[gtk/wip/chergert/macos-window-manager] macos: improve placement of windows

[Christian Hergert <chergert src gnome org>]

commit 89a351fd66cfb1ba7faa52b5ce6b9a158d052721
Author: Christian Hergert <christian hergert me>
Date:   Tue Feb 22 18:41:41 2022 -0800

    macos: improve placement of windows
    
    This does some very basic window management so that we place surfaces in
    locations where they can actually be interacted with correctly.

 gdk/macos/gdkmacosdisplay-private.h |   4 +
 gdk/macos/gdkmacosdisplay-wm.c      | 141 ++++++++++++++++++++++++++++++++++++
 gdk/macos/gdkmacossurface.c         |  19 +++--
 gdk/macos/gdkmacostoplevelsurface.c |  40 ++--------
 gdk/macos/meson.build               |   1 +
 5 files changed, 163 insertions(+), 42 deletions(-)
---
diff --git a/gdk/macos/gdkmacosdisplay-private.h b/gdk/macos/gdkmacosdisplay-private.h
index c25ff3b0c1..be2290b89a 100644
--- a/gdk/macos/gdkmacosdisplay-private.h
+++ b/gdk/macos/gdkmacosdisplay-private.h
@@ -174,6 +174,10 @@ void             _gdk_macos_display_set_drag                       (GdkMacosDisp
 void             _gdk_macos_display_set_drop                       (GdkMacosDisplay *self,
                                                                     NSInteger        sequence_number,
                                                                     GdkDrop         *drop);
+void             _gdk_macos_display_position_surface               (GdkMacosDisplay *self,
+                                                                    GdkMacosSurface *surface,
+                                                                    int             *x,
+                                                                    int             *y);
 
