whitelist fallback typefaces

src/utils/SkWhitelistTypefaces.cpp

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkChecksum.h"
+#include "SkFontDescriptor.h"
+#include "SkStream.h"
+#include "SkString.h"
+#include "SkTypeface.h"
+#include "SkUtils.h"
+
+#include "SkWhitelistChecksums.cpp"
+
+#define WHITELIST_DEBUG 0
+
+extern void WhitelistSerializeTypeface(const SkTypeface*, SkWStream* );
+extern SkTypeface* WhitelistDeserializeTypeface(SkStream* );
+extern bool CheckChecksums();
+extern bool GenerateChecksums();
+
+#if WHITELIST_DEBUG
+static bool timesNewRomanSerializedNameOnly = false;
+#endif
+
+struct NameRecord {
+    unsigned short fPlatformID;
+    unsigned short fEncodingID;
+    unsigned short fLanguageID;
+    unsigned short fNameID;
+    unsigned short fLength;
+    unsigned short fOffset;
+};
+
+struct NameTable {

[bungeman-skia, 2015/08/31 15:59:32]

Why not SkOTTableName?

+    unsigned short fFormat;
+    unsigned short fCount;
+    unsigned short fStringOffset;
+    NameRecord fRecord[1];
+};
+
+#define SUBNAME_PREFIX "sk_"
+
+static unsigned short swizzle(unsigned short x) {
+    return x << 8 | (x >> 8 & 0xff);
+}
+
+static bool font_name_is_local(const char* fontName, SkTypeface::Style style) {
+    if (!strcmp(fontName, "DejaVu Sans")) {
+        return true;
+    }
+    SkTypeface* defaultFace = SkTypeface::CreateFromName(nullptr, style);
+    SkTypeface* foundFace = SkTypeface::CreateFromName(fontName, style);
+    return defaultFace != foundFace;
+}
+
+static int name_table(const NameTable* nameTable, int tableIndex, const char** stringLocPtr) {
+    int nameTableCount = swizzle(nameTable->fCount);
+    for (int i = 0; i < nameTableCount; ++i) {
+        const NameRecord* nameRecord = &nameTable->fRecord[i];
+        int recordNameID = swizzle(nameRecord->fNameID);
+        if (recordNameID != tableIndex) {
+            continue;
+        }
+        int stringLen = swizzle(nameRecord->fLength);
+        if (!stringLen) {
+            break;
+        }
+        int recordOffset = swizzle(nameRecord->fOffset);
+        const char* stringLoc = (const char* ) nameTable + swizzle(nameTable->fStringOffset);
+        stringLoc += recordOffset;
+        *stringLocPtr = stringLoc;
+        return stringLen;
+    }
+    return -1;
+}
+
+static int whitelist_name_index(const SkTypeface* tf) {
+    static const SkFontTableTag nameTag = SkSetFourByteTag('n', 'a', 'm', 'e');
+    size_t nameSize = tf->getTableSize(nameTag);
+    if (!nameSize) {
+        return -1;
+    }
+    SkTDArray<char> name;
+    name.setCount((int) nameSize);
+    tf->getTableData(nameTag, 0, nameSize, name.begin());
+    const NameTable* nameTable = (const NameTable* ) name.begin();
+    const char* stringLoc;
+    int stringLen = name_table(nameTable, 1, &stringLoc);

[bungeman-skia, 2015/08/31 15:59:32]

Any reason not to use SkOTTableName::Iterator or LocalizedStrings_NameTable
here? The code here doesn't seem to handle PlatformID and EncodingID. This seems
to assume all names are UCS2 or UTF-16BE, but UCS4 and MacRoman are also used.
This seems to just turn those into garbage, so they probably won't compare equal
to any names in the whitelist, but it's not obvious that this is what is going
on.

Also, it would be nice for the 1, 16, and 21 values to be given names.

[caryclark, 2015/09/01 12:17:37]

I'll switch over to LocalizedStrings_NameTable in a separate CL.

