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content / browser / font_access / font_enumeration_data_source.h [blame]
// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_BROWSER_FONT_ACCESS_FONT_ENUMERATION_DATA_SOURCE_H_
#define CONTENT_BROWSER_FONT_ACCESS_FONT_ENUMERATION_DATA_SOURCE_H_
#include <memory>
#include <string>
#include "content/common/content_export.h"
#include "third_party/blink/public/common/font_access/font_enumeration_table.pb.h"
namespace content {
// Retrieves the font list used by the Font Access API from the underlying OS.
//
// Implementations are not expected to be thread-safe. All methods except for
// the constructor must be used on the same sequence. The sequence must allow
// blocking I/O operations.
//
// Implementations do not currently store any state, so the class infrastructure
// seems like overkill. However, the Font Access API will soon report changes to
// the list of installed fonts. Detecting changes will require storing
// OS-specific data.
class CONTENT_EXPORT FontEnumerationDataSource {
public:
// Factory method that instantiates the correct per-OS implementation.
//
// The result is guaranteed to be non-null.
static std::unique_ptr<FontEnumerationDataSource> Create();
// Exposed for std::make_unique. Instances should be obtained from Create().
FontEnumerationDataSource() = default;
FontEnumerationDataSource(const FontEnumerationDataSource&) = delete;
FontEnumerationDataSource& operator=(const FontEnumerationDataSource&) =
delete;
virtual ~FontEnumerationDataSource() = default;
// Heavyweight method whose result should be cached.
//
// Must be called on a sequence where blocking I/O operations are allowed.
virtual blink::FontEnumerationTable GetFonts(const std::string& locale) = 0;
// True if we have an implementation for the underlying OS.
//
// Tests can expect that GetData() returns a non-empty list on supported
// operating systems.
static bool IsOsSupported();
};
} // namespace content
#endif // CONTENT_BROWSER_FONT_ACCESS_FONT_ENUMERATION_DATA_SOURCE_H_