зеркало из https://github.com/mozilla/gecko-dev.git
78 строки
2.4 KiB
C++
78 строки
2.4 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "mozilla/StyleComplexColor.h"
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#include "mozilla/ComputedStyle.h"
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#include "mozilla/ComputedStyleInlines.h"
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#include "nsIFrame.h"
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#include "nsStyleStruct.h"
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using namespace mozilla;
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static uint32_t
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BlendColorComponent(uint32_t aBg, uint32_t aFg, uint32_t aFgAlpha)
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{
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return RoundingDivideBy255(aBg * (255 - aFgAlpha) + aFg * aFgAlpha);
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}
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// Blend one RGBA color with another based on a given ratio.
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// It is a linear interpolation on each channel with alpha premultipled.
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static nscolor
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LinearBlendColors(nscolor aBg, nscolor aFg, uint_fast8_t aFgRatio)
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{
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// Common case that either pure background or pure foreground
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if (aFgRatio == 0) {
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return aBg;
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}
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if (aFgRatio == 255) {
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return aFg;
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}
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// Common case that alpha channel is equal (usually both are opaque)
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if (NS_GET_A(aBg) == NS_GET_A(aFg)) {
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auto r = BlendColorComponent(NS_GET_R(aBg), NS_GET_R(aFg), aFgRatio);
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auto g = BlendColorComponent(NS_GET_G(aBg), NS_GET_G(aFg), aFgRatio);
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auto b = BlendColorComponent(NS_GET_B(aBg), NS_GET_B(aFg), aFgRatio);
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return NS_RGBA(r, g, b, NS_GET_A(aFg));
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}
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constexpr float kFactor = 1.0f / 255.0f;
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float p1 = kFactor * (255 - aFgRatio);
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float a1 = kFactor * NS_GET_A(aBg);
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float r1 = a1 * NS_GET_R(aBg);
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float g1 = a1 * NS_GET_G(aBg);
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float b1 = a1 * NS_GET_B(aBg);
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float p2 = 1.0f - p1;
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float a2 = kFactor * NS_GET_A(aFg);
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float r2 = a2 * NS_GET_R(aFg);
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float g2 = a2 * NS_GET_G(aFg);
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float b2 = a2 * NS_GET_B(aFg);
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float a = p1 * a1 + p2 * a2;
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if (a == 0.0) {
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return NS_RGBA(0, 0, 0, 0);
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}
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auto r = ClampColor((p1 * r1 + p2 * r2) / a);
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auto g = ClampColor((p1 * g1 + p2 * g2) / a);
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auto b = ClampColor((p1 * b1 + p2 * b2) / a);
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return NS_RGBA(r, g, b, NSToIntRound(a * 255));
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}
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nscolor
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StyleComplexColor::CalcColor(mozilla::ComputedStyle* aStyle) const {
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MOZ_ASSERT(aStyle);
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auto foregroundColor = aStyle->StyleColor()->mColor;
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return LinearBlendColors(mColor, foregroundColor, mForegroundRatio);
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}
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nscolor
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StyleComplexColor::CalcColor(const nsIFrame* aFrame) const {
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return CalcColor(aFrame->Style());
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}
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