Drag operation does not start until mouse has been dragged more than

a threshold distance. Using platform threshold when possible.
Moved some common dragging code on Windows into EffectFromState.

4 files changed, 91 insertions, 53 deletions

diff --git a/gtk/ScintillaGTK.cxx b/gtk/ScintillaGTK.cxx
index 2e0291eeb..a873f1ada 100644
--- a/gtk/ScintillaGTK.cxx
+++ b/gtk/ScintillaGTK.cxx
@@ -156,6 +156,7 @@ private:
 	virtual void Initialise();
 	virtual void Finalise();
 	virtual void DisplayCursor(Window::Cursor c);
+	virtual bool DragThreshold(Point ptStart, Point ptNow);
 	virtual void StartDrag();
 	int TargetAsUTF8(char *text);
 	int EncodedFromUTF8(char *utf8, char *encoded);
@@ -788,8 +789,18 @@ void ScintillaGTK::DisplayCursor(Window::Cursor c) {
 		wText.SetCursor(static_cast<Window::Cursor>(cursorMode));
 }
 
+bool ScintillaGTK::DragThreshold(Point ptStart, Point ptNow) {
+#if GTK_MAJOR_VERSION < 2
+	return Editor::DragThreshold(ptStart, ptNow);
+#else
+	return gtk_drag_check_threshold(GTK_WIDGET(PWidget(wMain)),
+		ptStart.x, ptStart.y, ptNow.x, ptNow.y);
+#endif
+}
+
 void ScintillaGTK::StartDrag() {
 	dragWasDropped = false;
+	inDragDrop = ddDragging;
 	static const GtkTargetEntry targets[] = {
 	    { "UTF8_STRING", 0, TARGET_UTF8_STRING },
 	    { "STRING", 0, TARGET_STRING },
@@ -2345,7 +2356,6 @@ gboolean ScintillaGTK::DragMotion(GtkWidget *widget, GdkDragContext *context,
                                  gint x, gint y, guint dragtime) {
 	ScintillaGTK *sciThis = ScintillaFromWidget(widget);
 	Point npt(x, y);
-	sciThis->inDragDrop = true;
 	sciThis->SetDragPosition(sciThis->PositionFromLocation(npt));
 	GdkDragAction preferredAction = context->suggested_action;
 	if (context->actions == static_cast<GdkDragAction>
@@ -2369,6 +2379,7 @@ void ScintillaGTK::DragEnd(GtkWidget *widget, GdkDragContext * /*context*/) {
 		sciThis->SetEmptySelection(sciThis->posDrag);
 	sciThis->SetDragPosition(invalidPosition);
 	//Platform::DebugPrintf("DragEnd %x %d\n", sciThis, sciThis->dragWasDropped);
+	sciThis->inDragDrop = ddNone;
 }
 
 gboolean ScintillaGTK::Drop(GtkWidget *widget, GdkDragContext * /*context*/,
diff --git a/src/Editor.cxx b/src/Editor.cxx
index addfedf6e..8a2000090 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -362,7 +362,7 @@ Editor::Editor() {
 	dwelling = false;
 	ptMouseLast.x = 0;
 	ptMouseLast.y = 0;
-	inDragDrop = false;
+	inDragDrop = ddNone;
 	dropWentOutside = false;
 	posDrag = invalidPosition;
 	posDrop = invalidPosition;
@@ -5000,6 +5000,13 @@ void Editor::DisplayCursor(Window::Cursor c) {
 		wMain.SetCursor(static_cast<Window::Cursor>(cursorMode));
 }
 
+bool Editor::DragThreshold(Point ptStart, Point ptNow) {
+	int xMove = ptStart.x - ptNow.x;
+	int yMove = ptStart.y - ptNow.y;
+	int distanceSquared = xMove * xMove + yMove * yMove;
+	return distanceSquared > 16;
+}
+
 void Editor::StartDrag() {
 	// Always handled by subclasses
 	//SetMouseCapture(true);
@@ -5007,8 +5014,8 @@ void Editor::StartDrag() {
 }
 
 void Editor::DropAt(int position, const char *value, bool moving, bool rectangular) {
-	//Platform::DebugPrintf("DropAt %d\n", inDragDrop);
-	if (inDragDrop)
+	//Platform::DebugPrintf("DropAt %d %d\n", inDragDrop, position);
+	if (inDragDrop == ddDragging)
 		dropWentOutside = false;
 
 	int positionWasInSelection = PositionInSelection(position);
@@ -5016,7 +5023,7 @@ void Editor::DropAt(int position, const char *value, bool moving, bool rectangul
 	bool positionOnEdgeOfSelection =
 	    (position == SelectionStart()) || (position == SelectionEnd());
 
