From ea7e7acd45e428cc17306de2bf65730c90d7e118 Mon Sep 17 00:00:00 2001

From: Sebastian Keller <skeller@gnome.org>

Date: Mon, 23 May 2022 23:01:23 +0200

Subject: [PATCH] magnifier: Request window-relative coordinates for

 focus/caret events

Absolute screen coordinates are impossible for Wayland clients to

provide, because the clients don't know where the window is positioned.

Some clients, such as the ones using GTK 3 were providing window

relative coordinates even when screen coordinates were requested,

while others, such as GTK 4 clients, were just returning an error for

caret events or also window-relative coordinates for focus events.

So for this to work on Wayland we have to request window-relative

coordinates and translate them to the current focus window.

To ensure the correct coordinates, we have to only consider events

coming from the current focus window. All other events are filtered out

now. As a side effect this also fixes the magnifier always jumping

to a terminal cursor whenever there was some output, even if the window

was not focused.

This also needs some special handling for events coming from the shell

itself, which should not be translated to the focus window either. As

another side effect this fixes another bug that was caused by these

events already including scaling and getting scaled again.

Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/5509

Part-of:

<https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2301>

---

 js/ui/magnifier.js | 77 +++++++++++++++++++++++++++++++++++++++++-----

 1 file changed, 70 insertions(+), 7 deletions(-)

diff --git a/js/ui/magnifier.js b/js/ui/magnifier.js

index 4c2e88f1a..9813664be 100644

--- a/js/ui/magnifier.js

+++ b/js/ui/magnifier.js

@@ -789,21 +789,81 @@ var ZoomRegion = class ZoomRegion {

         }

     }

+    _convertExtentsToScreenSpace(accessible, extents) {

+        const toplevelWindowTypes = new Set([

+            Atspi.Role.FRAME,

+            Atspi.Role.DIALOG,

+            Atspi.Role.WINDOW,

+        ]);

+

+        try {

+            let app = null;

+            let parentWindow = null;

+            let iter = accessible;

+            while (iter) {

+                if (iter.get_role() === Atspi.Role.APPLICATION) {

+                    app = iter;

+                    /* This is the last Accessible we are interested in */

+                    break;

+                } else if (toplevelWindowTypes.has(iter.get_role())) {

+                    parentWindow = iter;

+                }

+                iter = iter.get_parent();

+            }

+

+            /* We don't want to translate our own events to the focus window.

+             * They are also already scaled by clutter before being sent, so

+             * we don't need to do that here either. */

+            if (app && app.get_name() === 'gnome-shell')

+                return extents;

+

+            /* Only events from the focused widget of the focused window. Some

+             * widgets seem to claim to have focus when the window does not so

+             * check both. */

+            const windowActive = parentWindow &&

+                parentWindow.get_state_set().contains(Atspi.StateType.ACTIVE);

+            const accessibleFocused =

+                accessible.get_state_set().contains(Atspi.StateType.FOCUSED);

+            if (!windowActive || !accessibleFocused)

+                return null;

+        } catch (e) {

+            throw new Error(`Failed to validate parent window: ${e}`);

+        }

+

+        const focusWindowRect = global.display.focus_window?.get_frame_rect();

+        if (!focusWindowRect)

+            return null;

+

+        const scaleFactor = St.ThemeContext.get_for_stage(global.stage).scale_factor;

+        const screenSpaceExtents = new Atspi.Rect({

+            x: focusWindowRect.x + (scaleFactor * extents.x),

+            y: focusWindowRect.y + (scaleFactor * extents.y),

+            width: scaleFactor * extents.width,

+            height: scaleFactor * extents.height,

+        });

+

+        return screenSpaceExtents;

+    }

+

     _updateFocus(caller, event) {

         let component = event.source.get_component_iface();

         if (!component || event.detail1 != 1)

             return;

         let extents;

         try {

-            extents = component.get_extents(Atspi.CoordType.SCREEN);

+            extents = component.get_extents(Atspi.CoordType.WINDOW);

+            extents = this._convertExtentsToScreenSpace(event.source, extents);

+            if (!extents)

+                return;

         } catch (e) {

             log(`Failed to read extents of focused component: ${e.message}`);

             return;

         }

-        let scaleFactor = St.ThemeContext.get_for_stage(global.stage).scale_factor;

-        let [xFocus, yFocus] = [(extents.x + (extents.width / 2)) * scaleFactor,

-                                (extents.y + (extents.height / 2)) * scaleFactor];

+        const [xFocus, yFocus] = [

+            extents.x + (extents.width / 2),

+            extents.y + (extents.height / 2),

+        ];

         if (this._xFocus !== xFocus || this._yFocus !== yFocus) {

             [this._xFocus, this._yFocus] = [xFocus, yFocus];

@@ -817,14 +877,17 @@ var ZoomRegion = class ZoomRegion {

             return;

         let extents;

         try {

-            extents = text.get_character_extents(text.get_caret_offset(), 0);

+            extents = text.get_character_extents(text.get_caret_offset(),

+                Atspi.CoordType.WINDOW);

+            extents = this._convertExtentsToScreenSpace(text, extents);

+            if (!extents)

+                return;

         } catch (e) {

             log(`Failed to read extents of text caret: ${e.message}`);

             return;

         }

-        let scaleFactor = St.ThemeContext.get_for_stage(global.stage).scale_factor;

-        let [xCaret, yCaret] = [extents.x * scaleFactor, extents.y * scaleFactor];

+        const [xCaret, yCaret] = [extents.x, extents.y];

         // Ignore event(s) if the caret size is none (0x0). This happens a lot if

         // the cursor offset can't be translated into a location. This is a work

-- 

2.38.1