Add support for caching font files in the Android SkFontMgr.

src/ports/SkFontMgr_android.cpp

Index: src/ports/SkFontMgr_android.cpp
diff --git a/src/ports/SkFontMgr_android.cpp b/src/ports/SkFontMgr_android.cpp
index afa78734544f685bfba82be17062e89f6b2f543b..7532dfdb540570f43ad27c8304a507987751ca9b 100644
--- a/src/ports/SkFontMgr_android.cpp
+++ b/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,
@@ -60,10 +63,29 @@ public:
                              FontVariant variantStyle)
         : INHERITED(style, isFixedPitch, familyName)
         , fPathName(pathName)
+        , fCacheFontFiles(cacheFontFiles)
         , fIndex(index)
         , fAxes(axes, axesCount)
         , fLang(lang)
-        , fVariantStyle(variantStyle) { }
+        , fVariantStyle(variantStyle) {
+      if (fCacheFontFiles) {
+        fFile = sk_fopen(fPathName.c_str(), kRead_SkFILE_Flag);

[bungeman-skia, 2016/02/08 22:11:56]

This should just be handled in the init list with a fairly simple ternary.

[Khushal, 2016/02/09 00:53:40]

I wanted to add an assert here. It might as well fail on initialization if its
not able to read the font file. Does this look cleaner?

+        SkASSERT(fFile);
+      }
+    }
+
+    ~SkTypeface_AndroidSystem() {
+      if (fCacheFontFiles)
+        sk_fclose(fFile);
+    }
+
+    SkStreamAsset* onOpenStream() const {

[bungeman-skia, 2016/02/08 22:11:56]

The 'on' part of the name indicates that this is an implementation for a
superclass' wrapper to call, which this isn't this should be marked as private
and named something like 'createStream'.

[Khushal, 2016/02/09 00:53:40]

Done.

+      if (fCacheFontFiles) {
+        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);
@@ -73,18 +95,20 @@ public:
     }
     SkStreamAsset* onOpenStream(int* ttcIndex) const override {
         *ttcIndex = fIndex;
-        return SkStream::NewFromFile(fPathName.c_str());
+        return this->onOpenStream();
     }
     SkFontData* onCreateFontData() const override {
-        return new SkFontData(SkStream::NewFromFile(fPathName.c_str()), fIndex,
+        return new SkFontData(this->onOpenStream(), fIndex,
                               fAxes.begin(), fAxes.count());
     }
 
     const SkString fPathName;
+    const bool fCacheFontFiles;

[bungeman-skia, 2016/02/08 22:11:56]

This seems redundant with fFile being nullptr or not-nullptr.

[Khushal, 2016/02/09 00:53:40]

Removed.

     int fIndex;
     const SkSTArray<4, SkFixed, true> fAxes;
     const SkLanguage fLang;
     const FontVariant fVariantStyle;
+    FILE* fFile;

[bungeman-skia, 2016/02/08 22:11:56]

This should be SkAutoCallVProc<FILE, sk_fclose> so it automatic and no need for
explicit destructor.

[Khushal, 2016/02/09 00:53:40]

Done.

 
     typedef SkTypeface_Android INHERITED;
 };
@@ -125,7 +149,7 @@ 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) {

[bungeman-skia, 2016/02/08 22:11:56]

Skia has a 100 character limit (there are a few instances of long line below as
well).

Normally Skia doesn't normally declare a primitive parameter const. I don't
mind, since it states that the value isn't intended to change, but it looks odd
against the other Skia code.

[Khushal, 2016/02/09 00:53:40]

Done.
Yeah. Just wanted to make it explicit in the code that this shouldn't change
since there is some plumbing till it gets where it needs to go.

         const SkString* cannonicalFamilyName = nullptr;
         if (family.fNames.count() > 0) {
             cannonicalFamilyName = &family.fNames[0];
@@ -226,7 +250,7 @@ public:
             )
 
             fStyles.push_back().reset(new SkTypeface_AndroidSystem(
-                    pathName, ttcIndex, axisValues.get(), axisDefinitions.count(), style,
+                    pathName, cacheFontFiles, ttcIndex, axisValues.get(), axisDefinitions.count(), style,
                     isFixedWidth, familyName, lang, variant));
         }
     }
@@ -305,7 +329,8 @@ struct NameToFamily {
 
 class SkFontMgr_Android : public SkFontMgr {
 public:
-    SkFontMgr_Android(const SkFontMgr_Android_CustomFonts* custom) {
+    SkFontMgr_Android(const SkFontMgr_Android_CustomFonts* custom)
+        : fCacheFontFiles(custom ? custom->fCacheFontFiles : false) {

[bungeman-skia, 2016/02/08 22:11:56]

The '{' should go on the next line, four spaces in.

[Khushal, 2016/02/09 00:53:40]

Done.

         SkTDArray<FontFamily*> families;
         if (custom && SkFontMgr_Android_CustomFonts::kPreferSystem != custom->fSystemFontUse) {
             SkString base(custom->fBasePath);
@@ -520,7 +545,11 @@ protected:
             // named typeface so that the system/app can provide their own recovery
             // mechanism. On other platforms we'd provide a typeface from the
             // default family instead.
-            return this->onMatchFamilyStyle(familyName, style);
+            // We only return the default family when the font manager is caching

[bungeman-skia, 2016/02/08 22:11:56]

Why this change? Does blink on Linux do bad things when getting a nullptr back?
I'd rather not have a change in behavior here.

[Khushal, 2016/02/09 00:53:39]

It just crashes. Because like the comment above says, on other platforms there
is no recovery mechanism.

I tried looking at where this call is coming from, and it seems like it comes
internally from SkTypeFace public API calls, and I wasn't sure if I should be
changing the calls in blink to have an understanding that those calls on
SkTypeface can now return a nullptr.

+            // font families.
+            SkTypeface* typeface = this->onMatchFamilyStyle(familyName, style);
+            if (typeface || !fCacheFontFiles)
+              return typeface;
         }
         return fDefaultFamily->matchStyle(style);
     }
@@ -537,6 +566,8 @@ private:
     SkTDArray<NameToFamily> fNameToFamilyMap;
     SkTDArray<NameToFamily> fFallbackNameToFamilyMap;
 
+    const bool fCacheFontFiles;
+
     void buildNameToFamilyMap(SkTDArray<FontFamily*> families) {
         for (int i = 0; i < families.count(); i++) {
             FontFamily& family = *families[i];
@@ -551,7 +582,7 @@ private:
                 }
             }
 
-            SkFontStyleSet_Android* newSet = new SkFontStyleSet_Android(family, fScanner);
+            SkFontStyleSet_Android* newSet = new SkFontStyleSet_Android(family, fScanner, fCacheFontFiles);
             if (0 == newSet->count()) {
                 delete newSet;
                 continue;