android - Android setFocusArea和自动对焦

我已经使用此功能进行了几天的战斗...

看来，相机正在忽略我定义的对焦区域。以下是代码片段:

重点:

protected void focusOnTouch(MotionEvent event) {
    if (camera != null) {
        Rect rect = calculateFocusArea(event.getX(), event.getY());

        Parameters parameters = camera.getParameters();
        parameters.setFocusMode(Parameters.FOCUS_MODE_AUTO);
        parameters.setFocusAreas(Lists.newArrayList(new Camera.Area(rect, 500)));

        camera.setParameters(parameters);
        camera.autoFocus(this);
    }
}

重点领域计算:

private Rect calculateFocusArea(float x, float y) {
    int left = clamp(Float.valueOf((x / getSurfaceView().getWidth()) * 2000 - 1000).intValue(), focusAreaSize);
    int top = clamp(Float.valueOf((y / getSurfaceView().getHeight()) * 2000 - 1000).intValue(), focusAreaSize);

    return new Rect(left, top, left + focusAreaSize, top + focusAreaSize);
}

来自Camera.AutoFocusCallback#onAutoFocus的几个日志事件
Log.d(TAG, String.format("Auto focus success=%s. Focus mode: '%s'. Focused on: %s", focused, camera.getParameters().getFocusMode(), camera.getParameters().getFocusAreas().get(0).rect.toString()));

08-27 11:19:42.240: DEBUG/MyCameraActivity(26268): Auto focus success=true. Focus mode: 'auto'. Focused on: Rect(-109, 643 - -13, 739)
08-27 11:19:55.514: DEBUG/MyCameraActivity(26268): Auto focus success=true. Focus mode: 'auto'. Focused on: Rect(20, 457 - 116, 553)
08-27 11:19:58.037: DEBUG/MyCameraActivity(26268): Auto focus success=true. Focus mode: 'auto'. Focused on: Rect(-159, 536 - -63, 632)
08-27 11:20:00.129: DEBUG/MyCameraActivity(26268): Auto focus success=true. Focus mode: 'auto'. Focused on: Rect(-28, 577 - 68, 673)

从视觉上看，好像焦点已成功聚焦在记录的区域上，但是突然间它失去了焦点，而是聚焦在中心(0, 0)上，或者获得了SurfaceView的较大部分。

计算中使用的focusAreaSize约为210px(96dp)。
在htt_code是Camera.getParameters().getMaxNumFocusAreas()的HTC One上进行测试。

初始对焦模式(在第一次点击之前)设置为1。

我在这里做错什么了吗？
修补FOCUS_MODE_CONTINUOUS_PICTURE矩形大小或重量不会显示任何明显的效果。

最佳答案

我的问题要简单得多:)

我要做的就是取消以前称为自动对焦的功能。基本上，正确的操作顺序是这样的:

protected void focusOnTouch(MotionEvent event) {
    if (camera != null) {

        camera.cancelAutoFocus();
        Rect focusRect = calculateTapArea(event.getX(), event.getY(), 1f);
        Rect meteringRect = calculateTapArea(event.getX(), event.getY(), 1.5f);

        Parameters parameters = camera.getParameters();
        parameters.setFocusMode(Parameters.FOCUS_MODE_AUTO);
        parameters.setFocusAreas(Lists.newArrayList(new Camera.Area(focusRect, 1000)));

        if (meteringAreaSupported) {
            parameters.setMeteringAreas(Lists.newArrayList(new Camera.Area(meteringRect, 1000)));
        }

        camera.setParameters(parameters);
        camera.autoFocus(this);
    }
}

更新

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
    ...
    Parameters p = camera.getParameters();
    if (p.getMaxNumMeteringAreas() > 0) {
       this.meteringAreaSupported = true;
    }
    ...
}

/**
 * Convert touch position x:y to {@link Camera.Area} position -1000:-1000 to 1000:1000.
 */
private Rect calculateTapArea(float x, float y, float coefficient) {
    int areaSize = Float.valueOf(focusAreaSize * coefficient).intValue();

    int left = clamp((int) x - areaSize / 2, 0, getSurfaceView().getWidth() - areaSize);
    int top = clamp((int) y - areaSize / 2, 0, getSurfaceView().getHeight() - areaSize);

    RectF rectF = new RectF(left, top, left + areaSize, top + areaSize);
    matrix.mapRect(rectF);

    return new Rect(Math.round(rectF.left), Math.round(rectF.top), Math.round(rectF.right), Math.round(rectF.bottom));
}

private int clamp(int x, int min, int max) {
    if (x > max) {
        return max;
    }
    if (x < min) {
        return min;
    }
    return x;
}

关于android - Android setFocusArea和自动对焦，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/18460647/