src/ports/SkFontHost_simple.cpp - platform/external/skia - Git at Google

 /*
  * Copyright (C) 2011 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "SkFontHost.h"
 #include "SkDescriptor.h"
 #include "SkMMapStream.h"
 #include "SkPaint.h"
 #include "SkString.h"
 #include "SkStream.h"
 #include "SkThread.h"
 #include "SkTSearch.h"
 #include <stdio.h>

 #define FONT_CACHE_MEMORY_BUDGET    (768 * 1024)

 #ifdef SK_BUILD_FOR_MAC
     #define SK_FONT_FILE_PREFIX     "/Library/Fonts/"
 #else
     #define SK_FONT_FILE_PREFIX          "/skimages/"
 #endif

 SkTypeface::Style find_name_and_attributes(SkStream* stream, SkString* name,
                                            bool* isFixedWidth);

 static void GetFullPathForSysFonts(SkString* full, const char name[]) {
     full->set(SK_FONT_FILE_PREFIX);
     full->append(name);
 }

 ///////////////////////////////////////////////////////////////////////////////

 struct FamilyRec;

 /*  This guy holds a mapping of a name -> family, used for looking up fonts.
     Since it is stored in a stretchy array that doesn't preserve object
     semantics, we don't use constructor/destructors, but just have explicit
     helpers to manage our internal bookkeeping.
 */
 struct NameFamilyPair {
     const char* fName;      // we own this
     FamilyRec*  fFamily;    // we don't own this, we just reference it

     void construct(const char name[], FamilyRec* family) {
         fName = strdup(name);
         fFamily = family;   // we don't own this, so just record the referene
     }

     void destruct() {
         free((char*)fName);
         // we don't own family, so just ignore our reference
     }
 };

 // we use atomic_inc to grow this for each typeface we create
 static int32_t gUniqueFontID;

 // this is the mutex that protects these globals
 static SkMutex gFamilyMutex;
 static FamilyRec* gFamilyHead;
 static SkTDArray<NameFamilyPair> gNameList;

 struct FamilyRec {
     FamilyRec*  fNext;
     SkTypeface* fFaces[4];

     FamilyRec()
     {
         fNext = gFamilyHead;
         memset(fFaces, 0, sizeof(fFaces));
         gFamilyHead = this;
     }
 };

 static SkTypeface* find_best_face(const FamilyRec* family,
                                   SkTypeface::Style style) {
     SkTypeface* const* faces = family->fFaces;

     if (faces[style] != NULL) { // exact match
         return faces[style];
     }
     // look for a matching bold
     style = (SkTypeface::Style)(style ^ SkTypeface::kItalic);
     if (faces[style] != NULL) {
         return faces[style];
     }
     // look for the plain
     if (faces[SkTypeface::kNormal] != NULL) {
         return faces[SkTypeface::kNormal];
     }
     // look for anything
     for (int i = 0; i < 4; i++) {
         if (faces[i] != NULL) {
             return faces[i];
         }
     }
     // should never get here, since the faces list should not be empty
     SkASSERT(!"faces list is empty");
     return NULL;
 }

 static FamilyRec* find_family(const SkTypeface* member) {
     FamilyRec* curr = gFamilyHead;
     while (curr != NULL) {
         for (int i = 0; i < 4; i++) {
             if (curr->fFaces[i] == member) {
                 return curr;
             }
         }
         curr = curr->fNext;
     }
     return NULL;
 }

 /*  Returns the matching typeface, or NULL. If a typeface is found, its refcnt
     is not modified.
  */
 static SkTypeface* find_from_uniqueID(uint32_t uniqueID) {
     FamilyRec* curr = gFamilyHead;
     while (curr != NULL) {
         for (int i = 0; i < 4; i++) {
             SkTypeface* face = curr->fFaces[i];
             if (face != NULL && face->uniqueID() == uniqueID) {
                 return face;
             }
         }
         curr = curr->fNext;
     }
     return NULL;
 }

 /*  Remove reference to this face from its family. If the resulting family
     is empty (has no faces), return that family, otherwise return NULL
 */
 static FamilyRec* remove_from_family(const SkTypeface* face) {
     FamilyRec* family = find_family(face);
     SkASSERT(family->fFaces[face->style()] == face);
     family->fFaces[face->style()] = NULL;

     for (int i = 0; i < 4; i++) {
         if (family->fFaces[i] != NULL) {    // family is non-empty
             return NULL;
         }
     }
     return family;  // return the empty family
 }

 // maybe we should make FamilyRec be doubly-linked
 static void detach_and_delete_family(FamilyRec* family) {
     FamilyRec* curr = gFamilyHead;
     FamilyRec* prev = NULL;

     while (curr != NULL) {
         FamilyRec* next = curr->fNext;
         if (curr == family) {
             if (prev == NULL) {
                 gFamilyHead = next;
             } else {
                 prev->fNext = next;
             }
             SkDELETE(family);
             return;
         }
         prev = curr;
         curr = next;
     }
     SkASSERT(!"Yikes, couldn't find family in our list to remove/delete");
 }

 static SkTypeface* find_typeface(const char name[], SkTypeface::Style style) {
     NameFamilyPair* list = gNameList.begin();
     int             count = gNameList.count();

     int index = SkStrLCSearch(&list[0].fName, count, name, sizeof(list[0]));

     if (index >= 0) {
         return find_best_face(list[index].fFamily, style);
     }
     return NULL;
 }

 static SkTypeface* find_typeface(const SkTypeface* familyMember,
                                  SkTypeface::Style style) {
     const FamilyRec* family = find_family(familyMember);
     return family ? find_best_face(family, style) : NULL;
 }

 static void add_name(const char name[], FamilyRec* family) {
     SkAutoAsciiToLC tolc(name);
     name = tolc.lc();

