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/* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
#include "ScrollbarUtil.h"
#include "mozilla/RelativeLuminanceUtils.h"
#include "mozilla/StaticPrefs_widget.h"
#include "nsNativeTheme.h"
/*static*/
bool ScrollbarUtil::IsScrollbarWidthThin(ComputedStyle* aStyle) {
auto scrollbarWidth = aStyle->StyleUIReset()->mScrollbarWidth;
return scrollbarWidth == StyleScrollbarWidth::Thin;
}
/*static*/
bool ScrollbarUtil::IsScrollbarWidthThin(nsIFrame* aFrame) {
ComputedStyle* style = nsLayoutUtils::StyleForScrollbar(aFrame);
return IsScrollbarWidthThin(style);
}
/*static*/
ComputedStyle* ScrollbarUtil::GetCustomScrollbarStyle(nsIFrame* aFrame,
bool* aDarkScrollbar) {
ComputedStyle* style = nsLayoutUtils::StyleForScrollbar(aFrame);
if (style->StyleUI()->HasCustomScrollbars()) {
return style;
}
bool useDarkScrollbar = !StaticPrefs::widget_disable_dark_scrollbar() &&
nsNativeTheme::IsDarkBackground(aFrame);
if (useDarkScrollbar || IsScrollbarWidthThin(style)) {
if (aDarkScrollbar) {
*aDarkScrollbar = useDarkScrollbar;
}
return style;
}
return nullptr;
}
/*static*/
nscolor ScrollbarUtil::GetScrollbarButtonColor(nscolor aTrackColor,
EventStates aStates) {
// See numbers in GetScrollbarArrowColor.
// This function is written based on ratios between values listed there.
bool isActive = aStates.HasState(NS_EVENT_STATE_ACTIVE);
bool isHover = aStates.HasState(NS_EVENT_STATE_HOVER);
if (!isActive && !isHover) {
return aTrackColor;
}
float luminance = RelativeLuminanceUtils::Compute(aTrackColor);
if (isActive) {
if (luminance >= 0.18f) {
luminance *= 0.134f;
} else {
luminance /= 0.134f;
luminance = std::min(luminance, 1.0f);
}
} else {
if (luminance >= 0.18f) {
luminance *= 0.805f;
} else {
luminance /= 0.805f;
}
}
return RelativeLuminanceUtils::Adjust(aTrackColor, luminance);
}
/*static*/
nscolor ScrollbarUtil::GetScrollbarArrowColor(nscolor aButtonColor) {
// In Windows 10 scrollbar, there are several gray colors used:
//
// State | Background (lum) | Arrow | Contrast
// -------+------------------+---------+---------
// Normal | Gray 240 (87.1%) | Gray 96 | 5.5
// Hover | Gray 218 (70.1%) | Black | 15.0
// Active | Gray 96 (11.7%) | White | 6.3
//
// Contrast value is computed based on the definition in
// https://www.w3.org/TR/WCAG20/#contrast-ratiodef
//
// This function is written based on these values.
float luminance = RelativeLuminanceUtils::Compute(aButtonColor);
// Color with luminance larger than 0.72 has contrast ratio over 4.6
// to color with luminance of gray 96, so this value is chosen for
// this range. It is the luminance of gray 221.
if (luminance >= 0.72) {
// ComputeRelativeLuminanceFromComponents(96). That function cannot
// be constexpr because of std::pow.
const float GRAY96_LUMINANCE = 0.117f;
return RelativeLuminanceUtils::Adjust(aButtonColor, GRAY96_LUMINANCE);
}
// The contrast ratio of a color to black equals that to white when its
// luminance is around 0.18, with a contrast ratio ~4.6 to both sides,
// thus the value below. It's the lumanince of gray 118.
if (luminance >= 0.18) {
return NS_RGBA(0, 0, 0, NS_GET_A(aButtonColor));
}
return NS_RGBA(255, 255, 255, NS_GET_A(aButtonColor));
}
/*static*/
nscolor ScrollbarUtil::AdjustScrollbarFaceColor(nscolor aFaceColor,
EventStates aStates) {
// In Windows 10, scrollbar thumb has the following colors:
//
// State | Color | Luminance
// -------+----------+----------
// Normal | Gray 205 | 61.0%
// Hover | Gray 166 | 38.1%
// Active | Gray 96 | 11.7%
//
// This function is written based on the ratios between the values.
