Fix sizing wxBitmapButton used as wxPropertyGrid editor button

Since wxBitmapButton doesn't rescale embedded bitmap we need
to do this on our own to display entire bitmap even the button
is small.

Closes #18715.

src/propgrid/editors.cpp

@@ -2138,9 +2138,55 @@ void wxPGMultiButton::Add( const wxBitmap& bitmap, int itemid )
 {
     itemid = GenId(itemid);
     wxSize sz = GetSize();
-    wxButton* button = new wxBitmapButton( this, itemid, bitmap,
+
-                                           wxPoint(sz.x, 0),
+    // Internal margins around the bitmap inside the button
-                                           wxSize(sz.y, sz.y) );
+    const int margins =
+#if defined(__WXMSW__)
+            2*4;
+#elif defined(__WXGTK3__)
+            2*4;
+#elif defined(__WXGTK__)
+            2*8;
+#elif defined(__WXOSX__)
+            2*3;
+#else
+            0;
+#endif
+    // Maximal heigth of the bitmap
+    const int hMax = sz.y - margins;
+
+    wxBitmap scaledBmp;
+    // Scale bitmap down if necessary
+    if ( bitmap.GetHeight() > hMax )
+    {
+        double scale = (double)hMax / bitmap.GetHeight();
+        int w = wxRound(bitmap.GetWidth()*scale);
+        int h = wxRound(bitmap.GetHeight()*scale);
+#if wxUSE_IMAGE
+        // Here we use high-quality wxImage scaling functions available
+        wxImage img = bitmap.ConvertToImage();
+        img.Rescale(w, h, wxIMAGE_QUALITY_HIGH);
+        scaledBmp = img;
+#else // !wxUSE_IMAGE
+        scaledBmp.Create(w, h, bitmap.GetDepth());
+#if defined(__WXMSW__) || defined(__WXOSX__)
+        // wxBitmap::UseAlpha() is used only on wxMSW and wxOSX.
+        scaledBmp.UseAlpha(bitmap.HasAlpha());
+#endif // __WXMSW__ || __WXOSX__
+        {
+            wxMemoryDC dc(scaledBmp);
+            dc.SetUserScale(scale, scale);
+            dc.DrawBitmap(bitmap, 0, 0);
+        }
+#endif // wxUSE_IMAGE/!wxUSE_IMAGE
+    }
+    else
+    {
+        scaledBmp = bitmap;
+    }
+
+    wxBitmapButton* button = new wxBitmapButton(this, itemid, scaledBmp,
+                           wxPoint(sz.x, 0), wxSize(wxDefaultCoord, sz.y));
     DoAddButton( button, sz );
 }
 #endif

src/propgrid/propgrid.cpp

@@ -1331,9 +1331,7 @@ void wxPropertyGrid::CalculateFontAndBitmapStuff( int vspacing )
     GetTextExtent(wxS("jG"), &x, &y, 0, 0, &m_captionFont);
 
     m_lineHeight = m_fontHeight+(2*m_spacingy)+1;
-#if defined(__WXGTK3__)
+
-    m_lineHeight = wxMax(35, m_lineHeight);
-#endif
     // button spacing
     m_buttonSpacingY = (m_lineHeight - m_iconHeight) / 2;
     if ( m_buttonSpacingY < 0 ) m_buttonSpacingY = 0;