From 761000ec8f4b53d0fa06f235be2ed30b80ec5bcb Mon Sep 17 00:00:00 2001
Message-Id: <761000ec8f4b53d0fa06f235be2ed30b80ec5bcb.1553890447.git.jan.steffens@gmail.com>
From: "Jan Alexander Steffens (heftig)" <jan.steffens@gmail.com>
Date: Wed, 27 Mar 2019 00:38:02 +0100
Subject: [PATCH] wayland/output: Report unscaled size even in logical layout
 mode
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In physical layout mode, the size and scale of the `wl_output` matches
the actual monitor:

| Monitor      | `wl_output`  | `GdkMonitor` |
| ------------ | ------------ | ------------ |
| 3840×2160 @1 | 3840×2160 @1 | 3840×2160 @1 |
| 3840×2160 @2 | 3840×2160 @2 | 1920×1080 @2 |

GTK currently does not support `xdg_output`. To estimate the logical
output size for `GdkMonitor`, it divides the output's size by its scale
factor. There might be other legacy clients making the same assumption.

In logical layout mode, mutter currently reports logical geometry for
the `wl_output`s, but this no longer matches the monitors:

| Monitor        | `wl_output`  | `GdkMonitor` |
| -------------- | ------------ | ------------ |
| 3840×2160 @1   | 3840×2160 @1 | 3840×2160 @1 |
| 3840×2160 @2   | 1920×1080 @2 |  960×540  @2 |
| 3840×2160 @1.5 | 2560×1440 @2 | 1280×720  @2 |

This patch changes logical layout mode to multiply the sizes by the
`wl_output`'s scale factor before sending them to the client. Now the
sizes match the physical layout mode again:

| Monitor        | `wl_output`  | `GdkMonitor` |
| -------------- | ------------ | ------------ |
| 3840×2160 @1   | 3840×2160 @1 | 3840×2160 @1 |
| 3840×2160 @2   | 3840×2160 @2 | 1920×1080 @2 |
| 3840×2160 @1.5 | 5120×2880 @2 | 2560×1440 @2 |

Unfortunately, non-integer output scales are not representable in
`wl_output`. Still, I believe these values are better than before, and
the best we can do for clients that do not know about `xdg_output`: The
size of the output will match the size that a buffer for a fullscreen
surface should have at the indicated scale.

Fixes part of https://bugzilla.mozilla.org/show_bug.cgi?id=1534089
https://gitlab.gnome.org/GNOME/mutter/merge_requests/510
---
 src/wayland/meta-wayland-outputs.c | 33 +++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/src/wayland/meta-wayland-outputs.c b/src/wayland/meta-wayland-outputs.c
index 7695d86af..712a143a8 100644
--- a/src/wayland/meta-wayland-outputs.c
+++ b/src/wayland/meta-wayland-outputs.c
@@ -181,24 +181,36 @@ send_output_events (struct wl_resource *resource,
   MetaLogicalMonitor *old_logical_monitor;
   guint old_mode_flags;
   gint old_scale;
+  gint scale;
+  MetaRectangle old_rect;
+  MetaRectangle rect;
   float old_refresh_rate;
   float refresh_rate;
 
   old_logical_monitor = wayland_output->logical_monitor;
   old_mode_flags = wayland_output->mode_flags;
   old_scale = wayland_output->scale;
+  old_rect = old_logical_monitor->rect;
   old_refresh_rate = wayland_output->refresh_rate;
 
+  scale = calculate_wayland_output_scale (logical_monitor);
+  rect = logical_monitor->rect;
   monitor = pick_main_monitor (logical_monitor);
-
   current_mode = meta_monitor_get_current_mode (monitor);
   refresh_rate = meta_monitor_mode_get_refresh_rate (current_mode);
 
+  if (meta_is_stage_views_scaled ()) {
+    old_rect.width *= old_scale;
+    old_rect.height *= old_scale;
+    rect.width *= scale;
+    rect.height *= scale;
+  }
+
   gboolean need_done = FALSE;
 
   if (need_all_events ||
-      old_logical_monitor->rect.x != logical_monitor->rect.x ||
-      old_logical_monitor->rect.y != logical_monitor->rect.y ||
+      old_rect.x != rect.x ||
+      old_rect.y != rect.y ||
       is_different_rotation (old_logical_monitor, logical_monitor))
     {
       int width_mm, height_mm;
@@ -229,40 +241,37 @@ send_output_events (struct wl_resource *resource,
       transform = WL_OUTPUT_TRANSFORM_NORMAL;
 
       wl_output_send_geometry (resource,
-                               logical_monitor->rect.x,
-                               logical_monitor->rect.y,
+                               rect.x,
+                               rect.y,
                                width_mm,
                                height_mm,
                                subpixel_order,
                                vendor,
                                product,
                                transform);
       need_done = TRUE;
     }
 
   preferred_mode = meta_monitor_get_preferred_mode (monitor);
   if (current_mode == preferred_mode)
     mode_flags |= WL_OUTPUT_MODE_PREFERRED;
 
   if (need_all_events ||
-      old_logical_monitor->rect.width != logical_monitor->rect.width ||
-      old_logical_monitor->rect.height != logical_monitor->rect.height ||
+      old_rect.width != rect.width ||
+      old_rect.height != rect.height ||
       old_refresh_rate != refresh_rate ||
       old_mode_flags != mode_flags)
     {
       wl_output_send_mode (resource,
                            mode_flags,
-                           logical_monitor->rect.width,
-                           logical_monitor->rect.height,
+                           rect.width,
+                           rect.height,
                            (int32_t) (refresh_rate * 1000));
       need_done = TRUE;
     }
 
   if (version >= WL_OUTPUT_SCALE_SINCE_VERSION)
     {
-      int scale;
-
-      scale = calculate_wayland_output_scale (logical_monitor);
       if (need_all_events ||
           old_scale != scale)
         {
-- 
2.21.0