Downscale image to max OpenGL texture

imagescrollareagl.cpp

@@ -99,6 +99,7 @@ void ImageWidget::setImage(std::shared_ptr<RawImage> image, int index)
     if(image == nullptr)return;
     makeCurrent();
     m_rawImage = image;
+    m_rawImage->downscaleTo(m_maxTextureSize);
 
     m_imgWidth = image->width();
     m_imgHeight = image->height();
@@ -398,9 +399,12 @@ void ImageWidget::initializeGL()
             qDebug() << message;
         });
 
-    qDebug() << (char*)f->glGetString(GL_VENDOR);
+    qDebug() << "Vendor:"   << (char*)f->glGetString(GL_VENDOR);
-    qDebug() << (char*)f->glGetString(GL_RENDERER);
+    qDebug() << "Renderer:" << (char*)f->glGetString(GL_RENDERER);
-    qDebug() << (char*)f->glGetString(GL_VERSION);
+    qDebug() << "Version:"  << (char*)f->glGetString(GL_VERSION);
+    f->glGetIntegerv(GL_MAX_TEXTURE_SIZE, &m_maxTextureSize);
+    f->glGetIntegerv(GL_MAX_ARRAY_TEXTURE_LAYERS, &m_maxArrayLayers);
+    qDebug() << "Max texture size:" << m_maxTextureSize << "max layers:" << m_maxArrayLayers;
 
     //MANUAL_MIPMAP_GEN = QString((const char*)f->glGetString(GL_VENDOR)).startsWith("ATI Technologies Inc", Qt::CaseInsensitive);
 

imagescrollareagl.h

@@ -62,6 +62,8 @@ class ImageWidget : public QOpenGLWidget
     bool m_sizesDirty;
     bool m_srgb;
     int m_thumbnailCount;
+    int m_maxTextureSize;
+    int m_maxArrayLayers;
     QVector<ImageThumb> m_thumnails;
     Database *m_database;
 public:

rawimage.cpp

@@ -410,3 +410,13 @@ void RawImage::scaleToUnit()
         }
     }
 }
+
+void RawImage::downscaleTo(uint32_t size)
+{
+    if(size < width() || size < height())
+    {
+        double s = (double)size / std::max(width(), height());
+        cv::Size dsize(std::floor(width() * s), std::floor(height() * s));
+        cv::resize(m_img, m_img, dsize, 0, 0, cv::INTER_AREA);
+    }
+}

rawimage.h

@@ -86,6 +86,7 @@ public:
     const cv::Mat& mat() const;
     bool pixel(int x, int y, QVector3D &rgb) const;
     void scaleToUnit();
+    void downscaleTo(uint32_t size);
 };
 
 #endif // RAWIMAGE_H