add runtime config option to retain stream for custom typefaces

src/ports/SkFontHost_linux.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkFontHost.h"
 #include "SkFontHost_FreeType_common.h"
 #include "SkFontDescriptor.h"
 #include "SkFontMgr.h"
 #include "SkDescriptor.h"
 #include "SkOSFile.h"
 #include "SkPaint.h"
+#include "SkRTConf.h"
 #include "SkString.h"
 #include "SkStream.h"
 #include "SkThread.h"
 #include "SkTSearch.h"
 #include "SkTypefaceCache.h"
 #include "SkTArray.h"
 
 #include <limits>
 
 #ifndef SK_FONT_FILE_PREFIX
@@ skipping 69 matching lines @@
         *ttcIndex = this->getIndex();
         return fStream->duplicate();
     }
 
 private:
     const SkAutoTUnref<const SkStream> fStream;
 
     typedef SkTypeface_Custom INHERITED;
 };
 
+// This configuration option is useful if we need to open and hold handles to
+// all found system font data (e.g., for skfiddle, where the application can't
+// access the filesystem to read fonts on demand)
+
+SK_CONF_DECLARE(bool, c_CustomTypefaceRetain, "fonts.customFont.retainAllData", false,
+                "Retain the open stream for each found font on the system.");
+
 /** The file SkTypeface implementation for the custom font manager. */
 class SkTypeface_File : public SkTypeface_Custom {
 public:
     SkTypeface_File(const SkFontStyle& style, bool isFixedPitch, bool sysFont,
                     const SkString familyName, const char path[], int index)
         : INHERITED(style, isFixedPitch, sysFont, familyName, index)
         , fPath(path)
-    { }
+        , fStream(NULL)

[bungeman-skia, 2014/11/19 15:14:13]

I prefer the form

, fStream(c_CustomTypefaceRetain ? SkStream::NewFromFile(fPath.c_str()) : NULL)

as this means the declaration below can be

const SkAutoTUnref<SkStreamAsset> fStream;

making it clear that we won't try to switch streams at any point.

+    { 
+        if (c_CustomTypefaceRetain) {
+            fStream = SkStream::NewFromFile(fPath.c_str());
+        }
+    }
 
     virtual const char* getUniqueString() const SK_OVERRIDE {
         const char* str = strrchr(fPath.c_str(), '/');
         if (str) {
             str += 1;   // skip the '/'
         }
         return str;
     }
 
 protected:
     virtual SkStream* onOpenStream(int* ttcIndex) const SK_OVERRIDE {
         *ttcIndex = this->getIndex();
-        return SkStream::NewFromFile(fPath.c_str());
+        if (NULL != fStream) {

[bungeman-skia, 2014/11/19 15:14:14]

I think we're just using

if (fStream.get()) {

these days?

+            return fStream->duplicate();
+        } else {
+            return SkStream::NewFromFile(fPath.c_str());
+        }
     }
 
 private:
     SkString fPath;
+    SkAutoTUnref<SkStream> fStream;

[bungeman-skia, 2014/11/19 15:14:13]

Above (in SkTypeface_Stream) this is

const SkAutoTUnref<SkStream> fStream;

but that's just because reasons. Let's make this

const SkAutoTUnref<SkStreamAsset> fStream;

so we don't perpetuate the silliness. Sooner or later we'll be able to clean up
the one in SkTypeface_Stream.

 
     typedef SkTypeface_Custom INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 
 /**
  *  SkFontStyleSet_Custom
  *
  *  This class is used by SkFontMgr_Custom to hold SkTypeface_Custom families.
@@ skipping 278 matching lines @@
 
     SkTArray<SkAutoTUnref<SkFontStyleSet_Custom>, true> fFamilies;
     SkFontStyleSet_Custom* gDefaultFamily;
     SkTypeface* gDefaultNormal;
     SkTypeface_FreeType::Scanner fScanner;
 };
 
 SkFontMgr* SkFontMgr::Factory() {
     return new SkFontMgr_Custom(SK_FONT_FILE_PREFIX);
 }