From 38e339723770e5722c6e48a4fd1f4e42d5e46e3b Mon Sep 17 00:00:00 2001
From: Mukilan Thiyagarajan <mukilan@igalia.com>
Date: Tue, 14 Apr 2026 18:19:48 +0530
Subject: [PATCH] servoshell: Fix incorrect calculation of WebView dimension.
 (#44205)

The upgrade to egui 0.34.0 in #44053 replaced the usage of the
deprecated `Ui::available_rect` method with `Ui::content_rect` as
suggested in the deprecation notice in egui. However, `content_rect` is
not equivalent to `available_rect` and doesn't seem to account for the
area occupied by the egui panels.

Since `content_rect` returns the window's inner dimensions, we don't ask
the webview to resize itself to the correct dimension that excludes the
toolbar (tabs and url). We also pass the correct dimension to egui's
paint callback, which meant that the WebView appeared vertically
squashed.

Fix this by using `available_rect_before_wrap` method instead of
`content_rect`. This seems to return the correct area that we need for
the WebView's dimenstion. The code in egui also seems closer to what we
want as it relies on a cursor that is advanced after each widget is
added. However, I'm not sure in which scenario the wrapping matters as
there is no documentation for this method.

Testing: Tested manually as we don't have automated tests for the shell.
Fixes: #44136

Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>
---
 ports/servoshell/desktop/gui.rs | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/ports/servoshell/desktop/gui.rs b/ports/servoshell/desktop/gui.rs
index f08e924c261..80a92f64560 100644
--- a/ports/servoshell/desktop/gui.rs
+++ b/ports/servoshell/desktop/gui.rs
@@ -554,7 +554,7 @@ impl Gui {
 
             // If the top parts of the GUI changed size, then update the size of the WebView and also
             // the size of its RenderingContext.
-            let rect = ctx.content_rect();
+            let available_rect = ctx.available_rect_before_wrap();
 
             // Build a graft node for each WebView.
             for (webview_id, webview) in window.webviews() {
@@ -565,7 +565,7 @@ impl Gui {
                     });
                 }
             }
-            let size = Size2D::new(rect.width(), rect.height()) * scale;
+            let size = Size2D::new(available_rect.width(), available_rect.height()) * scale;
             if let Some(webview) = window.active_webview() &&
                 size != webview.size()
             {
@@ -580,7 +580,7 @@ impl Gui {
                     ctx.clone(),
                     LayerId::new(Order::Tooltip, Id::new("tooltip")),
                     "tooltip layer".into(),
-                    pos2(0.0, ctx.content_rect().max.y),
+                    pos2(0.0, available_rect.max.y),
                 )
                 .show(|ui| ui.add(Label::new(status_text.clone()).extend()));
                 window.set_needs_repaint();
@@ -589,12 +589,8 @@ impl Gui {
             window.repaint_webviews();
 
             if let Some(render_to_parent) = rendering_context.render_to_parent_callback() {
-                let rect = egui::Rect::from_two_pos(
-                    (0.0, toolbar_height.0).into(),
-                    ctx.content_rect().max,
-                );
                 ctx.layer_painter(LayerId::background()).add(PaintCallback {
-                    rect,
+                    rect: available_rect,
                     callback: Arc::new(CallbackFn::new(move |info, painter| {
                         let clip = info.viewport_in_pixels();
                         let rect_in_parent = Rect::new(