     NameFamilyPair* list = gNameList.begin();
     int             count = gNameList.count();

     int index = SkStrLCSearch(&list[0].fName, count, name, sizeof(list[0]));

     if (index < 0) {
         list = gNameList.insert(~index);
         list->construct(name, family);
     }
 }

 static void remove_from_names(FamilyRec* emptyFamily)
 {
 #ifdef SK_DEBUG
     for (int i = 0; i < 4; i++) {
         SkASSERT(emptyFamily->fFaces[i] == NULL);
     }
 #endif

     SkTDArray<NameFamilyPair>& list = gNameList;

     // must go backwards when removing
     for (int i = list.count() - 1; i >= 0; --i) {
         NameFamilyPair* pair = &list[i];
         if (pair->fFamily == emptyFamily) {
             pair->destruct();
             list.remove(i);
         }
     }
 }

 ///////////////////////////////////////////////////////////////////////////////

 class FamilyTypeface : public SkTypeface {
 public:
     FamilyTypeface(Style style, bool sysFont, SkTypeface* familyMember)
     : SkTypeface(style, sk_atomic_inc(&gUniqueFontID) + 1) {
         fIsSysFont = sysFont;

         SkAutoMutexAcquire  ac(gFamilyMutex);

         FamilyRec* rec = NULL;
         if (familyMember) {
             rec = find_family(familyMember);
             SkASSERT(rec);
         } else {
             rec = SkNEW(FamilyRec);
         }
         rec->fFaces[style] = this;
     }

     virtual ~FamilyTypeface() {
         SkAutoMutexAcquire  ac(gFamilyMutex);

         // remove us from our family. If the family is now empty, we return
         // that and then remove that family from the name list
         FamilyRec* family = remove_from_family(this);
         if (NULL != family) {
             remove_from_names(family);
             detach_and_delete_family(family);
         }
     }

     bool isSysFont() const { return fIsSysFont; }

     virtual SkStream* openStream() = 0;
     virtual const char* getUniqueString() const = 0;
     virtual const char* getFilePath() const = 0;

 private:
     bool    fIsSysFont;

     typedef SkTypeface INHERITED;
 };

 ///////////////////////////////////////////////////////////////////////////////

 class StreamTypeface : public FamilyTypeface {
 public:
     StreamTypeface(Style style, bool sysFont, SkTypeface* familyMember,
                    SkStream* stream)
     : INHERITED(style, sysFont, familyMember) {
         SkASSERT(stream);
         stream->ref();
         fStream = stream;
     }
     virtual ~StreamTypeface() {
         fStream->unref();
     }

     // overrides
     virtual SkStream* openStream() {
         // we just ref our existing stream, since the caller will call unref()
         // when they are through
         fStream->ref();
         return fStream;
     }
     virtual const char* getUniqueString() const { return NULL; }
     virtual const char* getFilePath() const { return NULL; }

 private:
     SkStream* fStream;

     typedef FamilyTypeface INHERITED;
 };

 class FileTypeface : public FamilyTypeface {
 public:
     FileTypeface(Style style, bool sysFont, SkTypeface* familyMember,
                  const char path[])
     : INHERITED(style, sysFont, familyMember) {
         SkString fullpath;

         if (sysFont) {
             GetFullPathForSysFonts(&fullpath, path);
             path = fullpath.c_str();
         }
         fPath.set(path);
     }

     // overrides
     virtual SkStream* openStream() {
         SkStream* stream = SkNEW_ARGS(SkMMAPStream, (fPath.c_str()));

         // check for failure
         if (stream->getLength() <= 0) {
             SkDELETE(stream);
             // maybe MMAP isn't supported. try FILE
             stream = SkNEW_ARGS(SkFILEStream, (fPath.c_str()));
             if (stream->getLength() <= 0) {
                 SkDELETE(stream);
                 stream = NULL;
             }
         }
         return stream;
     }
     virtual const char* getUniqueString() const {
         const char* str = strrchr(fPath.c_str(), '/');
         if (str) {
             str += 1;   // skip the '/'
         }
         return str;
     }
     virtual const char* getFilePath() const {
         return fPath.c_str();
     }

 private:
     SkString fPath;

     typedef FamilyTypeface INHERITED;
 };

 ///////////////////////////////////////////////////////////////////////////////
 ///////////////////////////////////////////////////////////////////////////////

 static bool get_name_and_style(const char path[], SkString* name,
                                SkTypeface::Style* style, bool isExpected) {
     bool            isFixedWidth;
     SkString        fullpath;
     GetFullPathForSysFonts(&fullpath, path);

