Linux: Add support for chrooted renderers.

skia/ext/SkFontHost_fontconfig_direct.cpp

+/* libs/graphics/ports/SkFontHost_fontconfig_direct.cpp
+**
+** Copyright 2009, Google Inc.
+**
+** 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_fontconfig_direct.h"
+
+#include <unistd.h>
+#include <fcntl.h>
+
+#include <fontconfig/fontconfig.h>
+
+FontConfigDirect::FontConfigDirect()
+    : next_file_id_(0) {
+  FcInit();
+}
+
+bool FontConfigDirect::Match(std::string* result_family,
+                             unsigned* result_fileid,
+                             bool fileid_valid, unsigned fileid,
+                             const std::string& family, int is_bold,
+                             int is_italic) {
+    SkAutoMutexAcquire ac(mutex_);
+    FcPattern* pattern = FcPatternCreate();
+
+    FcValue fcvalue;
+    if (fileid_valid) {
+        const std::map<unsigned, std::string>::const_iterator
+            i = fileid_to_filename_.find(fileid);
+        if (i == fileid_to_filename_.end()) {
+            FcPatternDestroy(pattern);
+            return false;
+        }
+
+        fcvalue.type = FcTypeString;
+        fcvalue.u.s = (FcChar8*) i->second.c_str();
+        FcPatternAdd(pattern, FC_FILE, fcvalue, 0);
+    }
+    if (!family.empty()) {
+        fcvalue.type = FcTypeString;
+        fcvalue.u.s = (FcChar8*) family.c_str();
+        FcPatternAdd(pattern, FC_FAMILY, fcvalue, 0);
+    }
+    if (is_bold > 0) {
+        fcvalue.type = FcTypeInteger;
+        fcvalue.u.i = is_bold ? FC_WEIGHT_BOLD : FC_WEIGHT_NORMAL;
+        FcPatternAdd(pattern, FC_WEIGHT, fcvalue, 0);
+    }
+    if (is_italic > 0) {
+        fcvalue.type = FcTypeInteger;
+        fcvalue.u.i = is_bold ? FC_SLANT_ITALIC : FC_SLANT_ROMAN;
+        FcPatternAdd(pattern, FC_SLANT, fcvalue, 0);
+    }
+
+    FcConfigSubstitute(0, pattern, FcMatchPattern);
+    FcDefaultSubstitute(pattern);
+
+    // Font matching:
+    // CSS often specifies a fallback list of families:
+    //    font-family: a, b, c, serif;
+    // However, fontconfig will always do its best to find *a* font when asked
+    // for something so we need a way to tell if the match which it has found is
+    // "good enough" for us. Otherwise, we can return NULL which gets piped up
+    // and lets WebKit know to try the next CSS family name. However, fontconfig
+    // configs allow substitutions (mapping "Arial -> Helvetica" etc) and we
+    // wish to support that.
+    //
+    // Thus, if a specific family is requested we set @family_requested. Then we
+    // record two strings: the family name after config processing and the
+    // family name after resolving. If the two are equal, it's a good match.
+    //
+    // So consider the case where a user has mapped Arial to Helvetica in their
+    // config.
+    //    requested family: "Arial"
+    //    post_config_family: "Helvetica"
+    //    post_match_family: "Helvetica"
+    //      -> good match
+    //
+    // and for a missing font:
+    //    requested family: "Monaco"
+    //    post_config_family: "Monaco"
+    //    post_match_family: "Times New Roman"
+    //      -> BAD match
+    FcChar8* post_config_family;
+    FcPatternGetString(pattern, FC_FAMILY, 0, &post_config_family);
+
+    FcResult result;
+    FcPattern* match = FcFontMatch(0, pattern, &result);
+    if (!match) {
+        FcPatternDestroy(pattern);
+        return false;
+    }
+
+    FcChar8* post_match_family;
+    FcPatternGetString(match, FC_FAMILY, 0, &post_match_family);
+    const bool family_names_match =
+        family.empty() ?
+        true :
+        strcasecmp((char *)post_config_family, (char *)post_match_family) == 0;
+
+    FcPatternDestroy(pattern);
+
+    if (!family_names_match) {
+        FcPatternDestroy(match);
+        return false;
+    }
+
+    FcChar8* c_filename;
+    if (FcPatternGetString(match, FC_FILE, 0, &c_filename) != FcResultMatch) {
+        FcPatternDestroy(match);
+        return NULL;
+    }
+    const std::string filename((char *) c_filename);
+
+    unsigned out_fileid;
+    if (fileid_valid) {
+        out_fileid = fileid;
+    } else {
+        const std::map<std::string, unsigned>::const_iterator
+            i = filename_to_fileid_.find(filename);
+        if (i == filename_to_fileid_.end()) {
+            out_fileid = next_file_id_++;
+            filename_to_fileid_[filename] = out_fileid;
+            fileid_to_filename_[out_fileid] = filename;
+        } else {
+            out_fileid = i->second;
+        }
+    }
+
+    if (*result_fileid)
+        *result_fileid = out_fileid;
+
+    FcChar8* c_family;
+    if (FcPatternGetString(match, FC_FAMILY, 0, &c_family)) {
+        FcPatternDestroy(match);
+        return NULL;
+    }
+
+    if (result_family)
+        *result_family = (char *) c_family;
+
+    return true;
+}
+
+int FontConfigDirect::Open(unsigned fileid) {
+    SkAutoMutexAcquire ac(mutex_);
+    const std::map<unsigned, std::string>::const_iterator
+        i = fileid_to_filename_.find(fileid);
+    if (i == fileid_to_filename_.end())
+        return -1;
+
+    return open(i->second.c_str(), O_RDONLY);
+}