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LibWeb: Move clip rect calculation to happen before painting

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With this change, clip rectangles for boxes with hidden overflow or the
clip property are no longer calculated during the recording of painting
commands. Instead, it has moved to the "pre-paint" phase, along with
the assignment of scrolling offsets, and works in the following way:

1. The paintable tree is traversed to collect all paintable boxes that
   have hidden overflow or use the CSS clip property. For each of these
   boxes, the "final" clip rectangle is calculated by intersecting clip
   rectangles in the containing block chain for a box.
2. The paintable tree is traversed another time, and a clip rectangle
   is assigned for each paintable box contained by a node with hidden
   overflow or the clip property.

This way, clipping becomes much easier during the painting commands
recording phase, as it only concerns the use of already assigned clip
rectangles. The same approach is applied to handle scrolling offsets.

Also, clip rectangle calculation is now implemented more correctly, as
we no longer stop at the stacking context boundary while intersecting
clip rectangles in the containing block chain.

Fixes:
https://github.com/SerenityOS/serenity/issues/22932
https://github.com/SerenityOS/serenity/issues/22883
https://github.com/SerenityOS/serenity/issues/22679
https://github.com/SerenityOS/serenity/issues/22534
This commit is contained in:
Aliaksandr Kalenik 2024-01-26 21:47:26 +01:00 • committed by Andreas Kling
parent eaf9a56c10
commit 0bf82f748f
21 changed files with 365 additions and 166 deletions
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134
Userland/Libraries/LibWeb/Painting/PaintableBox.cpp
View file

