vcl/inc/TextLayoutCache.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #pragma once
  21
  22 #include <sal/types.h>
  23 #include <rtl/ustring.hxx>
  24 #include <o3tl/hash_combine.hxx>
  25
  26 #include <vcl/dllapi.h>
  27
  28 #include <unicode/uscript.h>
  29
  30 #include <vector>
  31
  32 namespace vcl::text
  33 {
  34 struct Run
  35 {
  36     int32_t nStart;
  37     int32_t nEnd;
  38     UScriptCode nCode;
  39     Run(int32_t nStart_, int32_t nEnd_, UScriptCode nCode_)
  40         : nStart(nStart_)
  41         , nEnd(nEnd_)
  42         , nCode(nCode_)
  43     {
  44     }
  45 };
  46
  47 class VCL_DLLPUBLIC TextLayoutCache
  48 {
  49 public:
  50     std::vector<vcl::text::Run> runs;
  51     TextLayoutCache(sal_Unicode const* pStr, sal_Int32 const nEnd);
  52     // Creates a cached instance.
  53     static std::shared_ptr<const vcl::text::TextLayoutCache> Create(OUString const&);
  54 };
  55
  56 struct FirstCharsStringHash
  57 {
  58     size_t operator()(const OUString& str) const
  59     {
  60         // Strings passed to GenericSalLayout::CreateTextLayoutCache() may be very long,
  61         // and computing an entire hash could almost negate the gain of hashing. Hash just first
  62         // characters, that should be good enough.
  63         size_t hash
  64             = rtl_ustr_hashCode_WithLength(str.getStr(), std::min<size_t>(100, str.getLength()));
  65         o3tl::hash_combine(hash, str.getLength());
  66         return hash;
  67     }
  68 };
  69
  70 struct FastStringCompareEqual
  71 {
  72     bool operator()(const OUString& str1, const OUString& str2) const
  73     {
  74         // Strings passed to GenericSalLayout::CreateTextLayoutCache() may be very long,
  75         // and OUString operator == compares backwards and using hard-written code, while
  76         // memcmp() compares much faster.
  77         if (str1.getLength() != str2.getLength())
  78             return false;
  79         if (str1.getStr() == str2.getStr())
  80             return true;
  81         return memcmp(str1.getStr(), str2.getStr(), str1.getLength() * sizeof(str1.getStr()[0]))
  82                == 0;
  83     }
  84 };
  85 }
  86
  87 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */