gecko-dev/layout/style/StyleComplexColor.h

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3.9 KiB
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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* represent a color combines a numeric color and currentcolor */
#ifndef mozilla_StyleComplexColor_h_
#define mozilla_StyleComplexColor_h_
#include "nsColor.h"
class nsIFrame;
namespace mozilla {
class ComputedStyle;
/**
* This struct represents a combined color from a numeric color and
* the current foreground color (currentcolor keyword).
* Conceptually, the formula is "color * q + currentcolor * p"
* where p is mFgRatio and q is mBgRatio.
*
* It can also represent an "auto" value, which is valid for some
* properties. See comment of `Tag::eAuto`.
*/
class StyleComplexColor final {
public:
static StyleComplexColor FromColor(nscolor aColor) {
return {aColor, 0, eNumeric};
}
static StyleComplexColor CurrentColor() {
return {NS_RGBA(0, 0, 0, 0), 1, eForeground};
}
static StyleComplexColor Auto() { return {NS_RGBA(0, 0, 0, 0), 1, eAuto}; }
static StyleComplexColor Black() {
return StyleComplexColor::FromColor(NS_RGB(0, 0, 0));
}
static StyleComplexColor White() {
return StyleComplexColor::FromColor(NS_RGB(255, 255, 255));
}
static StyleComplexColor Transparent() {
return StyleComplexColor::FromColor(NS_RGBA(0, 0, 0, 0));
}
bool IsAuto() const { return mTag == eAuto; }
bool IsCurrentColor() const { return mTag == eForeground; }
bool operator==(const StyleComplexColor& aOther) const {
if (mTag != aOther.mTag) {
return false;
}
switch (mTag) {
case eAuto:
case eForeground:
return true;
case eNumeric:
return mColor == aOther.mColor;
case eComplex:
return (mBgRatio == aOther.mBgRatio && mFgRatio == aOther.mFgRatio &&
mColor == aOther.mColor);
default:
MOZ_ASSERT_UNREACHABLE("Unexpected StyleComplexColor type.");
return false;
}
}
bool operator!=(const StyleComplexColor& aOther) const {
return !(*this == aOther);
}
/**
* Is it possible that this StyleComplexColor is transparent?
*/
bool MaybeTransparent() const;
/**
* Compute the color for this StyleComplexColor, taking into account
* the foreground color, aForegroundColor.
*/
nscolor CalcColor(nscolor aForegroundColor) const;
/**
* Compute the color for this StyleComplexColor, taking into account
* the foreground color from aStyle.
*/
nscolor CalcColor(mozilla::ComputedStyle* aStyle) const;
/**
* Compute the color for this StyleComplexColor, taking into account
* the foreground color from aFrame's ComputedStyle.
*/
nscolor CalcColor(const nsIFrame* aFrame) const;
private:
enum Tag : uint8_t {
// This represents a computed-value time auto value. This
// indicates that this value should not be interpolatable with
// other colors. Other fields represent a currentcolor and
// properties can decide whether that should be used.
eAuto,
// This represents a numeric color; no currentcolor component.
eNumeric,
// This represents the current foreground color, currentcolor; no
// numeric color component.
eForeground,
// This represents a linear combination of numeric color and the
// foreground color: "mColor * mBgRatio + currentcolor *
// mFgRatio".
eComplex,
};
StyleComplexColor(nscolor aColor, float aFgRatio, Tag aTag)
: mColor(aColor),
mBgRatio(1.f - aFgRatio),
mFgRatio(aFgRatio),
mTag(aTag) {
MOZ_ASSERT(mTag != eNumeric || aFgRatio == 0.);
MOZ_ASSERT(!(mTag == eAuto || mTag == eForeground) || aFgRatio == 1.);
}
nscolor mColor;
float mBgRatio;
float mFgRatio;
Tag mTag;
};
} // namespace mozilla
#endif // mozilla_StyleComplexColor_h_