gfx/skia/skia/include/core/SkDataTable.h
author Wes Kocher <wkocher@mozilla.com>
Wed, 10 May 2017 10:01:18 -0700
changeset 407965 ce2218406119c36a551e3faea4e192186ee46cc5
parent 407937 af6f19870b2a00759ac1d83dedc3db57213abfee
child 408167 0ded74baeaf23d7985401fe9bbabdb3d9385ac22
permissions -rw-r--r--
Backed out 9 changesets (bug 1340627) for graphical glitches a=backout Backed out changeset 0b1371055c7f (bug 1340627) Backed out changeset f152be1fadb7 (bug 1340627) Backed out changeset c691e2ab6a0c (bug 1340627) Backed out changeset 3cb4bceb8d79 (bug 1340627) Backed out changeset 026aadd76d06 (bug 1340627) Backed out changeset fdbd5d281287 (bug 1340627) Backed out changeset 75fb0d9858a9 (bug 1340627) Backed out changeset 0d4ec7d38a00 (bug 1340627) Backed out changeset af6f19870b2a (bug 1340627) MozReview-Commit-ID: 9dHr7xMZezY

/*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkDataTable_DEFINED
#define SkDataTable_DEFINED

#include "../private/SkTDArray.h"
#include "SkChunkAlloc.h"
#include "SkData.h"
#include "SkString.h"

/**
 *  Like SkData, SkDataTable holds an immutable data buffer. The data buffer is
 *  organized into a table of entries, each with a length, so the entries are
 *  not required to all be the same size.
 */
class SK_API SkDataTable : public SkRefCnt {
public:
    /**
     *  Returns true if the table is empty (i.e. has no entries).
     */
    bool isEmpty() const { return 0 == fCount; }

    /**
     *  Return the number of entries in the table. 0 for an empty table
     */
    int count() const { return fCount; }

    /**
     *  Return the size of the index'th entry in the table. The caller must
     *  ensure that index is valid for this table.
     */
    size_t atSize(int index) const;

    /**
     *  Return a pointer to the data of the index'th entry in the table.
     *  The caller must ensure that index is valid for this table.
     *
     *  @param size If non-null, this returns the byte size of this entry. This
     *              will be the same value that atSize(index) would return.
     */
    const void* at(int index, size_t* size = NULL) const;

    template <typename T>
    const T* atT(int index, size_t* size = NULL) const {
        return reinterpret_cast<const T*>(this->at(index, size));
    }

    /**
     *  Returns the index'th entry as a c-string, and assumes that the trailing
     *  null byte had been copied into the table as well.
     */
    const char* atStr(int index) const {
        size_t size;
        const char* str = this->atT<const char>(index, &size);
        SkASSERT(strlen(str) + 1 == size);
        return str;
    }

    typedef void (*FreeProc)(void* context);

    static sk_sp<SkDataTable> MakeEmpty();

    /**
     *  Return a new DataTable that contains a copy of the data stored in each
     *  "array".
     *
     *  @param ptrs array of points to each element to be copied into the table.
     *  @param sizes array of byte-lengths for each entry in the corresponding
     *               ptrs[] array.
     *  @param count the number of array elements in ptrs[] and sizes[] to copy.
     */
    static sk_sp<SkDataTable> MakeCopyArrays(const void * const * ptrs,
                                             const size_t sizes[], int count);

    /**
     *  Return a new table that contains a copy of the data in array.
     *
     *  @param array contiguous array of data for all elements to be copied.
     *  @param elemSize byte-length for a given element.
     *  @param count the number of entries to be copied out of array. The number
     *               of bytes that will be copied is count * elemSize.
     */
    static sk_sp<SkDataTable> MakeCopyArray(const void* array, size_t elemSize, int count);

    static sk_sp<SkDataTable> MakeArrayProc(const void* array, size_t elemSize, int count,
                                            FreeProc proc, void* context);

private:
    struct Dir {
        const void* fPtr;
        uintptr_t   fSize;
    };

    int         fCount;
    size_t      fElemSize;
    union {
        const Dir*  fDir;
        const char* fElems;
    } fU;

    FreeProc    fFreeProc;
    void*       fFreeProcContext;

    SkDataTable();
    SkDataTable(const void* array, size_t elemSize, int count,
                FreeProc, void* context);
    SkDataTable(const Dir*, int count, FreeProc, void* context);
    virtual ~SkDataTable();

    friend class SkDataTableBuilder;    // access to Dir

    typedef SkRefCnt INHERITED;
};

/**
 *  Helper class that allows for incrementally building up the data needed to
 *  create a SkDataTable.
 */
class SK_API SkDataTableBuilder : SkNoncopyable {
public:
    SkDataTableBuilder(size_t minChunkSize);
    ~SkDataTableBuilder();

    int  count() const { return fDir.count(); }
    size_t minChunkSize() const { return fMinChunkSize; }

    /**
     *  Forget any previously appended entries, setting count() back to 0.
     */
    void reset(size_t minChunkSize);
    void reset() {
        this->reset(fMinChunkSize);
    }

    /**
     *  Copy size-bytes from data, and append it to the growing SkDataTable.
     */
    void append(const void* data, size_t size);

    /**
     *  Helper version of append() passes strlen() + 1 for the size,
     *  so the trailing-zero will be copied as well.
     */
    void appendStr(const char str[]) {
        this->append(str, strlen(str) + 1);
    }

    /**
     *  Helper version of append() passes string.size() + 1 for the size,
     *  so the trailing-zero will be copied as well.
     */
    void appendString(const SkString& string) {
        this->append(string.c_str(), string.size() + 1);
    }

    /**
     *  Return an SkDataTable from the accumulated entries that were added by
     *  calls to append(). This call also clears any accumluated entries from
     *  this builder, so its count() will be 0 after this call.
     */
    sk_sp<SkDataTable> detachDataTable();

private:
    SkTDArray<SkDataTable::Dir> fDir;
    SkChunkAlloc*               fHeap;
    size_t                      fMinChunkSize;
};

#endif