Use float based scale factor for ImageButton texture

CHANGELOG.md

@@ -131,6 +131,7 @@
     Bug #6753: Info records without a DATA subrecords are loaded incorrectly
     Bug #6794: Light sources are attached to mesh bounds centers instead of mesh origins when AttachLight NiNode is missing
     Bug #6799: Game crashes if an NPC has no Class attached
+    Bug #6849: ImageButton texture is not scaled properly
     Feature #890: OpenMW-CS: Column filtering
     Feature #1465: "Reset" argument for AI functions
     Feature #2491: Ability to make OpenMW "portable"

components/widgets/imagebutton.cpp

@@ -1,5 +1,7 @@
 #include "imagebutton.hpp"
 
+#include <cmath>
+
 #include <MyGUI_RenderManager.h>
 
 #include <components/debug/debuglog.hpp>
@@ -88,13 +90,17 @@ namespace Gui
 
         if (!mUseWholeTexture)
         {
-            int scale = 1.f;
+            float scale = 1.f;
             MyGUI::ITexture* texture = MyGUI::RenderManager::getInstance().getTexture(textureName);
             if (texture && getHeight() != 0)
-                scale = texture->getHeight() / getHeight();
-
-            setImageTile(MyGUI::IntSize(mTextureRect.width * scale, mTextureRect.height * scale));
-            MyGUI::IntCoord scaledSize(mTextureRect.left * scale, mTextureRect.top * scale, mTextureRect.width * scale, mTextureRect.height * scale);
+                scale = static_cast<float>(texture->getHeight()) / getHeight();
+
+            const int width = static_cast<int>(std::round(mTextureRect.width * scale));
+            const int height = static_cast<int>(std::round(mTextureRect.height * scale));
+            setImageTile(MyGUI::IntSize(width, height));
+            MyGUI::IntCoord scaledSize(static_cast<int>(std::round(mTextureRect.left * scale)),
+                                       static_cast<int>(std::round(mTextureRect.top * scale)),
+                                       width, height);
             setImageCoord(scaledSize);
         }