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/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* Copyright 2021, Blender Foundation.
*/
#pragma once
#include "BLI_assert.h"
#include "BLI_rect.h"
#include <iterator>
namespace blender::compositor {
/* Forward declarations. */
template<typename T> class BufferAreaIterator;
/**
* A rectangle area of buffer elements.
*/
template<typename T> class BufferArea : rcti {
public:
using Iterator = BufferAreaIterator<T>;
using ConstIterator = BufferAreaIterator<const T>;
private:
T *buffer_;
/* Number of elements in a buffer row. */
int buffer_width_;
/* Buffer element stride. */
int elem_stride_;
public:
constexpr BufferArea() = default;
/**
* Create a buffer area containing given rectangle area.
*/
constexpr BufferArea(T *buffer, int buffer_width, const rcti &area, int elem_stride = 1)
: rcti(area), buffer_(buffer), buffer_width_(buffer_width), elem_stride_(elem_stride)
{
}
/**
* Create a buffer area containing whole buffer with no offsets.
*/
constexpr BufferArea(T *buffer, int buffer_width, int buffer_height, int elem_stride = 1)
: buffer_(buffer), buffer_width_(buffer_width), elem_stride_(elem_stride)
{
BLI_rcti_init(this, 0, buffer_width, 0, buffer_height);
}
constexpr friend bool operator==(const BufferArea &a, const BufferArea &b)
{
return a.buffer_ == b.buffer_ && BLI_rcti_compare(&a, &b) && a.elem_stride_ == b.elem_stride_;
}
constexpr const rcti &get_rect() const
{
return *this;
}
/**
* Number of elements in a row.
*/
constexpr int width() const
{
return BLI_rcti_size_x(this);
}
/**
* Number of elements in a column.
*/
constexpr int height() const
{
return BLI_rcti_size_y(this);
}
constexpr Iterator begin()
{
return begin_iterator<Iterator>();
}
constexpr Iterator end()
{
return end_iterator<Iterator>();
}
constexpr ConstIterator begin() const
{
return begin_iterator<ConstIterator>();
}
constexpr ConstIterator end() const
{
return end_iterator<ConstIterator>();
}
private:
template<typename TIterator> constexpr TIterator begin_iterator() const
{
T *end_ptr = get_end_ptr();
if (elem_stride_ == 0) {
/* Iterate a single element. */
return TIterator(buffer_, end_ptr, 1, 1, 1);
}
T *begin_ptr = buffer_ + (intptr_t)this->ymin * buffer_width_ * elem_stride_ +
(intptr_t)this->xmin * elem_stride_;
return TIterator(begin_ptr, end_ptr, buffer_width_, BLI_rcti_size_x(this), elem_stride_);
}
template<typename TIterator> constexpr TIterator end_iterator() const
{
T *end_ptr = get_end_ptr();
if (elem_stride_ == 0) {
/* Iterate a single element. */
return TIterator(end_ptr, end_ptr, 1, 1, 1);
}
return TIterator(end_ptr, end_ptr, buffer_width_, BLI_rcti_size_x(this), elem_stride_);
}
T *get_end_ptr() const
{
if (elem_stride_ == 0) {
return buffer_ + 1;
}
return buffer_ + (intptr_t)(this->ymax - 1) * buffer_width_ * elem_stride_ +
(intptr_t)this->xmax * elem_stride_;
}
};
template<typename T> class BufferAreaIterator {
public:
using iterator_category = std::input_iterator_tag;
using value_type = T *;
using pointer = T *const *;
using reference = T *const &;
using difference_type = std::ptrdiff_t;
private:
int elem_stride_;
int row_stride_;
/* Stride between a row end and the next row start. */
int rows_gap_;
T *current_;
const T *row_end_;
const T *end_;
public:
constexpr BufferAreaIterator() = default;
constexpr BufferAreaIterator(
T *current, const T *end, int buffer_width, int area_width, int elem_stride = 1)
: elem_stride_(elem_stride),
row_stride_(buffer_width * elem_stride),
rows_gap_(row_stride_ - area_width * elem_stride),
current_(current),
row_end_(current + area_width * elem_stride),
end_(end)
{
}
constexpr BufferAreaIterator &operator++()
{
current_ += elem_stride_;
BLI_assert(current_ <= row_end_);
if (current_ == row_end_) {
BLI_assert(current_ <= end_);
if (current_ == end_) {
return *this;
}
current_ += rows_gap_;
row_end_ += row_stride_;
}
return *this;
}
constexpr BufferAreaIterator operator++(int) const
{
BufferAreaIterator copied_iterator = *this;
++copied_iterator;
return copied_iterator;
}
constexpr friend bool operator!=(const BufferAreaIterator &a, const BufferAreaIterator &b)
{
return a.current_ != b.current_;
}
constexpr friend bool operator==(const BufferAreaIterator &a, const BufferAreaIterator &b)
{
return a.current_ == b.current_;
}
constexpr T *operator*() const
{
return current_;
}
};
} // namespace blender::compositor
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