From 8e1f11548622297f7810ee153ffd52ff795c3e9d Mon Sep 17 00:00:00 2001
From: John Lindgren <john@jlindgren.net>
Date: Sat, 2 Apr 2022 21:34:51 -0400
Subject: [PATCH] cursor: Fix "jumping opposite edges" issue when resizing

Commit 08c537e ("xwayland: Honor size increments from
WM_SIZE_HINTS") adjusted only the window width/height according
to the size hints.  If resizing from the top or left edge of the
window, we also need to adjust the window position to keep the
bottom or right edge from jumping around.
---
 include/labwc.h |  2 +-
 src/cursor.c    | 40 +++++++++++++++++--------------------
 src/view.c      | 52 +++++++++++++++++++++++++++++++------------------
 src/xdg.c       |  9 +++------
 src/xwayland.c  | 34 ++++----------------------------
 5 files changed, 59 insertions(+), 78 deletions(-)

diff --git a/include/labwc.h b/include/labwc.h
index 44b4d34e..74c2167e 100644
--- a/include/labwc.h
+++ b/include/labwc.h
@@ -408,7 +408,7 @@ void view_update_title(struct view *view);
 void view_update_app_id(struct view *view);
 
 void view_impl_map(struct view *view);
-void view_min_size(struct view *view, int *w, int *h);
+void view_adjust_size(struct view *view, int *w, int *h);
 
 void foreign_toplevel_handle_create(struct view *view);
 
diff --git a/src/cursor.c b/src/cursor.c
index 41e091a8..87fc28eb 100644
--- a/src/cursor.c
+++ b/src/cursor.c
@@ -149,32 +149,28 @@ process_cursor_resize(struct server *server, uint32_t time)
 		.x = view->x, .y = view->y, .width = view->w, .height = view->h
 	};
 
-	int min_width, min_height;
-	view_min_size(view, &min_width, &min_height);
+	if (server->resize_edges & WLR_EDGE_TOP)
+		new_view_geo.height = server->grab_box.height - dy;
+	else if (server->resize_edges & WLR_EDGE_BOTTOM)
+		new_view_geo.height = server->grab_box.height + dy;
+
+	if (server->resize_edges & WLR_EDGE_LEFT)
+		new_view_geo.width = server->grab_box.width - dx;
+	else if (server->resize_edges & WLR_EDGE_RIGHT)
+		new_view_geo.width = server->grab_box.width + dx;
+
+	view_adjust_size(view, &new_view_geo.width, &new_view_geo.height);
 
 	if (server->resize_edges & WLR_EDGE_TOP) {
-		if (server->grab_box.height - dy < min_height) {
-			dy = server->grab_box.height - min_height;
-		}
-		new_view_geo.y = server->grab_box.y + dy;
-		new_view_geo.height = server->grab_box.height - dy;
-	} else if (server->resize_edges & WLR_EDGE_BOTTOM) {
-		if (server->grab_box.height + dy < min_height) {
-			dy = min_height - server->grab_box.height;
-		}
-		new_view_geo.height = server->grab_box.height + dy;
+		/* anchor bottom edge */
+		new_view_geo.y = server->grab_box.y +
+			server->grab_box.height - new_view_geo.height;
 	}
+
 	if (server->resize_edges & WLR_EDGE_LEFT) {
-		if (server->grab_box.width - dx < min_width) {
-			dx = server->grab_box.width - min_width;
-		}
-		new_view_geo.x = server->grab_box.x + dx;
-		new_view_geo.width = server->grab_box.width - dx;
-	} else if (server->resize_edges & WLR_EDGE_RIGHT) {
-		if (server->grab_box.width + dx < min_width) {
-			dx = min_width - server->grab_box.width;
-		}
-		new_view_geo.width = server->grab_box.width + dx;
+		/* anchor right edge */
+		new_view_geo.x = server->grab_box.x +
+			server->grab_box.width - new_view_geo.width;
 	}
 
 	resistance_resize_apply(view, &new_view_geo);
diff --git a/src/view.c b/src/view.c
index 91c9aadc..cfe9549b 100644
--- a/src/view.c
+++ b/src/view.c
@@ -4,6 +4,8 @@
 #include "labwc.h"
 #include "ssd.h"
 
+#define MAX(a, b) (((a) > (b)) ? (a) : (b))
+
 void
 view_set_activated(struct view *view, bool activated)
 {
@@ -52,32 +54,44 @@ view_move_resize(struct view *view, struct wlr_box geo)
 #define MIN_VIEW_WIDTH (100)
 #define MIN_VIEW_HEIGHT (60)
 
