureSessionRegister(void)
    {
        static CaptureSession_Callbacks captureSessionCallbacks = {
            .onFocusStateChange = CaptureSessionOnFocusStateChange,
            .onError = CaptureSessionOnError
        };
        return &captureSessionCallbacks;
    }
Camera_ErrorCode RegisterCallback(Camera_CaptureSession* captureSession)
{
    Camera_ErrorCode ret = OH_CaptureSession_RegisterCallback(captureSession, GetCaptureSessionRegister());
    if (ret != CAMERA_OK) {
        OH_LOG_ERROR(LOG_APP, "OH_CaptureSession_RegisterCallback failed.");
    }
    return ret;
}