[mutter/wip/carlosg/input-thread: 127/159] backends: Add method to get extents from viewport info

[Carlos Garnacho <carlosg src gnome org>]

commit 7c7d8a77903413abc430f481b360ed4da030bedb
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri Jul 31 19:10:53 2020 +0200

    backends: Add method to get extents from viewport info
    
    This way we know the stage extents without poking the stage.

 src/backends/meta-viewport-info.c | 23 +++++++++++++++++++++++
 src/backends/meta-viewport-info.h |  4 ++++
 2 files changed, 27 insertions(+)
---
diff --git a/src/backends/meta-viewport-info.c b/src/backends/meta-viewport-info.c
index 0e50dcbfea..12da50d0d8 100644
--- a/src/backends/meta-viewport-info.c
+++ b/src/backends/meta-viewport-info.c
@@ -187,3 +187,26 @@ meta_viewport_info_get_num_views (MetaViewportInfo *info)
 {
   return info->views->len;
 }
+
+void
+meta_viewport_info_get_extents (MetaViewportInfo *viewport_info,
+                                float            *width,
+                                float            *height)
+{
+  int min_x = G_MAXINT, min_y = G_MAXINT, max_x = G_MININT, max_y = G_MININT, i;
+
+  for (i = 0; i < viewport_info->views->len; i++)
+    {
+      ViewInfo *info = &g_array_index (viewport_info->views, ViewInfo, i);
+
+      min_x = MIN (min_x, info->rect.x);
+      max_x = MAX (max_x, info->rect.x + info->rect.width);
+      min_y = MIN (min_y, info->rect.y);
+      max_y = MAX (max_y, info->rect.y + info->rect.height);
+    }
+
+  if (width)
+    *width = (float) max_x - min_x;
+  if (height)
+    *height = (float) max_y - min_y;
+}
diff --git a/src/backends/meta-viewport-info.h b/src/backends/meta-viewport-info.h
index c9a8818695..ad091dc99e 100644
--- a/src/backends/meta-viewport-info.h
+++ b/src/backends/meta-viewport-info.h
@@ -50,4 +50,8 @@ int meta_viewport_info_get_neighbor (MetaViewportInfo     *info,
                                      MetaDisplayDirection  direction);
 int meta_viewport_info_get_num_views (MetaViewportInfo *info);
 
+void meta_viewport_info_get_extents (MetaViewportInfo *info,
+                                     float            *width,
+                                     float            *height);
+
 #endif /* META_VIEWPORT_INFO_H */