Bug 266236 part 8: Change nsRenderingContext::GetDeviceContext and ::GetFontMetrics to return bare pointers.

--HG--
rename : gfx/src/nsThebesRenderingContext.cpp => gfx/src/nsRenderingContext.cpp
rename : gfx/src/nsThebesRenderingContext.h => gfx/src/nsRenderingContext.h
extra : rebase_source : 36dd32d715cb75e99cd3a69e460c000c1777d6a6

gfx/src/nsRenderingContext.cpp

@@ -100,12 +100,9 @@ nsRenderingContext::Init(nsIDeviceContext* aContext,
     mP2A = mDeviceContext->AppUnitsPerDevPixel();
 }
 
-already_AddRefed<nsIDeviceContext>
-nsRenderingContext::GetDeviceContext()
-{
-    NS_IF_ADDREF(mDeviceContext);
-    return mDeviceContext.get();
-}
+//
+// graphics state
+//
 
 void
 nsRenderingContext::PushState()
@@ -119,10 +116,6 @@ nsRenderingContext::PopState()
     mThebes->Restore();
 }
 
-//
-// clipping
-//
-
 void
 nsRenderingContext::IntersectClip(const nsRect& aRect)
 {
@@ -208,6 +201,10 @@ nsRenderingContext::Scale(float aSx, float aSy)
     mThebes->Scale(aSx, aSy);
 }
 
+//
+// shapes
+//
+
 void
 nsRenderingContext::DrawLine(const nsPoint& aStartPt, const nsPoint& aEndPt)
 {
@@ -445,7 +442,9 @@ nsRenderingContext::FillPolygon(const nsPoint twPoints[], PRInt32 aNumPoints)
     mThebes->Fill();
 }
 
+//
 // text
+//
 
 void
 nsRenderingContext::SetRightToLeftText(PRBool aIsRTL)
@@ -485,13 +484,6 @@ nsRenderingContext::SetFont(nsIFontMetrics *aFontMetrics)
     mFontMetrics = static_cast<nsIThebesFontMetrics*>(aFontMetrics);
 }
 
-already_AddRefed<nsIFontMetrics>
-nsRenderingContext::GetFontMetrics()
-{
-    NS_IF_ADDREF(mFontMetrics);
-    return mFontMetrics.get();
-}
-
 PRInt32
 nsRenderingContext::GetMaxChunkLength()
 {

gfx/src/nsRenderingContext.h

@@ -142,8 +142,10 @@ public:
     void Init(nsIDeviceContext* aContext, gfxASurface* aThebesSurface);
     void Init(nsIDeviceContext* aContext, gfxContext* aThebesContext);
 
-    already_AddRefed<nsIDeviceContext> GetDeviceContext();
+    // These accessors will never return null.
     gfxContext *ThebesContext() { return mThebes; }
+    nsIDeviceContext *DeviceContext() { return mDeviceContext; }
+    PRInt32 AppUnitsPerDevPixel() { return mP2A; }
 
     // Graphics state
 
@@ -194,7 +196,7 @@ public:
                  gfxUserFontSet *aUserFontSet);
     void SetFont(const nsFont& aFont, gfxUserFontSet *aUserFontSet);
     void SetFont(nsIFontMetrics *aFontMetrics);
-    already_AddRefed<nsIFontMetrics> GetFontMetrics();
+    nsIThebesFontMetrics *FontMetrics() { return mFontMetrics; } // may be null
 
     void SetRightToLeftText(PRBool aIsRTL);
     void SetTextRunRTL(PRBool aIsRTL);

layout/base/nsBidiPresUtils.cpp

@@ -1785,10 +1785,8 @@ public:
   virtual void DrawText(nscoord aXOffset,
                         nscoord)
   {
-    nsCOMPtr<nsIFontMetrics> metrics = mCtx->GetFontMetrics();
-    nsIThebesFontMetrics* fm = static_cast<nsIThebesFontMetrics*>(metrics.get());
-    fm->DrawString(mText, mLength, mPt.x + aXOffset, mPt.y,
-                   mCtx, mTextRunConstructionContext);
+    mCtx->FontMetrics()->DrawString(mText, mLength, mPt.x + aXOffset, mPt.y,
+                                    mCtx, mTextRunConstructionContext);
   }
 