+#if HAVE_XWAYLAND
+static int
+round_to_increment(int val, int base, int inc)
+{
+	if (base < 0 || inc <= 0)
+		return val;
+	return base + (val - base + inc / 2) / inc * inc;
+}
+#endif
+
 void
-view_min_size(struct view *view, int *w, int *h)
+view_adjust_size(struct view *view, int *w, int *h)
 {
 	int min_width = MIN_VIEW_WIDTH;
 	int min_height = MIN_VIEW_HEIGHT;
 #if HAVE_XWAYLAND
-	if (view->type != LAB_XWAYLAND_VIEW) {
-		goto out;
-	}
-	if (!view->xwayland_surface->size_hints) {
-		goto out;
-	}
-	if (view->xwayland_surface->size_hints->min_width > 0
-			|| view->xwayland_surface->size_hints->min_height > 0) {
-		min_width = view->xwayland_surface->size_hints->min_width;
-		min_height = view->xwayland_surface->size_hints->min_height;
-	}
-out:
-#endif
+	if (view->type == LAB_XWAYLAND_VIEW) {
+		struct wlr_xwayland_surface_size_hints *hints =
+			view->xwayland_surface->size_hints;
+		/*
+		 * Honor size increments from WM_SIZE_HINTS. Typically, X11
+		 * terminal emulators will use WM_SIZE_HINTS to make sure that
+		 * the terminal is resized to a width/height evenly divisible by
+		 * the cell (character) size.
+		 */
+		if (hints) {
+			*w = round_to_increment(*w, hints->base_width,
+				hints->width_inc);
+			*h = round_to_increment(*h, hints->base_height,
+				hints->height_inc);
 
-	if (w) {
-		*w = min_width;
-	}
-	if (h) {
-		*h = min_height;
+			min_width = MAX(1, hints->min_width);
+			min_height = MAX(1, hints->min_height);
+		}
 	}
+#endif
+	*w = MAX(*w, min_width);
+	*h = MAX(*h, min_height);
 }
 
 void
diff --git a/src/xdg.c b/src/xdg.c
index 2e01a3c9..0294bcad 100644
--- a/src/xdg.c
+++ b/src/xdg.c
@@ -170,19 +170,17 @@ handle_set_app_id(struct wl_listener *listener, void *data)
 	view_update_app_id(view);
 }
 
-#define MAX(a, b)  (((a) > (b)) ? (a) : (b))
 static void
 xdg_toplevel_view_configure(struct view *view, struct wlr_box geo)
 {
-	int min_width, min_height;
-	view_min_size(view, &min_width, &min_height);
+	view_adjust_size(view, &geo.width, &geo.height);
 
 	view->pending_move_resize.update_x = geo.x != view->x;
 	view->pending_move_resize.update_y = geo.y != view->y;
 	view->pending_move_resize.x = geo.x;
 	view->pending_move_resize.y = geo.y;
-	view->pending_move_resize.width = MAX(geo.width, min_width);
-	view->pending_move_resize.height = MAX(geo.height, min_height);
+	view->pending_move_resize.width = geo.width;
+	view->pending_move_resize.height = geo.height;
 
 	uint32_t serial = wlr_xdg_toplevel_set_size(view->xdg_surface->toplevel,
 		(uint32_t)geo.width, (uint32_t)geo.height);
@@ -196,7 +194,6 @@ xdg_toplevel_view_configure(struct view *view, struct wlr_box geo)
 		ssd_update_geometry(view);
 	}
 }
-#undef MAX
 
 static void
 xdg_toplevel_view_move(struct view *view, double x, double y)
diff --git a/src/xwayland.c b/src/xwayland.c
index 242553b5..c35f3c21 100644
--- a/src/xwayland.c
+++ b/src/xwayland.c
@@ -119,21 +119,19 @@ handle_destroy(struct wl_listener *listener, void *data)
 	free(view);
 }
 
-#define MAX(a, b)  (((a) > (b)) ? (a) : (b))
 static void
 handle_request_configure(struct wl_listener *listener, void *data)
 {
 	struct view *view = wl_container_of(listener, view, request_configure);
 	struct wlr_xwayland_surface_configure_event *event = data;
 
-	int min_width, min_height;
-	view_min_size(view, &min_width, &min_height);
+	int width = event->width;
+	int height = event->height;
+	view_adjust_size(view, &width, &height);
 
 	wlr_xwayland_surface_configure(view->xwayland_surface,
-		event->x, event->y, MAX(event->width, min_width),
-		MAX(event->height, min_height));
+		event->x, event->y, width, height);
 }
-#undef MAX
 
 static void
 handle_request_activate(struct wl_listener *listener, void *data)
@@ -185,33 +183,9 @@ handle_set_class(struct wl_listener *listener, void *data)
 	view_update_app_id(view);
 }
 
-static int
-round_to_increment(int val, int base, int inc)
-{
-	if (base < 0 || inc <= 0) {
-		return val;
-	}
-	return base + (val - base + inc / 2) / inc * inc;
-}
-
 static void
 configure(struct view *view, struct wlr_box geo)
 {
-	/*
-	 * Honor size increments from WM_SIZE_HINTS. Typically, X11 terminal
-	 * emulators will use WM_SIZE_HINTS to make sure that the terminal is
-	 * resized to a width/height evenly divisible by the cell (character)
-	 * size.
-	 */
-	struct wlr_xwayland_surface_size_hints *hints =
-		view->xwayland_surface->size_hints;
-	if (hints) {
-		geo.width = round_to_increment(geo.width,
-			hints->base_width, hints->width_inc);
-		geo.height = round_to_increment(geo.height,
-			hints->base_height, hints->height_inc);
-	}
-
 	view->pending_move_resize.update_x = geo.x != view->x;
 	view->pending_move_resize.update_y = geo.y != view->y;
 	view->pending_move_resize.x = geo.x;