Android在ImageView上从URI设置图像

Question

更新了更多代码

我正在尝试抓取刚拍摄的照片并将其设置为ImageView编程.

按下图片按钮,

picture_button.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {
        takePhoto(mTextureView);
    }
});

它运行takePhoto方法:

public void takePhoto(View view) {
    try {
        mImageFile = createImageFile();
        final ImageView latest_picture = (ImageView) findViewById(R.id.latest_picture);
        final RelativeLayout latest_picture_container = (RelativeLayout) findViewById(R.id.latest_picture_container);
        final String mImageFileLocationNew = mImageFileLocation.replaceFirst("^/", "");
        Toast.makeText(getApplicationContext(), "" + mImageFile, Toast.LENGTH_SHORT).show();
        Uri uri = Uri.fromFile(mImageFile);
        Toast.makeText(getApplicationContext(), ""+uri, Toast.LENGTH_LONG).show();
        latest_picture.setImageURI(uri);
        latest_picture_container.setVisibility(View.VISIBLE);
    } catch (IOException e){
        e.printStackTrace();
    }
    lockFocus();
    captureStillImage();
}

哪个运行createImageFile()和captureStillImage()

private void captureStillImage() {
    try {
        CaptureRequest.Builder captureStillBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
        captureStillBuilder.addTarget(mImageReader.getSurface());
        int rotation = getWindowManager().getDefaultDisplay().getRotation();
        captureStillBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
        CameraCaptureSession.CaptureCallback captureCallback = new CameraCaptureSession.CaptureCallback() {
            @Override
            public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) {
                super.onCaptureCompleted(session, request, result);
                //Toast.makeText(getApplicationContext(), "Image Taken", Toast.LENGTH_SHORT).show();
                unLockFocus();
            }
        };
        mCameraCaptureSession.capture(captureStillBuilder.build(), captureCallback, null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

File createImageFile() throws IOException {
    String timestamp = new SimpleDateFormat("yyyyMMdd").format(new Date());
    String subFolder = "";
    if(pref_session_unique_gallery.equals("yes")){
        if(event_name != null){
            subFolder = event_name;
        } else {
            subFolder = timestamp;
        }
    } else {
        subFolder = "_GEN";
    }
    if(event_name == null){
        event_name = "";
    } else {
        event_name = event_name + "_";
    }
    String imageFileName = "CPB_"+event_name+timestamp+"_";
    File storageDirectory = new File(Environment.getExternalStorageDirectory() + File.separator + "CPB" + File.separator + subFolder);
    storageDirectory.mkdir();
    File image = File.createTempFile(imageFileName, ".jpg", storageDirectory);
    mImageFileLocation = image.getAbsolutePath();
    return image;
}

和图像保存在这里:

private static class ImageSaver implements Runnable {
    private final Image mImage;
    private ImageSaver(Image image) {
        mImage = image;
    }
    @Override
    public void run() {
        ByteBuffer byteBuffer = mImage.getPlanes()[0].getBuffer();
        byte[] bytes = new byte[byteBuffer.remaining()];
        byteBuffer.get(bytes);

        FileOutputStream fileOutputStream = null;

        try {
            fileOutputStream = new FileOutputStream(mImageFile);
            fileOutputStream.write(bytes);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            mImage.close();
            if(fileOutputStream != null){
                try {
                    fileOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        }

我正在获取图像的正确路径createImageFile()并烘烤它以显示它每次都是什么.但是,即使不setVisibility上latest_picture_container工作...如果我注释掉InputStream,Bitmap并且setImageBitmap,然后latest_picture_container显示为正常.不知道为什么这是错的.

出于某种原因,URI在文件后面会有三个斜杠,

file:///storage/0/...

Answer 1

该AssetManager#open()方法仅适用于您应用的资产；即，项目/assets文件夹中的文件。由于您尝试打​​开外部文件，因此您应该在从路径创建FileInputStream的File对象上使用 a 。此外，该takePhoto()方法在将ImageView任何内容写入文件之前设置图像，这将导致空的ImageView.

由于您的应用程序直接使用相机，我们可以从写入图像文件的相同字节数组中解码图像，并为自己节省不必要的存储读取。此外，在您的代码示例中，文件写入发生在单独的线程上，因此我们不妨在执行图像解码时利用这一点，因为它将最大限度地减少对 UI 线程的影响。

首先，我们将创建一个接口，通过该接口ImageSaver可以将图像传回Activity以显示在ImageView.

public interface OnImageDecodedListener {
    public void onImageDecoded(Bitmap b);
}

然后我们需要ImageSaver稍微改变类以Activity在构造函数中接受一个参数。我还添加了一个File参数，因此Activity的相应字段不必是static。

private static class ImageSaver implements Runnable {
    private final Activity mActivity;
    private final Image mImage;
    private final File mImageFile;

    public ImageSaver(Activity activity, Image image, File imageFile) {
        mActivity = activity;
        mImage = image;
        mImageFile = imageFile;
    }

    @Override
    public void run() {
        ByteBuffer byteBuffer = mImage.getPlanes()[0].getBuffer();
        byte[] bytes = new byte[byteBuffer.remaining()];
        byteBuffer.get(bytes);

        final Bitmap b = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
        mActivity.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    ((OnImageDecodedListener) mActivity).onImageDecoded(b);
                }
            }
        );

        FileOutputStream fileOutputStream = null;
        ...
    }
}

一旦我们获得字节数组中的图像数据，我们就对其进行解码并将其传递回Activity，因此它不必等待文件写入，可以在后台安静地进行。我们需要在 UI 线程上调用 interface 方法，因为我们正在“触摸”View那里。

在Activity将需要实现的接口，我们可以移动的View，从产权相关的东西takePhoto()的onImageDecoded()方法。

public class MainActivity extends Activity
    implements ImageSaver.OnImageDecodedListener {
    ...

    @Override
    public void onImageDecoded(Bitmap b) {
        final ImageView latest_picture =
            (ImageView) findViewById(R.id.latest_picture);
        final RelativeLayout latest_picture_container =
            (RelativeLayout) findViewById(R.id.latest_picture_container);

        latest_picture.setImageBitmap(b);
        latest_picture_container.setVisibility(View.VISIBLE);
    }

    public void takePhoto(View view) {
        try {
            mImageFile = createImageFile();
            captureStillImage();
            lockFocus();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }
    ...
}

最后，我们需要实际执行ImageSaverinImageReader的onImageAvailable()方法。再次按照这个例子，它会是这样的。

private final ImageReader.OnImageAvailableListener mOnImageAvailableListener = 
    new ImageReader.OnImageAvailableListener() {
    @Override
    public void onImageAvailable(ImageReader reader) {
        mBackgroundHandler.post(new ImageSaver(MainActivity.this,
                                               reader.acquireNextImage(),
                                               mImageFile)
        );
    }
};