     SkMMAPStream stream(fullpath.c_str());
     if (stream.getLength() > 0) {
         *style = find_name_and_attributes(&stream, name, &isFixedWidth);
         return true;
     }
     else {
         SkFILEStream stream(fullpath.c_str());
         if (stream.getLength() > 0) {
             *style = find_name_and_attributes(&stream, name, &isFixedWidth);
             return true;
         }
     }

     if (isExpected) {
         SkDebugf("---- failed to open <%s> as a font\n", fullpath.c_str());
     }
     return false;
 }

 // used to record our notion of the pre-existing fonts
 struct FontInitRec {
     const char*         fFileName;
     const char* const*  fNames;     // null-terminated list
 };

 static const char* gSansNames[] = {
     "sans-serif", "arial", "helvetica", "tahoma", "verdana", NULL
 };

 static const char* gSerifNames[] = {
     "serif", "times", "times new roman", "palatino", "georgia", "baskerville",
     "goudy", "fantasy", "cursive", "ITC Stone Serif", NULL
 };

 static const char* gMonoNames[] = {
     "monospace", "courier", "courier new", "monaco", NULL
 };

 // deliberately empty, but we use the address to identify fallback fonts
 static const char* gFBNames[] = { NULL };

 /*  Fonts must be grouped by family, with the first font in a family having the
     list of names (even if that list is empty), and the following members having
     null for the list. The names list must be NULL-terminated
 */
 static const FontInitRec gSystemFonts[] = {
     { "Arial.ttf",              gSansNames  },
     { "Times.ttf",              gSerifNames  },
     { "samplefont.ttf",              gSansNames  },
 };

 #define DEFAULT_NAMES   gSansNames

 // these globals are assigned (once) by load_system_fonts()
 static FamilyRec* gDefaultFamily;
 static SkTypeface* gDefaultNormal;

 /*  This is sized conservatively, assuming that it will never be a size issue.
     It will be initialized in load_system_fonts(), and will be filled with the
     fontIDs that can be used for fallback consideration, in sorted order (sorted
     meaning element[0] should be used first, then element[1], etc. When we hit
     a fontID==0 in the array, the list is done, hence our allocation size is
     +1 the total number of possible system fonts. Also see NextLogicalFont().
  */
 static uint32_t gFallbackFonts[SK_ARRAY_COUNT(gSystemFonts)+1];

 /*  Called once (ensured by the sentinel check at the beginning of our body).
     Initializes all the globals, and register the system fonts.
  */
 static void load_system_fonts() {
     // check if we've already be called
     if (NULL != gDefaultNormal) {
         return;
     }

     const FontInitRec* rec = gSystemFonts;
     SkTypeface* firstInFamily = NULL;
     int fallbackCount = 0;

     for (size_t i = 0; i < SK_ARRAY_COUNT(gSystemFonts); i++) {
         // if we're the first in a new family, clear firstInFamily
         if (rec[i].fNames != NULL) {
             firstInFamily = NULL;
         }

         SkString name;
         SkTypeface::Style style;

         // we expect all the fonts, except the "fallback" fonts
         bool isExpected = (rec[i].fNames != gFBNames);
         if (!get_name_and_style(rec[i].fFileName, &name, &style, isExpected)) {
             continue;
         }

         SkTypeface* tf = SkNEW_ARGS(FileTypeface,
                                     (style,
                                      true,  // system-font (cannot delete)
                                      firstInFamily, // what family to join
                                      rec[i].fFileName) // filename
                                     );

         if (rec[i].fNames != NULL) {
             // see if this is one of our fallback fonts
             if (rec[i].fNames == gFBNames) {
             //    SkDebugf("---- adding %s as fallback[%d] fontID %d\n",
             //             rec[i].fFileName, fallbackCount, tf->uniqueID());
                 gFallbackFonts[fallbackCount++] = tf->uniqueID();
             }

             firstInFamily = tf;
             FamilyRec* family = find_family(tf);
             const char* const* names = rec[i].fNames;

             // record the default family if this is it
             if (names == DEFAULT_NAMES) {
                 gDefaultFamily = family;
             }
             // add the names to map to this family
             while (*names) {
                 add_name(*names, family);
                 names += 1;
             }
         }
     }

     // do this after all fonts are loaded. This is our default font, and it
     // acts as a sentinel so we only execute load_system_fonts() once
     gDefaultNormal = find_best_face(gDefaultFamily, SkTypeface::kNormal);
     // now terminate our fallback list with the sentinel value
     gFallbackFonts[fallbackCount] = 0;
 }

 ///////////////////////////////////////////////////////////////////////////////

 void SkFontHost::Serialize(const SkTypeface* face, SkWStream* stream) {
     const char* name = ((FamilyTypeface*)face)->getUniqueString();

     stream->write8((uint8_t)face->style());

     if (NULL == name || 0 == *name) {
         stream->writePackedUInt(0);
 //        SkDebugf("--- fonthost serialize null\n");
     } else {
         uint32_t len = strlen(name);
         stream->writePackedUInt(len);
         stream->write(name, len);
 //      SkDebugf("--- fonthost serialize <%s> %d\n", name, face->style());
     }
 }

