CMS upload fails for images when LocalCopy=false

[markguinn]

The problem is that UploadField creates an Image object, which is then wrapped to CloudImage, but the initial reference is still an Image. This is a weakness in the architecture that I don't know how to overcome at this stage. The following code then fails in UploadField.php (currently line 911 - the call to SetRatioSize returns null because the width and height are not set):

    /**
     * @param File $file
     * @return string
     */
    protected function getThumbnailURLForFile(File $file) {
        if ($file->exists() && file_exists(Director::baseFolder() . '/' . $file->getFilename())) {
            $width = $this->getPreviewMaxWidth();
            $height = $this->getPreviewMaxHeight();
            if ($file->hasMethod('getThumbnail')) {
                return $file->getThumbnail($width, $height)->getURL();
            } elseif ($file->hasMethod('getThumbnailURL')) {
                return $file->getThumbnailURL($width, $height);
            } elseif ($file->hasMethod('SetRatioSize')) {
                return $file->SetRatioSize($width, $height)->getURL();
            } else {
                return $file->Icon();
            }
        }
        return false;
    }

Options:

1. Implement getThumbnail in CloudFileExtension. This would cover the above case but I'm uncomfortable with it b/c it feels hack-y.
2. Set $this->width and $this->height on the source image object during the wrapping process. This would cause SetRatioSize to at minimum return a CloudImageMissing placeholder. Again, not ideal.
3. Do the upload offline - either by requiring the QueuedJobs module or an additional cron job. I really don't want to have to do this.
4. Try to extend UploadField.