Factor out general X11 utilities

5 files changed, 98 insertions, 103 deletions

diff --git a/meson.build b/meson.build
index 8feb798..6793bb0 100644
--- a/meson.build
+++ b/meson.build
@@ -367,7 +367,7 @@ gtk_cpp_args = cpp.get_supported_arguments(gtk_args)
 if gtk2_dep.found() and gtk2_x11_dep.found() and x11_dep.found()
   shared_module(
     'suil_x11_in_gtk2',
-    files('src/x11_in_gtk2.c'),
+    files('src/x11_in_gtk2.c', 'src/x11_util.c'),
     c_args: c_suppressions + gtk_c_args + platform_defines,
     dependencies: [gtk2_dep, gtk2_x11_dep, lv2_dep, x11_dep],
     gnu_symbol_visibility: 'hidden',
@@ -381,7 +381,7 @@ endif
 if gtk3_dep.found() and gtk3_x11_dep.found() and x11_dep.found()
   shared_module(
     'suil_x11_in_gtk3',
-    files('src/x11_in_gtk3.c'),
+    files('src/x11_in_gtk3.c', 'src/x11_util.c'),
     c_args: c_suppressions + gtk_c_args + platform_defines,
     dependencies: [gtk3_dep, gtk3_x11_dep, lv2_dep, x11_dep],
     gnu_symbol_visibility: 'hidden',
diff --git a/src/x11_in_gtk2.c b/src/x11_in_gtk2.c
index dafeaea..2828b84 100644
--- a/src/x11_in_gtk2.c
+++ b/src/x11_in_gtk2.c
@@ -3,6 +3,7 @@
 
 #include "suil_internal.h"
 #include "warnings.h"
+#include "x11_util.h"
 
 #include <lv2/core/lv2.h>
 #include <lv2/options/options.h>
@@ -24,7 +25,6 @@ SUIL_DISABLE_GTK_WARNINGS
 #include <gtk/gtk.h>
 SUIL_RESTORE_WARNINGS
 
-#include <stdbool.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
@@ -54,62 +54,6 @@ suil_x11_wrapper_get_type(void); // Accessor for SUIL_TYPE_X11_WRAPPER
 
 G_DEFINE_TYPE(SuilX11Wrapper, suil_x11_wrapper, GTK_TYPE_SOCKET)
 
-/**
-   Check if 'swallowed' subwindow is known to the X server.
-
-   Gdk/GTK can mark the window as realized, mapped and visible even though
-   there is no window-ID on the X server for it yet.  Then,
-   suil_x11_on_size_allocate() will cause a "BadWinow" X error.
-*/
-static bool
-x_window_is_valid(SuilX11Wrapper* socket)
-{
-  GdkWindow* window     = gtk_widget_get_window(GTK_WIDGET(socket->plug));
-  Window     root       = 0;
-  Window     parent     = 0;
-  Window*    children   = NULL;
-  unsigned   childcount = 0;
-
-  XQueryTree(GDK_WINDOW_XDISPLAY(window),
-             GDK_WINDOW_XID(window),
-             &root,
-             &parent,
-             &children,
-             &childcount);
-
-  for (unsigned i = 0; i < childcount; ++i) {
-    if (children[i] == (Window)socket->instance->ui_widget) {
-      XFree(children);
-      return true;
-    }
-  }
-
-  if (children) {
-    XFree(children);
-  }
-
-  return false;
-}
-
-static Window
-get_parent_window(Display* display, Window child)
-{
-  Window   root     = 0;
-  Window   parent   = 0;
-  Window*  children = NULL;
-  unsigned count    = 0;
-
-  if (child) {
-    if (XQueryTree(display, child, &root, &parent, &children, &count)) {
-      if (children) {
-        XFree(children);
-      }
-    }
-  }
-
-  return (parent == root) ? 0 : parent;
-}
-
 static gboolean
 on_plug_removed(GtkSocket* sock, gpointer data)
 {
@@ -173,7 +117,7 @@ suil_x11_wrapper_realize(GtkWidget* w)
                     (unsigned char*)&plugin,
                     1);
 
