LibWeb: Apply scroll offset to PushStackingContext command

In cases where the stacking context painting requires a separate bitmap, the destination position needs to be translated by the scrolling offset to ensure it ends up in the correct position.
kalenikaliaksandr · Feb 1, 2024 · 621e737 · 621e737
1 parent 384c6cf
commit 621e737
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diff --git a/.../LibWeb/Ref/reference/scrollable-contains-boxes-with-hidden-overflow-and-opacity-ref.html b/.../LibWeb/Ref/reference/scrollable-contains-boxes-with-hidden-overflow-and-opacity-ref.html
@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<style>
+    html {
+        background: white;
+    }
+    body {
+        position: absolute;
+        inset: 0px;
+        display: flex;
+        background: pink;
+    }
+    #outer {
+        overflow: hidden;
+        background: orange;
+        margin-top: 100px;
+    }
+    #inner {
+        height: 1000px;
+        background: yellow;
+    }
+    .item {
+        box-sizing: border-box;
+        border: 1px solid black;
+        background: lime;
+        height: 50px;
+        width: 200px;
+        display: flex;
+        justify-content: center;
+        align-items: center;
+        opacity: 0.5;
+    }
+</style><body><div id="outer"><div id="inner">
+<div class="item">11</div>
+<div class="item">12</div>
+<div class="item">13</div>
+<div class="item">14</div>
+<div class="item">15</div>
+<div class="item">16</div>
+<div class="item">17</div>
+<div class="item">18</div>
+<div class="item">19</div>
+<div class="item">20</div>
+<div class="item">21</div>
+<div class="item">22</div>
+<div class="item">23</div>
+<div class="item">24</div>
+<div class="item">25</div>
+<div class="item">26</div>
+<div class="item">27</div>
+<div class="item">28</div>
+<div class="item">29</div>
+<div class="item">30</div>
diff --git a/Tests/LibWeb/Ref/scrollable-contains-boxes-with-hidden-overflow-and-opacity.html b/Tests/LibWeb/Ref/scrollable-contains-boxes-with-hidden-overflow-and-opacity.html
@@ -0,0 +1,91 @@
+<!DOCTYPE html>
+<link rel="match" href="reference/scrollable-contains-boxes-with-hidden-overflow-and-opacity-ref.html" />
+<style>
+    html {
+        background: white;
+    }
+    body {
+        position: absolute;
+        inset: 0px;
+        display: flex;
+        background: pink;
+    }
+    #outer {
+        overflow-x: hidden;
+        overflow-y: scroll;
+        background: orange;
+        margin-top: 100px;
+    }
+    #inner {
+        height: 1000px;
+        background: magenta;
+    }
+    .item {
+        background: yellow;
+    }
+    .wrapper {
+        box-sizing: border-box;
+        border: 1px solid black;
+        background: lime;
+        height: 50px;
+        width: 200px;
+        display: flex;
+        justify-content: center;
+        align-items: center;
+        opacity: 0.5;
+    }
+</style><body><div id="outer"><div id="inner">
+<div class="item"><div class="wrapper">1</div></div>
+<div class="item"><div class="wrapper">2</div></div>
+<div class="item"><div class="wrapper">3</div></div>
+<div class="item"><div class="wrapper">4</div></div>
+<div class="item"><div class="wrapper">5</div></div>
+<div class="item"><div class="wrapper">6</div></div>
+<div class="item"><div class="wrapper">7</div></div>
+<div class="item"><div class="wrapper">8</div></div>
+<div class="item"><div class="wrapper">9</div></div>
+<div class="item"><div class="wrapper">10</div></div>
+<div class="item"><div class="wrapper">11</div></div>
+<div class="item"><div class="wrapper">12</div></div>
+<div class="item"><div class="wrapper">13</div></div>
+<div class="item"><div class="wrapper">14</div></div>
+<div class="item"><div class="wrapper">15</div></div>
+<div class="item"><div class="wrapper">16</div></div>
+<div class="item"><div class="wrapper">17</div></div>
+<div class="item"><div class="wrapper">18</div></div>
+<div class="item"><div class="wrapper">19</div></div>
+<div class="item"><div class="wrapper">20</div></div>
+<div class="item"><div class="wrapper">21</div></div>
+<div class="item"><div class="wrapper">22</div></div>
+<div class="item"><div class="wrapper">23</div></div>
+<div class="item"><div class="wrapper">24</div></div>
+<div class="item"><div class="wrapper">25</div></div>
+<div class="item"><div class="wrapper">26</div></div>
+<div class="item"><div class="wrapper">27</div></div>
+<div class="item"><div class="wrapper">28</div></div>
+<div class="item"><div class="wrapper">29</div></div>
+<div class="item"><div class="wrapper">30</div></div>
+<div class="item"><div class="wrapper">31</div></div>
+<div class="item"><div class="wrapper">32</div></div>
+<div class="item"><div class="wrapper">33</div></div>
+<div class="item"><div class="wrapper">34</div></div>
+<div class="item"><div class="wrapper">35</div></div>
+<div class="item"><div class="wrapper">36</div></div>
+<div class="item"><div class="wrapper">37</div></div>
+<div class="item"><div class="wrapper">38</div></div>
+<div class="item"><div class="wrapper">39</div></div>
+<div class="item"><div class="wrapper">40</div></div>
+<div class="item"><div class="wrapper">41</div></div>
+<div class="item"><div class="wrapper">42</div></div>
+<div class="item"><div class="wrapper">43</div></div>
+<div class="item"><div class="wrapper">44</div></div>
+<div class="item"><div class="wrapper">45</div></div>
+<div class="item"><div class="wrapper">46</div></div>
+<div class="item"><div class="wrapper">47</div></div>
+<div class="item"><div class="wrapper">48</div></div>
+<div class="item"><div class="wrapper">49</div></div>
+<div class="item"><div class="wrapper">50</div></div>
+<script>
+    const scrollContainer = document.getElementById("outer");
+    scrollContainer.scrollTop = 500;
+</script>
diff --git a/Userland/Libraries/LibWeb/Painting/PaintableBox.h b/Userland/Libraries/LibWeb/Painting/PaintableBox.h
@@ -198,6 +198,8 @@ class PaintableBox : public Paintable {
     void set_enclosing_scroll_frame_offset(CSSPixelPoint offset) { m_enclosing_scroll_frame_offset = offset; }
     void set_corner_clip_radii(BorderRadiiData const& corner_radii) { m_corner_clip_radii = corner_radii; }
 