 G_END_DECLS
 
diff --git a/gdk/macos/gdkmacosdisplay-wm.c b/gdk/macos/gdkmacosdisplay-wm.c
new file mode 100644
index 0000000000..a0dd6dddae
--- /dev/null
+++ b/gdk/macos/gdkmacosdisplay-wm.c
@@ -0,0 +1,141 @@
+/*
+ * Copyright © 2022 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#include "config.h"
+
+#include "gdkmacosdisplay-private.h"
+#include "gdkmacosmonitor.h"
+#include "gdkmacossurface-private.h"
+#include "gdkmacostoplevelsurface-private.h"
+
+static void
+_gdk_macos_display_position_toplevel_with_parent (GdkMacosDisplay *self,
+                                                  GdkMacosSurface *surface,
+                                                  GdkMacosSurface *parent,
+                                                  int             *x,
+                                                  int             *y)
+{
+  GdkRectangle surface_rect;
+  GdkRectangle parent_rect;
+  GdkRectangle workarea;
+  GdkMonitor *monitor;
+
+  g_assert (GDK_IS_MACOS_DISPLAY (self));
+  g_assert (GDK_IS_MACOS_TOPLEVEL_SURFACE (surface));
+  g_assert (GDK_IS_MACOS_TOPLEVEL_SURFACE (parent));
+
+  /* If x/y is set, we should place relative to parent */
+  if (GDK_SURFACE (surface)->x != 0 || GDK_SURFACE (surface)->y != 0)
+    {
+      *x = parent->root_x + GDK_SURFACE (surface)->x;
+      *y = parent->root_y + GDK_SURFACE (surface)->y;
+      return;
+    }
+
+  /* Try to center on top of the parent but also try to make the whole thing
+   * visible in case that lands us under the topbar/panel/etc.
+   */
+  surface_rect.x = surface->root_x + surface->shadow_left;
+  surface_rect.y = surface->root_y + surface->shadow_top;
+  surface_rect.width = GDK_SURFACE (surface)->width - surface->shadow_left - surface->shadow_right;
+  surface_rect.height = GDK_SURFACE (surface)->height - surface->shadow_top - surface->shadow_bottom;
+
+  parent_rect.x = parent->root_x + surface->shadow_left;
+  parent_rect.y = parent->root_y + surface->shadow_top;
+  parent_rect.width = GDK_SURFACE (parent)->width - surface->shadow_left - surface->shadow_right;
+  parent_rect.height = GDK_SURFACE (parent)->height - surface->shadow_top - surface->shadow_bottom;
+
+  /* Try to place centered atop parent */
+  surface_rect.x = parent_rect.x + ((parent_rect.width - surface_rect.width) / 2);
+  surface_rect.y = parent_rect.y + ((parent_rect.height - surface_rect.height) / 2);
+
+  /* Now make sure that we don't overlap the top-bar */
+  monitor = _gdk_macos_surface_get_best_monitor (parent);
+  gdk_macos_monitor_get_workarea (monitor, &workarea);
+
+  if (surface_rect.x < workarea.x)
+    surface_rect.x = workarea.x;
+
+  if (surface_rect.y < workarea.y)
+    surface_rect.y = workarea.y;
+
+  *x = surface_rect.x - surface->shadow_left;
+  *y = surface_rect.y - surface->shadow_top;
+}
+
+static void
+_gdk_macos_display_position_toplevel (GdkMacosDisplay *self,
+                                      GdkMacosSurface *surface,
+                                      int             *x,
+                                      int             *y)
+{
+  cairo_rectangle_int_t surface_rect;
+  GdkRectangle workarea;
+  GdkMonitor *monitor;
+  CGPoint mouse;
+
+  g_assert (GDK_IS_MACOS_DISPLAY (self));
+  g_assert (GDK_IS_MACOS_TOPLEVEL_SURFACE (surface));
+
+  mouse = [NSEvent mouseLocation];
+  monitor = _gdk_macos_display_get_monitor_at_display_coords (self, mouse.x, mouse.y);
+  gdk_macos_monitor_get_workarea (monitor, &workarea);
+
+  /* First place at top-left of current monitor */
+  surface_rect.width = GDK_SURFACE (surface)->width - surface->shadow_left - surface->shadow_right;
+  surface_rect.height = GDK_SURFACE (surface)->height - surface->shadow_top - surface->shadow_bottom;
+  surface_rect.x = workarea.x + ((workarea.width - surface_rect.width) / 2);
+  surface_rect.y = workarea.y + ((workarea.height - surface_rect.height) / 2);
+
+  if (surface_rect.x < workarea.x)
+    surface_rect.x = workarea.x;
+
+  if (surface_rect.y < workarea.y)
+    surface_rect.y = workarea.y;
+
+  /* TODO: If there is another window at this same position, perhaps we should move it */
+
+  *x = surface_rect.x - surface->shadow_left;
+  *y = surface_rect.y - surface->shadow_top;
+}
+
+/*<private>
+ * _gdk_macos_display_position_surface:
+ *
+ * Tries to position a window on a screen without landing in edges
+ * and other weird areas the user can't use.
+ */
+void
+_gdk_macos_display_position_surface (GdkMacosDisplay *self,
+                                     GdkMacosSurface *surface,
+                                     int             *x,
+                                     int             *y)
+{
+  GdkSurface *transient_for;
+
+  g_return_if_fail (GDK_IS_MACOS_DISPLAY (self));
+  g_return_if_fail (GDK_IS_MACOS_TOPLEVEL_SURFACE (surface));
+
+  transient_for = GDK_SURFACE (surface)->transient_for;
+
+  if (transient_for != NULL)
+    _gdk_macos_display_position_toplevel_with_parent (self, surface, GDK_MACOS_SURFACE (transient_for), x, 
y);
+  else
+    _gdk_macos_display_position_toplevel (self, surface, x, y);
+}
diff --git a/gdk/macos/gdkmacossurface.c b/gdk/macos/gdkmacossurface.c
index ded5c19189..50e873a78d 100644
--- a/gdk/macos/gdkmacossurface.c
+++ b/gdk/macos/gdkmacossurface.c
@@ -746,15 +746,18 @@ _gdk_macos_surface_configure (GdkMacosSurface *self)
                                           content_rect.origin.y + content_rect.size.height,
                                           &self->root_x, &self->root_y);
 
