Add SCI_SETELEMENTCOLOUR and related APIs to change colours of visible elements.

Implement SC_ELEMENT_LIST* to change colours of autocompletion lists.

20 files changed, 129 insertions, 12 deletions

diff --git a/cocoa/ScintillaCocoa.h b/cocoa/ScintillaCocoa.h
index 8ea0f410f..2474ca6f1 100644
--- a/cocoa/ScintillaCocoa.h
+++ b/cocoa/ScintillaCocoa.h
@@ -22,6 +22,7 @@
 #include <string>
 #include <vector>
 #include <map>
+#include <set>
 #include <memory>
 
 #include "ILoader.h"
diff --git a/doc/ScintillaHistory.html b/doc/ScintillaHistory.html
index c518cd60e..d8aea7a2a 100644
--- a/doc/ScintillaHistory.html
+++ b/doc/ScintillaHistory.html
@@ -608,6 +608,10 @@
 	Add shapes with curved and rounded ends to EOL annotations as EOLANNOTATION_*.
 	</li>
 	<li>
+	Add SCI_SETELEMENTCOLOUR and related APIs to change colours of visible elements.
+	Implement SC_ELEMENT_LIST* to change colours of autocompletion lists.
+	</li>
+	<li>
 	Change graphics coordinates from float (32-bit) to double (64-bit).
 	Fixes uneven line heights in large documents on Cocoa.
 	Increases memory use.
diff --git a/gtk/ScintillaGTK.cxx b/gtk/ScintillaGTK.cxx
index 312ad1f94..09a389677 100755
--- a/gtk/ScintillaGTK.cxx
+++ b/gtk/ScintillaGTK.cxx
@@ -17,6 +17,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <optional>
 #include <algorithm>
 #include <memory>
diff --git a/gtk/ScintillaGTKAccessible.cxx b/gtk/ScintillaGTKAccessible.cxx
index 1aceddb8b..3023e5102 100644
--- a/gtk/ScintillaGTKAccessible.cxx
+++ b/gtk/ScintillaGTKAccessible.cxx
@@ -62,6 +62,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <optional>
 #include <algorithm>
 #include <memory>
diff --git a/include/Scintilla.h b/include/Scintilla.h
index dd1dd78e4..1ea5d3fa1 100644
--- a/include/Scintilla.h
+++ b/include/Scintilla.h
@@ -267,6 +267,15 @@ typedef sptr_t (*SciFnDirect)(sptr_t ptr, unsigned int iMessage, uptr_t wParam,
 #define SCI_STYLEGETWEIGHT 2064
 #define SCI_STYLESETCHARACTERSET 2066
 #define SCI_STYLESETHOTSPOT 2409
+#define SC_ELEMENT_LIST 0
+#define SC_ELEMENT_LIST_BACK 1
+#define SC_ELEMENT_LIST_SELECTED 2
+#define SC_ELEMENT_LIST_SELECTED_BACK 3
+#define SCI_SETELEMENTCOLOUR 2753
+#define SCI_GETELEMENTCOLOUR 2754
+#define SCI_RESETELEMENTCOLOUR 2755
+#define SCI_GETELEMENTISSET 2756
+#define SCI_GETELEMENTALLOWSTRANSLUCENT 2757
 #define SCI_SETSELFORE 2067
 #define SCI_SETSELBACK 2068
 #define SCI_GETSELALPHA 2477
diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index d0b8213e8..8cce965cc 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -53,8 +53,8 @@
 ##     bool -> integer, 1=true, 0=false
 ##     position -> intptr_t position in a document
 ##     line -> intptr_t line in a document
-##     colour -> colour integer containing red, green, and blue bytes.
-##     colouralpha -> colour integer containing red, green, blue, and alpha bytes.
+##     colour -> colour integer containing red, green, and blue bytes with red as least-significant and blue as most.
+##     colouralpha -> colour integer containing red, green, blue, and alpha bytes with red as least-significant and alpha as most.
 ##     string -> pointer to const character
 ##     stringresult -> pointer to character, NULL-> return size of result
 ##     cells -> pointer to array of cells, each cell containing a style byte and character byte
@@ -665,6 +665,29 @@ set void StyleSetCharacterSet=2066(int style, CharacterSet characterSet)
 # Set a style to be a hotspot or not.
 set void StyleSetHotSpot=2409(int style, bool hotspot)
 
