From c970cc687615f904e66004b6795636fbabb843cb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Sat, 6 Aug 2022 22:35:40 +0200
Subject: Ensure correct mouse position for double click.

---
 c/layout.cpp |  8 ++++----
 c/layout.h   | 37 ++++++++++++++++++++-----------------
 2 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/c/layout.cpp b/c/layout.cpp
index 24ad11f..09c0958 100644
--- a/c/layout.cpp
+++ b/c/layout.cpp
@@ -39,7 +39,7 @@ void UpdateLayout(int w, int h)
 	    RDW_ERASE|RDW_FRAME|RDW_INVALIDATE|RDW_ALLCHILDREN);
 }
 
-bool DlvDragger::InDragArea(const int x, const int y)
+bool DlvDragger::InDragArea(const int x, const int y) const
 {
 	RECT rrDlv;
 	Require(GetRelativeRect(g_dlv->hWnd, &rrDlv));
@@ -51,7 +51,7 @@ bool DlvDragger::InDragArea(const int x, const int y)
 	return true;
 }
 
-void DlvDragger::Drag(const int, const int y)
+void DlvDragger::Drag(const int, const int y) const
 {
 	RECT rrDlv;
 	Require(GetRelativeRect(g_dlv->hWnd, &rrDlv));
@@ -66,14 +66,14 @@ void DlvDragger::Drag(const int, const int y)
 	    RDW_ERASE|RDW_FRAME|RDW_INVALIDATE|RDW_ALLCHILDREN|RDW_UPDATENOW);
 }
 
-void DlvDragger::Reset()
+void DlvDragger::Reset() const
 {
 	g_dlv->SetHeight(0);
 	Pl("cfg","set_dlv_height",0);
 	UpdateLayout();
 }
 
-void DlvDragger::Done()
+void DlvDragger::Done() const
 {
 	Pl("cfg","set_dlv_height",g_dlv->Height());
 }
diff --git a/c/layout.h b/c/layout.h
index 3d9cc3b..29647e2 100644
--- a/c/layout.h
+++ b/c/layout.h
@@ -21,18 +21,19 @@ struct Dragger
 	bool HandleLButtonDown();
 	bool HandleSetCursor();
 protected:
-	bool IsDown();
-	bool IsDouble();
-	virtual bool InDragArea(int x, int y);
+	bool IsDown() const;
+	bool IsDouble(const long time, const POINT& pt);
+	virtual bool InDragArea(int x, int y) const;
 	/* Perform drag, resizing relevant windows. */
-	virtual void Drag(int x, int y);
+	virtual void Drag(int x, int y) const;
 	/* Reset dragger to automatic position. */
-	virtual void Reset();
+	virtual void Reset() const;
 	/* Called after drag, when mouse button is released. */
-	virtual void Done();
+	virtual void Done() const;
 private:
 	bool m_bActive = false;
-	long m_time = 0;
+	long m_time0 = 0;
+	POINT m_pt0 = {0, 0};
 };
 
 /* DlvDragger implements the draggable split between the data list
@@ -41,24 +42,26 @@ private:
 struct DlvDragger : public Dragger
 {
 private:
-	bool InDragArea(int x, int y) override;
-	void Drag(int x, int y) override;
-	void Reset() override;
-	void Done() override;
+	bool InDragArea(int x, int y) const override;
+	void Drag(int x, int y) const override;
+	void Reset() const override;
+	void Done() const override;
 };
 
 /* Below follows the implementation of the non-virtual member
  * functions of Dragger, on which derived objects rely. */
 
-inline bool Dragger::IsDouble()
+inline bool Dragger::IsDouble(const long time, const POINT& pt)
 {
-	const long time = GetMessageTime();
-	const bool dbl = time-m_time <= static_cast<long>(GetDoubleClickTime());
-	m_time = time;
+	const bool dbl = time-m_time0 <= static_cast<long>(GetDoubleClickTime())
+	&& abs(pt.x-m_pt0.x) <= Metric<SM_CXDOUBLECLK>
+	&& abs(pt.y-m_pt0.y) <= Metric<SM_CYDOUBLECLK>;
+	m_time0 = time;
+	m_pt0 = std::move(pt);
 	return dbl;
 }
 
-inline bool Dragger::IsDown()
+inline bool Dragger::IsDown() const
 {
 	return GetKeyState(VK_LBUTTON) & 0x8000;
 }
@@ -70,7 +73,7 @@ inline bool Dragger::HandleLButtonDown()
 	Require(GetRelativeCursorPos(g_hWnd, &pt));
 	if (!InDragArea(pt.x, pt.y)) return false;
 
-	if (IsDouble()) {
+	if (IsDouble(GetMessageTime(), pt)) {
 		m_bActive = false;
 		Reset();
 	} else
-- 
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