1 files changed, 87 insertions, 0 deletions
diff --git a/vcl/inc/TextLayoutCache.hxx b/vcl/inc/TextLayoutCache.hxx
new file mode 100644
index 000000000..46e5c80dc
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+++ b/vcl/inc/TextLayoutCache.hxx
@@ -0,0 +1,87 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you 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 .
+ */
+
+#pragma once
+
+#include <sal/types.h>
+#include <rtl/ustring.hxx>
+#include <o3tl/hash_combine.hxx>
+
+#include <vcl/dllapi.h>
+
+#include <hb-icu.h>
+
+#include <vector>
+
+namespace vcl::text
+{
+struct Run
+{
+    int32_t nStart;
+    int32_t nEnd;
+    UScriptCode nCode;
+    Run(int32_t nStart_, int32_t nEnd_, UScriptCode nCode_)
+        : nStart(nStart_)
+        , nEnd(nEnd_)
+        , nCode(nCode_)
+    {
+    }
+};
+
+class VCL_DLLPUBLIC TextLayoutCache
+{
+public:
+    std::vector<vcl::text::Run> runs;
+    TextLayoutCache(sal_Unicode const* pStr, sal_Int32 const nEnd);
+    // Creates a cached instance.
+    static std::shared_ptr<const vcl::text::TextLayoutCache> Create(OUString const&);
+};
+
+struct FirstCharsStringHash
+{
+    size_t operator()(const OUString& str) const
+    {
+        // Strings passed to GenericSalLayout::CreateTextLayoutCache() may be very long,
+        // and computing an entire hash could almost negate the gain of hashing. Hash just first
+        // characters, that should be good enough.
+        size_t hash
+            = rtl_ustr_hashCode_WithLength(str.getStr(), std::min<size_t>(100, str.getLength()));
+        o3tl::hash_combine(hash, str.getLength());
+        return hash;
+    }
+};
+
+struct FastStringCompareEqual
+{
+    bool operator()(const OUString& str1, const OUString& str2) const
+    {
+        // Strings passed to GenericSalLayout::CreateTextLayoutCache() may be very long,
+        // and OUString operator == compares backwards and using hard-written code, while
+        // memcmp() compares much faster.
+        if (str1.getLength() != str2.getLength())
+            return false;
+        if (str1.getStr() == str2.getStr())
+            return true;
+        return memcmp(str1.getStr(), str2.getStr(), str1.getLength() * sizeof(str1.getStr()[0]))
+               == 0;
+    }
+};
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */