Backport: Bug [#2063]. Make reverse arrow cursor scale with DPI.

Backport of changeset 8265:01940b16fb7e.

3 files changed, 67 insertions, 9 deletions

diff --git a/win32/PlatWin.cxx b/win32/PlatWin.cxx
index b125bd86d..7854966d1 100644
--- a/win32/PlatWin.cxx
+++ b/win32/PlatWin.cxx
@@ -277,8 +277,6 @@ void LoadDpiForWindow() noexcept {
 
 HINSTANCE hinstPlatformRes {};
 
-HCURSOR reverseArrowCursor {};
-
 FormatAndMetrics *FamFromFontID(void *fid) noexcept {
 	return static_cast<FormatAndMetrics *>(fid);
 }
@@ -1857,8 +1855,24 @@ void FlipBitmap(HBITMAP bitmap, int width, int height) noexcept {
 	}
 }
 
-void LoadReverseArrowCursor() noexcept {
+}
+
+HCURSOR LoadReverseArrowCursor(UINT dpi) noexcept {
+	HCURSOR reverseArrowCursor {};
+
+	bool created = false;
 	HCURSOR cursor = ::LoadCursor({}, IDC_ARROW);
+
+	if (dpi != uSystemDPI) {
+		const int width = SystemMetricsForDpi(SM_CXCURSOR, dpi);
+		const int height = SystemMetricsForDpi(SM_CYCURSOR, dpi);
+		HCURSOR copy = static_cast<HCURSOR>(::CopyImage(cursor, IMAGE_CURSOR, width, height, LR_COPYFROMRESOURCE | LR_COPYRETURNORG));
+		if (copy) {
+			created = copy != cursor;
+			cursor = copy;
+		}
+	}
+
 	ICONINFO info;
 	if (::GetIconInfo(cursor, &info)) {
 		BITMAP bmp;
@@ -1875,8 +1889,11 @@ void LoadReverseArrowCursor() noexcept {
 		if (info.hbmColor)
 			::DeleteObject(info.hbmColor);
 	}
-}
 
+	if (created) {
+		::DestroyCursor(cursor);
+	}
+	return reverseArrowCursor;
 }
 
 void Window::SetCursor(Cursor curs) {
@@ -1900,8 +1917,6 @@ void Window::SetCursor(Cursor curs) {
 		::SetCursor(::LoadCursor(NULL,IDC_HAND));
 		break;
 	case cursorReverseArrow:
-		::SetCursor(reverseArrowCursor);
-		break;
 	case cursorArrow:
 	case cursorInvalid:	// Should not occur, but just in case.
 		::SetCursor(::LoadCursor(NULL,IDC_ARROW));
@@ -2950,7 +2965,6 @@ void Platform::Assert(const char *c, const char *file, int line) {
 void Platform_Initialise(void *hInstance) {
 	hinstPlatformRes = static_cast<HINSTANCE>(hInstance);
 	LoadDpiForWindow();
-	LoadReverseArrowCursor();
 	ListBoxX_Register();
 }
 
@@ -2983,8 +2997,6 @@ void Platform_Finalise(bool fromDllMain) {
 		}
 	}
 #endif
-	if (reverseArrowCursor)
-		::DestroyCursor(reverseArrowCursor);
 	ListBoxX_Unregister();
 }
 
diff --git a/win32/PlatWin.h b/win32/PlatWin.h
index cce68f43c..2555daac0 100644
--- a/win32/PlatWin.h
+++ b/win32/PlatWin.h
@@ -56,6 +56,8 @@ UINT DpiForWindow(WindowID wid) noexcept;
 
 int SystemMetricsForDpi(int nIndex, UINT dpi) noexcept;
 
+HCURSOR LoadReverseArrowCursor(UINT dpi) noexcept;
+
 #if defined(USE_D2D)
 extern bool LoadD2D();
 extern ID2D1Factory *pD2DFactory;
diff --git a/win32/ScintillaWin.cxx b/win32/ScintillaWin.cxx
index a850812c7..dcae50140 100644
--- a/win32/ScintillaWin.cxx
+++ b/win32/ScintillaWin.cxx
@@ -266,6 +266,37 @@ public:
 	}
 };
 
+class ReverseArrowCursor {
+	UINT dpi = USER_DEFAULT_SCREEN_DPI;
+	HCURSOR cursor {};
+
+public:
+	ReverseArrowCursor() noexcept {}
+	// Deleted so ReverseArrowCursor objects can not be copied.
+	ReverseArrowCursor(const ReverseArrowCursor &) = delete;
+	ReverseArrowCursor(ReverseArrowCursor &&) = delete;
+	ReverseArrowCursor &operator=(const ReverseArrowCursor &) = delete;
+	ReverseArrowCursor &operator=(ReverseArrowCursor &&) = delete;
+	~ReverseArrowCursor() {
+		if (cursor) {
+			::DestroyCursor(cursor);
+		}
+	}
+
+	HCURSOR Load(UINT dpi_) noexcept {
+		if (cursor)	 {
+			if (dpi == dpi_) {
+				return cursor;
+			}
+			::DestroyCursor(cursor);
+		}
+
+		dpi = dpi_;
+		cursor = LoadReverseArrowCursor(dpi_);
+		return cursor ? cursor : ::LoadCursor({}, IDC_ARROW);
+	}
+};
+
 }
 
 /**
@@ -284,6 +315,7 @@ class ScintillaWin :
 	int wheelDelta; ///< Wheel delta from roll
 
 	UINT dpi = USER_DEFAULT_SCREEN_DPI;
+	ReverseArrowCursor reverseArrowCursor;
 
 	HRGN hRgnUpdate;
 
@@ -333,6 +365,7 @@ class ScintillaWin :
 
 	enum : UINT_PTR { invalidTimerID, standardTimerID, idleTimerID, fineTimerStart };
 
+	void DisplayCursor(Window::Cursor c) override;
 	bool DragThreshold(Point ptStart, Point ptNow) override;
 	void StartDrag() override;
 	static int MouseModifiers(uptr_t wParam) noexcept;
@@ -650,6 +683,17 @@ HWND ScintillaWin::MainHWND() const noexcept {
 	return HwndFromWindow(wMain);
 }
 
+void ScintillaWin::DisplayCursor(Window::Cursor c) {
+	if (cursorMode != SC_CURSORNORMAL) {
+		c = static_cast<Window::Cursor>(cursorMode);
+	}
+	if (c == Window::cursorReverseArrow) {
+		::SetCursor(reverseArrowCursor.Load(dpi));
+	} else {
+		wMain.SetCursor(c);
+	}
+}
+
 bool ScintillaWin::DragThreshold(Point ptStart, Point ptNow) {
 	const Point ptDifference = ptStart - ptNow;
 	const XYPOSITION xMove = std::trunc(std::abs(ptDifference.x));