forked from mirrors/gecko-dev
334258d77f
MozReview-Commit-ID: moE2CI7fT8 --HG-- extra : rebase_source : 7b64beccbd4c499d93567d62b913257dfa53c9fe
92 lines
2.5 KiB
C++
92 lines
2.5 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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// Blend one RGBA color with another based on a given ratios.
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// It is a linear combination of each channel with alpha premultipled.
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static nscolor
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LinearBlendColors(nscolor aBg, float aBgRatio, nscolor aFg, float aFgRatio)
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{
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constexpr float kFactor = 1.0f / 255.0f;
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float p1 = aBgRatio;
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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 = aFgRatio;
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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.f) {
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return NS_RGBA(0, 0, 0, 0);
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}
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if (a > 1.f) {
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a = 1.f;
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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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bool
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StyleComplexColor::MaybeTransparent() const {
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// We know that the color is opaque when it's a numeric color with
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// alpha == 255.
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// TODO(djg): Should we extend this to check Complex with bgRatio =
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// 0, and fgRatio * alpha >= 255?
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return mTag != eNumeric || NS_GET_A(mColor) != 255;
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}
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nscolor
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StyleComplexColor::CalcColor(nscolor aForegroundColor) const {
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switch (mTag) {
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case eNumeric:
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return mColor;
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case eForeground:
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case eAuto:
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return aForegroundColor;
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case eComplex:
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return LinearBlendColors(mColor, mBgRatio, aForegroundColor, mFgRatio);
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default:
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MOZ_ASSERT_UNREACHABLE("StyleComplexColor has invalid mTag");
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return mColor;
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}
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}
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nscolor
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StyleComplexColor::CalcColor(mozilla::ComputedStyle* aStyle) const {
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// Common case that is numeric color, which is pure background, we
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// can skip resolving StyleColor().
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// TODO(djg): Is this optimization worth it?
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if (mTag == eNumeric) {
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return mColor;
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}
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MOZ_ASSERT(aStyle);
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auto fgColor = aStyle->StyleColor()->mColor;
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return CalcColor(fgColor);
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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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