HarmonyOS相机的基本使用实战原创精华

钟洪发老师

发布于 2021-6-27 20:40

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HarmonyOS相机的基本使用实战-鸿蒙开发者社区
相机权限申请
config.json

"reqPermissions": [
  {"name": "ohos.permission.CAMERA" },
  { "name": "ohos.permission.WRITE_MEDIA"},
  {"name": "ohos.permission.MICROPHONE"},
  { "name": "ohos.permission.MEDIA_LOCATION"}
]
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MainAbility

@Override
public void onStart(Intent intent) {
    super.onStart(intent);
    super.setMainRoute(MainAbilitySlice.class.getName());
    requestPermissions();
}

private void requestPermissions() {
    String[] permissions = {
            SystemPermission.CAMERA,
            SystemPermission.MICROPHONE,
            SystemPermission.MEDIA_LOCATION,
            SystemPermission.WRITE_MEDIA
    };
    List<String> permissionFiltered = Arrays.stream(permissions)
            .filter(permission -> verifySelfPermission(permission) != IBundleManager.PERMISSION_GRANTED)
            .collect(Collectors.toList());
    requestPermissionsFromUser(permissionFiltered.toArray(new String[permissionFiltered.size()]), 0);
}

@Override
public void onRequestPermissionsFromUserResult(int requestCode, String[] permissions, int[] grantResults) {
    if (permissions == null || permissions.length == 0 || grantResults == null || grantResults.length == 0) {
        return;
    }
    for (int grantResult : grantResults) {
        if (grantResult != IBundleManager.PERMISSION_GRANTED) {
            terminateAbility();
            break;
        }
    }
}
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相机设备创建
布局文件上添加按钮：

<Button
    ohos:id="$+id:create_camera_btn"
    ohos:height="match_content"
    ohos:width="300vp"
    ohos:text="创建相机并配置"
    ohos:text_size="20fp"
    ohos:text_color="#ffffff"
    ohos:background_element="#0000ff"
    ohos:layout_alignment="horizontal_center"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:left_padding="40vp"
    ohos:right_padding="40vp"
    ohos:top_margin="20vp"
    />
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按钮的逻辑代码：

private void createCameraBtnFunc(Component component) {
    //openCamera(); //先测试创建相机
    initSurface(); //创建surface，里面包含的openCamera()
}

private void openCamera(){
    System.out.println("createCameraBtnFunc start...");
    CameraKit cameraKit = CameraKit.getInstance(getContext());
    if(cameraKit == null){
        System.out.println("cameraKit create error!");
    }
    System.out.println("cameraKit create success!"+cameraKit);
    try {
        // 获取当前设备的逻辑相机列表
        String[] cameraIds = cameraKit.getCameraIds();
        if (cameraIds.length <= 0) {
            System.out.println("cameraIds size is 0");
        }
        System.out.println("逻辑相机ids：" + Arrays.toString(cameraIds));
        //第一个参数cameraId
        //第二和第三个参数负责相机创建和相机运行时的数据和状态检测
        cameraKit.createCamera(cameraIds[0], new CameraStateCallbackImpl(), new EventHandler(EventRunner.create("CameraCb")));
    } catch (IllegalStateException e) {
        // 处理异常
    }
}

private class CameraStateCallbackImpl extends CameraStateCallback {
    @Override
    public void onCreated(Camera camera) {
        //创建相机成功的时候回调
    }

    @Override
    public void onConfigured(Camera camera) {

    }
}
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至此，相机设备的创建已经完成，执行成功意味着相机系统的硬件已经完成了上电。创建相机设备成功后，在CameraStateCallback中会触发onCreated(Camera camera)回调，并且带回Camera对象，用于执行相机设备的操作。当一个新的相机设备成功创建后，首先需要对相机进行配置，调用configure(CameraConfig)方法实现配置。

相机设备配置
相机配置主要是设置预览、拍照、录像所需要用到的Surface(ohos.agp.graphics.Surface)，没有配置过Surface，相应的功能不能使用。为了进行相机帧捕获结果的数据和状态检测，有时还需要在相机配置时调用setFrameStateCallback(FrameStateCallback, EventHandler)方法设置帧回调。相机配置成功后，在CameraStateCallback中会触发onConfigured(Camera camera)回调，然后才可以执行相机帧捕获相关的操作。

相机配置，布局文件上加一个布局：

<DirectionalLayout
    ohos:id="$+id:surface_container"
    ohos:height="400vp"
    ohos:width="match_parent"/>
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逻辑代码：

private SurfaceProvider surfaceProvider;
private DirectionalLayout surfaceContainer; //定义在最前面
private void initSurface() {
    getWindow().setTransparent(true);
    DirectionalLayout.LayoutConfig params = new DirectionalLayout.LayoutConfig(
            ComponentContainer.LayoutConfig.MATCH_PARENT, ComponentContainer.LayoutConfig.MATCH_PARENT);
    surfaceProvider = new SurfaceProvider(this);
    surfaceProvider.setLayoutConfig(params);
    surfaceProvider.pinToZTop(false);
    surfaceProvider.getSurfaceOps().get().addCallback(new SurfaceCallBack());
    surfaceContainer.addComponent(surfaceProvider);
}

private class SurfaceCallBack implements SurfaceOps.Callback {
    @Override
    public void surfaceCreated(SurfaceOps callbackSurfaceOps) {
        //surfaceCreated后可以创建相机对象, 按钮上点击后执行initSurface();
        openCamera();
    }
    @Override
    public void surfaceChanged(SurfaceOps callbackSurfaceOps, int format, int width, int height) {
    }
    @Override
    public void surfaceDestroyed(SurfaceOps callbackSurfaceOps) {
    }
}
 



