Android裁剪图像质量问题 [英] Android cropped image quality issue

问题描述

我正在尝试将图像保存为从Android裁剪，然后在我的应用中显示。我正在使用下面的代码，但是当我尝试在我的应用程序中查看图像时，图像质量不如附加图像中那么好。我做错了什么？任何帮助都会很棒。

I am trying to save an image as cropped from android and then show it in my app. I am using the code below, but when I try to view the image in my app the image quality is not good as in the attached image. Am doing anything wrong? Any help would be great.

< img src =https://i.stack.imgur.com/zHrxx.jpgalt =printscreeiphone6>

我的代码是：

dipToPixel = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 1, getResources().getDisplayMetrics());

public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

if (requestCode == 1 && resultCode == getActivity().RESULT_OK && data != null) {

    picUri = data.getData();

    performCrop();

}


if (requestCode == 111 && resultCode == getActivity().RESULT_OK && data != null) {

        Bundle extras = data.getExtras();

        Bitmap bitmapImage = extras.getParcelable("data");

        tweetImage.setImageBitmap(bitmapImage);

        tweetImage.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
            public boolean onPreDraw() {
                tweetImage.getViewTreeObserver().removeOnPreDrawListener(this);

                widthPixel = tweetImage.getMeasuredWidth();
                heightPixel = tweetImage.getMeasuredHeight();

                return true;

            }
        });

        System.out.println("photo added");

        addPhotoVar = 1;
        addPhotoBtn.setText("remove");


}

callbackManager.onActivityResult(requestCode, resultCode, data);


}


private void performCrop() {

try {

    //call the standard crop action intent (the user device may not support it)
    Intent cropIntent = new Intent("com.android.camera.action.CROP");
    //indicate image type and Uri
    cropIntent.setDataAndType(picUri, "image/*");
    //set crop properties
    cropIntent.putExtra("crop", "true");
    //indicate aspect of desired crop
    cropIntent.putExtra("aspectX", 1);
    cropIntent.putExtra("aspectY", 1);
    //indicate output X and Y

    cropIntent.putExtra("outputX", Math.round(screenWidth / dipToPixel)-10);
    cropIntent.putExtra("outputY", Math.round(screenWidth / dipToPixel)-10);
    //retrieve data on return
    cropIntent.putExtra("return-data", true);
    //start the activity - we handle returning in onActivityResult
    startActivityForResult(cropIntent, 111);
}
// respond to users whose devices do not support the crop action
catch (ActivityNotFoundException anfe) {
    // display an error message
    String errorMessage = "your device doesn't support the crop action!";
    Toast toast = Toast.makeText(getActivity(), errorMessage, Toast.LENGTH_SHORT);
    toast.show();
}
}

以下是我使用图片并保存的代码到数据库：

Below is the code that I use the image and save to database:

                tweetImage.buildDrawingCache();
                bm = tweetImage.getDrawingCache();

                if (widthPixel < heightPixel) {

                    basePixel = widthPixel;

                }

                else {

                    basePixel = heightPixel;

                }


                if (basePixel > 768) {

                    widthRatio = (float) 768/basePixel;
                    heightRatio = (float) 768/basePixel;


                }

                else {

                    widthRatio = 1;
                    heightRatio = 1;

                }


                Bitmap bmResized = Bitmap.createScaledBitmap(bm,(int)(widthPixel*widthRatio), (int)(heightPixel*heightRatio), true);

                ByteArrayOutputStream stream = new ByteArrayOutputStream();
                bmResized.compress(Bitmap.CompressFormat.JPEG, 100, stream);
                byteArray1 = stream.toByteArray();

                image1 = new ParseFile("profilePhoto.jpg", byteArray1, "image/jpg");

推荐答案

更改：

bmResized.compress(Bitmap.CompressFormat.JPEG, 100, stream);

to：

bmResized.compress(Bitmap.CompressFormat.PNG, 100, stream);

由于 JPEG 格式使用有损压缩，如果你不想要质量损失，你应该使用 PNG 来保存位图。

Since JPEG format uses a lossy compression, you should use PNG to save the bitmap, if you don't want quality loss.

另外，你应该避免使用 com.android.camera.action.CROP intent，因为它在所有设备上都不存在，如这里。

Also, you should avoid using com.android.camera.action.CROP intent as it doesn't exist on all the devices as explained here.

上面的链接中列出了一些替代方案，您可以使用其中一个。

There are some alternatives listed on the above link, you may use one of them.

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