patch 8.0.1211: cannot reorder tab pages with drag & dropv8.0.1211

Problem:    Cannot reorder tab pages with drag & drop.
Solution:   Support drag & drop for GTK and MS-Windows. (Ken Takata, Masamichi
            Abe)

1 files changed, 94 insertions, 0 deletions

diff --git a/src/gui_w32.c b/src/gui_w32.c
index c5564cd2ac..64acc76527 100644
--- a/src/gui_w32.c
+++ b/src/gui_w32.c
@@ -8151,6 +8151,34 @@ initialise_tabline(void)
 # endif
 }
 
+/*
+ * Get tabpage_T from POINT.
+ */
+    static tabpage_T *
+GetTabFromPoint(
+    HWND    hWnd,
+    POINT   pt)
+{
+    tabpage_T	*ptp = NULL;
+
+    if (gui_mch_showing_tabline())
+    {
+	TCHITTESTINFO htinfo;
+	htinfo.pt = pt;
+	/* ignore if a window under cusor is not tabcontrol. */
+	if (s_tabhwnd == hWnd)
+	{
+	    int idx = TabCtrl_HitTest(s_tabhwnd, &htinfo);
+	    if (idx != -1)
+		ptp = find_tabpage(idx + 1);
+	}
+    }
+    return ptp;
+}
+
+static POINT	    s_pt = {0, 0};
+static HCURSOR      s_hCursor = NULL;
+
     static LRESULT CALLBACK
 tabline_wndproc(
     HWND hwnd,
@@ -8158,7 +8186,73 @@ tabline_wndproc(
     WPARAM wParam,
     LPARAM lParam)
 {
+    POINT	pt;
+    tabpage_T	*tp;
+    RECT	rect;
+    int		nCenter;
+    int		idx0;
+    int		idx1;
+
     HandleMouseHide(uMsg, lParam);
+
+    switch (uMsg)
+    {
+	case WM_LBUTTONDOWN:
+	    {
+		s_pt.x = GET_X_LPARAM(lParam);
+		s_pt.y = GET_Y_LPARAM(lParam);
+		SetCapture(hwnd);
+		s_hCursor = GetCursor(); /* backup default cursor */
+		break;
+	    }
+	case WM_MOUSEMOVE:
+	    if (GetCapture() == hwnd
+		    && ((wParam & MK_LBUTTON)) != 0)
+	    {
+		pt.x = GET_X_LPARAM(lParam);
+		pt.y = s_pt.y;
+		if (abs(pt.x - s_pt.x) > GetSystemMetrics(SM_CXDRAG))
+		{
+		    SetCursor(LoadCursor(NULL, IDC_SIZEWE));
+
+		    tp = GetTabFromPoint(hwnd, pt);
+		    if (tp != NULL)
+		    {
+			idx0 = tabpage_index(curtab) - 1;
+			idx1 = tabpage_index(tp) - 1;
+
+			TabCtrl_GetItemRect(hwnd, idx1, &rect);
+			nCenter = rect.left + (rect.right - rect.left) / 2;
+
+			/* Check if the mouse cursor goes over the center of
+			 * the next tab to prevent "flickering". */
+			if ((idx0 < idx1) && (nCenter < pt.x))
+			{
+			    tabpage_move(idx1 + 1);
+			    update_screen(0);
+			}
+			else if ((idx1 < idx0) && (pt.x < nCenter))
+			{
+			    tabpage_move(idx1);
+			    update_screen(0);
+			}
+		    }
+		}
+	    }
+	    break;
+	case WM_LBUTTONUP:
+	    {
+		if (GetCapture() == hwnd)
+		{
+		    SetCursor(s_hCursor);
+		    ReleaseCapture();
+		}
+		break;
+	    }
+	default:
+	    break;
+    }
+
     return CallWindowProc(s_tabline_wndproc, hwnd, uMsg, wParam, lParam);
 }
 #endif