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ladybird/Libraries/LibGfx/GradientPainting.cpp

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LibWeb+LibGfx: Migrate (most of) the CSS gradient painting to LibGfx This moves the CSS gradient painting to the painter creating: - Painter::fill_rect_with_linear_gradient() - Painter::fill_rect_with_conic_gradient() - Painter::fill_rect_with_radial_gradient() This has a few benefits: - The gradients can now easily respect the painter scale - The Painter::fill_pixels() escape hatch can be removed - We can remove the old fixed color stop gradient code - The old functions are now just a shim - Anywhere can now easily use this gradient painting code! This only leaves the color stop resolution in LibWeb (which is fine). Just means in LibGfx you have to actually specify color stop positions. (Also while here add a small optimization to avoid generating excessively long gradient lines)
2023-01-10 01:07:06 +00:00
/*
* Copyright (c) 2022-2023, MacDue <macdue@dueutil.tech>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Math.h>
#include <LibGfx/Gradients.h>
LibGfx: Add paint styles and allow gradients to be used as them Also while here add option to disable pre-multiplied alpha for gradients (this will be handy later).
2023-01-15 22:10:36 +00:00
#include <LibGfx/PaintStyle.h>
LibWeb+LibGfx: Migrate (most of) the CSS gradient painting to LibGfx This moves the CSS gradient painting to the painter creating: - Painter::fill_rect_with_linear_gradient() - Painter::fill_rect_with_conic_gradient() - Painter::fill_rect_with_radial_gradient() This has a few benefits: - The gradients can now easily respect the painter scale - The Painter::fill_pixels() escape hatch can be removed - We can remove the old fixed color stop gradient code - The old functions are now just a shim - Anywhere can now easily use this gradient painting code! This only leaves the color stop resolution in LibWeb (which is fine). Just means in LibGfx you have to actually specify color stop positions. (Also while here add a small optimization to avoid generating excessively long gradient lines)
2023-01-10 01:07:06 +00:00
namespace Gfx {
LibGfx: Implement paint styles required for HTML canvas gradients This implements the gradients for: - CanvasRenderingContext2D.createLinearGradient() - CanvasRenderingContext2D.createConicGradient() - CanvasRenderingContext2D.createRadialGradient() As loosely defined in: https://html.spec.whatwg.org/multipage/canvas.html#fill-and-stroke-styles (It's really not very well defined for radial gradients) Actual implementation (for radial gradients) was done with a lot of trial and error, then visually comparing to other browsers.
2023-01-17 19:52:02 +00:00
// Note: This file implements the CSS/Canvas gradients for LibWeb according to the spec.
LibWeb+LibGfx: Migrate (most of) the CSS gradient painting to LibGfx This moves the CSS gradient painting to the painter creating: - Painter::fill_rect_with_linear_gradient() - Painter::fill_rect_with_conic_gradient() - Painter::fill_rect_with_radial_gradient() This has a few benefits: - The gradients can now easily respect the painter scale - The Painter::fill_pixels() escape hatch can be removed - We can remove the old fixed color stop gradient code - The old functions are now just a shim - Anywhere can now easily use this gradient painting code! This only leaves the color stop resolution in LibWeb (which is fine). Just means in LibGfx you have to actually specify color stop positions. (Also while here add a small optimization to avoid generating excessively long gradient lines)
2023-01-10 01:07:06 +00:00
// Please do not make ad-hoc changes that may break spec compliance!
LibGfx+LibWeb: Support CSS gradient "transition hints" in Skia painter Skia does not have built-in support for gradient transition hints. So instead of adding custom gradient painting, now we do the same thing as other engines and preprocess color stops by replacing transition hints with a bunch of points lying between adjacent color stops and calculated using non-linear formula from the spec. As a result we get visually close enough rendering we would get by applying spec-formula individually to each point of a gradient.
2024-07-10 15:54:49 +02:00
float color_stop_step(ColorStop const& previous_stop, ColorStop const& next_stop, float position)
LibWeb+LibGfx: Migrate (most of) the CSS gradient painting to LibGfx This moves the CSS gradient painting to the painter creating: - Painter::fill_rect_with_linear_gradient() - Painter::fill_rect_with_conic_gradient() - Painter::fill_rect_with_radial_gradient() This has a few benefits: - The gradients can now easily respect the painter scale - The Painter::fill_pixels() escape hatch can be removed - We can remove the old fixed color stop gradient code - The old functions are now just a shim - Anywhere can now easily use this gradient painting code! This only leaves the color stop resolution in LibWeb (which is fine). Just means in LibGfx you have to actually specify color stop positions. (Also while here add a small optimization to avoid generating excessively long gradient lines)
2023-01-10 01:07:06 +00:00
{
if (position < previous_stop.position)
return 0;
if (position > next_stop.position)
return 1;
// For any given point between the two color stops,
// determine the point’s location as a percentage of the distance between the two color stops.
// Let this percentage be P.
auto stop_length = next_stop.position - previous_stop.position;
// FIXME: Avoids NaNs... Still not quite correct?
if (stop_length <= 0)
return 1;
auto p = (position - previous_stop.position) / stop_length;
if (!next_stop.transition_hint.has_value())
return p;
if (*next_stop.transition_hint >= 1)
return 0;
if (*next_stop.transition_hint <= 0)
return 1;
// Let C, the color weighting at that point, be equal to P^(logH(.5)).
auto c = AK::pow(p, AK::log<float>(0.5) / AK::log(*next_stop.transition_hint));
// The color at that point is then a linear blend between the colors of the two color stops,
// blending (1 - C) of the first stop and C of the second stop.
return c;
}
LibGfx: Implement PaintStyle for SVG radial gradients This also slightly refactors things to share more implementation with the SVG linear gradients, and improve accuracy (which fixes some banding issues).
2023-05-02 22:43:46 +01:00
void SVGGradientPaintStyle::set_gradient_transform(AffineTransform transform)
{
// Note: The scaling is removed so enough points on the gradient line are generated.
// Otherwise, if you scale a tiny path the gradient looks pixelated.
m_scale = 1.0f;
if (auto inverse = transform.inverse(); inverse.has_value()) {
auto transform_scale = transform.scale();
m_scale = max(transform_scale.x(), transform_scale.y());
m_inverse_transform = AffineTransform {}.scale(m_scale, m_scale).multiply(*inverse);
} else {
m_inverse_transform = OptionalNone {};
}
}
LibWeb+LibGfx: Migrate (most of) the CSS gradient painting to LibGfx This moves the CSS gradient painting to the painter creating: - Painter::fill_rect_with_linear_gradient() - Painter::fill_rect_with_conic_gradient() - Painter::fill_rect_with_radial_gradient() This has a few benefits: - The gradients can now easily respect the painter scale - The Painter::fill_pixels() escape hatch can be removed - We can remove the old fixed color stop gradient code - The old functions are now just a shim - Anywhere can now easily use this gradient painting code! This only leaves the color stop resolution in LibWeb (which is fine). Just means in LibGfx you have to actually specify color stop positions. (Also while here add a small optimization to avoid generating excessively long gradient lines)
2023-01-10 01:07:06 +00:00
}
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