android - Zbar 扫描仪和自动对焦

Question

我用过安卓的zbar扫描仪，它很容易捕捉到条形码。但问题在于，在具有自动对焦功能的手机上，它捕捉条形码的速度太快而无法正确检测到。如果它可以再等待几毫秒，它就可以捕捉到更清晰的图像，从而不会显示“未找到”页面。

我怎么解决这个问题？是否有延迟关注条形码的规定？可能是捕捉图像的延迟？

Answer 1

您是在谈论示例代码CameraTestActivity.java吗？

实现一个计数器来计算类似的扫描结果。如果扫描结果保持不变（例如连续 10 次），我们可以认为结果是相当可靠的。

Answer 2

我真的很喜欢@Juuso_Ohtonen 的回复，实际上只是在我自己的阅读器中使用它，但是如果您想要 AutoFocus 延迟，您可以创建一个 Camera.AutoFocusCallback 对象并使用 .postDelayed 实现其 onAutoFocus 方法。然后在您的 Camera camera.autoFocus() 方法上使用该对象。

// Mimic continuous auto-focusing
Camera.AutoFocusCallback autoFocusCB = new Camera.AutoFocusCallback() {
    public void onAutoFocus(boolean success, Camera camera) {
        autoFocusHandler.postDelayed(doAutoFocus, 1000);
    }
};

这部分用于扩展SurfaceView的类中，然后实现surfaceChanged()；

public CameraPreview(Context context, Camera camera,
                      PreviewCallback previewCb,
                      AutoFocusCallback autoFocusCb) {
    super(context);
    mCamera = camera;
    previewCallback = previewCb;
    autoFocusCallback = autoFocusCb;

    // Install a SurfaceHolder.Callback so we get notified when the
    // underlying surface is created and destroyed.
    mHolder = getHolder();
    mHolder.addCallback(this);

    // deprecated setting, but required on Android versions prior to 3.0
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    /*
     * If your preview can change or rotate, take care of those events here.
     * Make sure to stop the preview before resizing or reformatting it.
     */
    if (mHolder.getSurface() == null) {
        // preview surface does not exist
        return;
    }

    // stop preview before making changes
    try {
        mCamera.stopPreview();
    } catch (Exception e) {
        // ignore: tried to stop a non-existent preview
    }

    try {
        mCamera.setPreviewDisplay(mHolder);
        mCamera.setPreviewCallback(previewCallback);
        mCamera.startPreview();
        mCamera.autoFocus(autoFocusCallback);
    } catch (Exception e) {
        Log.d("DBG", "Error starting camera preview: " + e.getMessage());
    }
}