 private:

layout/base/nsLayoutUtils.cpp

@@ -3264,8 +3264,7 @@ DrawImageInternal(nsRenderingContext* aRenderingContext,
                   const nsIntSize&     aImageSize,
                   PRUint32             aImageFlags)
 {
-  nsCOMPtr<nsIDeviceContext> dc = aRenderingContext->GetDeviceContext();
-  PRInt32 appUnitsPerDevPixel = dc->AppUnitsPerDevPixel();
+  PRInt32 appUnitsPerDevPixel = aRenderingContext->AppUnitsPerDevPixel();
   gfxContext* ctx = aRenderingContext->ThebesContext();
 
   SnappedImageDrawingParameters drawingParams =
@@ -3295,8 +3294,7 @@ nsLayoutUtils::DrawPixelSnapped(nsRenderingContext* aRenderingContext,
                                 const nsPoint&       aAnchor,
                                 const nsRect&        aDirty)
 {
-  nsCOMPtr<nsIDeviceContext> dc = aRenderingContext->GetDeviceContext();
-  PRInt32 appUnitsPerDevPixel = dc->AppUnitsPerDevPixel();
+  PRInt32 appUnitsPerDevPixel = aRenderingContext->AppUnitsPerDevPixel();
   gfxContext* ctx = aRenderingContext->ThebesContext();
   gfxIntSize drawableSize = aDrawable->Size();
   nsIntSize imageSize(drawableSize.width, drawableSize.height);

layout/generic/nsBRFrame.cpp

@@ -152,7 +152,7 @@ BRFrame::Reflow(nsPresContext* aPresContext,
       // normal inline frame.  That line-height is used is important
       // here for cases where the line-height is less than 1.
       nsLayoutUtils::SetFontFromStyle(aReflowState.rendContext, mStyleContext);
-      nsCOMPtr<nsIFontMetrics> fm = aReflowState.rendContext->GetFontMetrics();
+      nsIFontMetrics *fm = aReflowState.rendContext->FontMetrics();
       if (fm) {
         nscoord logicalHeight = aReflowState.CalcLineHeight();
         aMetrics.height = logicalHeight;

layout/generic/nsBlockFrame.cpp

@@ -2370,10 +2370,10 @@ nsBlockFrame::ReflowDirtyLines(nsBlockReflowState& aState)
 
       nsRenderingContext *rc = aState.mReflowState.rendContext;
       nsLayoutUtils::SetFontFromStyle(rc, GetStyleContext());
-      nsCOMPtr<nsIFontMetrics> fm = rc->GetFontMetrics();
 
       nscoord minAscent =
-        nsLayoutUtils::GetCenteredFontBaseline(fm, aState.mMinLineHeight);
+        nsLayoutUtils::GetCenteredFontBaseline(rc->FontMetrics(),
+                                               aState.mMinLineHeight);
       nscoord minDescent = aState.mMinLineHeight - minAscent;
 
       aState.mY += NS_MAX(minAscent, metrics.ascent) +

layout/generic/nsImageFrame.cpp

@@ -975,7 +975,7 @@ nsImageFrame::DisplayAltText(nsPresContext*      aPresContext,
   nsLayoutUtils::SetFontFromStyle(&aRenderingContext, mStyleContext);
 
   // Format the text to display within the formatting rect
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = aRenderingContext.FontMetrics();
 
   nscoord maxAscent, maxDescent, height;
   fm->GetMaxAscent(maxAscent);

layout/generic/nsInlineFrame.cpp

@@ -644,7 +644,7 @@ nsInlineFrame::ReflowFrames(nsPresContext* aPresContext,
   }
 
   nsLayoutUtils::SetFontFromStyle(aReflowState.rendContext, mStyleContext);
-  nsCOMPtr<nsIFontMetrics> fm = aReflowState.rendContext->GetFontMetrics();
+  nsIFontMetrics* fm = aReflowState.rendContext->FontMetrics();
 
   if (fm) {
     // Compute final height of the frame.

