layout/generic/nsTextRunTransformations.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef NSTEXTRUNTRANSFORMATIONS_H_
   7 #define NSTEXTRUNTRANSFORMATIONS_H_
   8
   9 #include "mozilla/Attributes.h"
  10 #include "mozilla/MemoryReporting.h"
  11 #include "gfxFont.h"
  12 #include "nsStyleContext.h"
  13
  14 class nsTransformedTextRun;
  15
  16 class nsTransformingTextRunFactory {
  17 public:
  18   virtual ~nsTransformingTextRunFactory() {}
  19
  20   // Default 8-bit path just transforms to Unicode and takes that path
  21   nsTransformedTextRun* MakeTextRun(const uint8_t* aString, uint32_t aLength,
  22                                     const gfxFontGroup::Parameters* aParams,
  23                                     gfxFontGroup* aFontGroup, uint32_t aFlags,
  24                                     nsStyleContext** aStyles, bool aOwnsFactory = true);
  25   nsTransformedTextRun* MakeTextRun(const char16_t* aString, uint32_t aLength,
  26                                     const gfxFontGroup::Parameters* aParams,
  27                                     gfxFontGroup* aFontGroup, uint32_t aFlags,
  28                                     nsStyleContext** aStyles, bool aOwnsFactory = true);
  29
  30   virtual void RebuildTextRun(nsTransformedTextRun* aTextRun, gfxContext* aRefContext) = 0;
  31 };
  32
  33 /**
  34  * Builds textruns that transform the text in some way (e.g., capitalize)
  35  * and then render the text using some other textrun implementation.
  36  */
  37 class nsCaseTransformTextRunFactory : public nsTransformingTextRunFactory {
  38 public:
  39   // We could add an optimization here so that when there is no inner
  40   // factory, no title-case conversion, and no upper-casing of SZLIG, we override
  41   // MakeTextRun (after making it virtual in the superclass) and have it
  42   // just convert the string to uppercase or lowercase and create the textrun
  43   // via the fontgroup.
  44
  45   // Takes ownership of aInnerTransformTextRunFactory
  46   explicit nsCaseTransformTextRunFactory(nsTransformingTextRunFactory* aInnerTransformingTextRunFactory,
  47                                          bool aAllUppercase = false)
  48     : mInnerTransformingTextRunFactory(aInnerTransformingTextRunFactory),
  49       mAllUppercase(aAllUppercase) {}
  50
  51   virtual void RebuildTextRun(nsTransformedTextRun* aTextRun, gfxContext* aRefContext) MOZ_OVERRIDE;
  52
  53   // Perform a transformation on the given string, writing the result into
  54   // aConvertedString. If aAllUppercase is true, the transform is (global)
  55   // upper-casing, and aLanguage is used to determine any language-specific
  56   // behavior; otherwise, an nsTransformedTextRun should be passed in
  57   // as aTextRun and its styles will be used to determine the transform(s)
  58   // to be applied.
  59   // If such an input textrun is provided, then its line-breaks and styles
  60   // will be copied to the output arrays, which must also be provided by
  61   // the caller. For the global upper-casing usage (no input textrun),
  62   // these are ignored.
  63   static bool TransformString(const nsAString& aString,
  64                               nsString& aConvertedString,
  65                               bool aAllUppercase,
  66                               const nsIAtom* aLanguage,
  67                               nsTArray<bool>& aCharsToMergeArray,
  68                               nsTArray<bool>& aDeletedCharsArray,
  69                               nsTransformedTextRun* aTextRun = nullptr,
  70                               nsTArray<uint8_t>* aCanBreakBeforeArray = nullptr,
  71                               nsTArray<nsStyleContext*>* aStyleArray = nullptr);
  72
  73 protected:
  74   nsAutoPtr<nsTransformingTextRunFactory> mInnerTransformingTextRunFactory;
  75   bool                                    mAllUppercase;
  76 };
  77
  78 /**
  79  * So that we can reshape as necessary, we store enough information
  80  * to fully rebuild the textrun contents.
