gecko-dev/widget/nsNativeTheme.cpp
Nicholas Nethercote ad0dd8414a Bug 1223310 (part 2) - Use LayoutDeviceIntRect for bounds-related functions in nsIWidget. r=kats.
The patch renames the existing functions (GetBounds(), GetClientBounds(), etc)
by adding an |Untyped| suffix. It then adds typed equivalents, and uses those
typed equivalents in all the call sites where it's easy to do so. The trickier
remaining call sites are converted to use the Untyped-suffix version.

--HG--
extra : rebase_source : 6bfb15bfc4698e2eba7d4db55497299d3dffcd51
2015-11-09 21:37:32 -08:00

778 lines
23 KiB
C++

/* -*- 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;
}
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;
}