@ -121,6 +121,26 @@ CSSPixelRect PaintableBox::compute_absolute_rect() const
return rect;
}
CSSPixelRect PaintableBox::compute_absolute_padding_rect_with_css_transform_applied() const
{
CSSPixelRect rect { offset(), content_size() };
for (auto const* block = containing_block(); block; block = block->containing_block()) {
auto offset = block->paintable_box()->offset();
auto affine_transform = Gfx::extract_2d_affine_transform(block->paintable_box()->transform());
offset.translate_by(affine_transform.translation().to_type<CSSPixels>());
rect.translate_by(offset);
}
auto affine_transform = Gfx::extract_2d_affine_transform(transform());
rect.translate_by(affine_transform.translation().to_type<CSSPixels>());
CSSPixelRect padding_rect;
padding_rect.set_x(rect.x() - box_model().padding.left);
padding_rect.set_width(content_width() + box_model().padding.left + box_model().padding.right);
padding_rect.set_y(rect.y() - box_model().padding.top);
padding_rect.set_height(content_height() + box_model().padding.top + box_model().padding.bottom);
return padding_rect;
}
CSSPixelRect PaintableBox::absolute_rect() const
{
if (!m_absolute_rect.has_value())
@ -171,11 +191,8 @@ void PaintableBox::before_paint(PaintContext& context, [[maybe_unused]] PaintPha
if (!is_visible())
return;
auto clip_rect = get_clip_rect();
if (clip_rect.has_value()) {
context.recording_painter().save();
context.recording_painter().add_clip_rect(clip_rect->to_type<int>());
}
apply_scroll_offset(context, phase);
apply_clip_overflow_rect(context, phase);
}
void PaintableBox::after_paint(PaintContext& context, [[maybe_unused]] PaintPhase phase) const
@ -183,8 +200,8 @@ void PaintableBox::after_paint(PaintContext& context, [[maybe_unused]] PaintPhas
if (!is_visible())
return;
if (get_clip_rect().has_value())
context.recording_painter().restore();
clear_clip_overflow_rect(context, phase);
reset_scroll_offset(context, phase);
}
void PaintableBox::paint(PaintContext& context, PaintPhase phase) const
@ -358,110 +375,63 @@ BorderRadiiData PaintableBox::normalized_border_radii_data(ShrinkRadiiForBorders
return border_radii_data;
}
Optional<CSSPixelRect> PaintableBox::calculate_overflow_clipped_rect() const
{
if (layout_node().is_viewport()) {
return {};
}
if (!m_clip_rect.has_value()) {
// NOTE: stacking context should not be crossed while aggregating rectangle to
// clip `overflow: hidden` because intersecting rectangles with different
// transforms doesn't make sense
// TODO: figure out if there are cases when stacking context should be
// crossed to calculate correct clip rect
if (!stacking_context() && containing_block() && containing_block()->paintable_box()) {
m_clip_rect = containing_block()->paintable_box()->calculate_overflow_clipped_rect();
}
auto overflow_x = computed_values().overflow_x();
auto overflow_y = computed_values().overflow_y();
if (overflow_x != CSS::Overflow::Visible && overflow_y != CSS::Overflow::Visible) {
if (m_clip_rect.has_value()) {
m_clip_rect->intersect(absolute_padding_box_rect());
} else {
m_clip_rect = absolute_padding_box_rect();
}
}
}
return m_clip_rect;
}
void PaintableBox::apply_scroll_offset(PaintContext& context, PaintPhase) const
{
if (context.scroll_frames().contains(this)) {
if (m_scroll_frame_id.has_value()) {
context.recording_painter().save();
context.recording_painter().set_scroll_frame_id(context.scroll_frames().get(this)->id);
context.recording_painter().set_scroll_frame_id(m_scroll_frame_id.value());
}
}
void PaintableBox::reset_scroll_offset(PaintContext& context, PaintPhase) const
{
if (context.scroll_frames().contains(this)) {
if (m_scroll_frame_id.has_value())
context.recording_painter().restore();
}
}
void PaintableBox::apply_clip_overflow_rect(PaintContext& context, PaintPhase phase) const
{
if (!AK::first_is_one_of(phase, PaintPhase::Background, PaintPhase::Border, PaintPhase::Foreground))
if (!AK::first_is_one_of(phase, PaintPhase::Background, PaintPhase::Border, PaintPhase::Foreground, PaintPhase::Outline))
return;
// FIXME: Support more overflow variations.
auto clip_rect = this->calculate_overflow_clipped_rect();
auto overflow_x = computed_values().overflow_x();
auto overflow_y = computed_values().overflow_y();
if (m_clip_rect.has_value()) {
auto overflow_clip_rect = m_clip_rect.value();
for (auto const* ancestor = &this->layout_box(); ancestor; ancestor = ancestor->containing_block()) {
auto affine_transform = Gfx::extract_2d_affine_transform(ancestor->paintable_box()->transform());
if (!affine_transform.is_identity()) {
// NOTE: Because the painting command executor applies CSS transform of the nearest stacking context
// and the m_clip_rect is determined considering CSS transforms, here transform of the nearest
// stacking context need to be compensated.
// This adjustment ensures the transform is accounted for just once.
overflow_clip_rect.translate_by(-affine_transform.translation().to_type<CSSPixels>());
break;
}
}
auto css_clip_property = get_clip_rect();
if (css_clip_property.has_value()) {
if (clip_rect.has_value())
clip_rect->intersect(css_clip_property.value());
else
clip_rect = css_clip_property.value();
}
if (!clip_rect.has_value())
return;
if (!m_clipping_overflow) {
context.recording_painter().save();
context.recording_painter().add_clip_rect(context.enclosing_device_rect(*clip_rect).to_type<int>());
m_clipping_overflow = true;
}
if (!clip_rect->is_empty() && overflow_y == CSS::Overflow::Hidden && overflow_x == CSS::Overflow::Hidden) {
auto border_radii_data = normalized_border_radii_data(ShrinkRadiiForBorders::Yes);
CornerRadii corner_radii {
.top_left = border_radii_data.top_left.as_corner(context),
.top_right = border_radii_data.top_right.as_corner(context),
.bottom_right = border_radii_data.bottom_right.as_corner(context),
.bottom_left = border_radii_data.bottom_left.as_corner(context)
};
if (corner_radii.has_any_radius()) {
context.recording_painter().save();
context.recording_painter().add_clip_rect(context.enclosing_device_rect(overflow_clip_rect).to_type<int>());
if (m_corner_clip_radii.has_value()) {
VERIFY(!m_corner_clipper_id.has_value());
m_corner_clipper_id = context.allocate_corner_clipper_id();
context.recording_painter().sample_under_corners(*m_corner_clipper_id, corner_radii, context.rounded_device_rect(*clip_rect).to_type<int>(), CornerClip::Outside);
context.recording_painter().sample_under_corners(*m_corner_clipper_id, *m_corner_clip_radii, context.rounded_device_rect(overflow_clip_rect).to_type<int>(), CornerClip::Outside);
}
}
}
void PaintableBox::clear_clip_overflow_rect(PaintContext& context, PaintPhase phase) const
{
if (!AK::first_is_one_of(phase, PaintPhase::Background, PaintPhase::Border, PaintPhase::Foreground))
if (!AK::first_is_one_of(phase, PaintPhase::Background, PaintPhase::Border, PaintPhase::Foreground, PaintPhase::Outline))
return;
// FIXME: Support more overflow variations.
if (m_clipping_overflow) {
context.recording_painter().restore();
m_clipping_overflow = false;
}
if (m_corner_clipper_id.has_value()) {
VERIFY(m_corner_clipper_id.has_value());
auto clip_rect = this->calculate_overflow_clipped_rect();
context.recording_painter().blit_corner_clipping(*m_corner_clipper_id, context.rounded_device_rect(*clip_rect).to_type<int>());
m_corner_clipper_id = {};
if (m_corner_clip_radii.has_value()) {
VERIFY(m_corner_clipper_id.has_value());
context.recording_painter().blit_corner_clipping(*m_corner_clipper_id, context.rounded_device_rect(*m_clip_rect).to_type<int>());
m_corner_clipper_id = {};
}
context.recording_painter().restore();
}
}