skia WIPjarred/canvas

1 files changed, 503 insertions, 0 deletions

diff --git a/src/deps/skia/include/core/SkTextBlob.h b/src/deps/skia/include/core/SkTextBlob.h
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+++ b/src/deps/skia/include/core/SkTextBlob.h
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+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkTextBlob_DEFINED
+#define SkTextBlob_DEFINED
+
+#include "include/core/SkFont.h"
+#include "include/core/SkPaint.h"
+#include "include/core/SkRefCnt.h"
+#include "include/core/SkString.h"
+#include "include/private/SkTemplates.h"
+
+#include <atomic>
+
+struct SkRSXform;
+struct SkSerialProcs;
+struct SkDeserialProcs;
+
+/** \class SkTextBlob
+    SkTextBlob combines multiple text runs into an immutable container. Each text
+    run consists of glyphs, SkPaint, and position. Only parts of SkPaint related to
+    fonts and text rendering are used by run.
+*/
+class SK_API SkTextBlob final : public SkNVRefCnt<SkTextBlob> {
+private:
+    class RunRecord;
+
+public:
+
+    /** Returns conservative bounding box. Uses SkPaint associated with each glyph to
+        determine glyph bounds, and unions all bounds. Returned bounds may be
+        larger than the bounds of all glyphs in runs.
+
+        @return  conservative bounding box
+    */
+    const SkRect& bounds() const { return fBounds; }
+
+    /** Returns a non-zero value unique among all text blobs.
+
+        @return  identifier for SkTextBlob
+    */
+    uint32_t uniqueID() const { return fUniqueID; }
+
+    /** Returns the number of intervals that intersect bounds.
+        bounds describes a pair of lines parallel to the text advance.
+        The return count is zero or a multiple of two, and is at most twice the number of glyphs in
+        the the blob.
+
+        Pass nullptr for intervals to determine the size of the interval array.
+
+        Runs within the blob that contain SkRSXform are ignored when computing intercepts.
+
+        @param bounds     lower and upper line parallel to the advance
+        @param intervals  returned intersections; may be nullptr
+        @param paint      specifies stroking, SkPathEffect that affects the result; may be nullptr
+        @return           number of intersections; may be zero
+     */
+    int getIntercepts(const SkScalar bounds[2], SkScalar intervals[],
+                      const SkPaint* paint = nullptr) const;
+
+    /** Creates SkTextBlob with a single run.
+
+        font contains attributes used to define the run text.
+
+        When encoding is SkTextEncoding::kUTF8, SkTextEncoding::kUTF16, or
+        SkTextEncoding::kUTF32, this function uses the default
+        character-to-glyph mapping from the SkTypeface in font.  It does not
+        perform typeface fallback for characters not found in the SkTypeface.
+        It does not perform kerning or other complex shaping; glyphs are
+        positioned based on their default advances.
+
+        @param text        character code points or glyphs drawn
+        @param byteLength  byte length of text array
+        @param font        text size, typeface, text scale, and so on, used to draw
+        @param encoding    text encoding used in the text array
+        @return            SkTextBlob constructed from one run
+    */
+    static sk_sp<SkTextBlob> MakeFromText(const void* text, size_t byteLength, const SkFont& font,
+                                          SkTextEncoding encoding = SkTextEncoding::kUTF8);
+
+    /** Creates SkTextBlob with a single run. string meaning depends on SkTextEncoding;
+        by default, string is encoded as UTF-8.
+
+        font contains attributes used to define the run text.
+
+        When encoding is SkTextEncoding::kUTF8, SkTextEncoding::kUTF16, or
+        SkTextEncoding::kUTF32, this function uses the default
+        character-to-glyph mapping from the SkTypeface in font.  It does not
+        perform typeface fallback for characters not found in the SkTypeface.
+        It does not perform kerning or other complex shaping; glyphs are
+        positioned based on their default advances.
+
+        @param string   character code points or glyphs drawn
+        @param font     text size, typeface, text scale, and so on, used to draw
+        @param encoding text encoding used in the text array
+        @return         SkTextBlob constructed from one run
+    */
+    static sk_sp<SkTextBlob> MakeFromString(const char* string, const SkFont& font,
+                                            SkTextEncoding encoding = SkTextEncoding::kUTF8) {
+        if (!string) {
+            return nullptr;
+        }
+        return MakeFromText(string, strlen(string), font, encoding);
+    }
+
+    /** Returns a textblob built from a single run of text with x-positions and a single y value.
