WIP SkFontMgrAndroid

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
new file mode 100644
index 0000000000000000000000000000000000000000..f44f093b7a9f168563bdf60d33825b5b1c3156a7
--- /dev/null
+++ b/src/ports/SkFontMgr_android.cpp
@@ -0,0 +1,399 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkFontConfigParser_android.h"
+#include "SkFontDescriptor.h"
+#include "SkFontHost_FreeType_common.h"
+#include "SkFontMgr.h"
+#include "SkFontStyle.h"
+#include "SkStream.h"
+#include "SkTDArray.h"
+#include "SkTSearch.h"
+#include "SkTypeface.h"
+#include "SkTypefaceCache.h"
+
+#include <limits>
+#include <stdlib.h>
+
+// TODO: document isLocal in getFontDescriptor:

[bungeman-skia, 2014/07/21 15:48:00]

We need to just change the name to 'shouldSerialize'. It really isn't about who
knows about the font, but whether the typeface thinks that it needs to be
serialized for correct use in a pipe that cannot keep the SkTypeface pointer.

[bungeman-skia, 2014/07/22 17:26:53]

Acknowledged.

+//   isLocal TRUE: this is a copy of the font local to my installation,
+// I need to serialize it.
+//   isLocal FALSE: this font is globally available - installed as part
+// of the system image - so I can just refer to it and the recipient is
+// guaranteed to have it available.
+
+// TODO?
+bool find_name_and_attributes(SkStream* stream, SkString* name,

[bungeman-skia, 2014/07/21 15:48:00]

This is now gone, replaced by SkTypeface_FreeType::Scan (it also takes a ttc
index now).

[bungeman-skia, 2014/07/22 17:26:52]

Done.

+                              SkTypeface::Style* style, bool* isFixedPitch);
+
+class SkTypeface_Android : public SkTypeface_FreeType {
+public:
+    SkTypeface_Android(Style style,
+                       bool isFixedPitch,
+                       const SkString familyName)
+        : INHERITED(style, SkTypefaceCache::NewFontID(), isFixedPitch)
+        , fFamilyName(familyName) {
+    }
+
+    const SkString& name () const { return fFamilyName; }

[bungeman-skia, 2014/07/21 15:48:00]

nit: name()

[bungeman-skia, 2014/07/22 17:26:53]

Done.

+
+protected:
+    SkString fFamilyName;
+

[bungeman-skia, 2014/07/21 15:48:00]

We can put an fTtcIndex right here, and use it as needed to get ttc goodness

[bungeman-skia, 2014/07/22 17:26:53]

Done.

+private:
+    typedef SkTypeface_FreeType INHERITED;
+};
+
+/// On Android, system fonts are installed on the device; the XML catalogs
+/// are read by SkFontConfigParser_android. We can't safely duplicate()
+/// them, so re-open them every time we need a fresh stream

[bungeman-skia, 2014/07/21 15:48:00]

This comment (or at least most of it) seems more attached to 'onOpenStream',
maybe it should go closer to it?

[bungeman-skia, 2014/07/22 17:26:53]

Done.

+class SkTypeface_AndroidSystem : public SkTypeface_Android {
+public:
+    SkTypeface_AndroidSystem(Style style,
+                             bool isFixedPitch,
+                             const SkString pathName,
+                             const SkString familyName)
+        : INHERITED(style, isFixedPitch, familyName)
+        , fPathName(pathName) {
+    }
+
+    void onGetFontDescriptor(SkFontDescriptor* desc, bool* isLocal)
+            const SK_OVERRIDE {
+        SkASSERT(desc);
+        SkASSERT(isLocal);
+        desc->setFamilyName(fFamilyName.c_str());
+        desc->setFontFileName(fPathName.c_str());
+        *isLocal = false;
+    }
+    SkStream* onOpenStream(int* ttcIndex) const SK_OVERRIDE {
+        *ttcIndex = 0; // TODO
+        return SkStream::NewFromFile(fPathName.c_str());
+    }
+
+private:
+    SkString fPathName;
+
+    typedef SkTypeface_Android INHERITED;
+};
+
+/// On Android, non-system fonts can be supplied through a SkStream,
+/// which we can cache in memory and duplicate() when necessary. We
+/// don't have a pathname for these fonts, however.
+class SkTypeface_AndroidStream : public SkTypeface_Android {
+public:
+    SkTypeface_AndroidStream(Style style,
+                             bool isFixedPitch,
+                             SkStream* stream,
+                             const SkString familyName)
+        : INHERITED(style, isFixedPitch, familyName)
+        , fStream(stream) {
+    }
+
+    void onGetFontDescriptor(SkFontDescriptor* desc, bool* isLocal)
+            const SK_OVERRIDE {
+        SkASSERT(desc);
+        SkASSERT(isLocal);
+        desc->setFamilyName(fFamilyName.c_str());
+        desc->setFontFileName(NULL);
+        *isLocal = true;
+    }
+
+    SkStream* onOpenStream(int* ttcIndex) const SK_OVERRIDE {
+        *ttcIndex = 0; // TODO
+        return fStream->duplicate();
+    }
+
+private:
+    SkAutoTUnref<SkStream> fStream;
+
+    typedef SkTypeface_Android INHERITED;
+};
+
+// TODO - need another implementation of Typeface_Android to hold faces
+// created from Streams; that one can call duplicate().

