Getting image data continuously from camera, SurfaceView or SurfaceHolder

问题

So I have this camera preview set up with Camera, SurfaceView and SurfaceHolder. I have also an ImageView where I will be putting a modified version of the camera image and I want this to update lets say once every second.

All code is ready and already working when I load images from "res" but I have a really hard time reading the image data from the camera.

I've tried following already:

Creating an intent for MediaStore.ACTION_IMAGE_CAPTURE and starting an onActivityResult getting a small thumbnail (enough for me actually) from (Bitmap)data.getExtras().get("data")

The problem is that this opens the camera App and you need to "manually" take a picture.
Creating a Camera.PreviewCallback, taking the YuvImage, and converting it to an image using YuvImage.compressToJpeg(...).

The problem here is that I can't get it to start no matter when or where i put the Camera.setPreviewCallbackWithBuffer(PreviewCallback).
Try to take the data directly from PreviewHolder by locking in to the canvas using lockCanvas() and trying to convert it to a bitmap

Obviously Doesn't work.

Edit: What is the best way to make this work? I mean QR-Code readers must read the image data out of the camera continuously, how do they work?

回答1:

I went for option number 2 and finally made it work.

used this callback, forgot the @Override before

private Camera.PreviewCallback  previewCallback= new Camera.PreviewCallback()
{   
    @Override
    public void onPreviewFrame(byte[] data,Camera cam)
    {
            Camera.Size previewSize = cam.getParameters().getPreviewSize();
            YuvImage yuvImage = new YuvImage(data, ImageFormat.NV21,previewSize.width,previewSize.height, null);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            yuvImage.compressToJpeg(new Rect(0,0,previewSize.width,previewSize.height),80,baos);
            byte[] jdata = baos.toByteArray();
            Bitmap bitmap = BitmapFactory.decodeByteArray(jdata,0,jdata.length);    
    }
};

And initiating it using setPreviewCallback rather than setPreviewCallbackWithBuffer

SurfaceHolder.Callback surfaceCallback=new SurfaceHolder.Callback() 
{   
    public void surfaceCreated(SurfaceHolder holder) {

        camera.setPreviewCallback(previewCallback);
    }
}

来源：https://stackoverflow.com/questions/20097698/getting-image-data-continuously-from-camera-surfaceview-or-surfaceholder

标签

java

android

camera

surfaceview

surfaceholder