-  if (surface->parent != NULL)
+  if (self->did_initial_present)
     {
-      surface->x = self->root_x - GDK_MACOS_SURFACE (surface->parent)->root_x;
-      surface->y = self->root_y - GDK_MACOS_SURFACE (surface->parent)->root_y;
-    }
-  else
-    {
-      surface->x = self->root_x;
-      surface->y = self->root_y;
+      if (surface->parent != NULL)
+        {
+          surface->x = self->root_x - GDK_MACOS_SURFACE (surface->parent)->root_x;
+          surface->y = self->root_y - GDK_MACOS_SURFACE (surface->parent)->root_y;
+        }
+      else
+        {
+          surface->x = self->root_x;
+          surface->y = self->root_y;
+        }
     }
 
   if (surface->width != content_rect.size.width ||
diff --git a/gdk/macos/gdkmacostoplevelsurface.c b/gdk/macos/gdkmacostoplevelsurface.c
index 862eb8f1e9..27289787ca 100644
--- a/gdk/macos/gdkmacostoplevelsurface.c
+++ b/gdk/macos/gdkmacostoplevelsurface.c
@@ -194,43 +194,15 @@ _gdk_macos_toplevel_surface_present (GdkToplevel       *toplevel,
         _gdk_macos_toplevel_surface_unfullscreen (self);
     }
 
-  if (GDK_SURFACE (self)->transient_for != NULL)
+  if (!GDK_MACOS_SURFACE (self)->did_initial_present)
     {
-    }
-  else
-    {
-      [nswindow setAnimationBehavior:NSWindowAnimationBehaviorDocumentWindow];
-
-      if (!self->decorated &&
-          !GDK_MACOS_SURFACE (self)->did_initial_present &&
-          GDK_SURFACE (self)->x == 0 &&
-          GDK_SURFACE (self)->y == 0 &&
-          (GDK_MACOS_SURFACE (self)->shadow_left ||
-           GDK_MACOS_SURFACE (self)->shadow_top))
-        {
-          int x = GDK_SURFACE (self)->x;
-          int y = GDK_SURFACE (self)->y;
-
-          monitor = _gdk_macos_surface_get_best_monitor (GDK_MACOS_SURFACE (self));
-
-          if (monitor != NULL)
-            {
-              GdkRectangle visible;
-
-              gdk_macos_monitor_get_workarea (monitor, &visible);
-
-              if (x < visible.x)
-                x = visible.x;
-
-              if (y < visible.y)
-                y = visible.y;
-            }
+      int x = 0, y = 0;
 
-          x -= GDK_MACOS_SURFACE (self)->shadow_left;
-          y -= GDK_MACOS_SURFACE (self)->shadow_top;
+      _gdk_macos_display_position_surface (GDK_MACOS_DISPLAY (display),
+                                           GDK_MACOS_SURFACE (self),
+                                           &x, &y);
 
-          _gdk_macos_surface_move (GDK_MACOS_SURFACE (self), x, y);
-        }
+      _gdk_macos_surface_move (GDK_MACOS_SURFACE (self), x, y);
     }
 
   _gdk_macos_surface_show (GDK_MACOS_SURFACE (self));
diff --git a/gdk/macos/meson.build b/gdk/macos/meson.build
index 3a10dbf944..f3d9fbb336 100644
--- a/gdk/macos/meson.build
+++ b/gdk/macos/meson.build
@@ -9,6 +9,7 @@ gdk_macos_sources = files([
   'gdkmacosdisplay.c',
   'gdkmacosdisplay-settings.c',
   'gdkmacosdisplay-translate.c',
+  'gdkmacosdisplay-wm.c',
   'gdkmacosdrag.c',
   'gdkmacosdrop.c',
   'gdkmacosdragsurface.c',