+        This is equivalent to using SkTextBlobBuilder and calling allocRunPosH().
+        Returns nullptr if byteLength is zero.
+
+        @param text        character code points or glyphs drawn (based on encoding)
+        @param byteLength  byte length of text array
+        @param xpos    array of x-positions, must contain values for all of the character points.
+        @param constY  shared y-position for each character point, to be paired with each xpos.
+        @param font    SkFont used for this run
+        @param encoding specifies the encoding of the text array.
+        @return        new textblob or nullptr
+     */
+    static sk_sp<SkTextBlob> MakeFromPosTextH(const void* text, size_t byteLength,
+                                      const SkScalar xpos[], SkScalar constY, const SkFont& font,
+                                      SkTextEncoding encoding = SkTextEncoding::kUTF8);
+
+    /** Returns a textblob built from a single run of text with positions.
+        This is equivalent to using SkTextBlobBuilder and calling allocRunPos().
+        Returns nullptr if byteLength is zero.
+
+        @param text        character code points or glyphs drawn (based on encoding)
+        @param byteLength  byte length of text array
+        @param pos     array of positions, must contain values for all of the character points.
+        @param font    SkFont used for this run
+        @param encoding specifies the encoding of the text array.
+        @return        new textblob or nullptr
+     */
+    static sk_sp<SkTextBlob> MakeFromPosText(const void* text, size_t byteLength,
+                                             const SkPoint pos[], const SkFont& font,
+                                             SkTextEncoding encoding = SkTextEncoding::kUTF8);
+
+    static sk_sp<SkTextBlob> MakeFromRSXform(const void* text, size_t byteLength,
+                                             const SkRSXform xform[], const SkFont& font,
+                                             SkTextEncoding encoding = SkTextEncoding::kUTF8);
+
+    /** Writes data to allow later reconstruction of SkTextBlob. memory points to storage
+        to receive the encoded data, and memory_size describes the size of storage.
+        Returns bytes used if provided storage is large enough to hold all data;
+        otherwise, returns zero.
+
+        procs.fTypefaceProc permits supplying a custom function to encode SkTypeface.
+        If procs.fTypefaceProc is nullptr, default encoding is used. procs.fTypefaceCtx
+        may be used to provide user context to procs.fTypefaceProc; procs.fTypefaceProc
+        is called with a pointer to SkTypeface and user context.
+
+        @param procs       custom serial data encoders; may be nullptr
+        @param memory      storage for data
+        @param memory_size size of storage
+        @return            bytes written, or zero if required storage is larger than memory_size
+
+        example: https://fiddle.skia.org/c/@TextBlob_serialize
+    */
+    size_t serialize(const SkSerialProcs& procs, void* memory, size_t memory_size) const;
+
+    /** Returns storage containing SkData describing SkTextBlob, using optional custom
+        encoders.
+
+        procs.fTypefaceProc permits supplying a custom function to encode SkTypeface.
+        If procs.fTypefaceProc is nullptr, default encoding is used. procs.fTypefaceCtx
+        may be used to provide user context to procs.fTypefaceProc; procs.fTypefaceProc
+        is called with a pointer to SkTypeface and user context.
+
+        @param procs  custom serial data encoders; may be nullptr
+        @return       storage containing serialized SkTextBlob
+
+        example: https://fiddle.skia.org/c/@TextBlob_serialize_2
+    */
+    sk_sp<SkData> serialize(const SkSerialProcs& procs) const;
+
+    /** Recreates SkTextBlob that was serialized into data. Returns constructed SkTextBlob
+        if successful; otherwise, returns nullptr. Fails if size is smaller than
+        required data length, or if data does not permit constructing valid SkTextBlob.
+
+        procs.fTypefaceProc permits supplying a custom function to decode SkTypeface.
+        If procs.fTypefaceProc is nullptr, default decoding is used. procs.fTypefaceCtx
+        may be used to provide user context to procs.fTypefaceProc; procs.fTypefaceProc
+        is called with a pointer to SkTypeface data, data byte length, and user context.