layout/generic/nsLineLayout.cpp

@@ -1563,7 +1563,7 @@ nsLineLayout::VerticalAlignFrames(PerSpanData* psd)
   nsStyleContext* styleContext = spanFrame->GetStyleContext();
   nsRenderingContext* rc = mBlockReflowState->rendContext;
   nsLayoutUtils::SetFontFromStyle(mBlockReflowState->rendContext, styleContext);
-  nsCOMPtr<nsIFontMetrics> fm = rc->GetFontMetrics();
+  nsIFontMetrics* fm = rc->FontMetrics();
 
   PRBool preMode = mStyleText->WhiteSpaceIsSignificant();
 

layout/mathml/nsMathMLContainerFrame.cpp

@@ -102,7 +102,7 @@ nsMathMLContainerFrame::ReflowError(nsRenderingContext& aRenderingContext,
     aRenderingContext.GetBoundingMetrics(errorMsg.get(), errorMsg.Length());
 
   // reflow metrics
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = aRenderingContext.FontMetrics();
   fm->GetMaxAscent(aDesiredSize.ascent);
   nscoord descent;
   fm->GetMaxDescent(descent);
@@ -144,8 +144,7 @@ void nsDisplayMathMLError::Paint(nsDisplayListBuilder* aBuilder,
   aCtx->SetColor(NS_RGB(255,255,255));
 
   nscoord ascent;
-  nsCOMPtr<nsIFontMetrics> fm = aCtx->GetFontMetrics();
-  fm->GetMaxAscent(ascent);
+  aCtx->FontMetrics()->GetMaxAscent(ascent);
 
   nsAutoString errorMsg; errorMsg.AssignLiteral("invalid-markup");
   aCtx->DrawString(errorMsg.get(), PRUint32(errorMsg.Length()), pt.x, pt.y+ascent);

layout/mathml/nsMathMLFrame.cpp

@@ -281,11 +281,10 @@ nsMathMLFrame::GetRuleThickness(nsRenderingContext& aRenderingContext,
 {
   // get the bounding metrics of the overbar char, the rendering context
   // is assumed to have been set with the font of the current style context
-#ifdef NS_DEBUG
-  nsCOMPtr<nsIFontMetrics> currFontMetrics = aRenderingContext.GetFontMetrics();
-  NS_ASSERTION(currFontMetrics->Font().Equals(aFontMetrics->Font()),
-      "unexpected state");
-#endif
+  NS_ASSERTION(aRenderingContext.FontMetrics()->Font().
+               Equals(aFontMetrics->Font()),
+               "unexpected state");
+
   nscoord xHeight;
   aFontMetrics->GetXHeight(xHeight);
   PRUnichar overBar = 0x00AF;
@@ -304,11 +303,10 @@ nsMathMLFrame::GetAxisHeight(nsRenderingContext& aRenderingContext,
 {
   // get the bounding metrics of the minus sign, the rendering context
   // is assumed to have been set with the font of the current style context
-#ifdef NS_DEBUG
-  nsCOMPtr<nsIFontMetrics> currFontMetrics = aRenderingContext.GetFontMetrics();
-  NS_ASSERTION(currFontMetrics->Font().Equals(aFontMetrics->Font()),
-	"unexpected state");
-#endif
+  NS_ASSERTION(aRenderingContext.FontMetrics()->Font().
+               Equals(aFontMetrics->Font()),
+               "unexpected state");
+
   nscoord xHeight;
   aFontMetrics->GetXHeight(xHeight);
   PRUnichar minus = 0x2212; // not '-', but official Unicode minus sign

layout/mathml/nsMathMLmencloseFrame.cpp

@@ -378,7 +378,7 @@ nsMathMLmencloseFrame::PlaceInternal(nsRenderingContext& aRenderingContext,
   nscoord mEmHeight;
   aRenderingContext.SetFont(GetStyleFont()->mFont,
                             PresContext()->GetUserFontSet());
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = aRenderingContext.FontMetrics();
   GetRuleThickness(aRenderingContext, fm, mRuleThickness);
   GetEmHeight(fm, mEmHeight);
 

layout/mathml/nsMathMLmfencedFrame.cpp

@@ -245,7 +245,7 @@ nsMathMLmfencedFrame::Reflow(nsPresContext*          aPresContext,
   const nsStyleFont* font = GetStyleFont();
   aReflowState.rendContext->SetFont(font->mFont,
                                     aPresContext->GetUserFontSet());
-  nsCOMPtr<nsIFontMetrics> fm = aReflowState.rendContext->GetFontMetrics();
+  nsIFontMetrics* fm = aReflowState.rendContext->FontMetrics();
   nscoord axisHeight, em;
   GetAxisHeight(*aReflowState.rendContext, fm, axisHeight);
   GetEmHeight(fm, em);