+    if (stringLen < 0) {
+        stringLen = name_table(nameTable, 16, &stringLoc);
+    }
+    if (stringLen < 0) {
+        stringLen = name_table(nameTable, 21, &stringLoc);
+    }
+    if (stringLen < 0) {
+        return -1;
+    }
+    SkString fontNameStr;
+    if (!*stringLoc) {
+        stringLen /= 2;
+        for (int i = 0; i < stringLen; ++i) {
+            fontNameStr.appendUnichar(swizzle(((const uint16_t*) stringLoc)[i]));
+        }
+    } else {
+        fontNameStr.resize(stringLen);
+        strncpy(fontNameStr.writable_str(), stringLoc, stringLen);
+    }
+    // check against permissible list of names
+    for (int i = 0; i < whitelistCount; ++i) {
+        if (fontNameStr.equals(whitelist[i].fFontName)) {
+            return i;
+        }
+    }
+    for (int i = 0; i < whitelistCount; ++i) {
+        if (fontNameStr.startsWith(whitelist[i].fFontName)) {
+#if WHITELIST_DEBUG
+            SkDebugf("partial match whitelist=\"%s\" fontName=\"%s\"\n", whitelist[i].fFontName,
+                    fontNameStr.c_str());
+#endif
+            return -1;
+        }
+    }
+#if WHITELIST_DEBUG
+    SkDebugf("no match fontName=\"%s\"\n", fontNameStr.c_str());
+#endif
+    return -1;
+}
+
+static uint32_t compute_checksum(const SkTypeface* tf) {
+    SkFontData* fontData = tf->createFontData();
+    if (!fontData) {
+        return 0;
+    }
+    SkStreamAsset* fontStream = fontData->getStream();
+    if (!fontStream) {
+        return 0;
+    }
+    SkTDArray<char> data;
+    size_t length = fontStream->getLength();
+    if (!length) {
+        return 0;
+    }
+    data.setCount((int) length);
+    if (!fontStream->peek(data.begin(), length)) {
+        return 0;
+    }
+    return SkChecksum::Murmur3(data.begin(), length);
+}
+
+static void serialize_sub(const char* fontName, SkTypeface::Style style, SkWStream* wstream) {
+    SkFontDescriptor desc(style);
+    SkString subName(SUBNAME_PREFIX);
+    subName.append(fontName);
+    const char* familyName = subName.c_str();
+    desc.setFamilyName(familyName);
+    desc.serialize(wstream);
+#if WHITELIST_DEBUG
+    for (int i = 0; i < whitelistCount; ++i) {
+        if (!strcmp(fontName, whitelist[i].fFontName)) {
+            if (!whitelist[i].fSerializedSub) {
+                whitelist[i].fSerializedSub = true;
+                SkDebugf("%s %s\n", __FUNCTION__, familyName);
+            }
+            break;
+        }
+    }
+#endif
+}
+
+static bool is_local(const SkTypeface* tf) {
+    bool isLocal = false;
+    SkFontDescriptor desc(tf->style());
+    tf->getFontDescriptor(&desc, &isLocal);
+    return isLocal;
+}
+
+static void serialize_full(const SkTypeface* tf, SkWStream* wstream) {
+    bool isLocal = false;
+    SkFontDescriptor desc(tf->style());
+    tf->getFontDescriptor(&desc, &isLocal);
+
+    // Embed font data if it's a local font.
+    if (isLocal && !desc.hasFontData()) {
+        desc.setFontData(tf->createFontData());
+    }
+    desc.serialize(wstream);
+}
+
+static void serialize_name_only(const SkTypeface* tf, SkWStream* wstream) {
+    bool isLocal = false;
+    SkFontDescriptor desc(tf->style());
+    tf->getFontDescriptor(&desc, &isLocal);
+    SkASSERT(!isLocal);
+#if WHITELIST_DEBUG
+    const char* familyName = desc.getFamilyName();
+    if (familyName) {
+        if (!strcmp(familyName, "Times New Roman")) {
+            if (!timesNewRomanSerializedNameOnly) {
+                timesNewRomanSerializedNameOnly = true;
+                SkDebugf("%s %s\n", __FUNCTION__, familyName);
+            }
+        } else {
+            for (int i = 0; i < whitelistCount; ++i) {
+                if (!strcmp(familyName, whitelist[i].fFontName)) {
+                    if (!whitelist[i].fSerializedNameOnly) {
+                        whitelist[i].fSerializedNameOnly = true;
+                        SkDebugf("%s %s\n", __FUNCTION__, familyName);
+                    }
+                    break;
+                }
+            }
+        }
+    }
+#endif
+    desc.serialize(wstream);
+}
+
+void WhitelistSerializeTypeface(const SkTypeface* tf, SkWStream* wstream) {
+    if (!is_local(tf)) {
+        serialize_name_only(tf, wstream);
+        return;
+    }
+    int whitelistIndex = whitelist_name_index(tf);
+    if (whitelistIndex < 0) {
+        serialize_full(tf, wstream);
+        return;
+    }
+    const char* fontName = whitelist[whitelistIndex].fFontName;
+    if (!font_name_is_local(fontName, tf->style())) {
+#if WHITELIST_DEBUG
