Question

这里是我的地面变化活动处理守则:

    public void surfaceChanged(SurfaceHolder holder,
                               int format, int width,
                               int height) {
    Camera.Parameters parameters = camera.getParameters();
    Camera.Size size = getBestPreviewSize(width, height,
                parameters);
       //...
    }


    private Camera.Size getBestPreviewSize(int width, int height,
                                       Camera.Parameters parameters) {
        Camera.Size result = null;

        // it fails with NullPointerExceptiopn here,
        // when accessing "getSupportedPreviewSizes" method:
        // that means "parameters" is null
        for (Camera.Size size : parameters.getSupportedPreviewSizes()) {
            ///...
        }
    }

我开始照相机。

    @Override
    public void onResume() {
        super.onResume();
        camera = Camera.open();
    }

这个问题在我的银河S Plus上没有发生,也没有出现在LG Bestus Black电话上。是否有任何人认为这里有什么错误?

Answer 1

页: 1

parameters.getSupportedPreviewSizes()

Backs NUL on银河塔。因此,我只作一次检查,看看它是否无效,没有在这种情况下确定新的审查规模。我在研究了标准摄像机应用来源后得出这一结论。

Answer 2

: >;<>>;<>>>;>;>;>;>;>;>;>;>;>;。

Answer 3

camera initialization depends a lot on the specific device. For instance a specific Samsung device GT5500 is reporting null (width = 0, height = 0) as a valid resolution for preview, but crashes the whole phone ("hard" reboot) if you try to use it. We experienced it with mixare augmented reality engine (http://www.mixare.org) and it was PITA to debug (since we didn t have the phone and could not reproduce the bug on any other hardware).

然而,在达到“权利”审查规模时,你可以研究一下我们关于兴奋剂的法典(它是一个自由和开放的来源)。在档案中:https://github.com/mixare/mixare/blobmaster/src/org/mixare/MixView.java (第871及以后各段)

        List<Camera.Size> supportedSizes = null;
        //On older devices (<1.6) the following will fail
        //the camera will work nevertheless
        supportedSizes = Compatibility.getSupportedPreviewSizes(parameters);

        //preview form factor
        float ff = (float)w/h;
        Log.d("Mixare", "Screen res: w:"+ w + " h:" + h + " aspect ratio:" + ff);

        //holder for the best form factor and size
        float bff = 0;
        int bestw = 0;
        int besth = 0;
        Iterator<Camera.Size> itr = supportedSizes.iterator();

        //we look for the best preview size, it has to be the closest to the
        //screen form factor, and be less wide than the screen itself
        //the latter requirement is because the HTC Hero with update 2.1 will
        //report camera preview sizes larger than the screen, and it will fail
        //to initialize the camera
        //other devices could work with previews larger than the screen though
        while(itr.hasNext()) {
            Camera.Size element = itr.next();
            //current form factor
            float cff = (float)element.width/element.height;
            //check if the current element is a candidate to replace the best match so far
            //current form factor should be closer to the bff
            //preview width should be less than screen width
            //preview width should be more than current bestw
            //this combination will ensure that the highest resolution will win
            Log.d("Mixare", "Candidate camera element: w:"+ element.width + " h:" + element.height + " aspect ratio:" + cff);
            if ((ff-cff <= ff-bff) && (element.width <= w) && (element.width >= bestw)) {
                bff=cff;
                bestw = element.width;
                besth = element.height;
            }
        } 
        Log.d("Mixare", "Chosen camera element: w:"+ bestw + " h:" + besth + " aspect ratio:" + bff);
        //Some Samsung phones will end up with bestw and besth = 0 because their minimum preview size is bigger then the screen size.
        //In this case, we use the default values: 480x320
        if ((bestw == 0) || (besth == 0)){
            Log.d("Mixare", "Using default camera parameters!");
            bestw = 480;
            besth = 320;
        }
        parameters.setPreviewSize(bestw, besth);

你们看到,我们没有直接使用要求获得照相机组的辅助性审查,而是增加了相容层(此代码是:,因为我们需要与旧电话相容。如果你不希望支持老年和roid释放,你可以直接使用照相机组的方法。

HTH Daniele

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