layout/mathml/nsMathMLmfracFrame.cpp

@@ -270,7 +270,7 @@ nsMathMLmfracFrame::PlaceInternal(nsRenderingContext& aRenderingContext,
 
   aRenderingContext.SetFont(GetStyleFont()->mFont,
                             presContext->GetUserFontSet());
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = aRenderingContext.FontMetrics();
 
   nscoord defaultRuleThickness, axisHeight;
   GetRuleThickness(aRenderingContext, fm, defaultRuleThickness);

layout/mathml/nsMathMLmmultiscriptsFrame.cpp

@@ -163,7 +163,7 @@ nsMathMLmmultiscriptsFrame::Place(nsRenderingContext& aRenderingContext,
   const nsStyleFont* font = GetStyleFont();
   aRenderingContext.SetFont(font->mFont,
                             PresContext()->GetUserFontSet());
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = aRenderingContext.FontMetrics();
 
   nscoord xHeight;
   fm->GetXHeight (xHeight);

layout/mathml/nsMathMLmoFrame.cpp

@@ -640,12 +640,12 @@ nsMathMLmoFrame::Stretch(nsRenderingContext& aRenderingContext,
   // get the axis height;
   aRenderingContext.SetFont(GetStyleFont()->mFont,
                             PresContext()->GetUserFontSet());
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = aRenderingContext.FontMetrics();
   nscoord axisHeight, height;
   GetAxisHeight(aRenderingContext, fm, axisHeight);
 
   // get the leading to be left at the top and the bottom of the stretched char
-  // this seems more reliable than using fm->GetLeading() on suspicious fonts               
+  // this seems more reliable than using fm->GetLeading() on suspicious fonts
   nscoord em;
   GetEmHeight(fm, em);
   nscoord leading = NSToCoordRound(0.2f * em);

layout/mathml/nsMathMLmoverFrame.cpp

@@ -284,7 +284,7 @@ nsMathMLmoverFrame::Place(nsRenderingContext& aRenderingContext,
 
   aRenderingContext.SetFont(GetStyleFont()->mFont,
                             PresContext()->GetUserFontSet());
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = aRenderingContext.FontMetrics();
 
   nscoord xHeight = 0;
   fm->GetXHeight (xHeight);

layout/mathml/nsMathMLmrootFrame.cpp

@@ -261,7 +261,7 @@ nsMathMLmrootFrame::Reflow(nsPresContext*          aPresContext,
 
   renderingContext.SetFont(GetStyleFont()->mFont,
                            aPresContext->GetUserFontSet());
-  nsCOMPtr<nsIFontMetrics> fm = renderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = renderingContext.FontMetrics();
 
   // For radical glyphs from TeX fonts and some of the radical glyphs from
   // Mathematica fonts, the thickness of the overline can be obtained from the
@@ -413,9 +413,9 @@ nsMathMLmrootFrame::GetIntrinsicWidth(nsRenderingContext* aRenderingContext)
                                          nsLayoutUtils::PREF_WIDTH);
   nscoord sqrWidth = mSqrChar.GetMaxWidth(PresContext(), *aRenderingContext);
 
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext->GetFontMetrics();
   nscoord dxSqr;
-  GetRadicalXOffsets(indexWidth, sqrWidth, fm, nsnull, &dxSqr);
+  GetRadicalXOffsets(indexWidth, sqrWidth, aRenderingContext->FontMetrics(),
+                     nsnull, &dxSqr);
 
   return dxSqr + sqrWidth + baseWidth;
 }

layout/mathml/nsMathMLmsubsupFrame.cpp

@@ -196,7 +196,7 @@ nsMathMLmsubsupFrame::PlaceSubSupScript(nsPresContext*      aPresContext,
 
   aRenderingContext.SetFont(baseFrame->GetStyleFont()->mFont,
                             aPresContext->GetUserFontSet());
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = aRenderingContext.FontMetrics();
 