bool isActive = aStates.HasState(NS_EVENT_STATE_ACTIVE);
bool isHover = aStates.HasState(NS_EVENT_STATE_HOVER);
if (!isActive && !isHover) {
return aFaceColor;
}
float luminance = RelativeLuminanceUtils::Compute(aFaceColor);
if (isActive) {
if (luminance >= 0.18f) {
luminance *= 0.192f;
} else {
luminance /= 0.192f;
}
} else {
if (luminance >= 0.18f) {
luminance *= 0.625f;
} else {
luminance /= 0.625f;
}
}
return RelativeLuminanceUtils::Adjust(aFaceColor, luminance);
}
/*static*/
nscolor ScrollbarUtil::GetScrollbarTrackColor(nsIFrame* aFrame) {
bool darkScrollbar = false;
ComputedStyle* style = GetCustomScrollbarStyle(aFrame, &darkScrollbar);
if (style) {
const nsStyleUI* ui = style->StyleUI();
auto* customColors = ui->mScrollbarColor.IsAuto()
? nullptr
: &ui->mScrollbarColor.AsColors();
if (customColors) {
return customColors->track.CalcColor(*style);
}
}
return darkScrollbar ? NS_RGBA(20, 20, 25, 77) : NS_RGB(240, 240, 240);
}
/*static*/
nscolor ScrollbarUtil::GetScrollbarThumbColor(nsIFrame* aFrame,
EventStates aEventStates) {
bool darkScrollbar = false;
ComputedStyle* style = GetCustomScrollbarStyle(aFrame, &darkScrollbar);
if (style) {
const nsStyleUI* ui = style->StyleUI();
auto* customColors = ui->mScrollbarColor.IsAuto()
? nullptr
: &ui->mScrollbarColor.AsColors();
if (customColors) {
nscolor faceColor = customColors->thumb.CalcColor(*style);
return AdjustScrollbarFaceColor(faceColor, aEventStates);
}
}
nscolor faceColor =
darkScrollbar ? NS_RGBA(249, 249, 250, 102) : NS_RGB(205, 205, 205);
return AdjustScrollbarFaceColor(faceColor, aEventStates);
}
/*static*/
Maybe<nsITheme::Transparency> ScrollbarUtil::GetScrollbarPartTransparency(
nsIFrame* aFrame, StyleAppearance aAppearance) {
if (nsNativeTheme::IsWidgetScrollbarPart(aAppearance)) {
if (ComputedStyle* style = ScrollbarUtil::GetCustomScrollbarStyle(aFrame)) {
auto* ui = style->StyleUI();
if (ui->mScrollbarColor.IsAuto() ||
ui->mScrollbarColor.AsColors().track.MaybeTransparent()) {
return Some(nsITheme::eTransparent);
}
// These widgets may be thinner than the track, so we need to return
// transparent for them to make the track visible.
switch (aAppearance) {
case StyleAppearance::ScrollbarthumbHorizontal:
case StyleAppearance::ScrollbarthumbVertical:
case StyleAppearance::ScrollbarbuttonUp:
case StyleAppearance::ScrollbarbuttonDown:
case StyleAppearance::ScrollbarbuttonLeft:
case StyleAppearance::ScrollbarbuttonRight:
return Some(nsITheme::eTransparent);
default:
break;
}
}
}
switch (aAppearance) {
case StyleAppearance::ScrollbarHorizontal:
case StyleAppearance::ScrollbarVertical:
case StyleAppearance::Scrollcorner:
case StyleAppearance::Statusbar:
// Knowing that scrollbars and statusbars are opaque improves
// performance, because we create layers for them. This better be
// true across all Windows themes! If it's not true, we should
// paint an opaque background for them to make it true!
return Some(nsITheme::eOpaque);
default:
break;
}
return Nothing();
}
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