[bungeman-skia, 2014/07/21 15:48:00]

Looks like you've done this todo?

[bungeman-skia, 2014/07/22 17:26:53]

Done.

+
+namespace {
+
+#ifndef SK_FONT_FILE_PREFIX
+#define SK_FONT_FILE_PREFIX          "/fonts/"
+#endif
+
+void get_path_for_sys_fonts(SkString* full, const SkString& name) {
+    full->set(getenv("ANDROID_ROOT"));
+    full->append(SK_FONT_FILE_PREFIX);
+    full->append(name);
+}
+
+}
+
+class SkFontStyleSet_Android : public SkFontStyleSet {
+public:
+    explicit SkFontStyleSet_Android(FontFamily* family) :
+        fFontFamily(family) {
+
+        // TODO? make this lazy
+
+        for (int i = 0; i < family->fFontFiles.count(); ++i) {
+            const SkString& fileName = family->fFontFiles[i].fFileName;

[bungeman-skia, 2014/07/21 15:48:00]

We have SkTTCFHeader.h and can write some simple code to sniff if it's a TTC and
how many fonts are in the TTC so we can pass the indexes in. Unless it's
supposed to be up to the FontFamily to contain the indexes, in which case we can
just blindly pass that around.

[bungeman-skia, 2014/07/22 17:26:53]

Done.

+            SkString pathName;
+            get_path_for_sys_fonts(&pathName, fileName);
+
+            SkAutoTUnref<SkStream> stream(SkStream::NewFromFile(pathName.c_str()));
+            SkASSERT(stream.get());
+            bool isFixedWidth;
+            SkTypeface::Style style;
+            SkString fontName;
+            find_name_and_attributes(stream.get(), &fontName, &style, &isFixedWidth);

[bungeman-skia, 2014/07/21 15:48:00]

We should check (at least assert or message) the return value of this for
failure.

[bungeman-skia, 2014/07/22 17:26:53]

Done.

+            fStyles.push_back().reset(SkNEW_ARGS(SkTypeface_AndroidSystem,
+                                                 (style, isFixedWidth,
+                                                  pathName, fontName)));
+        }
+    }
+
+    int count() SK_OVERRIDE {
+        return fStyles.count();
+    }
+    void getStyle(int index, SkFontStyle* style, SkString* name) SK_OVERRIDE {
+        SkASSERT(index >= 0 && index < fStyles.count());

[bungeman-skia, 2014/07/21 15:48:00]

Since this is public API, I think we should probably just be runtime checking
this always.

[bungeman-skia, 2014/07/22 17:26:52]

Done.

+        SkASSERT(style);
+        SkASSERT(name);

[bungeman-skia, 2014/07/21 15:48:01]

These need to be like 'if (style) ...'. Any subset may be NULL, indicating that
they aren't interested in that value.

[bungeman-skia, 2014/07/22 17:26:53]

Done.

+        *style = this->style(index);
+        name->reset();  // UNDEFINED SEMANTICS?

[bungeman-skia, 2014/07/21 15:48:00]

I think this is right for when it isn't supported (which is hardly ever). We'll
need to back-fill this later I think.

[bungeman-skia, 2014/07/22 17:26:52]

Acknowledged.