 SkTypeface* SkFontHost::Deserialize(SkStream* stream) {
     load_system_fonts();

     int style = stream->readU8();

     int len = stream->readPackedUInt();
     if (len > 0) {
         SkString str;
         str.resize(len);
         stream->read(str.writable_str(), len);

         const FontInitRec* rec = gSystemFonts;
         for (size_t i = 0; i < SK_ARRAY_COUNT(gSystemFonts); i++) {
             if (strcmp(rec[i].fFileName, str.c_str()) == 0) {
                 // backup until we hit the fNames
                 for (int j = i; j >= 0; --j) {
                     if (rec[j].fNames != NULL) {
                         return SkFontHost::CreateTypeface(NULL,
                                     rec[j].fNames[0], NULL, 0, (SkTypeface::Style)style);
                     }
                 }
             }
         }
     }
     return NULL;
 }

 ///////////////////////////////////////////////////////////////////////////////

 SkTypeface* SkFontHost::CreateTypeface(const SkTypeface* familyFace,
                                        const char familyName[],
                                        const void* data, size_t bytelength,
                                        SkTypeface::Style style) {
     load_system_fonts();

     SkAutoMutexAcquire  ac(gFamilyMutex);

     // clip to legal style bits
     style = (SkTypeface::Style)(style & SkTypeface::kBoldItalic);

     SkTypeface* tf = NULL;

     if (NULL != familyFace) {
         tf = find_typeface(familyFace, style);
     } else if (NULL != familyName) {
 //        SkDebugf("======= familyName <%s>\n", familyName);
         tf = find_typeface(familyName, style);
     }

     if (NULL == tf) {
         tf = find_best_face(gDefaultFamily, style);
     }

     // we ref(), since the symantic is to return a new instance
     tf->ref();
     return tf;
 }

 bool SkFontHost::ValidFontID(uint32_t fontID) {
     SkAutoMutexAcquire  ac(gFamilyMutex);

     return find_from_uniqueID(fontID) != NULL;
 }

 SkStream* SkFontHost::OpenStream(uint32_t fontID) {
     SkAutoMutexAcquire  ac(gFamilyMutex);

     FamilyTypeface* tf = (FamilyTypeface*)find_from_uniqueID(fontID);
     SkStream* stream = tf ? tf->openStream() : NULL;

     if (stream && stream->getLength() == 0) {
         stream->unref();
         stream = NULL;
     }
     return stream;
 }

 #if 0
 SkAdvancedTypefaceMetrics* SkFontHost::GetAdvancedTypefaceMetrics(
         uint32_t fontID,
         SkAdvancedTypefaceMetrics::PerGlyphInfo perGlyphInfo) {
     SkASSERT(!"SkFontHost::GetAdvancedTypefaceMetrics unimplemented");
     return NULL;
 }
 #endif

 size_t SkFontHost::GetFileName(SkFontID fontID, char path[], size_t length,
                                int32_t* index) {
     SkAutoMutexAcquire  ac(gFamilyMutex);

     FamilyTypeface* tf = (FamilyTypeface*)find_from_uniqueID(fontID);
     const char* src = tf ? tf->getFilePath() : NULL;

     if (src) {
         size_t size = strlen(src);
         if (path) {
             memcpy(path, src, SkMin32(size, length));
         }
         if (index) {
             *index = 0; // we don't have collections (yet)
         }
         return size;
     } else {
         return 0;
     }
 }

 SkFontID SkFontHost::NextLogicalFont(SkFontID currFontID, SkFontID origFontID) {
     load_system_fonts();

     /*  First see if fontID is already one of our fallbacks. If so, return
         its successor. If fontID is not in our list, then return the first one
         in our list. Note: list is zero-terminated, and returning zero means
         we have no more fonts to use for fallbacks.
      */
     const uint32_t* list = gFallbackFonts;
     for (int i = 0; list[i] != 0; i++) {
         if (list[i] == currFontID) {
             return list[i+1];
         }
     }
     return list[0];
 }

 ///////////////////////////////////////////////////////////////////////////////

 SkTypeface* SkFontHost::CreateTypefaceFromStream(SkStream* stream) {
     if (NULL == stream || stream->getLength() <= 0) {
         return NULL;
     }

     bool     isFixedWidth;
     SkString name;
     SkTypeface::Style style = find_name_and_attributes(stream, &name,
                                                        &isFixedWidth);

     return SkNEW_ARGS(StreamTypeface, (style, false, NULL, stream));
 }

 SkTypeface* SkFontHost::CreateTypefaceFromFile(const char path[]) {
     SkStream* stream = SkNEW_ARGS(SkMMAPStream, (path));
     SkTypeface* face = SkFontHost::CreateTypefaceFromStream(stream);
     // since we created the stream, we let go of our ref() here
     stream->unref();
     return face;
 }

