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tenfourfox/widget/nsNativeTheme.cpp

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/* -*- Mode: C++; tab-width: 2; 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 "nsNativeTheme.h"
#include "nsIWidget.h"
#include "nsIDocument.h"
#include "nsIContent.h"
#include "nsIFrame.h"
#include "nsIPresShell.h"
#include "nsNumberControlFrame.h"
#include "nsPresContext.h"
#include "nsString.h"
#include "nsNameSpaceManager.h"
#include "nsIDOMHTMLInputElement.h"
#include "nsIDOMXULMenuListElement.h"
#include "nsThemeConstants.h"
#include "nsIComponentManager.h"
#include "nsPIDOMWindow.h"
#include "nsProgressFrame.h"
#include "nsMeterFrame.h"
#include "nsMenuFrame.h"
#include "nsRangeFrame.h"
#include "nsCSSRendering.h"
#include "mozilla/EventStates.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/HTMLBodyElement.h"
#include "mozilla/dom/HTMLProgressElement.h"
#include "nsIDocumentInlines.h"
#include <algorithm>
using namespace mozilla;
using namespace mozilla::dom;
nsNativeTheme::nsNativeTheme()
: mAnimatedContentTimeout(UINT32_MAX)
{
}
NS_IMPL_ISUPPORTS(nsNativeTheme, nsITimerCallback)
nsIPresShell *
nsNativeTheme::GetPresShell(nsIFrame* aFrame)
{
if (!aFrame)
return nullptr;
nsPresContext* context = aFrame->PresContext();
return context ? context->GetPresShell() : nullptr;
}
EventStates
nsNativeTheme::GetContentState(nsIFrame* aFrame, uint8_t aWidgetType)
{
if (!aFrame)
return EventStates();
bool isXULCheckboxRadio =
(aWidgetType == NS_THEME_CHECKBOX ||
aWidgetType == NS_THEME_RADIO) &&
aFrame->GetContent()->IsXULElement();
if (isXULCheckboxRadio)
aFrame = aFrame->GetParent();
if (!aFrame->GetContent())
return EventStates();
nsIPresShell *shell = GetPresShell(aFrame);
if (!shell)
return EventStates();
nsIContent* frameContent = aFrame->GetContent();
EventStates flags;
if (frameContent->IsElement()) {
flags = frameContent->AsElement()->State();
// <input type=number> needs special handling since its nested native
// anonymous <input type=text> takes focus for it.
if (aWidgetType == NS_THEME_NUMBER_INPUT &&
frameContent->IsHTMLElement(nsGkAtoms::input)) {
nsNumberControlFrame *numberControlFrame = do_QueryFrame(aFrame);
if (numberControlFrame && numberControlFrame->IsFocused()) {
flags |= NS_EVENT_STATE_FOCUS;
}
}
nsNumberControlFrame* numberControlFrame =
nsNumberControlFrame::GetNumberControlFrameForSpinButton(aFrame);
if (numberControlFrame &&
numberControlFrame->GetContent()->AsElement()->State().
HasState(NS_EVENT_STATE_DISABLED)) {
flags |= NS_EVENT_STATE_DISABLED;
}
}
if (isXULCheckboxRadio && aWidgetType == NS_THEME_RADIO) {
if (IsFocused(aFrame))
flags |= NS_EVENT_STATE_FOCUS;
}
// On Windows and Mac, only draw focus rings if they should be shown. This
// means that focus rings are only shown once the keyboard has been used to
// focus something in the window.
#if defined(XP_MACOSX)
// Mac always draws focus rings for textboxes and lists.
if (aWidgetType == NS_THEME_NUMBER_INPUT ||
aWidgetType == NS_THEME_TEXTFIELD ||
aWidgetType == NS_THEME_TEXTFIELD_MULTILINE ||
aWidgetType == NS_THEME_SEARCHFIELD ||
aWidgetType == NS_THEME_LISTBOX) {
return flags;
}
#endif
#if defined(XP_WIN)
// On Windows, focused buttons are always drawn as such by the native theme.
