[mutter] clutter: Make stage capture support fractional scaling

[Marge Bot <marge-bot src gnome org>]

commit 64c9c9c5b005cf17103d8e1e0a08dec0b1094267
Author: kirbykevinson <kirbykevinson outlook com>
Date:   Sat May 8 18:22:27 2021 +0700

    clutter: Make stage capture support fractional scaling
    
    This commit adds scaling support to clutter_stage_capture_into, which
    is currently used when screencasting monitors. This is supposed to
    fix graphical issues that arise when using fractional scaling.
    
    Fixes #1131
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1855>

 clutter/clutter/clutter-mutter.h                   |  4 +++-
 clutter/clutter/clutter-stage.c                    | 11 +++++------
 src/backends/meta-screen-cast-monitor-stream-src.c |  9 ++++++++-
 3 files changed, 16 insertions(+), 8 deletions(-)
---
diff --git a/clutter/clutter/clutter-mutter.h b/clutter/clutter/clutter-mutter.h
index 88dee26587..91e1535862 100644
--- a/clutter/clutter/clutter-mutter.h
+++ b/clutter/clutter/clutter-mutter.h
@@ -52,7 +52,9 @@ int64_t clutter_stage_get_frame_counter (ClutterStage *stage);
 CLUTTER_EXPORT
 void clutter_stage_capture_into (ClutterStage          *stage,
                                  cairo_rectangle_int_t *rect,
-                                 uint8_t               *data);
+                                 float                  scale,
+                                 uint8_t               *data,
+                                 int                    stride);
 
 CLUTTER_EXPORT
 void clutter_stage_capture_view_into (ClutterStage          *stage,
diff --git a/clutter/clutter/clutter-stage.c b/clutter/clutter/clutter-stage.c
index 95e42e8589..8627c6a17f 100644
--- a/clutter/clutter/clutter-stage.c
+++ b/clutter/clutter/clutter-stage.c
@@ -3272,14 +3272,13 @@ clutter_stage_capture_view_into (ClutterStage          *stage,
 void
 clutter_stage_capture_into (ClutterStage          *stage,
                             cairo_rectangle_int_t *rect,
-                            uint8_t               *data)
+                            float                  scale,
+                            uint8_t               *data,
+                            int                    stride)
 {
   ClutterStagePrivate *priv = stage->priv;
   GList *l;
   int bpp = 4;
-  int stride;
-
-  stride = rect->width * 4;
 
   for (l = _clutter_stage_window_get_views (priv->impl); l; l = l->next)
     {
@@ -3296,8 +3295,8 @@ clutter_stage_capture_into (ClutterStage          *stage,
       cairo_region_get_extents (region, &capture_rect);
       cairo_region_destroy (region);
 
-      x_offset = capture_rect.x - rect->x;
-      y_offset = capture_rect.y - rect->y;
+      x_offset = roundf ((capture_rect.x - rect->x) * scale);
+      y_offset = roundf ((capture_rect.y - rect->y) * scale);
 
       clutter_stage_capture_view_into (stage, view,
                                        &capture_rect,
diff --git a/src/backends/meta-screen-cast-monitor-stream-src.c 
b/src/backends/meta-screen-cast-monitor-stream-src.c
index 008cd6de70..b85c44fe12 100644
--- a/src/backends/meta-screen-cast-monitor-stream-src.c
+++ b/src/backends/meta-screen-cast-monitor-stream-src.c
@@ -528,11 +528,18 @@ meta_screen_cast_monitor_stream_src_record_to_buffer (MetaScreenCastStreamSrc  *
   ClutterStage *stage;
   MetaMonitor *monitor;
   MetaLogicalMonitor *logical_monitor;
+  float scale;
 
   monitor = get_monitor (monitor_src);
   logical_monitor = meta_monitor_get_logical_monitor (monitor);
   stage = get_stage (monitor_src);
-  clutter_stage_capture_into (stage, &logical_monitor->rect, data);
+
+  if (meta_is_stage_views_scaled ())
+    scale = meta_logical_monitor_get_scale (logical_monitor);
+  else
+    scale = 1.0;
+
+  clutter_stage_capture_into (stage, &logical_monitor->rect, scale, data, stride);
 
   switch (meta_screen_cast_stream_get_cursor_mode (stream))
     {