+
+        @param data   pointer for serial data
+        @param size   size of data
+        @param procs  custom serial data decoders; may be nullptr
+        @return       SkTextBlob constructed from data in memory
+    */
+    static sk_sp<SkTextBlob> Deserialize(const void* data, size_t size,
+                                         const SkDeserialProcs& procs);
+
+    class SK_API Iter {
+    public:
+        struct Run {
+            SkTypeface*     fTypeface;
+            int             fGlyphCount;
+            const uint16_t* fGlyphIndices;
+#ifdef SK_UNTIL_CRBUG_1187654_IS_FIXED
+            const uint32_t* fClusterIndex_forTest;
+            int             fUtf8Size_forTest;
+            const char*     fUtf8_forTest;
+#endif
+        };
+
+        Iter(const SkTextBlob&);
+
+        /**
+         * Returns true for each "run" inside the textblob, setting the Run fields (if not null).
+         * If this returns false, there are no more runs, and the Run parameter will be ignored.
+         */
+        bool next(Run*);
+
+        // Experimental, DO NO USE, will change/go-away
+        struct ExperimentalRun {
+            SkFont          font;
+            int             count;
+            const uint16_t* glyphs;
+            const SkPoint*  positions;
+        };
+        bool experimentalNext(ExperimentalRun*);
+
+    private:
+        const RunRecord* fRunRecord;
+    };
+
+private:
+    friend class SkNVRefCnt<SkTextBlob>;
+
+    enum GlyphPositioning : uint8_t;
+
+    explicit SkTextBlob(const SkRect& bounds);
+
+    ~SkTextBlob();
+
+    // Memory for objects of this class is created with sk_malloc rather than operator new and must
+    // be freed with sk_free.
+    void operator delete(void* p);
+    void* operator new(size_t);
+    void* operator new(size_t, void* p);
+
+    static unsigned ScalarsPerGlyph(GlyphPositioning pos);
+
+    // Call when this blob is part of the key to a cache entry. This allows the cache
+    // to know automatically those entries can be purged when this SkTextBlob is deleted.
+    void notifyAddedToCache(uint32_t cacheID) const {
+        fCacheID.store(cacheID);
+    }
+
+    friend class SkGlyphRunList;
+    friend class GrTextBlobCache;
+    friend class SkTextBlobBuilder;
+    friend class SkTextBlobPriv;
+    friend class SkTextBlobRunIterator;
+
+    const SkRect                  fBounds;
+    const uint32_t                fUniqueID;
+    mutable std::atomic<uint32_t> fCacheID;
+
+    SkDEBUGCODE(size_t fStorageSize;)
+
+    // The actual payload resides in externally-managed storage, following the object.
+    // (see the .cpp for more details)
+
+    using INHERITED = SkRefCnt;
+};
+
+/** \class SkTextBlobBuilder
+    Helper class for constructing SkTextBlob.
+*/
+class SK_API SkTextBlobBuilder {
+public:
+
+    /** Constructs empty SkTextBlobBuilder. By default, SkTextBlobBuilder has no runs.
+
+        @return  empty SkTextBlobBuilder
+
+        example: https://fiddle.skia.org/c/@TextBlobBuilder_empty_constructor
+    */
+    SkTextBlobBuilder();
+
+    /** Deletes data allocated internally by SkTextBlobBuilder.
+    */
+    ~SkTextBlobBuilder();
+
+    /** Returns SkTextBlob built from runs of glyphs added by builder. Returned
+        SkTextBlob is immutable; it may be copied, but its contents may not be altered.
+        Returns nullptr if no runs of glyphs were added by builder.
+
+        Resets SkTextBlobBuilder to its initial empty state, allowing it to be
+        reused to build a new set of runs.
+
+        @return  SkTextBlob or nullptr
+
+        example: https://fiddle.skia.org/c/@TextBlobBuilder_make
+    */
+    sk_sp<SkTextBlob> make();
+
+    /** \struct SkTextBlobBuilder::RunBuffer
+        RunBuffer supplies storage for glyphs and positions within a run.
+
+        A run is a sequence of glyphs sharing font metrics and positioning.
+        Each run may position its glyphs in one of three ways:
+        by specifying where the first glyph is drawn, and allowing font metrics to
+        determine the advance to subsequent glyphs; by specifying a baseline, and
+        the position on that baseline for each glyph in run; or by providing SkPoint
+        array, one per glyph.
+    */
+    struct RunBuffer {
+        SkGlyphID* glyphs;   //!< storage for glyph indexes in run
+        SkScalar*  pos;      //!< storage for glyph positions in run
+        char*      utf8text; //!< storage for text UTF-8 code units in run
+        uint32_t*  clusters; //!< storage for glyph clusters (index of UTF-8 code unit)
+
+        // Helpers, since the "pos" field can be different types (always some number of floats).
