Commit 61d56fd0 authored by Kathleen Brade's avatar Kathleen Brade Committed by Georg Koppen
Browse files

Bug 6786: Do not expose system colors to CSS or canvas. 

Restore the portion of this fix that was not upstreamed as part of
https://bugzilla.mozilla.org/show_bug.cgi?id=232227: use properly
contrasting colors if the desktop theme specifies white on black
for text colors (see bug 7920). These color choices are not exposed
to content.
parent 68d8e949

layout/base/nsLayoutUtils.cpp

+50 −0
Original line number Diff line number Diff line
@@ -5465,13 +5465,63 @@ ShouldDarkenColors(nsPresContext* aPresContext) 
nscolor

nsLayoutUtils::GetColor(nsIFrame* aFrame, nsCSSProperty aProperty)

{

  if (aProperty == eCSSProperty_color)

  {

    nscolor nativeColor = NS_RGB(0, 0, 0);

    if (GetNativeTextColor(aFrame, nativeColor))

      return nativeColor;

  }



  nscolor color = aFrame->GetVisitedDependentColor(aProperty);

  if (ShouldDarkenColors(aFrame->PresContext())) {

    color = DarkenColor(color);

  }



  return color;

}



bool

nsLayoutUtils::GetNativeTextColor(nsIFrame* aFrame, nscolor& aColor)

{

  nsPresContext *presContext = aFrame->PresContext();

  if (!presContext->IsChrome()) {

    // If native appearance was used to draw the background of the containing

    // frame, return a contrasting native foreground color instead of the

    // color from the element's style.  This avoids a problem where black

    // text was displayed on a black background when a Windows theme such as

    // "High Contrast Black" was used.  The background is drawn inside

    // nsNativeThemeWin::ClassicDrawWidgetBackground().

    //

    // Because both the background color and this foreground color are used

    // directly without exposing the colors via CSS computed styles, the

    // native colors are not leaked to content.

    nsIFrame* bgFrame =

                    nsCSSRendering::FindNonTransparentBackgroundFrame(aFrame);

    if (bgFrame) {

      const nsStyleDisplay* displayData = bgFrame->StyleDisplay();

      uint8_t widgetType = displayData->mAppearance;

      nsITheme *theme = presContext->GetTheme();

      if (theme && widgetType && theme->ThemeSupportsWidget(presContext,

                                                            bgFrame,

                                                            widgetType)) {

        bool isDisabled = false;

        nsIContent* frameContent = bgFrame->GetContent();

        if (frameContent && frameContent->IsElement()) {

          EventStates es = frameContent->AsElement()->State();

          isDisabled = es.HasState(NS_EVENT_STATE_DISABLED);

        }



        if (NS_SUCCEEDED(LookAndFeel::GetColorForNativeAppearance(widgetType,

                                                       isDisabled, &aColor))) {

            return true;

        }

      }

    }

  }



  return false;

}



gfxFloat

nsLayoutUtils::GetSnappedBaselineY(nsIFrame* aFrame, gfxContext* aContext,

                                   nscoord aY, nscoord aAscent)

layout/base/nsLayoutUtils.h

+4 −0
Original line number Diff line number Diff line
@@ -1563,6 +1563,10 @@ public: 
  // Get a suitable foreground color for painting aProperty for aFrame.

  static nscolor GetColor(nsIFrame* aFrame, nsCSSProperty aProperty);



  // Get the native text color if appropriate.  If false is returned, callers

  // should fallback to the CSS color.

  static bool GetNativeTextColor(nsIFrame* aFrame, nscolor& aColor);



  // Get a baseline y position in app units that is snapped to device pixels.

  static gfxFloat GetSnappedBaselineY(nsIFrame* aFrame, gfxContext* aContext,

                                      nscoord aY, nscoord aAscent);

layout/generic/nsFrame.cpp

+5 −1
Original line number Diff line number Diff line
@@ -1580,7 +1580,11 @@ nsIFrame::DisplayCaret(nsDisplayListBuilder* aBuilder, 
nscolor

nsIFrame::GetCaretColorAt(int32_t aOffset)

{

  // Use text color.

  nscolor color = NS_RGB(0, 0, 0);

  if (nsLayoutUtils::GetNativeTextColor(this, color))

    return color;



  // Use CSS text color.

  return StyleColor()->mColor;

}

widget/LookAndFeel.h

+3 −0
Original line number Diff line number Diff line
@@ -535,6 +535,9 @@ public: 
  static nsresult GetColor(ColorID aID, bool aUseStandinsForNativeColors,

                           nscolor* aResult);



  static nsresult GetColorForNativeAppearance(uint8_t aWidgetType,

                                          bool aIsDisabled, nscolor* aResult);



  /**

   * GetInt() and GetFloat() return a int or float value for aID.  The result

   * might be distance, time, some flags or a int value which has particular

widget/nsXPLookAndFeel.cpp

+41 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include "nsLookAndFeel.h"

#include "nsCRT.h"

#include "nsFont.h"

#include "nsThemeConstants.h"

#include "mozilla/dom/ContentChild.h"

#include "mozilla/Preferences.h"

#include "mozilla/gfx/2D.h"
@@ -904,6 +905,46 @@ LookAndFeel::GetColor(ColorID aID, bool aUseStandinsForNativeColors, 
                                       aUseStandinsForNativeColors, *aResult);

}



// static

nsresult

LookAndFeel::GetColorForNativeAppearance(uint8_t aWidgetType, bool aIsDisabled,

                                         nscolor* aResult)

{

  NS_ENSURE_ARG_POINTER(aResult);



  ColorID colorID = eColorID_LAST_COLOR;

  switch (aWidgetType) {

    case NS_THEME_TEXTFIELD:

    case NS_THEME_TEXTFIELD_MULTILINE:

    case NS_THEME_LISTBOX:

    case NS_THEME_DROPDOWN:

    case NS_THEME_DROPDOWN_TEXTFIELD:

    case NS_THEME_TREEVIEW:

      colorID = (aIsDisabled) ? eColorID_graytext : eColorID__moz_fieldtext;

      break;



    case NS_THEME_TOOLTIP:

      colorID = eColorID_infotext;

      break;



    case NS_THEME_BUTTON:

    case NS_THEME_GROUPBOX:

    case NS_THEME_PROGRESSBAR:

    case NS_THEME_PROGRESSBAR_VERTICAL:

    case NS_THEME_TAB_PANEL:

    case NS_THEME_STATUSBAR:

    case NS_THEME_STATUSBAR_RESIZER_PANEL:

      colorID = (aIsDisabled) ? eColorID_graytext : eColorID_buttontext;

      break;

  }



  if (LookAndFeel::eColorID_LAST_COLOR == colorID)

    return NS_ERROR_FAILURE;



  *aResult = NS_RGB(0, 0, 0);

  return nsLookAndFeel::GetInstance()->NativeGetColor(colorID, *aResult);

}



// static

nsresult

LookAndFeel::GetInt(IntID aID, int32_t* aResult)