+        SkDebugf("name not found locally \"%s\" style=%d\n", fontName, tf->style());
+#endif
+        serialize_full(tf, wstream);
+        return;
+    }
+    uint32_t checksum = compute_checksum(tf);
+    if (whitelist[whitelistIndex].fChecksum != checksum) {
+#if WHITELIST_DEBUG
+        if (whitelist[whitelistIndex].fChecksum) {
+            SkDebugf("!!! checksum changed !!!\n");
+        }
+        SkDebugf("checksum updated\n");
+        SkDebugf("    { \"%s\", 0x%08x },\n", fontName, checksum);
+#endif
+        whitelist[whitelistIndex].fChecksum = checksum;
+    }
+    serialize_sub(fontName, tf->style(), wstream);
+}
+
+SkTypeface* WhitelistDeserializeTypeface(SkStream* stream) {
+    SkFontDescriptor desc(stream);
+    SkFontData* data = desc.detachFontData();
+    if (data) {
+        SkTypeface* typeface = SkTypeface::CreateFromFontData(data);
+        if (typeface) {
+            return typeface;
+        }
+    }
+    const char* familyName = desc.getFamilyName();
+    if (!strncmp(SUBNAME_PREFIX, familyName, sizeof(SUBNAME_PREFIX) - 1)) {
+        familyName += sizeof(SUBNAME_PREFIX) - 1;
+    }
+    return SkTypeface::CreateFromName(desc.getFamilyName(), desc.getStyle());
+}
+
+bool CheckChecksums() {
+    for (int i = 0; i < whitelistCount; ++i) {
+        const char* fontName = whitelist[i].fFontName;
+        SkTypeface* tf = SkTypeface::CreateFromName(fontName, SkTypeface::kNormal);
+        uint32_t checksum = compute_checksum(tf);
+        if (whitelist[i].fChecksum != checksum) {
+            return false;
+        }
+    }
+    return true;
+}
+
+const char checksumFileName[] = "SkWhitelistChecksums.cpp";
+
+const char checksumHeader[] =
+"/*"                                                                        "\n"
+" * Copyright 2015 Google Inc."                                             "\n"
+" *"                                                                        "\n"
+" * Use of this source code is governed by a BSD-style license that can be" "\n"
+" * found in the LICENSE file."                                             "\n"
+" *"                                                                        "\n"
+" * %s() in %s generated %s."                                               "\n"
+" * Run 'whitelist_typefaces --generate' to create anew."                   "\n"
+" */"                                                                       "\n"
+""                                                                          "\n"
+"#include \"SkTDArray.h\""                                                  "\n"
+""                                                                          "\n"
+"struct Whitelist {"                                                        "\n"
+"    const char* fFontName;"                                                "\n"
+"    uint32_t fChecksum;"                                                   "\n"
+"    bool fSerializedNameOnly;"                                             "\n"
+"    bool fSerializedSub;"                                                  "\n"
+"};"                                                                        "\n"
+""                                                                          "\n"
+"static Whitelist whitelist[] = {"                                          "\n";
+
+const char checksumEntry[] =
+"    { \"%s\", 0x%08x, false, false },"                                     "\n";
+
+const char checksumTrailer[] =
+"};"                                                                        "\n"
+""                                                                          "\n"
+"static const int whitelistCount = (int) SK_ARRAY_COUNT(whitelist);"        "\n";
+
+
+#include "SkOSFile.h"
+
+bool GenerateChecksums() {
+    SkFILE* file = sk_fopen(checksumFileName, kWrite_SkFILE_Flag);
+    if (!file) {
+        SkDebugf("Can't open %s for writing.\n", checksumFileName);
+        return false;
+    }
+    SkString line;
+    line.printf(checksumHeader, __FUNCTION__, __FILE__, checksumFileName);
+    sk_fwrite(line.c_str(), line.size(), file);
+    for (int i = 0; i < whitelistCount; ++i) {
+        const char* fontName = whitelist[i].fFontName;
+        SkTypeface* tf = SkTypeface::CreateFromName(fontName, SkTypeface::kNormal);
+        uint32_t checksum = compute_checksum(tf);
+        line.printf(checksumEntry, fontName, checksum);
+        sk_fwrite(line.c_str(), line.size(), file);
+    }
+    sk_fwrite(checksumTrailer, sizeof(checksumTrailer) - 1, file);
+    sk_fclose(file);
+    return true;
+}