Merge branch 'ribbon-colours'

Fix white pressed-button text becoming illegible in dark ribbon themes.

See #26741.

include/wx/private/colour.h

@@ -0,0 +1,70 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/private/colour.h
+// Purpose:     Private colour-related helper functions.
+// Author:      Vadim Zeitlin
+// Created:     2026-07-29 (extracted src/aui/tabart.cpp)
+// Copyright:   (c) 2026 wxWidgets team
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_PRIVATE_COLOUR_H_
+#define _WX_PRIVATE_COLOUR_H_
+
+#include "wx/colour.h"
+
+#include <cmath>
+
+// Helpers used only in this file itself.
+namespace wxPrivate
+{
+
+inline float wxGetSRGB(float r)
+{
+    return r <= 0.04045f ? r / 12.92f : std::pow((r + 0.055f) / 1.055f, 2.4f);
+}
+
+inline float wxGetRelativeLuminance(const wxColour& c)
+{
+    // See https://www.w3.org/TR/WCAG21/#dfn-relative-luminance
+    return
+        0.2126f * wxGetSRGB(c.Red()   / 255.0f) +
+        0.7152f * wxGetSRGB(c.Green() / 255.0f) +
+        0.0722f * wxGetSRGB(c.Blue()  / 255.0f);
+}
+
+inline float wxComputeContrast(const wxColour& c1, const wxColour& c2)
+{
+    // See https://www.w3.org/TR/WCAG21/#dfn-contrast-ratio
+    float L1 = wxGetRelativeLuminance(c1);
+    float L2 = wxGetRelativeLuminance(c2);
+    return L1 > L2 ? (L1 + 0.05f) / (L2 + 0.05f) : (L2 + 0.05f) / (L1 + 0.05f);
+}
+
+} // anonymous namespace
+
+// Return the colour if it has sufficient contrast ratio (4.5 recommended)
+// with the background or return either white or black if it doesn't.
+// (see https://www.w3.org/TR/WCAG21/#contrast-minimum)
+inline wxColour
+wxGetContrastingFgColour(const wxColour& fg, const wxColour& bg)
+{
+    using namespace wxPrivate;
+
+    // No need to change the colour if it has sufficient contrast.
+    if ( wxComputeContrast(fg, bg) >= 4.5f )
+        return fg;
+
+    // Otherwise pick the colour that provides better contrast.
+    return wxComputeContrast(*wxWHITE, bg) > wxComputeContrast(*wxBLACK, bg)
+            ? *wxWHITE
+            : *wxBLACK;
+}
+
+// Version of the above modifying the foregorund colour in place.
+inline void
+wxEnsureSufficientContrast(wxColour* fg, const wxColour& bg)
+{
+    *fg = wxGetContrastingFgColour(*fg, bg);
+}
+
+#endif // _WX_PRIVATE_COLOUR_H_

include/wx/ribbon/art.h

@@ -644,6 +644,9 @@ protected:
     void DrawDropdownArrow(wxDC& dc, int x, int y, const wxColour& colour);
     void DrawGalleryBackgroundCommon(wxDC& dc, wxRibbonGallery* wnd,
                         const wxRect& rect);
+    // Picks the button bar label colour appropriate for the given
+    // wxRIBBON_BUTTONBAR_BUTTON_* state flags.
+    wxColour GetButtonBarLabelColour(long state) const;
     virtual void DrawGalleryButton(wxDC& dc, wxRect rect,
         wxRibbonGalleryButtonState state, wxBitmapBundle* bundles, wxWindow* wnd);
     void DrawButtonBarButtonForeground(
@@ -674,6 +677,7 @@ protected:
 
     wxColour m_button_bar_label_colour;
     wxColour m_button_bar_label_disabled_colour;
+    wxColour m_button_bar_active_label_colour;
     wxColour m_tab_label_colour;
     wxColour m_tab_active_label_colour;
     wxColour m_tab_hover_label_colour;

src/aui/dockart.cpp

@@ -48,8 +48,7 @@
 #endif
 
 #include "wx/private/aui.h"
-
-#include <math.h>
+#include "wx/private/colour.h"
 
 wxColor wxAuiLightContrastColour(const wxColour& c)
 {
@@ -63,27 +62,6 @@ wxColor wxAuiLightContrastColour(const wxColour& c)
     return c.ChangeLightness(amount);
 }
 