 ///////////////////////////////////////////////////////////////////////////////

 size_t SkFontHost::ShouldPurgeFontCache(size_t sizeAllocatedSoFar) {
     if (sizeAllocatedSoFar > FONT_CACHE_MEMORY_BUDGET)
         return sizeAllocatedSoFar - FONT_CACHE_MEMORY_BUDGET;
     else
         return 0;   // nothing to do
 }
	/*
	* Copyright (C) 2011 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "SkFontHost.h"
	#include "SkDescriptor.h"
	#include "SkMMapStream.h"
	#include "SkPaint.h"
	#include "SkString.h"
	#include "SkStream.h"
	#include "SkThread.h"
	#include "SkTSearch.h"
	#include <stdio.h>

	#define FONT_CACHE_MEMORY_BUDGET (768 * 1024)

	#ifdef SK_BUILD_FOR_MAC
	#define SK_FONT_FILE_PREFIX "/Library/Fonts/"
	#else
	#define SK_FONT_FILE_PREFIX "/skimages/"
	#endif

	SkTypeface::Style find_name_and_attributes(SkStream* stream, SkString* name,
	bool* isFixedWidth);

	static void GetFullPathForSysFonts(SkString* full, const char name[]) {
	full->set(SK_FONT_FILE_PREFIX);
	full->append(name);
	}

	///////////////////////////////////////////////////////////////////////////////

	struct FamilyRec;

	/* This guy holds a mapping of a name -> family, used for looking up fonts.
	Since it is stored in a stretchy array that doesn't preserve object
	semantics, we don't use constructor/destructors, but just have explicit
	helpers to manage our internal bookkeeping.
	*/
	struct NameFamilyPair {
	const char* fName; // we own this
	FamilyRec* fFamily; // we don't own this, we just reference it

	void construct(const char name[], FamilyRec* family) {
	fName = strdup(name);
	fFamily = family; // we don't own this, so just record the referene
	}

	void destruct() {
	free((char*)fName);
	// we don't own family, so just ignore our reference
	}
	};

	// we use atomic_inc to grow this for each typeface we create
	static int32_t gUniqueFontID;

	// this is the mutex that protects these globals
	static SkMutex gFamilyMutex;
	static FamilyRec* gFamilyHead;
	static SkTDArray<NameFamilyPair> gNameList;

	struct FamilyRec {
	FamilyRec* fNext;
	SkTypeface* fFaces[4];

	FamilyRec()
	{
	fNext = gFamilyHead;
	memset(fFaces, 0, sizeof(fFaces));
	gFamilyHead = this;
	}
	};

	static SkTypeface* find_best_face(const FamilyRec* family,
	SkTypeface::Style style) {
	SkTypeface* const* faces = family->fFaces;

	if (faces[style] != NULL) { // exact match
	return faces[style];
	}
	// look for a matching bold
	style = (SkTypeface::Style)(style ^ SkTypeface::kItalic);
	if (faces[style] != NULL) {
	return faces[style];
	}
	// look for the plain
	if (faces[SkTypeface::kNormal] != NULL) {
	return faces[SkTypeface::kNormal];
	}
	// look for anything
	for (int i = 0; i < 4; i++) {
	if (faces[i] != NULL) {
	return faces[i];
	}
	}
	// should never get here, since the faces list should not be empty
	SkASSERT(!"faces list is empty");
	return NULL;
	}

	static FamilyRec* find_family(const SkTypeface* member) {
	FamilyRec* curr = gFamilyHead;
	while (curr != NULL) {
	for (int i = 0; i < 4; i++) {
	if (curr->fFaces[i] == member) {
	return curr;
	}
	}
	curr = curr->fNext;
	}
	return NULL;
	}

	/* Returns the matching typeface, or NULL. If a typeface is found, its refcnt
	is not modified.
	*/
	static SkTypeface* find_from_uniqueID(uint32_t uniqueID) {
	FamilyRec* curr = gFamilyHead;
	while (curr != NULL) {
	for (int i = 0; i < 4; i++) {
	SkTypeface* face = curr->fFaces[i];
	if (face != NULL && face->uniqueID() == uniqueID) {
	return face;
	}
	}
	curr = curr->fNext;
	}
	return NULL;
	}

	/* Remove reference to this face from its family. If the resulting family
	is empty (has no faces), return that family, otherwise return NULL
	*/
	static FamilyRec* remove_from_family(const SkTypeface* face) {
	FamilyRec* family = find_family(face);
	SkASSERT(family->fFaces[face->style()] == face);
	family->fFaces[face->style()] = NULL;

	for (int i = 0; i < 4; i++) {
	if (family->fFaces[i] != NULL) { // family is non-empty
	return NULL;
	}
	}
	return family; // return the empty family
	}