  81  */
  82 class nsTransformedTextRun MOZ_FINAL : public gfxTextRun {
  83 public:
  84   static nsTransformedTextRun *Create(const gfxTextRunFactory::Parameters* aParams,
  85                                       nsTransformingTextRunFactory* aFactory,
  86                                       gfxFontGroup* aFontGroup,
  87                                       const char16_t* aString, uint32_t aLength,
  88                                       const uint32_t aFlags, nsStyleContext** aStyles,
  89                                       bool aOwnsFactory);
  90
  91   ~nsTransformedTextRun() {
  92     if (mOwnsFactory) {
  93       delete mFactory;
  94     }
  95   }
  96
  97   void SetCapitalization(uint32_t aStart, uint32_t aLength,
  98                          bool* aCapitalization,
  99                          gfxContext* aRefContext);
 100   virtual bool SetPotentialLineBreaks(uint32_t aStart, uint32_t aLength,
 101                                         uint8_t* aBreakBefore,
 102                                         gfxContext* aRefContext);
 103   /**
 104    * Called after SetCapitalization and SetPotentialLineBreaks
 105    * are done and before we request any data from the textrun. Also always
 106    * called after a Create.
 107    */
 108   void FinishSettingProperties(gfxContext* aRefContext)
 109   {
 110     if (mNeedsRebuild) {
 111       mNeedsRebuild = false;
 112       mFactory->RebuildTextRun(this, aRefContext);
 113     }
 114   }
 115
 116   // override the gfxTextRun impls to account for additional members here
 117   virtual size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) MOZ_MUST_OVERRIDE;
 118   virtual size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) MOZ_MUST_OVERRIDE;
 119
 120   nsTransformingTextRunFactory       *mFactory;
 121   nsTArray<nsRefPtr<nsStyleContext> > mStyles;
 122   nsTArray<bool>                      mCapitalize;
 123   nsString                            mString;
 124   bool                                mOwnsFactory;
 125   bool                                mNeedsRebuild;
 126
 127 private:
 128   nsTransformedTextRun(const gfxTextRunFactory::Parameters* aParams,
 129                        nsTransformingTextRunFactory* aFactory,
 130                        gfxFontGroup* aFontGroup,
 131                        const char16_t* aString, uint32_t aLength,
 132                        const uint32_t aFlags, nsStyleContext** aStyles,
 133                        bool aOwnsFactory)
 134     : gfxTextRun(aParams, aLength, aFontGroup, aFlags),
 135       mFactory(aFactory), mString(aString, aLength),
 136       mOwnsFactory(aOwnsFactory), mNeedsRebuild(true)
 137   {
 138     mCharacterGlyphs = reinterpret_cast<CompressedGlyph*>(this + 1);
 139
 140     uint32_t i;
 141     for (i = 0; i < aLength; ++i) {
 142       mStyles.AppendElement(aStyles[i]);
 143     }
 144   }
 145 };
 146
 147 /**
 148  * Copy a given textrun, but merge certain characters into a single logical
 149  * character. Glyphs for a character are added to the glyph list for the previous
 150  * character and then the merged character is eliminated. Visually the results
 151  * are identical.
 152  *
 153  * This is used for text-transform:uppercase when we encounter a SZLIG,
 154  * whose uppercase form is "SS", or other ligature or precomposed form
 155  * that expands to multiple codepoints during case transformation,
 156  * and for Greek text when combining diacritics have been deleted.
 157  *
 158  * This function is unable to merge characters when they occur in different
 159  * glyph runs. This only happens in tricky edge cases where a character was
 160  * decomposed by case-mapping (e.g. there's no precomposed uppercase version
 161  * of an accented lowercase letter), and then font-matching caused the
 162  * diacritics to be assigned to a different font than the base character.
 163  * In this situation, the diacritic(s) get discarded, which is less than
 164  * ideal, but they probably weren't going to render very well anyway.
 165  * Bug 543200 will improve this by making font-matching operate on entire
 166  * clusters instead of individual codepoints.
 167  *
 168  * For simplicity, this produces a textrun containing all DetailedGlyphs,
 169  * no simple glyphs. So don't call it unless you really have merging to do.
 170  *
 171  * @param aCharsToMerge when aCharsToMerge[i] is true, this character in aSrc
 172  * is merged into the previous character
 173  *
 174  * @param aDeletedChars when aDeletedChars[i] is true, the character at this
 175  * position in aDest was deleted (has no corresponding char in aSrc)
 176  */
 177 void
 178 MergeCharactersInTextRun(gfxTextRun* aDest, gfxTextRun* aSrc,
 179                          const bool* aCharsToMerge, const bool* aDeletedChars);
 180
 181 gfxTextRunFactory::Parameters
 182 GetParametersForInner(nsTransformedTextRun* aTextRun, uint32_t* aFlags,
 183                       gfxContext* aRefContext);
 184
 185
 186 #endif /*NSTEXTRUNTRANSFORMATIONS_H_*/