Monitor size hints for X11 in Gtk3 like in Gtk2

The hints are accessed and cached like in Gtk2, but with the Gtk3 size model,
we can explicitly use the minimum size, and figure out the "natural" size from
the other hints or current size.

3 files changed, 96 insertions, 39 deletions

diff --git a/AUTHORS b/AUTHORS
index 8617acd..7e9e59e 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -19,3 +19,5 @@ Contributors:
  * Stefan Westerfeld
    * Qt5 in Gtk2 support
    * Initialization API
+ * Alexandros Theodotou
+   * X11 in Gtk3 improvements
diff --git a/NEWS b/NEWS
index e19ae3d..f608a94 100644
--- a/NEWS
+++ b/NEWS
@@ -2,8 +2,9 @@ suil (0.10.21) unstable; urgency=medium
 
   * Add support for X11 in Qt6
   * Fix library current_version on MacOS
+  * Monitor size hints for X11 in Gtk3
 
- -- David Robillard <d@drobilla.net>  Thu, 11 Jul 2024 23:40:43 +0000
+ -- David Robillard <d@drobilla.net>  Mon, 02 Dec 2024 03:05:37 +0000
 
 suil (0.10.20) stable; urgency=medium
 
diff --git a/src/x11_in_gtk3.c b/src/x11_in_gtk3.c
index 0a1aaf9..138fdcb 100644
--- a/src/x11_in_gtk3.c
+++ b/src/x11_in_gtk3.c
@@ -39,10 +39,8 @@ typedef struct {
   guint                       idle_id;
   guint                       idle_ms;
   guint                       idle_size_request_id;
-  int                         initial_width;
-  int                         initial_height;
-  int                         req_width;
-  int                         req_height;
+  XSizeHints                  size_hints;
+  gboolean                    size_hints_dirty;
 } SuilX11Wrapper;
 
 typedef struct {
@@ -197,6 +195,32 @@ idle_size_request(gpointer user_data)
 }
 
 static void
+update_wm_hints(SuilX11Wrapper* wrap, gboolean force)
+{
+  const XSizeHints old_hints = wrap->size_hints;
+  if (!wrap->size_hints_dirty && !force) {
+    return;
+  }
+
+  // Fetch hints from X
+  GdkWindow* window   = gtk_widget_get_window(GTK_WIDGET(wrap->plug));
+  long       supplied = 0;
+  XGetWMNormalHints(GDK_WINDOW_XDISPLAY(window),
+                    (Window)wrap->instance->ui_widget,
+                    &wrap->size_hints,
+                    &supplied);
+
+  // Preserve old "custom" size if necessary
+  if ((old_hints.flags & USSize) && old_hints.x && old_hints.y) {
+    wrap->size_hints.flags |= USSize;
+    wrap->size_hints.x = old_hints.x;
+    wrap->size_hints.y = old_hints.y;
+  }
+
+  wrap->size_hints_dirty = FALSE;
+}
+
+static void
 forward_size_request(SuilX11Wrapper* socket, GtkAllocation* allocation)
 {
   GdkWindow* gwindow   = gtk_widget_get_window(GTK_WIDGET(socket->plug));
@@ -266,16 +290,24 @@ suil_x11_wrapper_get_preferred_width(GtkWidget* widget,
   Window                ui_window = (Window)self->instance->ui_widget;
 
   if (suil_x11_is_valid_child(xdisplay, GDK_WINDOW_XID(gwindow), ui_window)) {
-    XSizeHints hints;
-    memset(&hints, 0, sizeof(hints));
-    long supplied = 0;
-    XGetWMNormalHints(xdisplay, ui_window, &hints, &supplied);
-    *natural_width =
-      ((hints.flags & PBaseSize) ? hints.base_width : self->initial_width);
-    *minimum_width =
-      ((hints.flags & PMinSize) ? hints.min_width : self->req_width);
-  } else {
-    *natural_width = *minimum_width = self->req_width;
+    update_wm_hints(self, FALSE);
+
+    if (self->size_hints.flags & USSize) {
+      *natural_width = self->size_hints.width;
+    } else if (self->size_hints.flags & PBaseSize) {
+      *natural_width = self->size_hints.base_width;
+    } else if (self->size_hints.flags & PMinSize) {
+      *natural_width = self->size_hints.min_width;
+    } else {
+      g_warning("UI size hints have no base or minimum size");
+      XWindowAttributes attrs;
+      XGetWindowAttributes(xdisplay, ui_window, &attrs);
+      *natural_width = attrs.width;
+    }
+
+    *minimum_width = (self->size_hints.flags & PMinSize)
+                       ? self->size_hints.min_width
+                       : *natural_width;
   }
 }
 