-	if ((!inDragDrop) || !(0 == positionWasInSelection) ||
+	if ((inDragDrop != ddDragging) || !(0 == positionWasInSelection) ||
 	        (positionOnEdgeOfSelection && !moving)) {
 
 		int selStart = SelectionStart();
@@ -5025,7 +5032,7 @@ void Editor::DropAt(int position, const char *value, bool moving, bool rectangul
 		pdoc->BeginUndoAction();
 
 		int positionAfterDeletion = position;
-		if (inDragDrop && moving) {
+		if ((inDragDrop == ddDragging) && moving) {
 			// Remove dragged out text
 			if (rectangular || selType == selLines) {
 				SelectionLineIterator lineIterator(this);
@@ -5059,7 +5066,7 @@ void Editor::DropAt(int position, const char *value, bool moving, bool rectangul
 			}
 			pdoc->EndUndoAction();
 		}
-	} else if (inDragDrop) {
+	} else if (inDragDrop == ddDragging) {
 		SetEmptySelection(position);
 	}
 }
@@ -5161,11 +5168,11 @@ void Editor::DwellEnd(bool mouseMoved) {
 }
 
 void Editor::ButtonDown(Point pt, unsigned int curTime, bool shift, bool ctrl, bool alt) {
-	//Platform::DebugPrintf("Scintilla:ButtonDown %d %d = %d alt=%d\n", curTime, lastClickTime, curTime - lastClickTime, alt);
+	//Platform::DebugPrintf("ButtonDown %d %d = %d alt=%d %d\n", curTime, lastClickTime, curTime - lastClickTime, alt, inDragDrop);
 	ptMouseLast = pt;
 	int newPos = PositionFromLocation(pt);
 	newPos = MovePositionOutsideChar(newPos, currentPos - newPos);
-	inDragDrop = false;
+	inDragDrop = ddNone;
 	moveExtendsSelection = false;
 
 	bool processed = NotifyMarginClick(pt, shift, ctrl, alt);
@@ -5250,16 +5257,14 @@ void Editor::ButtonDown(Point pt, unsigned int curTime, bool shift, bool ctrl, b
 				NotifyHotSpotClicked(newPos, shift, ctrl, alt);
 			}
 			if (!shift) {
-				inDragDrop = PointInSelection(pt) && !SelectionEmpty();
+				if (PointInSelection(pt) && !SelectionEmpty())
+					inDragDrop = ddInitial;
+				else
+					inDragDrop = ddNone;
 			}
-			if (inDragDrop) {
-				SetMouseCapture(false);
-				SetDragPosition(newPos);
-				CopySelectionRange(&drag);
-				StartDrag();
-			} else {
+			SetMouseCapture(true);
+			if (inDragDrop != ddInitial) {
 				SetDragPosition(invalidPosition);
-				SetMouseCapture(true);
 				if (!shift) {
 					SetEmptySelection(newPos);
 				}
@@ -5328,6 +5333,20 @@ void Editor::ButtonMove(Point pt) {
 	if ((ptMouseLast.x != pt.x) || (ptMouseLast.y != pt.y)) {
 		DwellEnd(true);
 	}
+
+	int movePos = PositionFromLocation(pt);
+	movePos = MovePositionOutsideChar(movePos, currentPos - movePos);
+
+	if (inDragDrop == ddInitial) {
+		if (DragThreshold(ptMouseLast, pt)) {
+			SetMouseCapture(false);
+			SetDragPosition(movePos);
+			CopySelectionRange(&drag);
+			StartDrag();
+		}
+		return;
+	}
+
 	ptMouseLast = pt;
 	//Platform::DebugPrintf("Move %d %d\n", pt.x, pt.y);
 	if (HaveMouseCapture()) {
@@ -5339,8 +5358,6 @@ void Editor::ButtonMove(Point pt) {
 		autoScrollTimer.ticksToWait = autoScrollDelay;
 