	// maybe we should make FamilyRec be doubly-linked
	static void detach_and_delete_family(FamilyRec* family) {
	FamilyRec* curr = gFamilyHead;
	FamilyRec* prev = NULL;

	while (curr != NULL) {
	FamilyRec* next = curr->fNext;
	if (curr == family) {
	if (prev == NULL) {
	gFamilyHead = next;
	} else {
	prev->fNext = next;
	}
	SkDELETE(family);
	return;
	}
	prev = curr;
	curr = next;
	}
	SkASSERT(!"Yikes, couldn't find family in our list to remove/delete");
	}

	static SkTypeface* find_typeface(const char name[], SkTypeface::Style style) {
	NameFamilyPair* list = gNameList.begin();
	int count = gNameList.count();

	int index = SkStrLCSearch(&list[0].fName, count, name, sizeof(list[0]));

	if (index >= 0) {
	return find_best_face(list[index].fFamily, style);
	}
	return NULL;
	}

	static SkTypeface* find_typeface(const SkTypeface* familyMember,
	SkTypeface::Style style) {
	const FamilyRec* family = find_family(familyMember);
	return family ? find_best_face(family, style) : NULL;
	}

	static void add_name(const char name[], FamilyRec* family) {
	SkAutoAsciiToLC tolc(name);
	name = tolc.lc();

	NameFamilyPair* list = gNameList.begin();
	int count = gNameList.count();

	int index = SkStrLCSearch(&list[0].fName, count, name, sizeof(list[0]));

	if (index < 0) {
	list = gNameList.insert(~index);
	list->construct(name, family);
	}
	}

	static void remove_from_names(FamilyRec* emptyFamily)
	{
	#ifdef SK_DEBUG
	for (int i = 0; i < 4; i++) {
	SkASSERT(emptyFamily->fFaces[i] == NULL);
	}
	#endif

	SkTDArray<NameFamilyPair>& list = gNameList;

	// must go backwards when removing
	for (int i = list.count() - 1; i >= 0; --i) {
	NameFamilyPair* pair = &list[i];
	if (pair->fFamily == emptyFamily) {
	pair->destruct();
	list.remove(i);
	}
	}
	}

	///////////////////////////////////////////////////////////////////////////////

	class FamilyTypeface : public SkTypeface {
	public:
	FamilyTypeface(Style style, bool sysFont, SkTypeface* familyMember)
	: SkTypeface(style, sk_atomic_inc(&gUniqueFontID) + 1) {
	fIsSysFont = sysFont;

	SkAutoMutexAcquire ac(gFamilyMutex);

	FamilyRec* rec = NULL;
	if (familyMember) {
	rec = find_family(familyMember);
	SkASSERT(rec);
	} else {
	rec = SkNEW(FamilyRec);
	}
	rec->fFaces[style] = this;
	}

	virtual ~FamilyTypeface() {
	SkAutoMutexAcquire ac(gFamilyMutex);

	// remove us from our family. If the family is now empty, we return
	// that and then remove that family from the name list
	FamilyRec* family = remove_from_family(this);
	if (NULL != family) {
	remove_from_names(family);
	detach_and_delete_family(family);
	}
	}

	bool isSysFont() const { return fIsSysFont; }

	virtual SkStream* openStream() = 0;
	virtual const char* getUniqueString() const = 0;
	virtual const char* getFilePath() const = 0;

	private:
	bool fIsSysFont;

	typedef SkTypeface INHERITED;
	};

	///////////////////////////////////////////////////////////////////////////////

	class StreamTypeface : public FamilyTypeface {
	public:
	StreamTypeface(Style style, bool sysFont, SkTypeface* familyMember,
	SkStream* stream)
	: INHERITED(style, sysFont, familyMember) {
	SkASSERT(stream);
	stream->ref();
	fStream = stream;
	}
	virtual ~StreamTypeface() {
	fStream->unref();
	}

	// overrides
	virtual SkStream* openStream() {
	// we just ref our existing stream, since the caller will call unref()
	// when they are through
	fStream->ref();
	return fStream;
	}
	virtual const char* getUniqueString() const { return NULL; }
	virtual const char* getFilePath() const { return NULL; }

	private:
	SkStream* fStream;

	typedef FamilyTypeface INHERITED;
	};

	class FileTypeface : public FamilyTypeface {
	public:
	FileTypeface(Style style, bool sysFont, SkTypeface* familyMember,
	const char path[])
	: INHERITED(style, sysFont, familyMember) {
	SkString fullpath;

	if (sysFont) {
	GetFullPathForSysFonts(&fullpath, path);
	path = fullpath.c_str();
	}
	fPath.set(path);
	}

	// overrides
	virtual SkStream* openStream() {
	SkStream* stream = SkNEW_ARGS(SkMMAPStream, (fPath.c_str()));

	// check for failure
	if (stream->getLength() <= 0) {
	SkDELETE(stream);
	// maybe MMAP isn't supported. try FILE
	stream = SkNEW_ARGS(SkFILEStream, (fPath.c_str()));
	if (stream->getLength() <= 0) {
	SkDELETE(stream);
	stream = NULL;
	}
	}
	return stream;
	}
	virtual const char* getUniqueString() const {
	const char* str = strrchr(fPath.c_str(), '/');
	if (str) {
	str += 1; // skip the '/'
	}
	return str;
	}
	virtual const char* getFilePath() const {
	return fPath.c_str();
	}

	private:
	SkString fPath;

	typedef FamilyTypeface INHERITED;
	};

	///////////////////////////////////////////////////////////////////////////////
	///////////////////////////////////////////////////////////////////////////////

	static bool get_name_and_style(const char path[], SkString* name,
	SkTypeface::Style* style, bool isExpected) {
	bool isFixedWidth;
	SkString fullpath;
	GetFullPathForSysFonts(&fullpath, path);