+    }
+    SkTypeface* createTypeface(int index) SK_OVERRIDE {
+        SkASSERT(index >= 0 && index < fStyles.count());
+        return SkRef(fStyles[index].get());
+    }
+
+    /// Find the typeface in this style set that most closely matches the given pattern.
+    /// TODO: consider replacing with SkStyleSet_Indirect::matchStyle(); this simpler
+    /// version using match_score() passes all our tests.
+    SkTypeface* matchStyle(const SkFontStyle& pattern) SK_OVERRIDE {
+        if (0 == fStyles.count()) {
+            return NULL;
+        }
+        SkTypeface* closest = fStyles[0];
+        int minScore = std::numeric_limits<int>::max();
+        for (int i = 0; i < fStyles.count(); ++i) {
+            SkFontStyle style = this->style(i);
+            int score = match_score(pattern, style);
+            if (score < minScore) {
+                closest = fStyles[i];
+                minScore = score;
+            }
+        }
+        return SkRef(closest);
+    }
+
+private:
+    SkFontStyle style(int index) {
+        return SkFontStyle(this->weight(index), SkFontStyle::kNormal_Width,
+                           this->slant(index));
+    }
+    SkFontStyle::Weight weight(int index) {
+        if (fStyles[index]->isBold()) return SkFontStyle::kBold_Weight;
+        return SkFontStyle::kNormal_Weight;
+    }
+    SkFontStyle::Slant slant(int index) {
+        if (fStyles[index]->isItalic()) return SkFontStyle::kItalic_Slant;
+        return SkFontStyle::kUpright_Slant;
+    }
+    static int match_score(const SkFontStyle& pattern, const SkFontStyle& candidate) {
+        int score = 0;
+        score += abs((pattern.width() - candidate.width()) * 100);
+        score += abs((pattern.isItalic() == candidate.isItalic()) ? 0 : 1000);
+        score += abs(pattern.weight() - candidate.weight());
+        return score;
+    }
+
+
+    FontFamily* fFontFamily;
+    SkTArray<SkAutoTUnref<SkTypeface>, true> fStyles;
+
+    friend struct NameToFamily;
+    friend class SkFontMgr_Android;
+
+    typedef SkFontStyleSet INHERITED;
+};
+
+/** On Android a single family can have many names, but our API assumes unique names.
+    Map names to the back end so that all names for a given family refer to the same
+    (non-replicated) set of typefaces.
+    SkTDict<> doesn't let us do index-based lookup, so we write our own mapping. */
+struct NameToFamily {
+    SkString name;
+    SkFontStyleSet_Android* styleSet;
+};
+
+class SkFontMgr_Android : public SkFontMgr {
+public:
+    SkFontMgr_Android() {
+        SkTDArray<FontFamily*> fontFamilies;
+        SkFontConfigParser::GetFontFamilies(fontFamilies);
+        this->buildNameToFamilyMap(fontFamilies);
+        this->findDefaultFont();
+    }
+
+protected:
+    /// On Android: Returns not how many families we have, but how many unique names
+    /// exist among the families.
+    virtual int onCountFamilies() const SK_OVERRIDE {
+        return fNameToFamilyMap.count();
+    }
+    virtual void onGetFamilyName(int index, SkString* familyName) const SK_OVERRIDE {
+        SkASSERT(index >= 0 && index < fNameToFamilyMap.count());
+        familyName->set(fNameToFamilyMap[index].name);
+    }
+    virtual SkFontStyleSet* onCreateStyleSet(int index) const SK_OVERRIDE {
+        SkASSERT(index >= 0 && index < fNameToFamilyMap.count());
+        return SkRef(fNameToFamilyMap[index].styleSet);
+    }
+
+    virtual SkFontStyleSet* onMatchFamily(const char familyName[]) const SK_OVERRIDE {
+        if (!familyName) {
+            return NULL;
+        }
+        SkAutoAsciiToLC tolc(familyName);
+        for (int i = 0; i < fNameToFamilyMap.count(); ++i) {
+            if (fNameToFamilyMap[i].name.equals(tolc.lc())) {
+                return SkRef(fNameToFamilyMap[i].styleSet);
+            }
+        }
+        return NULL;
+    }
+
+    virtual SkTypeface* onMatchFamilyStyle(const char familyName[],
+                                           const SkFontStyle& style) const SK_OVERRIDE {
+        SkAutoTUnref<SkFontStyleSet> sset(this->matchFamily(familyName));
+        return sset->matchStyle(style);
+    }
+
+    virtual SkTypeface* onMatchFaceStyle(const SkTypeface* typeface,
+                                         const SkFontStyle& style) const SK_OVERRIDE {
+        for (int i = 0; i < fFontStyleSets.count(); ++i) {
+            for (int j = 0; j < fFontStyleSets[i]->fStyles.count(); ++j) {
+                if (fFontStyleSets[i]->fStyles[j] == typeface) {
