Add support for caching font files in the Android SkFontMgr.

SkFontMgr_Android lazily access font files from disk, which is not
possible when it is used in the renderer sandbox on Linux. Add a flag to
SkFontMgr_Android_CustomFonts for caching readonly FILE streams when
creating the font mgr.

Since the font mgr is created before the sandbox is initialized, it can
access these files on initialization, and use these cached streams safely
for its lifetime.

Review URL: https://codereview.chromium.org/1673373003

include/ports/SkFontMgr_android.h

@@ -39,6 +39,11 @@ struct SkFontMgr_Android_CustomFonts {
      *  In the new style (version > 21) fontsXml format is used, this should be NULL.
      */
     const char* fFallbackFontsXml;
+
+    /** Optional custom flag. If set to true the SkFontMgr will acquire all requisite
+     *  system IO resources on initialization.
+     */
+    bool fIsolated;
 };
 
 /** Create a font manager for Android. If 'custom' is NULL, use only system fonts. */

src/ports/SkFontMgr_android.cpp

@@ -7,6 +7,7 @@
 
 #include "SkTypes.h"
 
+#include "SkData.h"
 #include "SkFixed.h"
 #include "SkFontDescriptor.h"
 #include "SkFontHost_FreeType_common.h"
@@ -14,6 +15,7 @@
 #include "SkFontMgr_android.h"
 #include "SkFontMgr_android_parser.h"
 #include "SkFontStyle.h"
+#include "SkOSFile.h"
 #include "SkPaint.h"
 #include "SkRefCnt.h"
 #include "SkString.h"
@@ -51,6 +53,7 @@ private:
 class SkTypeface_AndroidSystem : public SkTypeface_Android {
 public:
     SkTypeface_AndroidSystem(const SkString& pathName,
+                             const bool cacheFontFiles,
                              int index,
                              const SkFixed* axes, int axesCount,
                              const SkFontStyle& style,
@@ -63,7 +66,20 @@ public:
         , fIndex(index)
         , fAxes(axes, axesCount)
         , fLang(lang)
-        , fVariantStyle(variantStyle) { }
+        , fVariantStyle(variantStyle)
+        , fFile(cacheFontFiles ? sk_fopen(fPathName.c_str(), kRead_SkFILE_Flag) : nullptr) {
+        if (cacheFontFiles) {
+            SkASSERT(fFile);
+        }
+    }
+
+    SkStreamAsset* createStream() const {
+        if (fFile) {
+            SkData* data = SkData::NewFromFILE(fFile);
+            return data ? new SkMemoryStream(data) : nullptr;
+        }
+        return SkStream::NewFromFile(fPathName.c_str());
+    }
 
     virtual void onGetFontDescriptor(SkFontDescriptor* desc, bool* serialize) const override {
         SkASSERT(desc);
@@ -73,11 +89,10 @@ public:
     }
     SkStreamAsset* onOpenStream(int* ttcIndex) const override {
         *ttcIndex = fIndex;
-        return SkStream::NewFromFile(fPathName.c_str());
+        return this->createStream();
     }
     SkFontData* onCreateFontData() const override {
-        return new SkFontData(SkStream::NewFromFile(fPathName.c_str()), fIndex,
-                              fAxes.begin(), fAxes.count());
+        return new SkFontData(this->createStream(), fIndex, fAxes.begin(), fAxes.count());
     }
 
     const SkString fPathName;
@@ -85,6 +100,7 @@ public:
     const SkSTArray<4, SkFixed, true> fAxes;
     const SkLanguage fLang;
     const FontVariant fVariantStyle;
+    SkAutoTCallVProc<FILE, sk_fclose> fFile;
 
     typedef SkTypeface_Android INHERITED;
 };
@@ -125,7 +141,8 @@ class SkFontStyleSet_Android : public SkFontStyleSet {
     typedef SkTypeface_FreeType::Scanner Scanner;
 
 public:
-    explicit SkFontStyleSet_Android(const FontFamily& family, const Scanner& scanner) {
+    explicit SkFontStyleSet_Android(const FontFamily& family, const Scanner& scanner,
+                                    const bool cacheFontFiles) {
         const SkString* cannonicalFamilyName = nullptr;
         if (family.fNames.count() > 0) {
             cannonicalFamilyName = &family.fNames[0];
@@ -226,8 +243,8 @@ public:
             )
 
             fStyles.push_back().reset(new SkTypeface_AndroidSystem(
-                    pathName, ttcIndex, axisValues.get(), axisDefinitions.count(), style,
-                    isFixedWidth, familyName, lang, variant));
+                    pathName, cacheFontFiles, ttcIndex, axisValues.get(), axisDefinitions.count(),
+                    style, isFixedWidth, familyName, lang, variant));
         }
     }
 
@@ -322,7 +339,7 @@ public:
             SkFontMgr_Android_Parser::GetCustomFontFamilies(
                 families, base, custom->fFontsXml, custom->fFallbackFontsXml);
         }
-        this->buildNameToFamilyMap(families);
+        this->buildNameToFamilyMap(families, custom ? custom->fIsolated : false);
         this->findDefaultFont();
         families.deleteAll();
     }
@@ -537,7 +554,7 @@ private:
     SkTDArray<NameToFamily> fNameToFamilyMap;
     SkTDArray<NameToFamily> fFallbackNameToFamilyMap;
 
-    void buildNameToFamilyMap(SkTDArray<FontFamily*> families) {
+    void buildNameToFamilyMap(SkTDArray<FontFamily*> families, const bool isolated) {
         for (int i = 0; i < families.count(); i++) {
             FontFamily& family = *families[i];
 
@@ -551,7 +568,7 @@ private:
                 }
             }
 
-            SkFontStyleSet_Android* newSet = new SkFontStyleSet_Android(family, fScanner);
+            SkFontStyleSet_Android* newSet = new SkFontStyleSet_Android(family, fScanner, isolated);
             if (0 == newSet->count()) {
                 delete newSet;
                 continue;

src/ports/SkFontMgr_android_factory.cpp

@@ -36,7 +36,8 @@ SkFontMgr* SkFontMgr::Factory() {
             SkFontMgr_Android_CustomFonts::kOnlyCustom,
             gTestBasePath,
             gTestFontsXml,
-            gTestFallbackFontsXml
+            gTestFallbackFontsXml,
+            false /* fIsolated */
         };
         return SkFontMgr_New_Android(&custom);
     }