Add makeCurrent to all methods that calls OpenGL

imagescrollareagl.cpp

@@ -182,6 +182,7 @@ void ImageWidget::blockRepaint(bool block)
 
 void ImageWidget::allocateThumbnails(const QStringList &paths)
 {
+    makeCurrent();
     int count = paths.size();
     m_thumbnailCount = count;
     m_thumnails.clear();
@@ -253,6 +254,7 @@ QImage ImageWidget::renderToImage()
 
 void ImageWidget::thumbnailLoaded(const Image *image)
 {
+    makeCurrent();
     const RawImage *raw = image->thumbnail();
     m_thumbnailTexture->setData(0, image->number(), QOpenGLTexture::RGB, QOpenGLTexture::UInt16, raw->data(), m_transferOptions.get());
     float a = raw->thumbAspect();