 		// Adjust selection
-		int movePos = PositionFromLocation(pt);
-		movePos = MovePositionOutsideChar(movePos, currentPos - movePos);
 		if (posDrag >= 0) {
 			SetDragPosition(movePos);
 		} else {
@@ -5416,7 +5433,13 @@ void Editor::ButtonMove(Point pt) {
 }
 
 void Editor::ButtonUp(Point pt, unsigned int curTime, bool ctrl) {
-	//Platform::DebugPrintf("ButtonUp %d\n", HaveMouseCapture());
+	//Platform::DebugPrintf("ButtonUp %d %d\n", HaveMouseCapture(), inDragDrop);
+	int newPos = PositionFromLocation(pt);
+	newPos = MovePositionOutsideChar(newPos, currentPos - newPos);
+	if (inDragDrop == ddInitial) {
+		inDragDrop = ddNone;
+		SetEmptySelection(newPos);
+	}
 	if (HaveMouseCapture()) {
 		if (PointInSelMargin(pt)) {
 			DisplayCursor(Window::cursorReverseArrow);
@@ -5429,7 +5452,7 @@ void Editor::ButtonUp(Point pt, unsigned int curTime, bool ctrl) {
 		int newPos = PositionFromLocation(pt);
 		newPos = MovePositionOutsideChar(newPos, currentPos - newPos);
 		NotifyIndicatorClick(false, newPos, false, false, false);
-		if (inDragDrop) {
+		if (inDragDrop == ddDragging) {
 			int selStart = SelectionStart();
 			int selEnd = SelectionEnd();
 			if (selStart < selEnd) {
@@ -5468,7 +5491,7 @@ void Editor::ButtonUp(Point pt, unsigned int curTime, bool ctrl) {
 		if (selType == selStream) {
 			SetLastXChosen();
 		}
-		inDragDrop = false;
+		inDragDrop = ddNone;
 		EnsureCaretVisible(false);
 	}
 }
diff --git a/src/Editor.h b/src/Editor.h
index 04bf21958..ef061e46f 100644
--- a/src/Editor.h
+++ b/src/Editor.h
@@ -246,7 +246,7 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	bool dwelling;
 	enum { selChar, selWord, selLine } selectionType;
 	Point ptMouseLast;
-	bool inDragDrop;
+	enum { ddNone, ddInitial, ddDragging } inDragDrop;
 	bool dropWentOutside;
 	int posDrag;
 	int posDrop;
@@ -415,7 +415,7 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	virtual void AddCharUTF(char *s, unsigned int len, bool treatAsDBCS=false);
 	void ClearSelection();
 	void ClearAll();
-    	void ClearDocumentStyle();
+	void ClearDocumentStyle();
 	void Cut();
 	void PasteRectangular(int pos, const char *ptr, int len);
 	virtual void Copy() = 0;
@@ -489,6 +489,7 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	void CopyText(int length, const char *text);
 	void SetDragPosition(int newPos);
 	virtual void DisplayCursor(Window::Cursor c);
+	virtual bool DragThreshold(Point ptStart, Point ptNow);
 	virtual void StartDrag();
 	void DropAt(int position, const char *value, bool moving, bool rectangular);
 	/** PositionInSelection returns 0 if position in selection, -1 if position before selection, and 1 if after.
diff --git a/win32/ScintillaWin.cxx b/win32/ScintillaWin.cxx
index 62d87fd9d..6d7f1268d 100644
--- a/win32/ScintillaWin.cxx
+++ b/win32/ScintillaWin.cxx
@@ -183,6 +183,7 @@ class ScintillaWin :
 
 	enum { invalidTimerID, standardTimerID, idleTimerID };
 
+	virtual bool DragThreshold(Point ptStart, Point ptNow);
 	virtual void StartDrag();
 	sptr_t WndPaint(uptr_t wParam);
 	sptr_t HandleComposition(uptr_t wParam, sptr_t lParam);
@@ -224,6 +225,7 @@ class ScintillaWin :
 	void FullPaint();
 	void FullPaintDC(HDC dc);
 	bool IsCompatibleDC(HDC dc);
+	DWORD EffectFromState(DWORD grfKeyState);
 
 	virtual int SetScrollInfo(int nBar, LPCSCROLLINFO lpsi, BOOL bRedraw);
 	virtual bool GetScrollInfo(int nBar, LPSCROLLINFO lpsi);
@@ -335,7 +337,15 @@ HWND ScintillaWin::MainHWND() {
 	return reinterpret_cast<HWND>(wMain.GetID());
 }
 
+bool ScintillaWin::DragThreshold(Point ptStart, Point ptNow) {
+	int xMove = abs(ptStart.x - ptNow.x);
+	int yMove = abs(ptStart.y - ptNow.y);
+	return (xMove > ::GetSystemMetrics(SM_CXDRAG)) ||
+		(yMove > ::GetSystemMetrics(SM_CYDRAG));
+}
+
 void ScintillaWin::StartDrag() {
+	inDragDrop = ddDragging;
 	DWORD dwEffect = 0;
 	dropWentOutside = true;
 	IDataObject *pDataObject = reinterpret_cast<IDataObject *>(&dob);
@@ -352,7 +362,7 @@ void ScintillaWin::StartDrag() {
 			ClearSelection();
 		}
 	}
-	inDragDrop = false;
+	inDragDrop = ddNone;
 	SetDragPosition(invalidPosition);
 }
 