	SkMMAPStream stream(fullpath.c_str());
	if (stream.getLength() > 0) {
	*style = find_name_and_attributes(&stream, name, &isFixedWidth);
	return true;
	}
	else {
	SkFILEStream stream(fullpath.c_str());
	if (stream.getLength() > 0) {
	*style = find_name_and_attributes(&stream, name, &isFixedWidth);
	return true;
	}
	}

	if (isExpected) {
	SkDebugf("---- failed to open <%s> as a font\n", fullpath.c_str());
	}
	return false;
	}

	// used to record our notion of the pre-existing fonts
	struct FontInitRec {
	const char* fFileName;
	const char* const* fNames; // null-terminated list
	};

	static const char* gSansNames[] = {
	"sans-serif", "arial", "helvetica", "tahoma", "verdana", NULL
	};

	static const char* gSerifNames[] = {
	"serif", "times", "times new roman", "palatino", "georgia", "baskerville",
	"goudy", "fantasy", "cursive", "ITC Stone Serif", NULL
	};

	static const char* gMonoNames[] = {
	"monospace", "courier", "courier new", "monaco", NULL
	};

	// deliberately empty, but we use the address to identify fallback fonts
	static const char* gFBNames[] = { NULL };

	/* Fonts must be grouped by family, with the first font in a family having the
	list of names (even if that list is empty), and the following members having
	null for the list. The names list must be NULL-terminated
	*/
	static const FontInitRec gSystemFonts[] = {
	{ "Arial.ttf", gSansNames },
	{ "Times.ttf", gSerifNames },
	{ "samplefont.ttf", gSansNames },
	};

	#define DEFAULT_NAMES gSansNames

	// these globals are assigned (once) by load_system_fonts()
	static FamilyRec* gDefaultFamily;
	static SkTypeface* gDefaultNormal;

	/* This is sized conservatively, assuming that it will never be a size issue.
	It will be initialized in load_system_fonts(), and will be filled with the
	fontIDs that can be used for fallback consideration, in sorted order (sorted
	meaning element[0] should be used first, then element[1], etc. When we hit
	a fontID==0 in the array, the list is done, hence our allocation size is
	+1 the total number of possible system fonts. Also see NextLogicalFont().
	*/
	static uint32_t gFallbackFonts[SK_ARRAY_COUNT(gSystemFonts)+1];

	/* Called once (ensured by the sentinel check at the beginning of our body).
	Initializes all the globals, and register the system fonts.
	*/
	static void load_system_fonts() {
	// check if we've already be called
	if (NULL != gDefaultNormal) {
	return;
	}

	const FontInitRec* rec = gSystemFonts;
	SkTypeface* firstInFamily = NULL;
	int fallbackCount = 0;

	for (size_t i = 0; i < SK_ARRAY_COUNT(gSystemFonts); i++) {
	// if we're the first in a new family, clear firstInFamily
	if (rec[i].fNames != NULL) {
	firstInFamily = NULL;
	}

	SkString name;
	SkTypeface::Style style;

	// we expect all the fonts, except the "fallback" fonts
	bool isExpected = (rec[i].fNames != gFBNames);
	if (!get_name_and_style(rec[i].fFileName, &name, &style, isExpected)) {
	continue;
	}

	SkTypeface* tf = SkNEW_ARGS(FileTypeface,
	(style,
	true, // system-font (cannot delete)
	firstInFamily, // what family to join
	rec[i].fFileName) // filename
	);

	if (rec[i].fNames != NULL) {
	// see if this is one of our fallback fonts
	if (rec[i].fNames == gFBNames) {
	// SkDebugf("---- adding %s as fallback[%d] fontID %d\n",
	// rec[i].fFileName, fallbackCount, tf->uniqueID());
	gFallbackFonts[fallbackCount++] = tf->uniqueID();
	}

	firstInFamily = tf;
	FamilyRec* family = find_family(tf);
	const char* const* names = rec[i].fNames;

	// record the default family if this is it
	if (names == DEFAULT_NAMES) {
	gDefaultFamily = family;
	}
	// add the names to map to this family
	while (*names) {
	add_name(*names, family);
	names += 1;
	}
	}
	}

	// do this after all fonts are loaded. This is our default font, and it
	// acts as a sentinel so we only execute load_system_fonts() once
	gDefaultNormal = find_best_face(gDefaultFamily, SkTypeface::kNormal);
	// now terminate our fallback list with the sentinel value
	gFallbackFonts[fallbackCount] = 0;
	}

	///////////////////////////////////////////////////////////////////////////////

	void SkFontHost::Serialize(const SkTypeface* face, SkWStream* stream) {
	const char* name = ((FamilyTypeface*)face)->getUniqueString();

	stream->write8((uint8_t)face->style());

	if (NULL == name \|\| 0 == *name) {
	stream->writePackedUInt(0);
	// SkDebugf("--- fonthost serialize null\n");
	} else {
	uint32_t len = strlen(name);
	stream->writePackedUInt(len);
	stream->write(name, len);
	// SkDebugf("--- fonthost serialize <%s> %d\n", name, face->style());
	}
	}

