fixing crash when trying to measure or draw 0-length strings.

removing HDC param/member that is no longer used.
bug 329574. r=vlad


git-svn-id: svn://10.0.0.236/trunk@191940 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/gfx/src/thebes/nsThebesFontMetrics.cpp

@@ -95,7 +95,7 @@ nsThebesFontMetrics::Init(const nsFont& aFont, nsIAtom* aLangGroup,
                                   aFont.systemFont, aFont.familyNameQuirks);
 
 #if defined(XP_WIN)
-    mFontGroup = new gfxWindowsFontGroup(aFont.name, mFontStyle, (HDC)mDeviceContext->GetHDC());
+    mFontGroup = new gfxWindowsFontGroup(aFont.name, mFontStyle);
 #elif defined(MOZ_ENABLE_PANGO)
     mFontGroup = new gfxPangoFontGroup(aFont.name, mFontStyle);
 #elif defined(XP_MACOSX)
@@ -276,6 +276,11 @@ nsresult
 nsThebesFontMetrics::GetWidth(const char* aString, PRUint32 aLength, nscoord& aWidth,
                               nsThebesRenderingContext *aContext)
 {
+    if (aLength == 0) {
+        aWidth = 0;
+        return NS_OK;
+    }
+
     const nsDependentCSubstring& theString = nsDependentCSubstring(aString, aString+aLength);
     nsRefPtr<gfxTextRun> textrun = mFontGroup->MakeTextRun(theString);
 
@@ -291,6 +296,11 @@ nsThebesFontMetrics::GetWidth(const PRUnichar* aString, PRUint32 aLength,
                               nscoord& aWidth, PRInt32 *aFontID,
                               nsThebesRenderingContext *aContext)
 {
+    if (aLength == 0) {
+        aWidth = 0;
+        return NS_OK;
+    }
+
     const nsDependentSubstring& theString = nsDependentSubstring(aString, aString+aLength);
     nsRefPtr<gfxTextRun> textrun = mFontGroup->MakeTextRun(theString);
 
@@ -346,6 +356,9 @@ nsThebesFontMetrics::DrawString(const char *aString, PRUint32 aLength,
                                 const nscoord* aSpacing,
                                 nsThebesRenderingContext *aContext)
 {
+    if (aLength == 0)
+        return NS_OK;
+
     float app2dev = mDeviceContext->AppUnitsToDevUnits();
 
     const nsDependentCSubstring& theString = nsDependentCSubstring(aString, aString+aLength);
@@ -366,6 +379,9 @@ nsThebesFontMetrics::DrawString(const PRUnichar* aString, PRUint32 aLength,
                             const nscoord* aSpacing,
                             nsThebesRenderingContext *aContext)
 {
+    if (aLength == 0)
+        return NS_OK;
+
     float app2dev = mDeviceContext->AppUnitsToDevUnits();
 
     const nsDependentSubstring& theString = nsDependentSubstring(aString, aString+aLength);

mozilla/gfx/thebes/public/gfxWindowsFonts.h

@@ -56,7 +56,7 @@ class gfxWindowsFont : public gfxFont {
     THEBES_DECL_ISUPPORTS_INHERITED
 
 public:
-    gfxWindowsFont(const nsAString &aName, const gfxFontGroup *aFontGroup, HDC aHWnd);
+    gfxWindowsFont(const nsAString &aName, const gfxFontGroup *aFontGroup);
     gfxWindowsFont(HFONT aFont, const gfxFontGroup *aFontGroup, PRBool aIsMLangFont);
 
     virtual ~gfxWindowsFont();
@@ -100,7 +100,7 @@ private:
 class NS_EXPORT gfxWindowsFontGroup : public gfxFontGroup {
 
 public:
-    gfxWindowsFontGroup(const nsAString& aFamilies, const gfxFontStyle* aStyle, HDC hwnd);
+    gfxWindowsFontGroup(const nsAString& aFamilies, const gfxFontStyle* aStyle);
     virtual ~gfxWindowsFontGroup();
 
     virtual gfxTextRun *MakeTextRun(const nsAString& aString);
@@ -114,8 +114,6 @@ protected:
     static PRBool MakeFont(const nsAString& fontName, const nsAString& genericName, void *closure);
 
 private:
-    HDC mDC;
-
     friend class gfxWindowsTextRun;
 };
 

mozilla/gfx/thebes/src/gfxWindowsFonts.cpp

@@ -57,7 +57,7 @@
 
 THEBES_IMPL_REFCOUNTING(gfxWindowsFont)
 
-gfxWindowsFont::gfxWindowsFont(const nsAString &aName, const gfxFontGroup *aFontGroup, HDC aDC)
+gfxWindowsFont::gfxWindowsFont(const nsAString &aName, const gfxFontGroup *aFontGroup)
     : mFont(nsnull), mScriptCache(nsnull), mMetrics(nsnull), mIsMLangFont(PR_FALSE)
 {
     mName = aName;
@@ -319,14 +319,14 @@ PRBool
 gfxWindowsFontGroup::MakeFont(const nsAString& aName, const nsAString& aGenericName, void *closure)
 {
     gfxWindowsFontGroup *fg = NS_STATIC_CAST(gfxWindowsFontGroup*, closure);
-    gfxFont *font = new gfxWindowsFont(aName, fg, fg->mDC);
+    gfxFont *font = new gfxWindowsFont(aName, fg);
     fg->mFonts.AppendElement(font);
     return PR_TRUE;
 }
 
 
-gfxWindowsFontGroup::gfxWindowsFontGroup(const nsAString& aFamilies, const gfxFontStyle *aStyle, HDC dc)
-    : gfxFontGroup(aFamilies, aStyle), mDC(dc)
+gfxWindowsFontGroup::gfxWindowsFontGroup(const nsAString& aFamilies, const gfxFontStyle *aStyle)
+    : gfxFontGroup(aFamilies, aStyle)
 {
     ForEachFont(MakeFont, this);
 }
@@ -339,12 +339,20 @@ gfxWindowsFontGroup::~gfxWindowsFontGroup()
 gfxTextRun *
 gfxWindowsFontGroup::MakeTextRun(const nsAString& aString)
 {
+    if (aString.IsEmpty()) {
+        NS_WARNING("It is illegal to create a gfxTextRun with empty strings");
+        return nsnull;
+    }
     return new gfxWindowsTextRun(aString, this);
 }
 
 gfxTextRun *
 gfxWindowsFontGroup::MakeTextRun(const nsACString& aString)
 {
+    if (aString.IsEmpty()) {
+        NS_WARNING("It is illegal to create a gfxTextRun with empty strings");
+        return nsnull;
+    }
     return new gfxWindowsTextRun(aString, this);
 }