+        SkPoint*    points() const { return reinterpret_cast<SkPoint*>(pos); }
+        SkRSXform*  xforms() const { return reinterpret_cast<SkRSXform*>(pos); }
+    };
+
+    /** Returns run with storage for glyphs. Caller must write count glyphs to
+        RunBuffer::glyphs before next call to SkTextBlobBuilder.
+
+        RunBuffer::pos, RunBuffer::utf8text, and RunBuffer::clusters should be ignored.
+
+        Glyphs share metrics in font.
+
+        Glyphs are positioned on a baseline at (x, y), using font metrics to
+        determine their relative placement.
+
+        bounds defines an optional bounding box, used to suppress drawing when SkTextBlob
+        bounds does not intersect SkSurface bounds. If bounds is nullptr, SkTextBlob bounds
+        is computed from (x, y) and RunBuffer::glyphs metrics.
+
+        @param font    SkFont used for this run
+        @param count   number of glyphs
+        @param x       horizontal offset within the blob
+        @param y       vertical offset within the blob
+        @param bounds  optional run bounding box
+        @return writable glyph buffer
+    */
+    const RunBuffer& allocRun(const SkFont& font, int count, SkScalar x, SkScalar y,
+                              const SkRect* bounds = nullptr);
+
+    /** Returns run with storage for glyphs and positions along baseline. Caller must
+        write count glyphs to RunBuffer::glyphs and count scalars to RunBuffer::pos
+        before next call to SkTextBlobBuilder.
+
+        RunBuffer::utf8text and RunBuffer::clusters should be ignored.
+
+        Glyphs share metrics in font.
+
+        Glyphs are positioned on a baseline at y, using x-axis positions written by
+        caller to RunBuffer::pos.
+
+        bounds defines an optional bounding box, used to suppress drawing when SkTextBlob
+        bounds does not intersect SkSurface bounds. If bounds is nullptr, SkTextBlob bounds
+        is computed from y, RunBuffer::pos, and RunBuffer::glyphs metrics.
+
+        @param font    SkFont used for this run
+        @param count   number of glyphs
+        @param y       vertical offset within the blob
+        @param bounds  optional run bounding box
+        @return writable glyph buffer and x-axis position buffer
+    */
+    const RunBuffer& allocRunPosH(const SkFont& font, int count, SkScalar y,
+                                  const SkRect* bounds = nullptr);
+
+    /** Returns run with storage for glyphs and SkPoint positions. Caller must
+        write count glyphs to RunBuffer::glyphs and count SkPoint to RunBuffer::pos
+        before next call to SkTextBlobBuilder.
+
+        RunBuffer::utf8text and RunBuffer::clusters should be ignored.
+
+        Glyphs share metrics in font.
+
+        Glyphs are positioned using SkPoint written by caller to RunBuffer::pos, using
+        two scalar values for each SkPoint.
+
+        bounds defines an optional bounding box, used to suppress drawing when SkTextBlob
+        bounds does not intersect SkSurface bounds. If bounds is nullptr, SkTextBlob bounds
+        is computed from RunBuffer::pos, and RunBuffer::glyphs metrics.
+
+        @param font    SkFont used for this run
+        @param count   number of glyphs
+        @param bounds  optional run bounding box
+        @return writable glyph buffer and SkPoint buffer
+    */
+    const RunBuffer& allocRunPos(const SkFont& font, int count,
+                                 const SkRect* bounds = nullptr);
+
+    // RunBuffer.pos points to SkRSXform array
+    const RunBuffer& allocRunRSXform(const SkFont& font, int count);
+
+    /** Returns run with storage for glyphs, text, and clusters. Caller must
+        write count glyphs to RunBuffer::glyphs, textByteCount UTF-8 code units
+        into RunBuffer::utf8text, and count monotonic indexes into utf8text
+        into RunBuffer::clusters before next call to SkTextBlobBuilder.
+
+        RunBuffer::pos should be ignored.
+
+        Glyphs share metrics in font.
+
+        Glyphs are positioned on a baseline at (x, y), using font metrics to
+        determine their relative placement.
+
+        bounds defines an optional bounding box, used to suppress drawing when SkTextBlob
+        bounds does not intersect SkSurface bounds. If bounds is nullptr, SkTextBlob bounds
+        is computed from (x, y) and RunBuffer::glyphs metrics.