-inline float wxAuiGetSRGB(float r) {
-    return r <= 0.03928f ? r / 12.92f : std::pow((r + 0.055f) / 1.055f, 2.4f);
-}
-
-float wxAuiGetRelativeLuminance(const wxColour& c)
-{
-    // based on https://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef
-    return
-        0.2126f * wxAuiGetSRGB(c.Red()   / 255.0f) +
-        0.7152f * wxAuiGetSRGB(c.Green() / 255.0f) +
-        0.0722f * wxAuiGetSRGB(c.Blue()  / 255.0f);
-}
-
-float wxAuiGetColourContrast(const wxColour& c1, const wxColour& c2)
-{
-    // based on https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast7.html
-    float L1 = wxAuiGetRelativeLuminance(c1);
-    float L2 = wxAuiGetRelativeLuminance(c2);
-    return L1 > L2 ? (L1 + 0.05f) / (L2 + 0.05f) : (L2 + 0.05f) / (L1 + 0.05f);
-}
-
 #ifdef wxHAS_SVG
 wxBitmapBundle wxAuiCreateBitmap(const char* svgData, int w, int h,
                                    const wxColour& color)

src/aui/tabart.cpp

@@ -36,31 +36,15 @@
 #endif
 
 #include "wx/private/aui.h"
+#include "wx/private/colour.h"
 
 // -- GUI helper classes and functions --
 
 // these functions live in dockart.cpp -- they'll eventually
 // be moved to a new utility cpp file
 
-float wxAuiGetColourContrast(const wxColour& c1, const wxColour& c2);
-
 wxString wxAuiChopText(wxDC& dc, const wxString& text, int max_size);
 
-// Check if the given colour has sufficient contrast ratio (4.5 recommended)
-// with the background and replace it with either white or black if it doesn't.
-// (based on https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast7.html)
-static void
-wxAuiEnsureSufficientContrast(wxColour* fg, const wxColour& bg)
-{
-    // No need to change the colour if it has sufficient contrast.
-    if ( wxAuiGetColourContrast(*fg, bg) >= 4.5f )
-        return;
-
-    // Otherwise pick the colour that provides better contrast.
-    *fg = wxAuiGetColourContrast(*wxWHITE, bg)
-          > wxAuiGetColourContrast(*wxBLACK, bg) ? *wxWHITE : *wxBLACK;
-}
-
 // Create a "disabled" version of the given colour by adjusting its lightness
 // in the direction depending on the theme.
 static wxColour wxAuiDimColour(wxColour colour, int delta = 30)
@@ -1263,7 +1247,7 @@ int wxAuiGenericTabArt::DrawPageTab(
     // draw tab text
     wxColor font_color = wxSystemSettings::GetColour(
         page.active ? wxSYS_COLOUR_CAPTIONTEXT : wxSYS_COLOUR_INACTIVECAPTIONTEXT);
-    wxAuiEnsureSufficientContrast(&font_color, back_color);
+    wxEnsureSufficientContrast(&font_color, back_color);
     dc.SetTextForeground(font_color);
     dc.DrawText(draw_text,
                 text_offset,
@@ -1617,7 +1601,7 @@ void wxAuiSimpleTabArt::DrawTab(wxDC& dc,
     wxColor back_color = dc.GetBrush().GetColour();
     wxColor font_color = wxSystemSettings::GetColour(
         page.active ? wxSYS_COLOUR_CAPTIONTEXT : wxSYS_COLOUR_INACTIVECAPTIONTEXT);
-    wxAuiEnsureSufficientContrast(&font_color, back_color);
+    wxEnsureSufficientContrast(&font_color, back_color);
     dc.SetTextForeground(font_color);
 
     const auto textY = tab_y + (tab_height - texty) / 2 + 1;

src/ribbon/art_aui.cpp

@@ -29,6 +29,8 @@
 #include "wx/osx/private.h"
 #endif
 
+#include "wx/private/colour.h"
+
 wxRibbonAUIArtProvider::wxRibbonAUIArtProvider()
     : wxRibbonMSWArtProvider(false)
 {
@@ -287,6 +289,8 @@ void wxRibbonAUIArtProvider::SetColourScheme(
     m_button_bar_hover_background_brush = LikeSecondary(1.7f);
     m_button_bar_active_background_brush = LikeSecondary(1.4f);
     m_button_bar_label_colour = m_tab_label_colour;
+    m_button_bar_active_label_colour = wxGetContrastingFgColour(
+        m_button_bar_label_colour, m_button_bar_active_background_brush.GetColour());
 #ifdef __WXOSX__
     m_button_bar_label_disabled_colour = wxSystemSettings::GetColour(wxSYS_COLOUR_INACTIVECAPTIONTEXT);
 #else
@@ -1145,9 +1149,7 @@ void wxRibbonAUIArtProvider::DrawButtonBarButton(
     }
 
     dc.SetFont(m_button_bar_label_font);
-    dc.SetTextForeground(state & wxRIBBON_BUTTONBAR_BUTTON_DISABLED
-                            ? m_button_bar_label_disabled_colour
-                            : m_button_bar_label_colour);
+    dc.SetTextForeground(GetButtonBarLabelColour(state));
     DrawButtonBarButtonForeground(dc, rect, kind, state, label, bitmap_large,
         bitmap_small);
 }

src/ribbon/art_internal.cpp

@@ -9,7 +9,6 @@
 
 #include "wx/wxprec.h"
 
