Support DPI change in wxToolBar

Manually resize the embedded controls and Realize the toolbar again.

include/wx/msw/toolbar.h

@@ -139,6 +139,9 @@ protected:
     // set native toolbar padding
     void MSWSetPadding(WXWORD padding);
 
+    void RealizeHelper();
+    void OnDPIChanged(wxDPIChangedEvent& event);
+
     // the big bitmap containing all bitmaps of the toolbar buttons
     WXHBITMAP m_hBitmap;
 

src/msw/toolbar.cpp

@@ -38,6 +38,7 @@
     #include "wx/region.h"
     #include "wx/dcmemory.h"
     #include "wx/control.h"
+    #include "wx/choice.h"
     #include "wx/app.h"         // for GetComCtl32Version
     #include "wx/image.h"
     #include "wx/stattext.h"
@@ -127,6 +128,7 @@ wxBEGIN_EVENT_TABLE(wxToolBar, wxToolBarBase)
     EVT_MOUSE_EVENTS(wxToolBar::OnMouseEvent)
     EVT_SYS_COLOUR_CHANGED(wxToolBar::OnSysColourChanged)
     EVT_ERASE_BACKGROUND(wxToolBar::OnEraseBackground)
+    EVT_DPI_CHANGED(wxToolBar::OnDPIChanged)
 wxEND_EVENT_TABLE()
 
 // ----------------------------------------------------------------------------
@@ -1895,6 +1897,52 @@ void wxToolBar::OnEraseBackground(wxEraseEvent& event)
 #endif // wxHAS_MSW_BACKGROUND_ERASE_HOOK
 }
 
+void wxToolBar::RealizeHelper()
+{
+    Realize();
+}
+
+void wxToolBar::OnDPIChanged(wxDPIChangedEvent& event)
+{
+    // Manually scale the size of the controls. Even though the font has been
+    // updated, the internal size of the controls does not.
+    const float scaleFactor = (float)event.GetNewDPI().y / event.GetOldDPI().y;
+
+    wxToolBarToolsList::compatibility_iterator node;
+    for ( node = m_tools.GetFirst(); node; node = node->GetNext() )
+    {
+        wxToolBarTool* const tool = static_cast<wxToolBarTool*>(node->GetData());
+        if ( !tool->IsControl() )
+            continue;
+
+        if ( wxControl* const control = tool->GetControl() )
+        {
+            const wxSize oldSize = control->GetSize();
+            wxSize newSize = oldSize * scaleFactor;
+
+            // choice based controls seem to automatically adjust their height
+            // when the font size increases, keep this size
+            if ( dynamic_cast<wxChoiceBase*>(control) && scaleFactor > 1 )
+                newSize.y = oldSize.y;
+
+            control->SetSize(newSize);
+        }
+
+        if ( wxStaticText* const staticText = tool->GetStaticText() )
+        {
+            // Use the best size for the label
+            staticText->SetSize(staticText->GetBestSize());
+        }
+    }
+
+    // Use CallAfter because creating the toolbar directly does sometimes not
+    // work. E.g. when switching from 125% to 150%. All the sizes are set
+    // correctly, but after all dpi events are handled, 5px of the toolbar are
+    // gone and a dark-gray bar appears. After resizing the window, the gray
+    // bar disapears as well.
+    CallAfter(&wxToolBar::RealizeHelper);
+}
+
 bool wxToolBar::HandleSize(WXWPARAM WXUNUSED(wParam), WXLPARAM WXUNUSED(lParam))
 {
     // wait until we have some tools