+
+        @param font          SkFont used for this run
+        @param count         number of glyphs
+        @param x             horizontal offset within the blob
+        @param y             vertical offset within the blob
+        @param textByteCount number of UTF-8 code units
+        @param bounds        optional run bounding box
+        @return writable glyph buffer, text buffer, and cluster buffer
+    */
+    const RunBuffer& allocRunText(const SkFont& font, int count, SkScalar x, SkScalar y,
+                                  int textByteCount, const SkRect* bounds = nullptr);
+
+    /** Returns run with storage for glyphs, positions along baseline, text,
+        and clusters. Caller must write count glyphs to RunBuffer::glyphs,
+        count scalars to RunBuffer::pos, textByteCount UTF-8 code units into
+        RunBuffer::utf8text, and count monotonic indexes into utf8text into
+        RunBuffer::clusters before next call to SkTextBlobBuilder.
+
+        Glyphs share metrics in font.
+
+        Glyphs are positioned on a baseline at y, using x-axis positions written by
+        caller to RunBuffer::pos.
+
+        bounds defines an optional bounding box, used to suppress drawing when SkTextBlob
+        bounds does not intersect SkSurface bounds. If bounds is nullptr, SkTextBlob bounds
+        is computed from y, RunBuffer::pos, and RunBuffer::glyphs metrics.
+
+        @param font          SkFont used for this run
+        @param count         number of glyphs
+        @param y             vertical offset within the blob
+        @param textByteCount number of UTF-8 code units
+        @param bounds        optional run bounding box
+        @return writable glyph buffer, x-axis position buffer, text buffer, and cluster buffer
+    */
+    const RunBuffer& allocRunTextPosH(const SkFont& font, int count, SkScalar y, int textByteCount,
+                                      const SkRect* bounds = nullptr);
+
+    /** Returns run with storage for glyphs, SkPoint positions, text, and
+        clusters. Caller must write count glyphs to RunBuffer::glyphs, count
+        SkPoint to RunBuffer::pos, textByteCount UTF-8 code units into
+        RunBuffer::utf8text, and count monotonic indexes into utf8text into
+        RunBuffer::clusters before next call to SkTextBlobBuilder.
+
+        Glyphs share metrics in font.
+
+        Glyphs are positioned using SkPoint written by caller to RunBuffer::pos, using
+        two scalar values for each SkPoint.
+
+        bounds defines an optional bounding box, used to suppress drawing when SkTextBlob
+        bounds does not intersect SkSurface bounds. If bounds is nullptr, SkTextBlob bounds
+        is computed from RunBuffer::pos, and RunBuffer::glyphs metrics.
+
+        @param font          SkFont used for this run
+        @param count         number of glyphs
+        @param textByteCount number of UTF-8 code units
+        @param bounds        optional run bounding box
+        @return writable glyph buffer, SkPoint buffer, text buffer, and cluster buffer
+    */
+    const RunBuffer& allocRunTextPos(const SkFont& font, int count, int textByteCount,
+                                     const SkRect* bounds = nullptr);
+
+    // RunBuffer.pos points to SkRSXform array
+    const RunBuffer& allocRunTextRSXform(const SkFont& font, int count, int textByteCount,
+                                         const SkRect* bounds = nullptr);
+
+private:
+    void reserve(size_t size);
+    void allocInternal(const SkFont& font, SkTextBlob::GlyphPositioning positioning,
+                       int count, int textBytes, SkPoint offset, const SkRect* bounds);
+    bool mergeRun(const SkFont& font, SkTextBlob::GlyphPositioning positioning,
+                  uint32_t count, SkPoint offset);
+    void updateDeferredBounds();
+
+    static SkRect ConservativeRunBounds(const SkTextBlob::RunRecord&);
+    static SkRect TightRunBounds(const SkTextBlob::RunRecord&);
+
+    friend class SkTextBlobPriv;
+    friend class SkTextBlobBuilderPriv;
+
+    SkAutoTMalloc<uint8_t> fStorage;
+    size_t                 fStorageSize;
+    size_t                 fStorageUsed;
+
+    SkRect                 fBounds;
+    int                    fRunCount;
+    bool                   fDeferredBounds;
+    size_t                 fLastRun; // index into fStorage
+
+    RunBuffer              fCurrentRunBuffer;
+};
+
+#endif // SkTextBlob_DEFINED