Fix "Smooth scaling" artifact

[abaeyens]

Fix #103.

Used generative AI: Claude Opus 4.7

The following PR must be merged first:

• Fix image artifacts when enabling zoom1 #102

[abaeyens]

While reviewing, you may want to apply the following diff:

diff --git a/src/rqt_image_view/ratio_layouted_frame.cpp b/src/rqt_image_view/ratio_layouted_frame.cpp
index 442b4b7..7941b46 100644
--- a/src/rqt_image_view/ratio_layouted_frame.cpp
+++ b/src/rqt_image_view/ratio_layouted_frame.cpp
@@ -33,6 +33,7 @@
 
 #include <assert.h>
 #include <QMouseEvent>
+#include <iostream>
 
 #include <rqt_image_view/ratio_layouted_frame.hpp>
 
@@ -85,6 +86,7 @@ void RatioLayoutedFrame::resizeToFitAspectRatio()
   double width;
   double height;
 
+  std::cout << "contentsRect() shape: " << contentsRect().width() << ", " << contentsRect().height() << std::endl;
   if (outer_layout_) {
     width = outer_layout_->contentsRect().width();
     height = outer_layout_->contentsRect().height();
@@ -162,6 +164,7 @@ void RatioLayoutedFrame::paintEvent(QPaintEvent * event)
     // TODO(anyone): check if full draw is really necessary
     // QPaintEvent* paint_event = dynamic_cast<QPaintEvent*>(event);
     // painter.drawImage(paint_event->rect(), qimage_);
+    std::cout << "original image shape:   " << qimage_.width() << ", " << qimage_.height() << "px" << std::endl;
     if (!smoothImage_) {
       painter.drawImage(contentsRect(), qimage_);
     } else {
@@ -170,9 +173,12 @@ void RatioLayoutedFrame::paintEvent(QPaintEvent * event)
       } else {
         QImage image = qimage_.scaled(contentsRect().width(), contentsRect().height(),
                                       Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
+        std::cout << "scaled image shape:   " << image.width() << ", " << image.height() << "px" << std::endl;
         painter.drawImage(contentsRect(), image);
       }
     }
+    std::cout << "contentsRect() shape: " << contentsRect().width() << ", " << contentsRect().height() << " px" << std::endl;
+    std::cout << std::endl;
   } else {
     // default image with gradient
     QLinearGradient gradient(0, 0, frameRect().width(), frameRect().height());