+                    return fFontStyleSets[i]->matchStyle(style);
+                }
+            }
+        }
+        return NULL;
+    }
+
+    virtual SkTypeface* onCreateFromData(SkData* data, int ttcIndex) const SK_OVERRIDE {
+        SkAutoTUnref<SkStream> stream(new SkMemoryStream(data));
+        return this->createFromStream(stream, ttcIndex);
+    }
+
+    virtual SkTypeface* onCreateFromStream(SkStream* stream, int ttcIndex) const SK_OVERRIDE {
+        if (NULL == stream || stream->getLength() <= 0) {
+            SkDELETE(stream);
+            return NULL;
+        }
+
+        bool isFixedPitch;
+        SkTypeface::Style style;
+        SkString name;
+        if (find_name_and_attributes(stream, &name, &style, &isFixedPitch)) {
+            return SkNEW_ARGS(SkTypeface_AndroidStream,
+                              (style, isFixedPitch, stream, name));
+        } else {
+            return NULL;
+        }
+    }
+
+    virtual SkTypeface* onCreateFromFile(const char path[], int ttcIndex) const SK_OVERRIDE {
+        SkAutoTUnref<SkStream> stream(SkStream::NewFromFile(path));
+        return stream.get() ? this->createFromStream(stream, ttcIndex) : NULL;
+    }
+
+    virtual SkTypeface* onLegacyCreateTypeface(const char familyName[],
+                                               unsigned styleBits) const SK_OVERRIDE {
+        SkTypeface::Style oldStyle = (SkTypeface::Style)styleBits;
+        SkFontStyle style = SkFontStyle(oldStyle & SkTypeface::kBold
+                                                 ? SkFontStyle::kBold_Weight
+                                                 : SkFontStyle::kNormal_Weight,
+                                        SkFontStyle::kNormal_Width,
+                                        oldStyle & SkTypeface::kItalic
+                                                 ? SkFontStyle::kItalic_Slant
+                                                 : SkFontStyle::kUpright_Slant);
+        SkTypeface* tf = NULL;
+
+        if (NULL != familyName) {
+            // On Android, we must return NULL when we can't find the requested
+            // 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.
+            tf = this->onMatchFamilyStyle(familyName, style);
+        } else {
+            tf = gDefaultFamily->matchStyle(style);
+        }
+
+        // TODO: double ref? qv matchStyle()
+        return SkSafeRef(tf);
+    }
+
+
+private:
+
+    SkTArray<SkAutoTUnref<SkFontStyleSet_Android>, true> fFontStyleSets;
+    SkFontStyleSet* gDefaultFamily;
+    SkTypeface* gDefaultTypeface;
+
+    SkTDArray<NameToFamily> fNameToFamilyMap;
+
+    void buildNameToFamilyMap(SkTDArray<FontFamily*> families) {
+        for (int i = 0; i < families.count(); i++) {
+            fFontStyleSets.push_back().reset(SkNEW_ARGS(SkFontStyleSet_Android,
+                                                        (families[i])));
+            for (int j = 0; j < families[i]->fNames.count(); j++) {
+                NameToFamily* nextEntry = fNameToFamilyMap.append();
+                SkNEW_PLACEMENT_ARGS(&nextEntry->name, SkString, (families[i]->fNames[j]));
+                nextEntry->styleSet = fFontStyleSets.back().get();
+            }
+        }
+    }
+
+    void findDefaultFont() {
+        SkASSERT(!fFontStyleSets.empty()); // TODO?
+
+        // TODO: hardwired list of names - should there be more?
+        // TODO: Previous version was NULL-terminated; why??
+        // Currently passing NULL to onMatchFamily crashes.
+        static const char* gDefaultNames[] = { "Droid Sans" };
+        for (size_t i = 0; i < SK_ARRAY_COUNT(gDefaultNames); ++i) {
+            SkFontStyleSet* set = this->onMatchFamily(gDefaultNames[i]);
+            if (NULL == set) {
+                continue;
+            }
+            SkTypeface* tf = set->matchStyle(SkFontStyle());
+            if (NULL == tf) {
+                continue;
+            }
+            gDefaultFamily = set;
+            gDefaultTypeface = tf;
+            break;
+        }
+        if (NULL == gDefaultTypeface) {
+            gDefaultFamily = fFontStyleSets[0];
+            gDefaultTypeface = gDefaultFamily->createTypeface(0);
+        }
+        SkASSERT(gDefaultFamily);
+        SkASSERT(gDefaultTypeface);
+    }
+
+    typedef SkFontMgr INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+SkFontMgr* SkFontMgr::Factory() {
+    return SkNEW(SkFontMgr_Android);
+}
+
+
+