if (aWidgetType == NS_THEME_BUTTON)
return flags;
#endif
#if defined(XP_MACOSX) || defined(XP_WIN)
nsIDocument* doc = aFrame->GetContent()->OwnerDoc();
nsPIDOMWindow* window = doc->GetWindow();
if (window && !window->ShouldShowFocusRing())
flags &= ~NS_EVENT_STATE_FOCUS;
#endif
return flags;
}
/* static */
bool
nsNativeTheme::CheckBooleanAttr(nsIFrame* aFrame, nsIAtom* aAtom)
{
if (!aFrame)
return false;
nsIContent* content = aFrame->GetContent();
if (!content)
return false;
if (content->IsHTMLElement())
return content->HasAttr(kNameSpaceID_None, aAtom);
// For XML/XUL elements, an attribute must be equal to the literal
// string "true" to be counted as true. An empty string should _not_
// be counted as true.
return content->AttrValueIs(kNameSpaceID_None, aAtom,
NS_LITERAL_STRING("true"), eCaseMatters);
}
/* static */
int32_t
nsNativeTheme::CheckIntAttr(nsIFrame* aFrame, nsIAtom* aAtom, int32_t defaultValue)
{
if (!aFrame)
return defaultValue;
nsAutoString attr;
aFrame->GetContent()->GetAttr(kNameSpaceID_None, aAtom, attr);
nsresult err;
int32_t value = attr.ToInteger(&err);
if (attr.IsEmpty() || NS_FAILED(err))
return defaultValue;
return value;
}
/* static */
double
nsNativeTheme::GetProgressValue(nsIFrame* aFrame)
{
// When we are using the HTML progress element,
// we can get the value from the IDL property.
if (aFrame && aFrame->GetContent()->IsHTMLElement(nsGkAtoms::progress)) {
return static_cast<HTMLProgressElement*>(aFrame->GetContent())->Value();
}
return (double)nsNativeTheme::CheckIntAttr(aFrame, nsGkAtoms::value, 0);
}
/* static */
double
nsNativeTheme::GetProgressMaxValue(nsIFrame* aFrame)
{
// When we are using the HTML progress element,
// we can get the max from the IDL property.
if (aFrame && aFrame->GetContent()->IsHTMLElement(nsGkAtoms::progress)) {
return static_cast<HTMLProgressElement*>(aFrame->GetContent())->Max();
}
return (double)std::max(nsNativeTheme::CheckIntAttr(aFrame, nsGkAtoms::max, 100), 1);
}
bool
nsNativeTheme::GetCheckedOrSelected(nsIFrame* aFrame, bool aCheckSelected)
{
if (!aFrame)
return false;
nsIContent* content = aFrame->GetContent();
if (content->IsXULElement()) {
// For a XUL checkbox or radio button, the state of the parent determines
// the checked state
aFrame = aFrame->GetParent();
} else {
// Check for an HTML input element
nsCOMPtr<nsIDOMHTMLInputElement> inputElt = do_QueryInterface(content);
if (inputElt) {
bool checked;
inputElt->GetChecked(&checked);
return checked;
}
}
return CheckBooleanAttr(aFrame, aCheckSelected ? nsGkAtoms::selected
: nsGkAtoms::checked);
}
bool
nsNativeTheme::IsButtonTypeMenu(nsIFrame* aFrame)
{
if (!aFrame)
return false;
nsIContent* content = aFrame->GetContent();
return content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::type,
NS_LITERAL_STRING("menu"), eCaseMatters);
}
bool
nsNativeTheme::IsPressedButton(nsIFrame* aFrame)
{
EventStates eventState = GetContentState(aFrame, NS_THEME_TOOLBAR_BUTTON);
if (IsDisabled(aFrame, eventState))
return false;
return IsOpenButton(aFrame) ||
eventState.HasAllStates(NS_EVENT_STATE_ACTIVE | NS_EVENT_STATE_HOVER);
}
bool
nsNativeTheme::GetIndeterminate(nsIFrame* aFrame)
{
if (!aFrame)
return false;
nsIContent* content = aFrame->GetContent();
if (content->IsXULElement()) {
// For a XUL checkbox or radio button, the state of the parent determines
// the state
return CheckBooleanAttr(aFrame->GetParent(), nsGkAtoms::indeterminate);
}
// Check for an HTML input element
nsCOMPtr<nsIDOMHTMLInputElement> inputElt = do_QueryInterface(content);
if (inputElt) {
bool indeterminate;
inputElt->GetIndeterminate(&indeterminate);
return indeterminate;
}
return false;
}
// backout bug 672050
bool
nsNativeTheme::IsLastTab(nsIFrame* aFrame)
{
if (!aFrame)
return false;
while ((aFrame = aFrame->GetNextSibling())) {
if (aFrame->GetRect().width > 0 && aFrame->GetContent()->NodeInfo()->NameAtom() == nsGkAtoms::tab)
return false;
}
return true;
}
bool
nsNativeTheme::IsWidgetStyled(nsPresContext* aPresContext, nsIFrame* aFrame,
uint8_t aWidgetType)
{
// Check for specific widgets to see if HTML has overridden the style.
