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LibGfx: Fix segfault and painting off-by-one in fill_path()

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Previously, this would paint scanlines one pixel too long and segfault
when painting AA scanlines that were <= 1px long.
This commit is contained in:
MacDue 2023-03-11 20:00:33 +00:00 • committed by Andreas Kling
parent a425b6f772
commit 952222ec4d
1 changed files with 9 additions and 5 deletions
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14
Userland/Libraries/LibGfx/FillPathImplementation.cpp
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@ -63,11 +63,15 @@ ALWAYS_INLINE void Painter::draw_scanline_for_fill_path(int y, T x_start, T x_en
u8 color_alpha = (alpha * color_at_offset.alpha()) / 255; u8 color_alpha = (alpha * color_at_offset.alpha()) / 255;
return color_at_offset.with_alpha(color_alpha); return color_at_offset.with_alpha(color_alpha);
}; };
if (clipped.left() == scanline.left() && left_subpixel_alpha) bool paint_left_subpixel = clipped.left() == scanline.left() && left_subpixel_alpha;
bool paint_right_subpixel = clipped.right() == scanline.right() && right_subpixel_alpha;
if (paint_left_subpixel)
set_physical_pixel(clipped.top_left(), get_color_with_alpha(0, left_subpixel_alpha), true); set_physical_pixel(clipped.top_left(), get_color_with_alpha(0, left_subpixel_alpha), true);
if (clipped.right() == scanline.right() && right_subpixel_alpha) if (paint_right_subpixel)
set_physical_pixel(clipped.top_right(), get_color_with_alpha(scanline.width(), right_subpixel_alpha), true); set_physical_pixel(clipped.top_right(), get_color_with_alpha(scanline.width(), right_subpixel_alpha), true);
clipped.shrink(0, right_subpixel_alpha > 0, 0, left_subpixel_alpha > 0); clipped.shrink(0, paint_right_subpixel, 0, paint_left_subpixel);
if (clipped.is_empty())
return;
} }
if constexpr (has_constant_color) { if constexpr (has_constant_color) {
@ -122,9 +126,9 @@ void Painter::fill_path_impl(Path const& path, ColorOrFunction color, Gfx::Paint
if (x1 > x2) if (x1 > x2)
swap(x1, x2); swap(x1, x2);
if constexpr (IsSameIgnoringCV<ColorOrFunction, Color>) { if constexpr (IsSameIgnoringCV<ColorOrFunction, Color>) {
draw_scanline_for_fill_path(y, x1, x2 + 1, color); draw_scanline_for_fill_path(y, x1, x2, color);
} else { } else {
draw_scanline_for_fill_path(y, x1, x2 + 1, [&](int offset) { draw_scanline_for_fill_path(y, x1, x2, [&](int offset) {
return color(IntPoint(x1 + offset, y) - draw_origin); return color(IntPoint(x1 + offset, y) - draw_origin);
}); });
} }