+    Optional<int> scroll_frame_id() const { return m_scroll_frame_id; }
+
 protected:
     explicit PaintableBox(Layout::Box const&);
 

diff --git a/Userland/Libraries/LibWeb/Painting/RecordingPainter.h b/Userland/Libraries/LibWeb/Painting/RecordingPainter.h
@@ -122,7 +122,7 @@ struct PushStackingContext {
 
     void translate_by(Gfx::IntPoint const& offset)
     {
-        post_transform_translation.translate_by(offset);
+        source_paintable_rect.translate_by(offset);
     }
 };
 

diff --git a/Userland/Libraries/LibWeb/Painting/StackingContext.cpp b/Userland/Libraries/LibWeb/Painting/StackingContext.cpp
@@ -319,9 +319,13 @@ void StackingContext::paint(PaintContext& context) const
         }
     }
 
+    context.recording_painter().save();
+    if (paintable().is_paintable_box() && paintable_box().scroll_frame_id().has_value())
+        context.recording_painter().set_scroll_frame_id(*paintable_box().scroll_frame_id());
     context.recording_painter().push_stacking_context(push_stacking_context_params);
     paint_internal(context);
     context.recording_painter().pop_stacking_context();
+    context.recording_painter().restore();
 }
 
 template<typename Callback>
-Original file line number
+Diff line change
@@ Expand Up / @@ -122,7 +122,7 @@ struct PushStackingContext { @@
         void translate_by(Gfx::IntPoint const& offset)
         {
-            post_transform_translation.translate_by(offset);
+            source_paintable_rect.translate_by(offset);
         }
     };
@@ Expand Down @@