ANDROID：保存previewCallback图像作为一个字节数组导致损坏的文件为.jpg [英] ANDROID: Saving PreviewCallback image as a .jpg from a byte array results in a corrupt file

问题描述

我一直在充实的QR扫描库Zxing扫描后立即保存照片。我被告知这样做在previewCallback.java上previewFrame方法内是这样的：

I have been augmenting the QR scanning library Zxing to save a photo instantly upon scan. I was advised to do so within the onPreviewFrame method within PreviewCallback.java as thus:

 public void onPreviewFrame(byte[] data, Camera camera) {
Point cameraResolution = configManager.getCameraResolution();
Handler thePreviewHandler = previewHandler;

YuvImage im = new YuvImage(data, ImageFormat.NV21, 1200,
        800, null);
        Rect r = new Rect(0, 0, 1200, 800);
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        im.compressToJpeg(r, 50, baos);

        try {
            FileOutputStream output = new FileOutputStream("/sdcard/test_jpg.jpg");
            output.write(baos.toByteArray());
            output.flush();
            output.close();

            System.out.println("Attempting to save file");
            System.out.println(data);
        } catch (FileNotFoundException e) {
            System.out.println("Saving to file failed");
        } catch (IOException e) {
            System.out.println("Saving to file failed");
        }

if (cameraResolution != null && thePreviewHandler != null) {
  Message message = thePreviewHandler.obtainMessage(previewMessage, cameraResolution.x,
      cameraResolution.y, data);
  message.sendToTarget();
  previewHandler = null;

} else {
  Log.d(TAG, "Got preview callback, but no handler or resolution available");
}}

运行此code的结果是在设定的文件目录损坏的图像。我相信这是因为code正在运行的每一帧。有没有办法来限制这每一秒左右，如果将允许完整的图像保存，或者是有一种方法，我可以用它来使图像只能保存在完成扫描。

The result of running this code is a corrupt image at the set file directory. I believe this is due to the code being run every frame. Is there a way to limit this to every second or so if that will allow the full image to save, or is there a method I can use to cause the image to only save upon completed scan.

我有一个不太有利的替代工作，因为我可以成功地保存显示在扫描黑白图像;颜色当然是preferable选项。

I have a less favourable working alternative, in that I can successfully save the black and white image that is shown upon scan; colour is the preferable option of course.

更新：code变更为（理论上）适应任何设备上的摄像头分辨率。图片仍然是腐败的。

Update: Code changed to (in theory) accommodate camera resolution on any device. Image is still corrupt.

public void onPreviewFrame(byte[] data, Camera camera) {
Point cameraResolution = configManager.getCameraResolution();
Handler thePreviewHandler = previewHandler;

android.hardware.Camera.Parameters parameters = camera.getParameters();
android.hardware.Camera.Size size = parameters.getPictureSize();

int height = size.height;
int width = size.width;

YuvImage im = new YuvImage(data, ImageFormat.NV21, width,
        height, null);
        Rect r = new Rect(0, 0, width, height);
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        im.compressToJpeg(r, 50, baos);

        try {
            FileOutputStream output = new FileOutputStream("/sdcard/test_jpg.jpg");
            output.write(baos.toByteArray());
            output.flush();
            output.close();

            System.out.println("Attempting to save file");
            System.out.println(data);

        } catch (FileNotFoundException e) {             
            System.out.println("Saving to file failed");                
        } catch (IOException e) {               
            System.out.println("Saving to file failed");                
        }    
if (cameraResolution != null && thePreviewHandler != null) {
  Message message = thePreviewHandler.obtainMessage(previewMessage, cameraResolution.x,
      cameraResolution.y, data);
  message.sendToTarget();
  previewHandler = null;

} else {
  Log.d(TAG, "Got preview callback, but no handler or resolution available");
}}

检查过的宽度和高度可变正确设置到了Nexus 7的照相机和宽度的1280×960的高度。我相信这个问题是来自企图保存图像的每一帧，为试图保存到文件显得有些迅速logcat的范围内;几次。这也可能是值得注意的是节省了腐败的图像是方形的（ISH）。

Having checked the width and height variable are correctly set to the Nexus 7's camera width and height of 1280x960. I am confident the issue comes from attempting to save the image every frame, as "Attempting to save to file" appears somewhat rapidly within the logcat; several times a second. It may also be worth noting that the corrupt image saved is square(ish).

在此先感谢。

推荐答案

1200 x 800的？你确定这是你的preVIEW大小？检查你的参数。也许这是1280×720

1200 x 800? are you sure this is your preview size? check your parameters. Probably it's 1280 x 720

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