Home | History | Annotate | Download | only in canvas 
      1 /*
      2  * Copyright (C) 2009 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef ArrayBufferView_h
     27 #define ArrayBufferView_h
     28 
     29 #include "ArrayBuffer.h"
     30 #include "ExceptionCode.h"
     31 
     32 #include <algorithm>
     33 #include <limits.h>
     34 #include <wtf/PassRefPtr.h>
     35 #include <wtf/RefCounted.h>
     36 #include <wtf/RefPtr.h>
     37 
     38 namespace WebCore {
     39 
     40 class ArrayBufferView : public RefCounted<ArrayBufferView> {
     41   public:
     42     virtual bool isByteArray() const { return false; }
     43     virtual bool isUnsignedByteArray() const { return false; }
     44     virtual bool isShortArray() const { return false; }
     45     virtual bool isUnsignedShortArray() const { return false; }
     46     virtual bool isIntArray() const { return false; }
     47     virtual bool isUnsignedIntArray() const { return false; }
     48     virtual bool isFloatArray() const { return false; }
     49     virtual bool isDataView() const { return false; }
     50 
     51     PassRefPtr<ArrayBuffer> buffer() const
     52     {
     53         return m_buffer;
     54     }
     55 
     56     void* baseAddress() const
     57     {
     58         return m_baseAddress;
     59     }
     60 
     61     unsigned byteOffset() const
     62     {
     63         return m_byteOffset;
     64     }
     65 
     66     virtual unsigned byteLength() const = 0;
     67 
     68     virtual ~ArrayBufferView();
     69 
     70   protected:
     71     ArrayBufferView(PassRefPtr<ArrayBuffer> buffer, unsigned byteOffset);
     72 
     73     void setImpl(ArrayBufferView* array, unsigned byteOffset, ExceptionCode& ec);
     74 
     75     void setRangeImpl(const char* data, size_t dataByteLength, unsigned byteOffset, ExceptionCode& ec);
     76 
     77     void zeroRangeImpl(unsigned byteOffset, size_t rangeByteLength, ExceptionCode& ec);
     78 
     79     static void calculateOffsetAndLength(int start, int end, unsigned arraySize,
     80                                          unsigned* offset, unsigned* length);
     81 
     82     // Helper to verify that a given sub-range of an ArrayBuffer is
     83     // within range.
     84     template <typename T>
     85     static bool verifySubRange(PassRefPtr<ArrayBuffer> buffer,
     86                                unsigned byteOffset,
     87                                unsigned numElements)
     88     {
     89         if (!buffer)
     90             return false;
     91         if (sizeof(T) > 1 && byteOffset % sizeof(T))
     92             return false;
     93         if (byteOffset > buffer->byteLength())
     94             return false;
     95         unsigned remainingElements = (buffer->byteLength() - byteOffset) / sizeof(T);
     96         if (numElements > remainingElements)
     97             return false;
     98         return true;
     99     }
    100 
    101     // Input offset is in number of elements from this array's view;
    102     // output offset is in number of bytes from the underlying buffer's view.
    103     template <typename T>
    104     static void clampOffsetAndNumElements(PassRefPtr<ArrayBuffer> buffer,
    105                                           unsigned arrayByteOffset,
    106                                           unsigned *offset,
    107                                           unsigned *numElements)
    108     {
    109         unsigned maxOffset = (UINT_MAX - arrayByteOffset) / sizeof(T);
    110         if (*offset > maxOffset) {
    111             *offset = buffer->byteLength();
    112             *numElements = 0;
    113             return;
    114         }
    115         *offset = arrayByteOffset + *offset * sizeof(T);
    116         *offset = std::min(buffer->byteLength(), *offset);
    117         unsigned remainingElements = (buffer->byteLength() - *offset) / sizeof(T);
    118         *numElements = std::min(remainingElements, *numElements);
    119     }
    120 
    121     // This is the address of the ArrayBuffer's storage, plus the byte offset.
    122     void* m_baseAddress;
    123 
    124     unsigned m_byteOffset;
    125 
    126   private:
    127     RefPtr<ArrayBuffer> m_buffer;
    128 };
    129 
    130 } // namespace WebCore
    131 
    132 #endif // ArrayBufferView_h
    133