+enu Element=SC_ELEMENT_
+val SC_ELEMENT_LIST=0
+val SC_ELEMENT_LIST_BACK=1
+val SC_ELEMENT_LIST_SELECTED=2
+val SC_ELEMENT_LIST_SELECTED_BACK=3
+
+# Set the colour of an element. Translucency (alpha) may or may not be significant
+# and this may depend on the platform. The alpha byte should commonly be 0xff for opaque.
+set void SetElementColour=2753(Element element, colouralpha colourElement)
+
+# Get the colour of an element.
+get colouralpha GetElementColour=2754(Element element,)
+
+# Use the default or platform-defined colour for an element.
+fun void ResetElementColour=2755(Element element,)
+
+# Get whether an element has been set by SetElementColour.
+# When false, a platform-defined or default colour is used.
+get bool GetElementIsSet=2756(Element element,)
+
+# Get whether an element supports translucency.
+get bool GetElementAllowsTranslucent=2757(Element element,)
+
 # Set the foreground colour of the main and additional selections and whether to use this setting.
 fun void SetSelFore=2067(bool useSetting, colour fore)
 
diff --git a/qt/ScintillaEdit/ScintillaDocument.cpp b/qt/ScintillaEdit/ScintillaDocument.cpp
index daa212130..c1605dbd2 100644
--- a/qt/ScintillaEdit/ScintillaDocument.cpp
+++ b/qt/ScintillaEdit/ScintillaDocument.cpp
@@ -6,6 +6,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <optional>
 #include <memory>
 
diff --git a/qt/ScintillaEditBase/ScintillaQt.h b/qt/ScintillaEditBase/ScintillaQt.h
index 72d78f589..617635e55 100644
--- a/qt/ScintillaEditBase/ScintillaQt.h
+++ b/qt/ScintillaEditBase/ScintillaQt.h
@@ -24,6 +24,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <optional>
 #include <algorithm>
 #include <memory>
diff --git a/scripts/HeaderOrder.txt b/scripts/HeaderOrder.txt
index a5cb6a2e8..a45d798de 100644
--- a/scripts/HeaderOrder.txt
+++ b/scripts/HeaderOrder.txt
@@ -42,6 +42,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <forward_list>
 #include <optional>
 #include <algorithm>
diff --git a/src/EditModel.cxx b/src/EditModel.cxx
index 58b9306a2..11827c471 100644
--- a/src/EditModel.cxx
+++ b/src/EditModel.cxx
@@ -16,6 +16,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <optional>
 #include <algorithm>
 #include <memory>
diff --git a/src/EditView.cxx b/src/EditView.cxx
index f22b281c5..b2714f7ac 100644
--- a/src/EditView.cxx
+++ b/src/EditView.cxx
@@ -17,6 +17,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <forward_list>
 #include <optional>
 #include <algorithm>
diff --git a/src/Editor.cxx b/src/Editor.cxx
index ad56a8eb8..fa356fe15 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -17,6 +17,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <forward_list>
 #include <optional>
 #include <algorithm>
@@ -7185,6 +7186,23 @@ sptr_t Editor::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam) {
 		InvalidateStyleRedraw();
 		break;
 
+	case SCI_SETELEMENTCOLOUR:
+		vs.elementColours[static_cast<int>(wParam)] = ColourAlpha(static_cast<int>(lParam));
+		break;
+
+	case SCI_GETELEMENTCOLOUR:
+		return vs.ElementColour(static_cast<int>(wParam)).value_or(ColourAlpha()).AsInteger();
+
+	case SCI_RESETELEMENTCOLOUR:
+		vs.elementColours[static_cast<int>(wParam)].reset();
+		break;
+
+	case SCI_GETELEMENTISSET:
+		return vs.ElementColour(static_cast<int>(wParam)).has_value();
+
+	case SCI_GETELEMENTALLOWSTRANSLUCENT:
+		return vs.ElementAllowsTranslucent(static_cast<int>(wParam));
+
 #ifdef INCLUDE_DEPRECATED_FEATURES
 	case SCI_SETSTYLEBITS:
 		vs.EnsureStyle(0xff);
diff --git a/src/MarginView.cxx b/src/MarginView.cxx
index 7c7998e07..8b6f80695 100644
--- a/src/MarginView.cxx
+++ b/src/MarginView.cxx
@@ -17,6 +17,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <optional>
 #include <algorithm>
 #include <memory>
diff --git a/src/Platform.h b/src/Platform.h
index 98e6440aa..ffe52446c 100644
--- a/src/Platform.h
+++ b/src/Platform.h
@@ -304,6 +304,10 @@ public:
 };
 
 struct ListOptions {
+	std::optional<ColourAlpha> fore;
+	std::optional<ColourAlpha> back;
+	std::optional<ColourAlpha> foreSelected;
+	std::optional<ColourAlpha> backSelected;
 };
 