-    xwindow = get_parent_window(GDK_WINDOW_XDISPLAY(gwindow), xwindow);
+    xwindow = suil_x11_get_parent(GDK_WINDOW_XDISPLAY(gwindow), xwindow);
   }
 }
 
@@ -257,7 +201,9 @@ static void
 forward_size_request(SuilX11Wrapper* socket, GtkAllocation* allocation)
 {
   GdkWindow* window = gtk_widget_get_window(GTK_WIDGET(socket->plug));
-  if (x_window_is_valid(socket)) {
+  if (suil_x11_is_valid_child(GDK_WINDOW_XDISPLAY(window),
+                              GDK_WINDOW_XID(window),
+                              (Window)socket->instance->ui_widget)) {
     // Calculate allocation size constrained to X11 limits for widget
     int width  = allocation->width;
     int height = allocation->height;
@@ -448,7 +394,7 @@ wrapper_wrap(SuilWrapper* wrapper, SuilInstance* instance)
   Window      xwindow  = (Window)instance->ui_widget;
 
   gdk_display_sync(display);
-  if (x_window_is_valid(wrap)) {
+  if (suil_x11_is_valid_child(xdisplay, GDK_WINDOW_XID(window), xwindow)) {
     XWindowAttributes attrs;
     XGetWindowAttributes(xdisplay, xwindow, &attrs);
 
diff --git a/src/x11_in_gtk3.c b/src/x11_in_gtk3.c
index 5ac5306..4addc03 100644
--- a/src/x11_in_gtk3.c
+++ b/src/x11_in_gtk3.c
@@ -3,6 +3,7 @@
 
 #include "suil_internal.h"
 #include "warnings.h"
+#include "x11_util.h"
 
 #include <lv2/core/lv2.h>
 #include <lv2/options/options.h>
@@ -24,7 +25,6 @@ SUIL_DISABLE_GTK_WARNINGS
 #include <gtk/gtkx.h>
 SUIL_RESTORE_WARNINGS
 
-#include <stdbool.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
@@ -57,39 +57,6 @@ suil_x11_wrapper_get_type(void); // Accessor for SUIL_TYPE_X11_WRAPPER
 
 G_DEFINE_TYPE(SuilX11Wrapper, suil_x11_wrapper, GTK_TYPE_SOCKET)
 