//在上面的CameraStateCallbackImpl的onCreated方法中添加代码
private Camera cameraDevice;
private Surface previewSurface;
private CameraConfig.Builder cameraConfigBuilder; //放前面
private final class CameraStateCallbackImpl extends CameraStateCallback {
    @Override
    public void onCreated(Camera camera) {
        //创建相机成功的时候回调
        cameraDevice = camera;
        previewSurface = surfaceProvider.getSurfaceOps().get().getSurface();
        cameraConfigBuilder = camera.getCameraConfigBuilder();
        if (cameraConfigBuilder == null) {
            System.out.println("onCreated cameraConfigBuilder is null");
            return;
        }
        // 配置预览的Surface
        cameraConfigBuilder.addSurface(previewSurface);
        
        // 配置帧结果的回调
        cameraConfigBuilder.setFrameStateCallback(frameStateCallbackImpl, new EventHandler(EventRunner.create()));
        try {
            // 相机设备配置
            camera.configure(cameraConfigBuilder.build());
        } catch (IllegalArgumentException e) {
            System.out.println("Argument Exception");
        } catch (IllegalStateException e) {
            System.out.println("State Exception");
        }
    }
}

private FrameStateCallback frameStateCallbackImpl = new FrameStateCallback(){
    //....更具需要实现接口里的方法
};
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配置完成后，会回调public void onConfigured(Camera camera)方法，在这个方法里铺货相机拍摄的帧。

相机帧捕获
用户一般都是先看见预览画面才执行拍照或者其他功能，所以对于一个普通的相机应用，预览是必不可少的。通过getFrameConfigBuilder(FRAME_CONFIG_PREVIEW)方法获取预览配置模板，更多的帧配置项以及详细使用方法请参考API接口说明的FrameConfig.Builder部分。

通过triggerLoopingCapture(FrameConfig)方法实现循环帧捕获实现预览：

//在CameraStateCallbackImpl的onConfigured添加代码
private FrameConfig.Builder frameConfigBuilder;
private FrameConfig previewFrameConfig;
private final class CameraStateCallbackImpl extends CameraStateCallback {
    @Override
    public void onConfigured(Camera camera) {
        //配置成功的时候回调
        // 获取预览配置模板
        frameConfigBuilder = camera.getFrameConfigBuilder(Camera.FrameConfigType.FRAME_CONFIG_PREVIEW);
        // 配置预览Surface
        frameConfigBuilder.addSurface(previewSurface);
        previewFrameConfig = frameConfigBuilder.build();
        try {
            // 启动循环帧捕获
            int triggerId = camera.triggerLoopingCapture(previewFrameConfig);
        } catch (IllegalArgumentException e) {
            System.out.println("Argument Exception");
        } catch (IllegalStateException e) {
            System.out.println("State Exception");
        }
    }
}
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经过以上的操作，相机应用已经可以正常进行实时预览了。在预览状态下，开发者还可以执行其他操作，比如：当预览帧配置更改时，可以通过triggerLoopingCapture(FrameConfig)方法实现预览帧配置的更新；

<Button
    ohos:id="$+id:change_camera_config_btn"
    ohos:height="match_content"
    ohos:width="300vp"
    ohos:text="改变相机焦距配置"
    ohos:text_size="20fp"
    ohos:text_color="#ffffff"
    ohos:background_element="#0000ff"
    ohos:layout_alignment="horizontal_center"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:left_padding="40vp"
    ohos:right_padding="40vp"
    ohos:top_margin="20vp"
    />
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//改变相机焦距配置
private void changeCameraConfigBtnFunc(Component component) {
    // 预览帧变焦值变更
    frameConfigBuilder.setZoom(1.5f);
    // 调用triggerLoopingCapture方法实现预览帧配置更新
    cameraDevice.triggerLoopingCapture(frameConfigBuilder.build());
}
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通过stopLoopingCapture()方法停止循环帧捕获(停止预览)。

<Button
    ohos:id="$+id:stop_camera_preview_btn"
    ohos:height="match_content"
    ohos:width="300vp"
    ohos:text="停止相机预览"
    ohos:text_size="20fp"
    ohos:text_color="#ffffff"
    ohos:background_element="#0000ff"
    ohos:layout_alignment="horizontal_center"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:left_padding="40vp"
    ohos:right_padding="40vp"
    ohos:top_margin="20vp"
    />
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//停止相机预览
private void stopCameraBtnFunc(Component component) {
    // 停止预览帧捕获
    cameraDevice.stopLoopingCapture();
}
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到这里相机的基本用户流程，基本搞清楚，使用相机最后一步就是释放了。

<Button
    ohos:id="$+id:release_camera_btn"
    ohos:height="match_content"
    ohos:width="300vp"
    ohos:text="释放相机"
    ohos:text_size="20fp"
    ohos:text_color="#ffffff"
    ohos:background_element="#0000ff"
    ohos:layout_alignment="horizontal_center"
    ohos:top_padding="8vp"
    ohos:bottom_padding="8vp"
    ohos:left_padding="40vp"
    ohos:right_padding="40vp"
    ohos:top_margin="20vp"
    />
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private void releaseCameraBtnFunc(Component component) {
    if (cameraDevice != null) {
        // 关闭相机和释放资源
        cameraDevice.release();
        cameraDevice = null;
    }
    // 预览配置模板置空
    previewFrameConfig = null;
}
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