Bug 407761. Don't try to get/use extents for missing glyphs, and tolerate glyph extents that might be missing due to OOM. r=vlad

gfx/thebes/public/gfxFont.h

@@ -272,7 +272,10 @@ public:
     }
 
     // Get glyph extents; a rectangle relative to the left baseline origin
-    gfxRect GetTightGlyphExtentsAppUnits(gfxFont *aFont, gfxContext *aContext, PRUint32 aGlyphID);
+    // Returns true on success. Can fail on OOM or when aContext is null
+    // and extents were not (successfully) prefetched.
+    PRBool GetTightGlyphExtentsAppUnits(gfxFont *aFont, gfxContext *aContext,
+            PRUint32 aGlyphID, gfxRect *aExtents);
 
     void SetContainedGlyphWidthAppUnits(PRUint32 aGlyphID, PRUint16 aWidth) {
         mContainedGlyphWidths.Set(aGlyphID, aWidth);
@@ -488,6 +491,8 @@ public:
      * the advance width for the character run,y=-(font ascent), and height=
      * font ascent + font descent). Otherwise, we must return as tight as possible
      * an approximation to the area actually painted by glyphs.
+     * @param aContextForTightBoundingBox when aTight is true, this must
+     * be non-null.
      * @param aSpacing spacing to insert before and after glyphs. The bounding box
      * need not include the spacing itself, but the spacing affects the glyph
      * positions. null if there is no spacing.
@@ -1203,6 +1208,12 @@ public:
     void SetMissingGlyph(PRUint32 aCharIndex, PRUint32 aUnicodeChar);
     void SetSpaceGlyph(gfxFont *aFont, gfxContext *aContext, PRUint32 aCharIndex);
     
+    /**
+     * Prefetch all the glyph extents needed to ensure that Measure calls
+     * on this textrun with aTightBoundingBox false will succeed. Note
+     * that some glyph extents might not be fetched due to OOM or other
+     * errors.
+     */
     void FetchGlyphExtents(gfxContext *aRefContext);
 
     // API for access to the raw glyph data, needed by gfxFont::Draw
@@ -1402,6 +1413,7 @@ public:
      * Make a textrun for a given string.
      * If aText is not persistent (aFlags & TEXT_IS_PERSISTENT), the
      * textrun will copy it.
+     * This calls FetchGlyphExtents on the textrun.
      */
     virtual gfxTextRun *MakeTextRun(const PRUnichar *aString, PRUint32 aLength,
                                     const Parameters *aParams, PRUint32 aFlags) = 0;
@@ -1409,6 +1421,7 @@ public:
      * Make a textrun for a given string.
      * If aText is not persistent (aFlags & TEXT_IS_PERSISTENT), the
      * textrun will copy it.
+     * This calls FetchGlyphExtents on the textrun.
      */
     virtual gfxTextRun *MakeTextRun(const PRUint8 *aString, PRUint32 aLength,
                                     const Parameters *aParams, PRUint32 aFlags) = 0;

gfx/thebes/src/gfxFont.cpp

@@ -405,14 +405,18 @@ gfxFont::Measure(gfxTextRun *aTextRun,
             double advance = glyphData->GetSimpleAdvance();
             // Only get the real glyph horizontal extent if we were asked
             // for the tight bounding box or we're in quality mode
-            if (aTightBoundingBox || NeedsGlyphExtents(aTextRun)) {
+            if ((aTightBoundingBox || NeedsGlyphExtents(aTextRun)) && extents) {
                 PRUint32 glyphIndex = glyphData->GetSimpleGlyph();
                 PRUint16 extentsWidth = extents->GetContainedGlyphWidthAppUnits(glyphIndex);
                 if (extentsWidth != gfxGlyphExtents::INVALID_WIDTH && !aTightBoundingBox) {
                     UnionWithXPoint(&metrics.mBoundingBox, x + direction*extentsWidth);
                 } else {
-                    gfxRect glyphRect =
-                        extents->GetTightGlyphExtentsAppUnits(this, aRefContext, glyphIndex);
+                    gfxRect glyphRect;
+                    if (!extents->GetTightGlyphExtentsAppUnits(this,
+                            aRefContext, glyphIndex, &glyphRect)) {
+                        glyphRect = gfxRect(0, metrics.mBoundingBox.Y(),
+                            advance, metrics.mBoundingBox.Height());
+                    }
                     if (isRTL) {
                         glyphRect.pos.x -= advance;
                     }
@@ -429,8 +433,15 @@ gfxFont::Measure(gfxTextRun *aTextRun,
                 PRUint32 glyphIndex = details->mGlyphID;
                 gfxPoint glyphPt(x + details->mXOffset, details->mYOffset);
                 double advance = details->mAdvance;
-                gfxRect glyphRect =
-                    extents->GetTightGlyphExtentsAppUnits(this, aRefContext, glyphIndex);
+                gfxRect glyphRect;
+                if (glyphData->IsMissing() || !extents ||
+                    !extents->GetTightGlyphExtentsAppUnits(this,
+                            aRefContext, glyphIndex, &glyphRect)) {
+                    // We might have failed to get glyph extents due to
+                    // OOM or something
+                    glyphRect = gfxRect(0, metrics.mBoundingBox.Y(),
+                        advance, metrics.mBoundingBox.Height());
+                }
                 if (isRTL) {
                     glyphRect.pos.x -= advance;
                 }
@@ -522,12 +533,17 @@ gfxGlyphExtents::~gfxGlyphExtents()
     MOZ_COUNT_DTOR(gfxGlyphExtents);
 }
 
-gfxRect
+PRBool
 gfxGlyphExtents::GetTightGlyphExtentsAppUnits(gfxFont *aFont,
-    gfxContext *aContext, PRUint32 aGlyphID)
+    gfxContext *aContext, PRUint32 aGlyphID, gfxRect *aExtents)
 {
     HashEntry *entry = mTightGlyphExtents.GetEntry(aGlyphID);
     if (!entry) {
+        if (!aContext) {
+            NS_WARNING("Could not get glyph extents (no aContext)");
+            return PR_FALSE;
+        }
+
         aFont->SetupCairoFont(aContext);
 #ifdef DEBUG_TEXT_RUN_STORAGE_METRICS
         ++gGlyphExtentsSetupLazyTight;
@@ -536,11 +552,12 @@ gfxGlyphExtents::GetTightGlyphExtentsAppUnits(gfxFont *aFont,
         entry = mTightGlyphExtents.GetEntry(aGlyphID);
         if (!entry) {
             NS_WARNING("Could not get glyph extents");
-            return gfxRect(0,0,0,0);
+            return PR_FALSE;
         }
     }
     
-    return gfxRect(entry->x, entry->y, entry->width, entry->height);
+    *aExtents = gfxRect(entry->x, entry->y, entry->width, entry->height);
+    return PR_TRUE;
 }
 
 gfxGlyphExtents::GlyphWidths::~GlyphWidths()
@@ -1931,7 +1948,7 @@ gfxTextRun::FetchGlyphExtents(gfxContext *aRefContext)
                         font->SetupGlyphExtents(aRefContext, glyphIndex, PR_FALSE, extents);
                     }
                 }
-            } else {
+            } else if (!glyphData->IsMissing()) {
                 PRUint32 k;
                 PRUint32 glyphCount = glyphData->GetGlyphCount();
                 const gfxTextRun::DetailedGlyph *details = GetDetailedGlyphs(j);