-/**
-   Check if 'swallowed' subwindow is known to the X server.
-
-   Gdk/GTK can mark the window as realized, mapped and visible even though
-   there is no window-ID on the X server for it yet.  Then,
-   suil_x11_on_size_allocate() will cause a "BadWinow" X error.
-*/
-static bool
-x_window_is_valid(SuilX11Wrapper* socket)
-{
-  GdkWindow* window     = gtk_widget_get_window(GTK_WIDGET(socket->plug));
-  Window     root       = 0;
-  Window     parent     = 0;
-  Window*    children   = NULL;
-  unsigned   childcount = 0;
-
-  XQueryTree(GDK_WINDOW_XDISPLAY(window),
-             GDK_WINDOW_XID(window),
-             &root,
-             &parent,
-             &children,
-             &childcount);
-  for (unsigned i = 0; i < childcount; ++i) {
-    if (children[i] == (Window)socket->instance->ui_widget) {
-      XFree(children);
-      return true;
-    }
-  }
-
-  XFree(children);
-  return false;
-}
-
 static gboolean
 on_plug_removed(GtkSocket* sock, gpointer data)
 {
@@ -212,7 +179,9 @@ static void
 forward_size_request(SuilX11Wrapper* socket, GtkAllocation* allocation)
 {
   GdkWindow* window = gtk_widget_get_window(GTK_WIDGET(socket->plug));
-  if (x_window_is_valid(socket)) {
+  if (suil_x11_is_valid_child(GDK_WINDOW_XDISPLAY(window),
+                              GDK_WINDOW_XID(window),
+                              (Window)socket->instance->ui_widget)) {
     // Calculate allocation size constrained to X11 limits for widget
     int        width  = allocation->width;
     int        height = allocation->height;
@@ -281,9 +250,11 @@ suil_x11_wrapper_get_preferred_width(GtkWidget* widget,
                                      gint*      minimum_width,
                                      gint*      natural_width)
 {
-  SuilX11Wrapper* const self = SUIL_X11_WRAPPER(widget);
-  if (x_window_is_valid(self)) {
-    GdkWindow* window = gtk_widget_get_window(GTK_WIDGET(self->plug));
+  SuilX11Wrapper* const self   = SUIL_X11_WRAPPER(widget);
+  GdkWindow* const      window = gtk_widget_get_window(GTK_WIDGET(self->plug));
+  if (suil_x11_is_valid_child(GDK_WINDOW_XDISPLAY(window),
+                              GDK_WINDOW_XID(window),
+                              (Window)self->instance->ui_widget)) {
     XSizeHints hints;
     memset(&hints, 0, sizeof(hints));
     long supplied = 0;
@@ -305,9 +276,11 @@ suil_x11_wrapper_get_preferred_height(GtkWidget* widget,
                                       gint*      minimum_height,
                                       gint*      natural_height)
 {
-  SuilX11Wrapper* const self = SUIL_X11_WRAPPER(widget);
-  if (x_window_is_valid(self)) {
-    GdkWindow* window = gtk_widget_get_window(GTK_WIDGET(self->plug));
+  SuilX11Wrapper* const self   = SUIL_X11_WRAPPER(widget);
+  GdkWindow* const      window = gtk_widget_get_window(GTK_WIDGET(self->plug));
+  if (suil_x11_is_valid_child(GDK_WINDOW_XDISPLAY(window),
+                              GDK_WINDOW_XID(window),
+                              (Window)self->instance->ui_widget)) {
     XSizeHints hints;
     memset(&hints, 0, sizeof(hints));
     long supplied = 0;
diff --git a/src/x11_util.c b/src/x11_util.c
new file mode 100644
index 0000000..f5f1c87
--- /dev/null
+++ b/src/x11_util.c
@@ -0,0 +1,56 @@
+// Copyright 2020-2024 David Robillard <d@drobilla.net>
+// SPDX-License-Identifier: ISC
+
+#include "x11_util.h"
+
+#include <X11/X.h>
+#include <X11/Xlib.h>
+
+#include <stddef.h>
+
+bool
+suil_x11_is_valid_child(Display* const display,
+                        const Window   parent,
+                        const Window   child)
+{
+  Window   root        = 0U;
+  Window   grandparent = 0U;
+  Window*  children    = NULL;
+  unsigned n_children  = 0U;
+
+  XQueryTree(display, parent, &root, &grandparent, &children, &n_children);
+
+  for (unsigned i = 0U; i < n_children; ++i) {
+    if (children[i] == child) {
+      if (children) {
+        XFree(children);
+      }
+      return true;
+    }
+  }
+
+  if (children) {
+    XFree(children);
+  }
+
+  return false;
+}
+
+Window
+suil_x11_get_parent(Display* display, Window child)
+{
+  Window   root     = 0U;
+  Window   parent   = 0U;
+  Window*  children = NULL;
+  unsigned count    = 0U;
+
+  if (child) {
+    if (XQueryTree(display, child, &root, &parent, &children, &count)) {
+      if (children) {
+        XFree(children);
+      }
+    }
+  }
+
+  return (parent == root) ? 0 : parent;
+}
diff --git a/src/x11_util.h b/src/x11_util.h
new file mode 100644
index 0000000..7ca2e7c
--- /dev/null
+++ b/src/x11_util.h
@@ -0,0 +1,20 @@
+// Copyright 2020-2024 David Robillard <d@drobilla.net>
+// SPDX-License-Identifier: ISC
+
+#ifndef SUIL_X11_UTIL
+#define SUIL_X11_UTIL
+
+#include <X11/X.h>
+#include <X11/Xlib.h>
+
+#include <stdbool.h>
+
+/// Return whether `child` can be found in the subtree under `parent`
+bool
+suil_x11_is_valid_child(Display* display, Window parent, Window child);
+
+/// Return the non-root parent window of `child` if it has one, or zero
+Window
+suil_x11_get_parent(Display* display, Window child);
+
+#endif // SUIL_X11_UTIL