From a438713b9276cc1fae310f2f135632d7e2fe25c3 Mon Sep 17 00:00:00 2001
From: Ollie <ollie@dev>
Date: Sat, 23 May 2026 19:07:54 +0200
Subject: [PATCH] WINGs/wview_wl: implement internal DnD for Wayland

Implement wl_drag_begin as a simple internal drag-and-drop state machine
for WINGs-to-WINGs drag operations (color wells, text widgets).

On button press, waits for motion to confirm drag intent, then enters
a drag loop tracking the cursor. On release, finds the view under the
cursor and if it has drag destination procs + matching types, fetches
data from the source and calls performDragOperation on the destination.

This handles same-process DnD without needing wl_data_device protocol.
---
 WINGs/wview_wl.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 63 insertions(+), 1 deletion(-)

diff --git a/WINGs/wview_wl.c b/WINGs/wview_wl.c
index 6cadf8b..ec6cd13 100644
--- a/WINGs/wview_wl.c
+++ b/WINGs/wview_wl.c
@@ -555,7 +555,69 @@ static void wl_balloon_draw(void *vctx, W_View *view, int x, int y,
 
 static void wl_drag_begin(void *vctx, W_View *view, WMEvent *event)
 {
-	(void)vctx; (void)view; (void)event;
+	W_Screen *scr = (W_Screen *)vctx;
+	if (!view->dragSourceProcs || event->type != WME_BUTTON_PRESS)
+		return;
+
+	/* Wait for motion to confirm drag */
+	WMEvent ev;
+	WMMaskEvent(scr, ButtonMotionMask | ButtonReleaseMask, &ev);
+	if (ev.type != WME_MOTION)
+		return;
+
+	if (view->dragSourceProcs->beganDrag) {
+		WMPoint pt = wmkpoint(ev.u.motion.x_root, ev.u.motion.y_root);
+		view->dragSourceProcs->beganDrag(view, &pt);
+	}
+
+	/* Drag loop */
+	W_View *destView = NULL;
+	Bool deposited = False;
+	int done = 0;
+
+	while (!done) {
+		WMMaskEvent(scr, ButtonMotionMask | ButtonReleaseMask, &ev);
+		switch (ev.type) {
+		case WME_MOTION:
+			/* Find view under cursor */
+			{
+				W_View *top = scr->rootView;
+				int mx = ev.u.motion.x_root;
+				int my = ev.u.motion.y_root;
+				destView = W_FindViewAtPoint(top, mx, my);
+			}
+			break;
+
+		case WME_BUTTON_RELEASE:
+			if (destView && destView->dragDestinationProcs &&
+			    destView->droppableTypes && view->dragSourceProcs->dropDataTypes) {
+				WMArray *types = view->dragSourceProcs->dropDataTypes(view);
+				WMArray *dropData = WMCreateArray(WMGetArrayItemCount(types));
+				int i;
+				for (i = 0; i < WMGetArrayItemCount(types); i++) {
+					char *type = WMGetFromArray(types, i);
+					WMData *data = view->dragSourceProcs->fetchDragData(view, type);
+					if (data)
+						WMAddToArray(dropData, data);
+				}
+				if (WMGetArrayItemCount(dropData) > 0 &&
+				    destView->dragDestinationProcs->performDragOperation) {
+					WMPoint pt = wmkpoint(ev.u.button.x_root, ev.u.button.y_root);
+					destView->dragDestinationProcs->performDragOperation(
+						destView, dropData, NULL, &pt);
+					deposited = True;
+				}
+				WMFreeArray(dropData);
+			}
+			done = 1;
+			break;
+		}
+	}
+
+	if (view->dragSourceProcs->endedDrag) {
+		WMPoint pt = wmkpoint(ev.u.button.x_root, ev.u.button.y_root);
+		view->dragSourceProcs->endedDrag(view, &pt, deposited);
+	}
 }
 
 static void wl_flush(void *vctx)