if (!aFrame)
return false;
// Resizers have some special handling, dependent on whether in a scrollable
// container or not. If so, use the scrollable container's to determine
// whether the style is overriden instead of the resizer. This allows a
// non-native transparent resizer to be used instead. Otherwise, we just
// fall through and return false.
if (aWidgetType == NS_THEME_RESIZER) {
nsIFrame* parentFrame = aFrame->GetParent();
if (parentFrame && parentFrame->GetType() == nsGkAtoms::scrollFrame) {
// if the parent is a scrollframe, the resizer should be native themed
// only if the scrollable area doesn't override the widget style.
parentFrame = parentFrame->GetParent();
if (parentFrame) {
return IsWidgetStyled(aPresContext, parentFrame,
parentFrame->StyleDisplay()->mAppearance);
}
}
}
/**
* Progress bar appearance should be the same for the bar and the container
* frame. nsProgressFrame owns the logic and will tell us what we should do.
*/
if (aWidgetType == NS_THEME_PROGRESSBAR_CHUNK ||
aWidgetType == NS_THEME_PROGRESSBAR) {
nsProgressFrame* progressFrame = do_QueryFrame(aWidgetType == NS_THEME_PROGRESSBAR_CHUNK
? aFrame->GetParent() : aFrame);
if (progressFrame) {
return !progressFrame->ShouldUseNativeStyle();
}
}
/**
* Meter bar appearance should be the same for the bar and the container
* frame. nsMeterFrame owns the logic and will tell us what we should do.
*/
if (aWidgetType == NS_THEME_METERBAR_CHUNK ||
aWidgetType == NS_THEME_METERBAR) {
nsMeterFrame* meterFrame = do_QueryFrame(aWidgetType == NS_THEME_METERBAR_CHUNK
? aFrame->GetParent() : aFrame);
if (meterFrame) {
return !meterFrame->ShouldUseNativeStyle();
}
}
/**
* An nsRangeFrame and its children are treated atomically when it
* comes to native theming (either all parts, or no parts, are themed).
* nsRangeFrame owns the logic and will tell us what we should do.
*/
if (aWidgetType == NS_THEME_RANGE ||
aWidgetType == NS_THEME_RANGE_THUMB) {
nsRangeFrame* rangeFrame =
do_QueryFrame(aWidgetType == NS_THEME_RANGE_THUMB
? aFrame->GetParent() : aFrame);
if (rangeFrame) {
return !rangeFrame->ShouldUseNativeStyle();
}
}
if (aWidgetType == NS_THEME_SPINNER_UP_BUTTON ||
aWidgetType == NS_THEME_SPINNER_DOWN_BUTTON) {
nsNumberControlFrame* numberControlFrame =
nsNumberControlFrame::GetNumberControlFrameForSpinButton(aFrame);
if (numberControlFrame) {
return !numberControlFrame->ShouldUseNativeStyleForSpinner();
}
}
return (aWidgetType == NS_THEME_NUMBER_INPUT ||
aWidgetType == NS_THEME_BUTTON ||
aWidgetType == NS_THEME_TEXTFIELD ||
aWidgetType == NS_THEME_TEXTFIELD_MULTILINE ||
aWidgetType == NS_THEME_LISTBOX ||
aWidgetType == NS_THEME_DROPDOWN) &&
aFrame->GetContent()->IsHTMLElement() &&
aPresContext->HasAuthorSpecifiedRules(aFrame,
NS_AUTHOR_SPECIFIED_BORDER |
NS_AUTHOR_SPECIFIED_BACKGROUND);
}
bool
nsNativeTheme::IsDisabled(nsIFrame* aFrame, EventStates aEventStates)
{
if (!aFrame) {
return false;
}
nsIContent* content = aFrame->GetContent();
if (!content) {
return false;
}
if (content->IsHTMLElement()) {
return aEventStates.HasState(NS_EVENT_STATE_DISABLED);
}
// For XML/XUL elements, an attribute must be equal to the literal
// string "true" to be counted as true. An empty string should _not_
// be counted as true.
