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WindowServer: Fix alpha hit-test accessing out-of-bounds pixels

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It's possible that the backing store hasn't been updated yet, so
when performing an alpha hit-test make sure the bitmap actually
contains it.

Fixes #6731
This commit is contained in:
Tom 2021-04-29 09:52:47 -06:00 • committed by Linus Groh
parent ba294efd8e
commit b88b19272e
2 changed files with 24 additions and 10 deletions
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28
Userland/Services/WindowServer/WindowFrame.cpp
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@ -584,17 +584,29 @@ bool WindowFrame::hit_test(const Gfx::IntPoint& point) const
u8 alpha = 0xff;
auto relative_point = point.translated(-render_rect().location());
if (point.y() < window_rect.y()) {
if (m_top_bottom)
alpha = m_top_bottom->get_pixel(relative_point * m_top_bottom->scale()).alpha();
if (m_top_bottom) {
auto scaled_relative_point = relative_point * m_top_bottom->scale();
if (m_top_bottom->rect().contains(scaled_relative_point))
alpha = m_top_bottom->get_pixel(scaled_relative_point).alpha();
}
} else if (point.y() > window_rect.bottom()) {
if (m_top_bottom)
alpha = m_top_bottom->get_pixel(relative_point.x() * m_top_bottom->scale(), m_bottom_y * m_top_bottom->scale() + point.y() - window_rect.bottom() - 1).alpha();
if (m_top_bottom) {
Gfx::IntPoint scaled_relative_point { relative_point.x() * m_top_bottom->scale(), m_bottom_y * m_top_bottom->scale() + point.y() - window_rect.bottom() - 1 };
if (m_top_bottom->rect().contains(scaled_relative_point))
alpha = m_top_bottom->get_pixel(scaled_relative_point).alpha();
}
} else if (point.x() < window_rect.x()) {
if (m_left_right)
alpha = m_left_right->get_pixel(relative_point.x() * m_left_right->scale(), (relative_point.y() - m_bottom_y) * m_left_right->scale()).alpha();
if (m_left_right) {
Gfx::IntPoint scaled_relative_point { relative_point.x() * m_left_right->scale(), (relative_point.y() - m_bottom_y) * m_left_right->scale() };
if (m_left_right->rect().contains(scaled_relative_point))
alpha = m_left_right->get_pixel(scaled_relative_point).alpha();
}
} else if (point.x() > window_rect.right()) {
if (m_left_right)
alpha = m_left_right->get_pixel(m_right_x * m_left_right->scale() + point.x() - window_rect.right() - 1, (relative_point.y() - m_bottom_y) * m_left_right->scale()).alpha();
if (m_left_right) {
Gfx::IntPoint scaled_relative_point { m_right_x * m_left_right->scale() + point.x() - window_rect.right() - 1, (relative_point.y() - m_bottom_y) * m_left_right->scale() };
if (m_left_right->rect().contains(scaled_relative_point))
alpha = m_left_right->get_pixel(scaled_relative_point).alpha();
}
} else {
return false;
}