 class ListBox : public Window {
diff --git a/src/PositionCache.cxx b/src/PositionCache.cxx
index 50858edd7..c9b886119 100644
--- a/src/PositionCache.cxx
+++ b/src/PositionCache.cxx
@@ -15,6 +15,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <optional>
 #include <algorithm>
 #include <iterator>
diff --git a/src/ScintillaBase.cxx b/src/ScintillaBase.cxx
index 1e55fcfbf..e2fb58206 100644
--- a/src/ScintillaBase.cxx
+++ b/src/ScintillaBase.cxx
@@ -15,6 +15,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <optional>
 #include <algorithm>
 #include <memory>
@@ -260,6 +261,14 @@ void ScintillaBase::AutoCompleteStart(Sci::Position lenEntered, const char *list
 	ac.Start(wMain, idAutoComplete, sel.MainCaret(), PointMainCaret(),
 				lenEntered, vs.lineHeight, IsUnicodeMode(), technology);
 
+	ListOptions options{
+		vs.ElementColour(SC_ELEMENT_LIST),
+		vs.ElementColour(SC_ELEMENT_LIST_BACK),
+		vs.ElementColour(SC_ELEMENT_LIST_SELECTED),
+		vs.ElementColour(SC_ELEMENT_LIST_SELECTED_BACK)
+	};
+	ac.lb->SetOptions(options);
+
 	const PRectangle rcClient = GetClientRectangle();
 	Point pt = LocationFromPosition(sel.MainCaret() - lenEntered);
 	PRectangle rcPopupBounds = wMain.GetMonitorRect(pt);
diff --git a/src/ViewStyle.cxx b/src/ViewStyle.cxx
index d1f866906..6aa459895 100644
--- a/src/ViewStyle.cxx
+++ b/src/ViewStyle.cxx
@@ -13,6 +13,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <optional>
 #include <algorithm>
 #include <memory>
@@ -517,6 +518,20 @@ void ViewStyle::AddMultiEdge(uptr_t wParam, sptr_t lParam) {
 		EdgeProperties(column, lParam));
 }
 
+std::optional<ColourAlpha> ViewStyle::ElementColour(int index) const noexcept {
+	auto search = elementColours.find(index);
+	if (search != elementColours.end()) {
+		if (search->second.has_value()) {
+			return search->second;
+		}
+	}
+	return {};
+}
+
+bool ViewStyle::ElementAllowsTranslucent(int index) const noexcept {
+	return elementAllowsTranslucent.count(index) > 0;
+}
+
 bool ViewStyle::SetWrapState(int wrapState_) noexcept {
 	WrapMode wrapStateWanted;
 	switch (wrapState_) {
diff --git a/src/ViewStyle.h b/src/ViewStyle.h
index b07c34a08..d33feb485 100644
--- a/src/ViewStyle.h
+++ b/src/ViewStyle.h
@@ -158,6 +158,9 @@ public:
 	int ctrlCharPadding; // the padding around control character text blobs
 	int lastSegItalicsOffset; // the offset so as not to clip italic characters at EOLs
 
+	std::map<int, std::optional<ColourAlpha>> elementColours;
+	std::set<int> elementAllowsTranslucent;
+
 	// Wrapping support
 	WrapMode wrapState;
 	int wrapVisualFlags;
@@ -195,6 +198,9 @@ public:
 
 	void AddMultiEdge(uptr_t wParam, sptr_t lParam);
 
+	std::optional<ColourAlpha> ElementColour(int index) const noexcept;
+	bool ElementAllowsTranslucent(int index) const noexcept;
+
 	bool SetWrapState(int wrapState_) noexcept;
 	bool SetWrapVisualFlags(int wrapVisualFlags_) noexcept;
 	bool SetWrapVisualFlagsLocation(int wrapVisualFlagsLocation_) noexcept;
diff --git a/win32/PlatWin.cxx b/win32/PlatWin.cxx
index 064871463..b2b188cb6 100644
--- a/win32/PlatWin.cxx
+++ b/win32/PlatWin.cxx
@@ -2934,7 +2934,7 @@ class ListBoxX : public ListBox {
 	void StartResize(WPARAM);
 	LRESULT NcHitTest(WPARAM, LPARAM) const;
 	void CentreItem(int n);
-	void Paint(HDC) noexcept;
+	void Paint(HDC);
 	static LRESULT PASCAL ControlWndProc(HWND hWnd, UINT iMessage, WPARAM wParam, LPARAM lParam);
 
 	static constexpr Point ItemInset {0, 0};	// Padding around whole item
@@ -3141,6 +3141,24 @@ void ListBoxX::ClearRegisteredImages() {
 	images.Clear();
 }
 
