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LibGfx: Speed up fill_path() with per scanline clipping & fast fills

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This improves fill_path() performance by adding an API to the painter
that allows painting an entire scanline rather than just a pixel.
With this paths can be clipped a scanline at a time rather than each
pixel, removing a fair amount of checks.

Along with optimized clipping, this can now use a fast_u32_fill() to
paint all but the subpixels of a scanline if a solid color with no
alpha channel is used (which is quite common in SVGs).

This reduces scrolling around on svg.html from 21% in set_pixel() and
19% in fill_path() to just 7.8% in fill_path (with set_pixel()
eliminated). Now fill_path() is far from the slowest code when
scrolling the page.
This commit is contained in:
MacDue 2023-03-08 20:49:00 +01:00 • committed by Linus Groh
parent be958a14cf
commit b1a72d66f6
4 changed files with 81 additions and 23 deletions
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27
Userland/Libraries/LibGfx/FillPathImplementation.h
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@ -41,13 +41,13 @@ enum class FillPathMode {
AllowFloatingPoints,
};
template<FillPathMode fill_path_mode, typename ColorFunction>
void fill_path(Painter& painter, Path const& path, ColorFunction color_function, Gfx::Painter::WindingRule winding_rule, Optional<FloatPoint> offset = {})
template<FillPathMode fill_path_mode, typename ColorOrFunction>
void fill_path(Painter& painter, Path const& path, ColorOrFunction color, Gfx::Painter::WindingRule winding_rule, Optional<FloatPoint> offset = {})
{
using GridCoordinateType = Conditional<fill_path_mode == FillPathMode::PlaceOnIntGrid, int, float>;
using PointType = Point<GridCoordinateType>;
auto draw_scanline = [&](int y, float x1, float x2) {
auto draw_scanline = [&](int y, GridCoordinateType x1, GridCoordinateType x2) {
const auto draw_offset = offset.value_or({ 0, 0 });
const auto draw_origin = (path.bounding_box().top_left() + draw_offset).to_type<int>();
// FIMXE: Offset is added here to handle floating point translations in the AA painter,
@ -57,23 +57,12 @@ void fill_path(Painter& painter, Path const& path, ColorFunction color_function,
x2 += draw_offset.x();
if (x1 > x2)
swap(x1, x2);
auto set_pixel = [&](int x, int y, Color color) {
painter.set_pixel(x, y, color, true);
};
if constexpr (fill_path_mode == FillPathMode::AllowFloatingPoints) {
int int_x1 = ceilf(x1);
int int_x2 = floorf(x2);
float left_subpixel = int_x1 - x1;
float right_subpixel = x2 - int_x2;
auto left_color = color_function(IntPoint(int_x1 - 1, y) - draw_origin);
auto right_color = color_function(IntPoint(int_x2, y) - draw_origin);
set_pixel(int_x1 - 1, y, left_color.with_alpha(left_color.alpha() * left_subpixel));
set_pixel(int_x2, y, right_color.with_alpha(right_color.alpha() * right_subpixel));
for (int x = int_x1; x < int_x2; x++)
set_pixel(x, y, color_function(IntPoint(x, y) - draw_origin));
if constexpr (IsSameIgnoringCV<ColorOrFunction, Color>) {
painter.draw_scanline_for_fill_path(y, x1, x2 + 1, color);
} else {
for (int x = x1; x < int(x2); x++)
set_pixel(x, y, color_function(IntPoint(x, y) - draw_origin));
painter.draw_scanline_for_fill_path(y, x1, x2 + 1, [&](int offset) {
return color(IntPoint(x1 + offset, y) - draw_origin);
});
}
};