-
 #if wxUSE_RIBBON
 
 #include "wx/ribbon/art.h"

src/ribbon/art_msw.cpp

@@ -26,6 +26,8 @@
 #include "wx/msw/private.h"
 #endif
 
+#include "wx/private/colour.h"
+
 static const char* const gallery_up_xpm[] = {
   "5 5 2 1",
   "  c None",
@@ -293,6 +295,12 @@ void wxRibbonMSWArtProvider::SetColourScheme(
     m_button_bar_active_background_colour = LikeSecondary(-9.9f, 0.14f, -0.14f);
     m_button_bar_active_background_gradient_colour = LikeSecondary(-8.7f, 0.17f, -0.03f);
 
+    // The active/pressed background can end up much lighter (or darker)
+    // than the normal button label colour was chosen for, so pick a label
+    // colour that stays legible against it specifically.
+    m_button_bar_active_label_colour = wxGetContrastingFgColour(
+        m_button_bar_label_colour, m_button_bar_active_background_colour);
+
     m_toolbar_border_pen = LikePrimary(1.4f, -0.21f, -0.16f);
     SetColour(wxRIBBON_ART_TOOLBAR_FACE_COLOUR, LikePrimary(1.4f, -0.17f, -0.22f));
     m_tool_background_top_colour = LikePrimary(-1.9f, -0.07f, 0.06f);
@@ -366,6 +374,7 @@ void wxRibbonMSWArtProvider::CloneTo(wxRibbonMSWArtProvider* copy) const
 
     copy->m_button_bar_label_colour = m_button_bar_label_colour;
     copy->m_button_bar_label_disabled_colour = m_button_bar_label_disabled_colour;
+    copy->m_button_bar_active_label_colour = m_button_bar_active_label_colour;
     copy->m_tab_label_colour = m_tab_label_colour;
     copy->m_tab_active_label_colour = m_tab_active_label_colour;
     copy->m_tab_hover_label_colour = m_tab_hover_label_colour;
@@ -2305,6 +2314,15 @@ void wxRibbonMSWArtProvider::DrawPartialPageBackground(
     dc.DrawRectangle(rect.x, rect.y, rect.width, rect.height);
 }
 
+wxColour wxRibbonMSWArtProvider::GetButtonBarLabelColour(long state) const
+{
+    if(state & wxRIBBON_BUTTONBAR_BUTTON_DISABLED)
+        return m_button_bar_label_disabled_colour;
+    if(state & wxRIBBON_BUTTONBAR_BUTTON_ACTIVE_MASK)
+        return m_button_bar_active_label_colour;
+    return m_button_bar_label_colour;
+}
+
 void wxRibbonMSWArtProvider::DrawButtonBarButton(
                         wxDC& dc,
                         wxWindow* WXUNUSED(wnd),
@@ -2425,9 +2443,7 @@ void wxRibbonMSWArtProvider::DrawButtonBarButton(
     }
 
     dc.SetFont(m_button_bar_label_font);
-    dc.SetTextForeground(state & wxRIBBON_BUTTONBAR_BUTTON_DISABLED
-                            ? m_button_bar_label_disabled_colour
-                            : m_button_bar_label_colour);
+    dc.SetTextForeground(GetButtonBarLabelColour(state));
     DrawButtonBarButtonForeground(dc, rect, kind, state, label, bitmap_large,
         bitmap_small);
 }
@@ -2441,10 +2457,7 @@ void wxRibbonMSWArtProvider::DrawButtonBarButtonForeground(
                         const wxBitmap& bitmap_large,
                         const wxBitmap& bitmap_small)
 {
-    const wxColour
-        arrowColour(state & wxRIBBON_BUTTONBAR_BUTTON_DISABLED
-                        ? m_button_bar_label_disabled_colour
-                        : m_button_bar_label_colour);
+    const wxColour arrowColour(GetButtonBarLabelColour(state));
 
     switch(state & wxRIBBON_BUTTONBAR_BUTTON_SIZE_MASK)
     {

src/ribbon/art_msw_flat.cpp

@@ -782,9 +782,7 @@ void wxRibbonMSWFlatArtProvider::DrawButtonBarButton(
     }
 
     dc.SetFont(m_button_bar_label_font);
-    dc.SetTextForeground(state & wxRIBBON_BUTTONBAR_BUTTON_DISABLED
-                            ? m_button_bar_label_disabled_colour
-                            : m_button_bar_label_colour);
+    dc.SetTextForeground(GetButtonBarLabelColour(state));
     DrawButtonBarButtonForeground(dc, rect, kind, state, label, bitmap_large,
         bitmap_small);
 }