	SkTypeface* SkFontHost::Deserialize(SkStream* stream) {
	load_system_fonts();

	int style = stream->readU8();

	int len = stream->readPackedUInt();
	if (len > 0) {
	SkString str;
	str.resize(len);
	stream->read(str.writable_str(), len);

	const FontInitRec* rec = gSystemFonts;
	for (size_t i = 0; i < SK_ARRAY_COUNT(gSystemFonts); i++) {
	if (strcmp(rec[i].fFileName, str.c_str()) == 0) {
	// backup until we hit the fNames
	for (int j = i; j >= 0; --j) {
	if (rec[j].fNames != NULL) {
	return SkFontHost::CreateTypeface(NULL,
	rec[j].fNames[0], NULL, 0, (SkTypeface::Style)style);
	}
	}
	}
	}
	}
	return NULL;
	}

	///////////////////////////////////////////////////////////////////////////////

	SkTypeface* SkFontHost::CreateTypeface(const SkTypeface* familyFace,
	const char familyName[],
	const void* data, size_t bytelength,
	SkTypeface::Style style) {
	load_system_fonts();

	SkAutoMutexAcquire ac(gFamilyMutex);

	// clip to legal style bits
	style = (SkTypeface::Style)(style & SkTypeface::kBoldItalic);

	SkTypeface* tf = NULL;

	if (NULL != familyFace) {
	tf = find_typeface(familyFace, style);
	} else if (NULL != familyName) {
	// SkDebugf("======= familyName <%s>\n", familyName);
	tf = find_typeface(familyName, style);
	}

	if (NULL == tf) {
	tf = find_best_face(gDefaultFamily, style);
	}

	// we ref(), since the symantic is to return a new instance
	tf->ref();
	return tf;
	}

	bool SkFontHost::ValidFontID(uint32_t fontID) {
	SkAutoMutexAcquire ac(gFamilyMutex);

	return find_from_uniqueID(fontID) != NULL;
	}

	SkStream* SkFontHost::OpenStream(uint32_t fontID) {
	SkAutoMutexAcquire ac(gFamilyMutex);

	FamilyTypeface* tf = (FamilyTypeface*)find_from_uniqueID(fontID);
	SkStream* stream = tf ? tf->openStream() : NULL;

	if (stream && stream->getLength() == 0) {
	stream->unref();
	stream = NULL;
	}
	return stream;
	}

	#if 0
	SkAdvancedTypefaceMetrics* SkFontHost::GetAdvancedTypefaceMetrics(
	uint32_t fontID,
	SkAdvancedTypefaceMetrics::PerGlyphInfo perGlyphInfo) {
	SkASSERT(!"SkFontHost::GetAdvancedTypefaceMetrics unimplemented");
	return NULL;
	}
	#endif

	size_t SkFontHost::GetFileName(SkFontID fontID, char path[], size_t length,
	int32_t* index) {
	SkAutoMutexAcquire ac(gFamilyMutex);

	FamilyTypeface* tf = (FamilyTypeface*)find_from_uniqueID(fontID);
	const char* src = tf ? tf->getFilePath() : NULL;

	if (src) {
	size_t size = strlen(src);
	if (path) {
	memcpy(path, src, SkMin32(size, length));
	}
	if (index) {
	*index = 0; // we don't have collections (yet)
	}
	return size;
	} else {
	return 0;
	}
	}

	SkFontID SkFontHost::NextLogicalFont(SkFontID currFontID, SkFontID origFontID) {
	load_system_fonts();

	/* First see if fontID is already one of our fallbacks. If so, return
	its successor. If fontID is not in our list, then return the first one
	in our list. Note: list is zero-terminated, and returning zero means
	we have no more fonts to use for fallbacks.
	*/
	const uint32_t* list = gFallbackFonts;
	for (int i = 0; list[i] != 0; i++) {
	if (list[i] == currFontID) {
	return list[i+1];
	}
	}
	return list[0];
	}

	///////////////////////////////////////////////////////////////////////////////

	SkTypeface* SkFontHost::CreateTypefaceFromStream(SkStream* stream) {
	if (NULL == stream \|\| stream->getLength() <= 0) {
	return NULL;
	}

	bool isFixedWidth;
	SkString name;
	SkTypeface::Style style = find_name_and_attributes(stream, &name,
	&isFixedWidth);

	return SkNEW_ARGS(StreamTypeface, (style, false, NULL, stream));
	}

	SkTypeface* SkFontHost::CreateTypefaceFromFile(const char path[]) {
	SkStream* stream = SkNEW_ARGS(SkMMAPStream, (path));
	SkTypeface* face = SkFontHost::CreateTypefaceFromStream(stream);
	// since we created the stream, we let go of our ref() here
	stream->unref();
	return face;
	}

	///////////////////////////////////////////////////////////////////////////////

	size_t SkFontHost::ShouldPurgeFontCache(size_t sizeAllocatedSoFar) {
	if (sizeAllocatedSoFar > FONT_CACHE_MEMORY_BUDGET)
	return sizeAllocatedSoFar - FONT_CACHE_MEMORY_BUDGET;
	else
	return 0; // nothing to do
	}