return content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::disabled,
NS_LITERAL_STRING("true"), eCaseMatters);
}
bool
nsNativeTheme::IsFrameRTL(nsIFrame* aFrame)
{
if (!aFrame) {
return false;
}
WritingMode wm = aFrame->GetWritingMode();
return !(wm.IsVertical() ? wm.IsVerticalLR() : wm.IsBidiLTR());
}
bool
nsNativeTheme::IsHTMLContent(nsIFrame *aFrame)
{
if (!aFrame) {
return false;
}
nsIContent* content = aFrame->GetContent();
return content && content->IsHTMLElement();
}
// scrollbar button:
int32_t
nsNativeTheme::GetScrollbarButtonType(nsIFrame* aFrame)
{
if (!aFrame)
return 0;
static nsIContent::AttrValuesArray strings[] =
{&nsGkAtoms::scrollbarDownBottom, &nsGkAtoms::scrollbarDownTop,
&nsGkAtoms::scrollbarUpBottom, &nsGkAtoms::scrollbarUpTop,
nullptr};
switch (aFrame->GetContent()->FindAttrValueIn(kNameSpaceID_None,
nsGkAtoms::sbattr,
strings, eCaseMatters)) {
case 0: return eScrollbarButton_Down | eScrollbarButton_Bottom;
case 1: return eScrollbarButton_Down;
case 2: return eScrollbarButton_Bottom;
case 3: return eScrollbarButton_UpTop;
}
return 0;
}
// treeheadercell:
nsNativeTheme::TreeSortDirection
nsNativeTheme::GetTreeSortDirection(nsIFrame* aFrame)
{
if (!aFrame || !aFrame->GetContent())
return eTreeSortDirection_Natural;
static nsIContent::AttrValuesArray strings[] =
{&nsGkAtoms::descending, &nsGkAtoms::ascending, nullptr};
switch (aFrame->GetContent()->FindAttrValueIn(kNameSpaceID_None,
nsGkAtoms::sortDirection,
strings, eCaseMatters)) {
case 0: return eTreeSortDirection_Descending;
case 1: return eTreeSortDirection_Ascending;
}
return eTreeSortDirection_Natural;
}
bool
nsNativeTheme::IsLastTreeHeaderCell(nsIFrame* aFrame)
{
if (!aFrame)
return false;
// A tree column picker is always the last header cell.
if (aFrame->GetContent()->IsXULElement(nsGkAtoms::treecolpicker))
return true;
// Find the parent tree.
nsIContent* parent = aFrame->GetContent()->GetParent();
while (parent && !parent->IsXULElement(nsGkAtoms::tree)) {
parent = parent->GetParent();
}
// If the column picker is visible, this can't be the last column.
if (parent && !parent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::hidecolumnpicker,
NS_LITERAL_STRING("true"), eCaseMatters))
return false;
while ((aFrame = aFrame->GetNextSibling())) {
if (aFrame->GetRect().width > 0)
return false;
}
return true;
}
// tab:
bool
nsNativeTheme::IsBottomTab(nsIFrame* aFrame)
{
if (!aFrame)
return false;
nsAutoString classStr;
aFrame->GetContent()->GetAttr(kNameSpaceID_None, nsGkAtoms::_class, classStr);
return !classStr.IsEmpty() && classStr.Find("tab-bottom") != kNotFound;
}
bool
nsNativeTheme::IsFirstTab(nsIFrame* aFrame)
{
if (!aFrame)
return false;
nsIFrame* first = aFrame->GetParent()->GetFirstPrincipalChild();
while (first) {
if (first->GetRect().width > 0 &&
first->GetContent()->IsXULElement(nsGkAtoms::tab))
return (first == aFrame);
first = first->GetNextSibling();
}
return false;
}
bool
nsNativeTheme::IsHorizontal(nsIFrame* aFrame)
{
if (!aFrame)
return false;
return !aFrame->GetContent()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::orient,
nsGkAtoms::vertical,
eCaseMatters);
}
bool
nsNativeTheme::IsNextToSelectedTab(nsIFrame* aFrame, int32_t aOffset)
{
if (!aFrame)
return false;
if (aOffset == 0)
return IsSelectedTab(aFrame);
int32_t thisTabIndex = -1, selectedTabIndex = -1;
nsIFrame* currentTab = aFrame->GetParent()->GetFirstPrincipalChild();
for (int32_t i = 0; currentTab; currentTab = currentTab->GetNextSibling()) {
if (currentTab->GetRect().width == 0)
continue;