+namespace {
+
+int ColourOfElement(std::optional<ColourAlpha> colour, int nIndex) {
+	if (colour.has_value()) {
+		return colour.value().GetColour().AsInteger();
+	} else {
+		return ::GetSysColor(nIndex);
+	}
+}
+
+void FillRectColour(HDC hdc, const RECT *lprc, int colour) noexcept {
+	const HBRUSH brush = ::CreateSolidBrush(colour);
+	::FillRect(hdc, lprc, brush);
+	::DeleteObject(brush);
+}
+
+}
+
 void ListBoxX::Draw(DRAWITEMSTRUCT *pDrawItem) {
 	if ((pDrawItem->itemAction == ODA_SELECT) || (pDrawItem->itemAction == ODA_DRAWENTIRE)) {
 		RECT rcBox = pDrawItem->rcItem;
@@ -3149,14 +3167,14 @@ void ListBoxX::Draw(DRAWITEMSTRUCT *pDrawItem) {
 			RECT rcImage = pDrawItem->rcItem;
 			rcImage.right = rcBox.left;
 			// The image is not highlighted
-			::FillRect(pDrawItem->hDC, &rcImage, reinterpret_cast<HBRUSH>(COLOR_WINDOW+1));
-			::FillRect(pDrawItem->hDC, &rcBox, reinterpret_cast<HBRUSH>(COLOR_HIGHLIGHT+1));
-			::SetBkColor(pDrawItem->hDC, ::GetSysColor(COLOR_HIGHLIGHT));
-			::SetTextColor(pDrawItem->hDC, ::GetSysColor(COLOR_HIGHLIGHTTEXT));
+			FillRectColour(pDrawItem->hDC, &rcImage, ColourOfElement(options.back, COLOR_WINDOW));
+			FillRectColour(pDrawItem->hDC, &rcBox, ColourOfElement(options.backSelected, COLOR_HIGHLIGHT));
+			::SetBkColor(pDrawItem->hDC, ColourOfElement(options.backSelected, COLOR_HIGHLIGHT));
+			::SetTextColor(pDrawItem->hDC, ColourOfElement(options.foreSelected, COLOR_HIGHLIGHTTEXT));
 		} else {
-			::FillRect(pDrawItem->hDC, &pDrawItem->rcItem, reinterpret_cast<HBRUSH>(COLOR_WINDOW+1));
-			::SetBkColor(pDrawItem->hDC, ::GetSysColor(COLOR_WINDOW));
-			::SetTextColor(pDrawItem->hDC, ::GetSysColor(COLOR_WINDOWTEXT));
+			FillRectColour(pDrawItem->hDC, &pDrawItem->rcItem, ColourOfElement(options.back, COLOR_WINDOW));
+			::SetBkColor(pDrawItem->hDC, ColourOfElement(options.back, COLOR_WINDOW));
+			::SetTextColor(pDrawItem->hDC, ColourOfElement(options.fore, COLOR_WINDOWTEXT));
 		}
 
 		const ListItemData item = lti.Get(pDrawItem->itemID);
@@ -3503,7 +3521,7 @@ void ListBoxX::CentreItem(int n) {
 }
 
 // Performs a double-buffered paint operation to avoid flicker
-void ListBoxX::Paint(HDC hDC) noexcept {
+void ListBoxX::Paint(HDC hDC) {
 	const POINT extent = GetClientExtent();
 	HBITMAP hBitmap = ::CreateCompatibleBitmap(hDC, extent.x, extent.y);
 	HDC bitmapDC = ::CreateCompatibleDC(hDC);
@@ -3512,7 +3530,7 @@ void ListBoxX::Paint(HDC hDC) noexcept {
 	// unpainted area when at the end of a non-integrally sized list with a
 	// vertical scroll bar
 	const RECT rc = { 0, 0, extent.x, extent.y };
-	::FillRect(bitmapDC, &rc, reinterpret_cast<HBRUSH>(COLOR_WINDOW+1));
+	FillRectColour(bitmapDC, &rc, ColourOfElement(options.back, COLOR_WINDOWTEXT));
 	// Paint the entire client area and vertical scrollbar
 	::SendMessage(lb, WM_PRINT, reinterpret_cast<WPARAM>(bitmapDC), PRF_CLIENT|PRF_NONCLIENT);
 	::BitBlt(hDC, 0, 0, extent.x, extent.y, bitmapDC, 0, 0, SRCCOPY);
diff --git a/win32/ScintillaWin.cxx b/win32/ScintillaWin.cxx
index 4a8d1c5e9..8779a3c20 100644
--- a/win32/ScintillaWin.cxx
+++ b/win32/ScintillaWin.cxx
@@ -19,6 +19,7 @@
 #include <string_view>
 #include <vector>
 #include <map>
+#include <set>
 #include <optional>
 #include <algorithm>
 #include <memory>