Linux: Add support for chrooted renderers.

skia/ext/SkFontHost_fontconfig.cpp

+/* libs/graphics/ports/SkFontHost_fontconfig.cpp
+**
+** Copyright 2008, 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.
+*/
+
+// -----------------------------------------------------------------------------
+// This file provides implementations of the font resolution members of
+// SkFontHost by using the fontconfig[1] library. Fontconfig is usually found
+// on Linux systems and handles configuration, parsing and caching issues
+// involved with enumerating and matching fonts.
+//
+// [1] http://fontconfig.org
+// -----------------------------------------------------------------------------
+
+#include <map>
+#include <string>
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "SkFontHost.h"
+#include "SkStream.h"
+#include "SkFontHost_fontconfig_impl.h"
+#include "SkFontHost_fontconfig_direct.h"
+#include "SkFontHost_fontconfig_ipc.h"
+
+static FontConfigInterface* global_fc_impl = NULL;
+
+void SkiaFontConfigUseDirectImplementation() {
+    global_fc_impl = new FontConfigDirect;
+}
+
+void SkiaFontConfigUseIPCImplementation(int fd) {
+    global_fc_impl = new FontConfigIPC(fd);
+}
+
+static SkMutex global_fc_map_lock;
+static std::map<uint32_t, SkTypeface *> global_fc_typefaces;
+
+// This is the maximum size of the font cache.
+static const unsigned kFontCacheMemoryBudget = 2 * 1024 * 1024;  // 2MB
+
+// UniqueIds are encoded as (fileid << 8) | style
+
+static unsigned UniqueIdToFileId(unsigned uniqueid)
+{
+    return uniqueid >> 8;
+}
+
+static SkTypeface::Style UniqueIdToStyle(unsigned uniqueid)
+{
+    return static_cast<SkTypeface::Style>(uniqueid & 0xff);
+}
+
+static unsigned FileIdAndStyleToUniqueId(unsigned fileid,
+                                         SkTypeface::Style style)
+{
+    SkASSERT(style & 0xff == style);
+    return (fileid << 8) | static_cast<int>(style);
+}
+
+class FontConfigTypeface : public SkTypeface {
+public:
+    FontConfigTypeface(Style style, uint32_t id)
+        : SkTypeface(style, id)
+    { }
+};
+
+// static
+SkTypeface* SkFontHost::CreateTypeface(const SkTypeface* familyFace,
+                                       const char familyName[],
+                                       SkTypeface::Style style)
+{
+    std::string resolved_family_name;
+
+    if (familyFace) {
+        // Given the fileid we can ask fontconfig for the familyname of the
+        // font.
+        const unsigned fileid = UniqueIdToFileId(familyFace->uniqueID());
+        if (!global_fc_impl->Match(
+          &resolved_family_name, NULL, true /* fileid valid */, fileid, "",
+          -1, -1)) {
+            return NULL;
+        }
+    } else if (familyName) {
+        resolved_family_name = familyName;
+    } else {
+        return NULL;
+    }
+
+    const bool bold = style & SkTypeface::kBold;
+    const bool italic = style & SkTypeface::kItalic;
+    unsigned fileid;
+    if (!global_fc_impl->Match(NULL, &fileid, false, -1, /* no fileid */
+                               resolved_family_name, bold, italic)) {
+        return NULL;
+    }
+
+    const unsigned id = FileIdAndStyleToUniqueId(fileid, style);
+    SkTypeface* typeface = SkNEW_ARGS(FontConfigTypeface, (style, id));
+
+    {
+        SkAutoMutexAcquire ac(global_fc_map_lock);
+        global_fc_typefaces[id] = typeface;
+    }
+
+    return typeface;
+}
+
+// static
+SkTypeface* SkFontHost::CreateTypefaceFromStream(SkStream* stream)
+{
+    SkASSERT(!"SkFontHost::CreateTypefaceFromStream unimplemented");
+    return NULL;
+}
+
+// static
+SkTypeface* SkFontHost::CreateTypefaceFromFile(const char path[])
+{
+    SkASSERT(!"SkFontHost::CreateTypefaceFromFile unimplemented");
+    return NULL;
+}
+
+// static
+bool SkFontHost::ValidFontID(SkFontID uniqueID) {
+    SkAutoMutexAcquire ac(global_fc_map_lock);
+    return global_fc_typefaces.find(uniqueID) != global_fc_typefaces.end();
+}
+
+void SkFontHost::Serialize(const SkTypeface*, SkWStream*) {
+    SkASSERT(!"SkFontHost::Serialize unimplemented");
+}
+
+SkTypeface* SkFontHost::Deserialize(SkStream* stream) {
+    SkASSERT(!"SkFontHost::Deserialize unimplemented");
+    return NULL;
+}
+
+// static
+uint32_t SkFontHost::NextLogicalFont(SkFontID fontID) {
+    // We don't handle font fallback, WebKit does.
+    return 0;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+class SkFileDescriptorStream : public SkStream {
+  public:
+    SkFileDescriptorStream(int fd)
+        : fd_(fd) {
+    }
+
+    ~SkFileDescriptorStream() {
+        close(fd_);
+    }
+
+    virtual bool rewind() {
+        if (lseek(fd_, 0, SEEK_SET) == -1)
+            return false;
+        return true;
+    }
+
+    // SkStream implementation.
+    virtual size_t read(void* buffer, size_t size) {
+        if (!buffer && !size) {
+            // This is request for the length of the stream.
+            struct stat st;
+            if (fstat(fd_, &st) == -1)
+                return 0;
+            return st.st_size;
+        }
+
+        if (!buffer) {
+            // This is a request to skip bytes.
+            const off_t current_position = lseek(fd_, 0, SEEK_CUR);
+            if (current_position == -1)
+                return 0;
+            const off_t new_position = lseek(fd_, size, SEEK_CUR);
+            if (new_position == -1)
+                return 0;
+            if (new_position < current_position) {
+                lseek(fd_, current_position, SEEK_SET);
+                return 0;
+            }
+            return new_position;
+        }
+
+        // This is a request to read bytes.
+        return ::read(fd_, buffer, size);
+    }
+
+  private:
+    const int fd_;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+// static
+SkStream* SkFontHost::OpenStream(uint32_t id)
+{
+    const unsigned fileid = UniqueIdToFileId(id);
+    const int fd = global_fc_impl->Open(fileid);
+    if (fd < 0)
+        return NULL;
+
+    return SkNEW_ARGS(SkFileDescriptorStream, (fd));
+}
+
+size_t SkFontHost::ShouldPurgeFontCache(size_t sizeAllocatedSoFar)
+{
+    if (sizeAllocatedSoFar > kFontCacheMemoryBudget)
+        return sizeAllocatedSoFar - kFontCacheMemoryBudget;
+    else
+        return 0;   // nothing to do
+}