if (aFrame == currentTab)
thisTabIndex = i;
if (IsSelectedTab(currentTab))
selectedTabIndex = i;
++i;
}
if (thisTabIndex == -1 || selectedTabIndex == -1)
return false;
return (thisTabIndex - selectedTabIndex == aOffset);
}
// progressbar:
bool
nsNativeTheme::IsIndeterminateProgress(nsIFrame* aFrame,
EventStates aEventStates)
{
if (!aFrame || !aFrame->GetContent())
return false;
if (aFrame->GetContent()->IsHTMLElement(nsGkAtoms::progress)) {
return aEventStates.HasState(NS_EVENT_STATE_INDETERMINATE);
}
return aFrame->GetContent()->AttrValueIs(kNameSpaceID_None, nsGkAtoms::mode,
NS_LITERAL_STRING("undetermined"),
eCaseMatters);
}
bool
nsNativeTheme::IsVerticalProgress(nsIFrame* aFrame)
{
if (!aFrame) {
return false;
}
return IsVerticalMeter(aFrame);
}
bool
nsNativeTheme::IsVerticalMeter(nsIFrame* aFrame)
{
NS_PRECONDITION(aFrame, "You have to pass a non-null aFrame");
switch (aFrame->StyleDisplay()->mOrient) {
case NS_STYLE_ORIENT_HORIZONTAL:
return false;
case NS_STYLE_ORIENT_VERTICAL:
return true;
case NS_STYLE_ORIENT_INLINE:
return aFrame->GetWritingMode().IsVertical();
case NS_STYLE_ORIENT_BLOCK:
return !aFrame->GetWritingMode().IsVertical();
}
NS_NOTREACHED("unexpected -moz-orient value");
return false;
}
// menupopup:
bool
nsNativeTheme::IsSubmenu(nsIFrame* aFrame, bool* aLeftOfParent)
{
if (!aFrame)
return false;
nsIContent* parentContent = aFrame->GetContent()->GetParent();
if (!parentContent || !parentContent->IsXULElement(nsGkAtoms::menu))
return false;
nsIFrame* parent = aFrame;
while ((parent = parent->GetParent())) {
if (parent->GetContent() == parentContent) {
if (aLeftOfParent) {
LayoutDeviceIntRect selfBounds, parentBounds;
aFrame->GetNearestWidget()->GetScreenBounds(selfBounds);
parent->GetNearestWidget()->GetScreenBounds(parentBounds);
*aLeftOfParent = selfBounds.x < parentBounds.x;
}
return true;
}
}
return false;
}
bool
nsNativeTheme::IsRegularMenuItem(nsIFrame *aFrame)
{
nsMenuFrame *menuFrame = do_QueryFrame(aFrame);
return !(menuFrame && (menuFrame->IsOnMenuBar() ||
menuFrame->GetParentMenuListType() != eNotMenuList));
}
bool
nsNativeTheme::IsMenuListEditable(nsIFrame *aFrame)
{
bool isEditable = false;
nsCOMPtr<nsIDOMXULMenuListElement> menulist = do_QueryInterface(aFrame->GetContent());
if (menulist)
menulist->GetEditable(&isEditable);
return isEditable;
}
bool
nsNativeTheme::QueueAnimatedContentForRefresh(nsIContent* aContent,
uint32_t aMinimumFrameRate)
{
NS_ASSERTION(aContent, "Null pointer!");
NS_ASSERTION(aMinimumFrameRate, "aMinimumFrameRate must be non-zero!");
NS_ASSERTION(aMinimumFrameRate <= 1000,
"aMinimumFrameRate must be less than 1000!");
uint32_t timeout = 1000 / aMinimumFrameRate;
timeout = std::min(mAnimatedContentTimeout, timeout);
if (!mAnimatedContentTimer) {
mAnimatedContentTimer = do_CreateInstance(NS_TIMER_CONTRACTID);
NS_ENSURE_TRUE(mAnimatedContentTimer, false);
}
if (mAnimatedContentList.IsEmpty() || timeout != mAnimatedContentTimeout) {
nsresult rv;
if (!mAnimatedContentList.IsEmpty()) {
rv = mAnimatedContentTimer->Cancel();
NS_ENSURE_SUCCESS(rv, false);
}
rv = mAnimatedContentTimer->InitWithCallback(this, timeout,
nsITimer::TYPE_ONE_SHOT);
NS_ENSURE_SUCCESS(rv, false);
mAnimatedContentTimeout = timeout;
}
if (!mAnimatedContentList.AppendElement(aContent)) {
NS_WARNING("Out of memory!");
return false;
}
return true;
}
NS_IMETHODIMP
nsNativeTheme::Notify(nsITimer* aTimer)
{
NS_ASSERTION(aTimer == mAnimatedContentTimer, "Wrong timer!");
// XXX Assumes that calling nsIFrame::Invalidate won't reenter
// QueueAnimatedContentForRefresh.