   // get x-height (an ex)
   nscoord xHeight;

layout/mathml/nsMathMLmtableFrame.cpp

@@ -639,9 +639,10 @@ nsMathMLmtableOuterFrame::Reflow(nsPresContext*          aPresContext,
       // XXX should instead use style data from the row of reference here ?
       aReflowState.rendContext->SetFont(GetStyleFont()->mFont,
                                         aPresContext->GetUserFontSet());
-      nsCOMPtr<nsIFontMetrics> fm = aReflowState.rendContext->GetFontMetrics();
       nscoord axisHeight;
-      GetAxisHeight(*aReflowState.rendContext, fm, axisHeight);
+      GetAxisHeight(*aReflowState.rendContext,
+                    aReflowState.rendContext->FontMetrics(),
+                    axisHeight);
       if (rowFrame) {
         // anchor the table on the axis of the row of reference
         // XXX fallback to baseline because it is a hard problem

layout/mathml/nsMathMLmunderFrame.cpp

@@ -281,7 +281,7 @@ nsMathMLmunderFrame::Place(nsRenderingContext& aRenderingContext,
 
   aRenderingContext.SetFont(GetStyleFont()->mFont,
                             PresContext()->GetUserFontSet());
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = aRenderingContext.FontMetrics();
 
   nscoord xHeight = 0;
   fm->GetXHeight (xHeight);

layout/mathml/nsMathMLmunderoverFrame.cpp

@@ -323,7 +323,7 @@ nsMathMLmunderoverFrame::Place(nsRenderingContext& aRenderingContext,
 
   aRenderingContext.SetFont(GetStyleFont()->mFont,
                             PresContext()->GetUserFontSet());
-  nsCOMPtr<nsIFontMetrics> fm = aRenderingContext.GetFontMetrics();
+  nsIFontMetrics* fm = aRenderingContext.FontMetrics();
 
   nscoord xHeight = 0;
   fm->GetXHeight (xHeight);

layout/xul/base/src/nsTextBoxFrame.cpp

@@ -657,8 +657,7 @@ nsTextBoxFrame::CalculateUnderline(nsRenderingContext& aRenderingContext)
                                                     mAccesskeyIndex]);
 
          nscoord offset, baseline;
-         nsCOMPtr<nsIFontMetrics> metrics
-             = aRenderingContext.GetFontMetrics();
+         nsIFontMetrics* metrics = aRenderingContext.FontMetrics();
          metrics->GetUnderline(offset, mAccessKeyInfo->mAccessUnderlineSize);
          metrics->GetMaxAscent(baseline);
          mAccessKeyInfo->mAccessOffset = baseline - offset;

widget/src/cocoa/nsNativeThemeCocoa.mm

@@ -1494,17 +1494,19 @@ nsNativeThemeCocoa::DrawResizer(CGContextRef cgContext, const HIRect& aRect,
 }
 
 NS_IMETHODIMP
-nsNativeThemeCocoa::DrawWidgetBackground(nsRenderingContext* aContext, nsIFrame* aFrame,
-                                         PRUint8 aWidgetType, const nsRect& aRect,
+nsNativeThemeCocoa::DrawWidgetBackground(nsRenderingContext* aContext,
+                                         nsIFrame* aFrame,
+                                         PRUint8 aWidgetType,
+                                         const nsRect& aRect,
                                          const nsRect& aDirtyRect)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
   // setup to draw into the correct port
-  nsCOMPtr<nsIDeviceContext> dctx = aContext->GetDeviceContext();
-  PRInt32 p2a = dctx->AppUnitsPerDevPixel();
+  PRInt32 p2a = aContext->AppUnitsPerDevPixel();
 
-  gfxRect nativeDirtyRect(aDirtyRect.x, aDirtyRect.y, aDirtyRect.width, aDirtyRect.height);
+  gfxRect nativeDirtyRect(aDirtyRect.x, aDirtyRect.y,
+                          aDirtyRect.width, aDirtyRect.height);
   gfxRect nativeWidgetRect(aRect.x, aRect.y, aRect.width, aRect.height);
   nativeWidgetRect.ScaleInverse(gfxFloat(p2a));
   nativeDirtyRect.ScaleInverse(gfxFloat(p2a));
@@ -1512,7 +1514,7 @@ nsNativeThemeCocoa::DrawWidgetBackground(nsRenderingContext* aContext, nsIFrame*
   if (nativeWidgetRect.IsEmpty())
     return NS_OK; // Don't attempt to draw invisible widgets.
 