@@ -696,7 +706,7 @@ sptr_t ScintillaWin::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam
 
 	case WM_SETCURSOR:
 		if (LoWord(lParam) == HTCLIENT) {
-			if (inDragDrop) {
+			if (inDragDrop == ddDragging) {
 				DisplayCursor(Window::cursorUp);
 			} else {
 				// Display regular (drag) cursor over selection
@@ -868,8 +878,8 @@ sptr_t ScintillaWin::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam
 		capturedMouse = false;
 		return 0;
 
-        // These are not handled in Scintilla and its faster to dispatch them here.
-        // Also moves time out to here so profile doesn't count lots of empty message calls.
+	// These are not handled in Scintilla and its faster to dispatch them here.
+	// Also moves time out to here so profile doesn't count lots of empty message calls.
 
 	case WM_MOVE:
 	case WM_MOUSEACTIVATE:
@@ -1978,6 +1988,20 @@ bool ScintillaWin::IsCompatibleDC(HDC hOtherDC) {
 	return isCompatible;
 }
 
+DWORD ScintillaWin::EffectFromState(DWORD grfKeyState) {
+	// These are the Wordpad semantics.
+	DWORD dwEffect;
+	if (inDragDrop == ddDragging)	// Internal defaults to move
+		dwEffect = DROPEFFECT_MOVE;
+	else
+		dwEffect = DROPEFFECT_COPY;
+	if (grfKeyState & MK_ALT)
+		dwEffect = DROPEFFECT_MOVE;
+	if (grfKeyState & MK_CONTROL)
+		dwEffect = DROPEFFECT_COPY;
+	return dwEffect;
+}
+
 /// Implement IUnknown
 STDMETHODIMP ScintillaWin::QueryInterface(REFIID riid, PVOID *ppv) {
 	*ppv = NULL;
@@ -2020,14 +2044,7 @@ STDMETHODIMP ScintillaWin::DragEnter(LPDATAOBJECT pIDataSource, DWORD grfKeyStat
 		return S_OK;
 	}
 
-	if (inDragDrop)	// Internal defaults to move
-		*pdwEffect = DROPEFFECT_MOVE;
-	else
-		*pdwEffect = DROPEFFECT_COPY;
-	if (grfKeyState & MK_ALT)
-		*pdwEffect = DROPEFFECT_MOVE;
-	if (grfKeyState & MK_CONTROL)
-		*pdwEffect = DROPEFFECT_COPY;
+	*pdwEffect = EffectFromState(grfKeyState);
 	return S_OK;
 }
 
@@ -2037,15 +2054,8 @@ STDMETHODIMP ScintillaWin::DragOver(DWORD grfKeyState, POINTL pt, PDWORD pdwEffe
 		return S_OK;
 	}
 
-	// These are the Wordpad semantics.
-	if (inDragDrop)	// Internal defaults to move
-		*pdwEffect = DROPEFFECT_MOVE;
-	else
-		*pdwEffect = DROPEFFECT_COPY;
-	if (grfKeyState & MK_ALT)
-		*pdwEffect = DROPEFFECT_MOVE;
-	if (grfKeyState & MK_CONTROL)
-		*pdwEffect = DROPEFFECT_COPY;
+	*pdwEffect = EffectFromState(grfKeyState);
+
 	// Update the cursor.
 	POINT rpt = {pt.x, pt.y};
 	::ScreenToClient(MainHWND(), &rpt);
@@ -2061,14 +2071,7 @@ STDMETHODIMP ScintillaWin::DragLeave() {
 
 STDMETHODIMP ScintillaWin::Drop(LPDATAOBJECT pIDataSource, DWORD grfKeyState,
                                 POINTL pt, PDWORD pdwEffect) {
-	if (inDragDrop)	// Internal defaults to move
-		*pdwEffect = DROPEFFECT_MOVE;
-	else
-		*pdwEffect = DROPEFFECT_COPY;
-	if (grfKeyState & MK_ALT)
-		*pdwEffect = DROPEFFECT_MOVE;
-	if (grfKeyState & MK_CONTROL)
-		*pdwEffect = DROPEFFECT_COPY;
+	*pdwEffect = EffectFromState(grfKeyState);
 
 	if (pIDataSource == NULL)
 		return E_POINTER;