uint32_t count = mAnimatedContentList.Length();
for (uint32_t index = 0; index < count; index++) {
nsIFrame* frame = mAnimatedContentList[index]->GetPrimaryFrame();
if (frame) {
frame->InvalidateFrame();
}
}
mAnimatedContentList.Clear();
mAnimatedContentTimeout = UINT32_MAX;
return NS_OK;
}
nsIFrame*
nsNativeTheme::GetAdjacentSiblingFrameWithSameAppearance(nsIFrame* aFrame,
bool aNextSibling)
{
if (!aFrame)
return nullptr;
// Find the next visible sibling.
nsIFrame* sibling = aFrame;
do {
sibling = aNextSibling ? sibling->GetNextSibling() : sibling->GetPrevSibling();
} while (sibling && sibling->GetRect().width == 0);
// Check same appearance and adjacency.
if (!sibling ||
sibling->StyleDisplay()->mAppearance != aFrame->StyleDisplay()->mAppearance ||
(sibling->GetRect().XMost() != aFrame->GetRect().x &&
aFrame->GetRect().XMost() != sibling->GetRect().x))
return nullptr;
return sibling;
}
bool
nsNativeTheme::IsRangeHorizontal(nsIFrame* aFrame)
{
nsIFrame* rangeFrame = aFrame;
if (rangeFrame->GetType() != nsGkAtoms::rangeFrame) {
// If the thumb's frame is passed in, get its range parent:
rangeFrame = aFrame->GetParent();
}
if (rangeFrame->GetType() == nsGkAtoms::rangeFrame) {
return static_cast<nsRangeFrame*>(rangeFrame)->IsHorizontal();
}
// Not actually a range frame - just use the ratio of the frame's size to
// decide:
return aFrame->GetSize().width >= aFrame->GetSize().height;
}
static nsIFrame*
GetBodyFrame(nsIFrame* aCanvasFrame)
{
nsIContent* content = aCanvasFrame->GetContent();
if (!content) {
return nullptr;
}
nsIDocument* document = content->OwnerDoc();
nsIContent* body = document->GetBodyElement();
if (!body) {
return nullptr;
}
return body->GetPrimaryFrame();
}
bool
nsNativeTheme::IsDarkBackground(nsIFrame* aFrame)
{
nsIScrollableFrame* scrollFrame = nullptr;
while (!scrollFrame && aFrame) {
scrollFrame = aFrame->GetScrollTargetFrame();
aFrame = aFrame->GetParent();
}
if (!scrollFrame)
return false;
nsIFrame* frame = scrollFrame->GetScrolledFrame();
if (nsCSSRendering::IsCanvasFrame(frame)) {
// For canvas frames, prefer to look at the body first, because the body
// background color is most likely what will be visible as the background
// color of the page, even if the html element has a different background
// color which prevents that of the body frame to propagate to the viewport.
nsIFrame* bodyFrame = GetBodyFrame(frame);
if (bodyFrame) {
frame = bodyFrame;
}
}
nsStyleContext* bgSC = nullptr;
if (!nsCSSRendering::FindBackground(frame, &bgSC) ||
bgSC->StyleBackground()->IsTransparent()) {
nsIFrame* backgroundFrame = nsCSSRendering::FindNonTransparentBackgroundFrame(frame, true);
nsCSSRendering::FindBackground(backgroundFrame, &bgSC);
}
if (bgSC) {
nscolor bgColor = bgSC->StyleBackground()->mBackgroundColor;
// Consider the background color dark if the sum of the r, g and b values is
// less than 384 in a semi-transparent document. This heuristic matches what
// WebKit does, and we can improve it later if needed.
return NS_GET_A(bgColor) > 127 &&
NS_GET_R(bgColor) + NS_GET_G(bgColor) + NS_GET_B(bgColor) < 384;
}
return false;
}
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