-  nsRefPtr<gfxContext> thebesCtx = aContext->ThebesContext();
+  gfxContext* thebesCtx = aContext->ThebesContext();
   if (!thebesCtx)
     return NS_ERROR_FAILURE;
 

widget/src/gtk2/nsNativeThemeGTK.cpp

@@ -1135,11 +1135,9 @@ nsNativeThemeGTK::GetMinimumWidgetSize(nsRenderingContext* aContext,
   case NS_THEME_TREEVIEW_HEADER_CELL:
     {
       // Just include our border, and let the box code augment the size.
-
-      nsCOMPtr<nsIDeviceContext> dc = aContext->GetDeviceContext();
-
       nsIntMargin border;
-      nsNativeThemeGTK::GetWidgetBorder(dc, aFrame, aWidgetType, &border);
+      nsNativeThemeGTK::GetWidgetBorder(aContext->DeviceContext(),
+                                        aFrame, aWidgetType, &border);
       aResult->width = border.left + border.right;
       aResult->height = border.top + border.bottom;
     }

widget/src/qt/nsNativeThemeQt.cpp

@@ -200,7 +200,7 @@ nsNativeThemeQt::DrawWidgetBackground(QPainter *qPainter,
     QMatrix qctm(ctm.xx, ctm.yx, ctm.xy, ctm.yy, ctm.x0, ctm.y0);
     qPainter->setWorldMatrix(qctm, true);
 
-    PRInt32 p2a = GetAppUnitsPerDevPixel(aContext);
+    PRInt32 p2a = aContext->AppUnitsPerDevPixel();
 
     QRect r = qRectInPixels(aRect, p2a);
     QRect cr = qRectInPixels(aClipRect, p2a);
@@ -395,7 +395,7 @@ nsNativeThemeQt::GetMinimumWidgetSize(nsRenderingContext* aContext, nsIFrame* aF
 
     QStyle *s = qApp->style();
 
-    PRInt32 p2a = GetAppUnitsPerDevPixel(aContext);
+    PRInt32 p2a = aContext->AppUnitsPerDevPixel();
 
     switch (aWidgetType) {
     case NS_THEME_RADIO:

widget/src/qt/nsNativeThemeQt.h

@@ -111,11 +111,6 @@ private:
                                        const nsRect& aRect,
                                        const nsRect& aClipRect);
 
-  inline PRInt32 GetAppUnitsPerDevPixel(nsRenderingContext* aContext){
-    nsCOMPtr<nsIDeviceContext> dctx = aContext->GetDeviceContext();
-    return dctx->AppUnitsPerDevPixel();
-  }
-
   void InitButtonStyle(PRUint8 widgetType,
                        nsIFrame* aFrame,
                        QRect rect,

widget/src/windows/nsNativeThemeWin.cpp

@@ -1246,8 +1246,7 @@ nsNativeThemeWin::DrawWidgetBackground(nsRenderingContext* aContext,
   if (NS_FAILED(rv))
     return rv;
 
-  nsCOMPtr<nsIDeviceContext> dc = aContext->GetDeviceContext();
-  gfxFloat p2a = gfxFloat(dc->AppUnitsPerDevPixel());
+  gfxFloat p2a = gfxFloat(aContext->AppUnitsPerDevPixel());
   RECT widgetRect;
   RECT clipRect;
   gfxRect tr(aRect.x, aRect.y, aRect.width, aRect.height),
@@ -3114,8 +3113,7 @@ nsresult nsNativeThemeWin::ClassicDrawWidgetBackground(nsRenderingContext* aCont
   if (NS_FAILED(rv))
     return rv;
 
-  nsCOMPtr<nsIDeviceContext> dc = aContext->GetDeviceContext();
-  gfxFloat p2a = gfxFloat(dc->AppUnitsPerDevPixel());
+  gfxFloat p2a = gfxFloat(aContext->AppUnitsPerDevPixel());
   RECT widgetRect;
   gfxRect tr(aRect.x, aRect.y, aRect.width, aRect.height),
           dr(aDirtyRect.x, aDirtyRect.y, aDirtyRect.width, aDirtyRect.height);