@@ -290,16 +322,24 @@ suil_x11_wrapper_get_preferred_height(GtkWidget* widget,
   Window                ui_window = (Window)self->instance->ui_widget;
 
   if (suil_x11_is_valid_child(xdisplay, GDK_WINDOW_XID(gwindow), ui_window)) {
-    XSizeHints hints;
-    memset(&hints, 0, sizeof(hints));
-    long supplied = 0;
-    XGetWMNormalHints(xdisplay, ui_window, &hints, &supplied);
-    *natural_height =
-      ((hints.flags & PBaseSize) ? hints.base_height : self->initial_height);
-    *minimum_height =
-      ((hints.flags & PMinSize) ? hints.min_height : self->req_height);
-  } else {
-    *natural_height = *minimum_height = self->req_height;
+    update_wm_hints(self, FALSE);
+
+    if (self->size_hints.flags & USSize) {
+      *natural_height = self->size_hints.height;
+    } else if (self->size_hints.flags & PBaseSize) {
+      *natural_height = self->size_hints.base_height;
+    } else if (self->size_hints.flags & PMinSize) {
+      *natural_height = self->size_hints.min_height;
+    } else {
+      g_warning("UI size hints have no base or minimum size");
+      XWindowAttributes attrs;
+      XGetWindowAttributes(xdisplay, ui_window, &attrs);
+      *natural_height = attrs.height;
+    }
+
+    *minimum_height = (self->size_hints.flags & PMinSize)
+                        ? self->size_hints.min_height
+                        : *natural_height;
   }
 }
 
@@ -332,13 +372,14 @@ suil_x11_wrapper_class_init(SuilX11WrapperClass* klass)
 static void
 suil_x11_wrapper_init(SuilX11Wrapper* self)
 {
-  self->plug       = GTK_PLUG(gtk_plug_new(0));
-  self->wrapper    = NULL;
-  self->instance   = NULL;
-  self->idle_iface = NULL;
-  self->idle_ms    = 1000 / 30; // 30 Hz default
-  self->req_width  = 0;
-  self->req_height = 0;
+  self->plug             = GTK_PLUG(gtk_plug_new(0));
+  self->wrapper          = NULL;
+  self->instance         = NULL;
+  self->idle_iface       = NULL;
+  self->idle_ms          = 1000 / 30; // 30 Hz default
+  self->size_hints_dirty = TRUE;
+
+  memset(&self->size_hints, 0, sizeof(self->size_hints));
 }
 
 static int
@@ -346,8 +387,14 @@ wrapper_resize(LV2UI_Feature_Handle handle, int width, int height)
 {
   SuilX11Wrapper* const wrap = SUIL_X11_WRAPPER(handle);
 
-  wrap->req_width  = width;
-  wrap->req_height = height;
+  wrap->size_hints.width  = width;
+  wrap->size_hints.height = height;
+  if (width > 0 && height > 0) {
+    wrap->size_hints.flags |= USSize;
+  }
+
+  // Fetch hints to get size constraints (probably) updated by plugin
+  wrap->size_hints_dirty = TRUE;
 
   gtk_widget_queue_resize(GTK_WIDGET(handle));
   return 0;
@@ -378,11 +425,18 @@ wrapper_wrap(SuilWrapper* wrapper, SuilInstance* instance)
   Window      ui_window = (Window)instance->ui_widget;
 
   gdk_display_sync(display);
-
-  XWindowAttributes attrs;
-  XGetWindowAttributes(xdisplay, ui_window, &attrs);
-  wrap->initial_width  = attrs.width;
-  wrap->initial_height = attrs.height;
+  if (suil_x11_is_valid_child(xdisplay, GDK_WINDOW_XID(gwindow), ui_window)) {
+    XWindowAttributes attrs;
+    XGetWindowAttributes(xdisplay, ui_window, &attrs);
+
+    update_wm_hints(wrap, TRUE);
+    if (!(wrap->size_hints.flags & PBaseSize)) {
+      // Fall back to using initial size as base size
+      wrap->size_hints.flags |= PBaseSize;
+      wrap->size_hints.base_width  = attrs.width;
+      wrap->size_hints.base_height = attrs.height;
+    }
+  }
 
   const LV2UI_Idle_Interface* idle_iface = NULL;
   if (instance->descriptor->extension_data) {