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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_rect.h"
#include "BLI_vector.hh"
namespace blender::compositor {
/**
* Builds an iterator for simultaneously iterating an area of elements in an output buffer and any
* number of input buffers. It's not a standard C++ iterator and it does not support neither
* deference, equality or postfix increment operators.
*/
template<typename T> class BuffersIteratorBuilder {
public:
class Iterator {
const T *out_end_;
const T *out_row_end_;
int out_elem_stride_;
int out_row_stride_;
/* Stride between an output row end and the next row start. */
int out_rows_gap_;
struct In {
int elem_stride;
int rows_gap;
const T *in;
};
Vector<In, 6> ins_;
friend class BuffersIteratorBuilder;
public:
/**
* Current output element.
*/
T *out;
public:
/**
* Get current element from an input.
*/
const T *in(int input_index) const
{
BLI_assert(input_index < ins_.size());
return ins_[input_index].in;
}
int get_num_inputs() const
{
return ins_.size();
}
/**
* Has the end of the area been reached.
*/
bool is_end() const
{
return out >= out_end_;
}
/**
* Go to the next element in the area.
*/
void next()
{
out += out_elem_stride_;
for (In &in : ins_) {
in.in += in.elem_stride;
}
if (out == out_row_end_) {
out += out_rows_gap_;
out_row_end_ += out_row_stride_;
for (In &in : ins_) {
in.in += in.rows_gap;
}
}
}
Iterator &operator++()
{
this->next();
return *this;
}
};
private:
Iterator iterator_;
rcti area_;
bool is_built_;
public:
/**
* Create a buffers iterator builder to iterate given output buffer area.
* \param output: Output buffer.
* \param buffer_width: Number of elements in an output buffer row.
* \param area: Rectangle area to be iterated in all buffers.
* \param elem_stride: Output buffer element stride.
*/
BuffersIteratorBuilder(T *output, int buffer_width, const rcti &area, int elem_stride = 1)
: area_(area), is_built_(false)
{
iterator_.out_elem_stride_ = elem_stride;
iterator_.out_row_stride_ = buffer_width * elem_stride;
iterator_.out_rows_gap_ = iterator_.out_row_stride_ - BLI_rcti_size_x(&area) * elem_stride;
iterator_.out = output + (intptr_t)area.ymin * iterator_.out_row_stride_ +
(intptr_t)area.xmin * elem_stride;
iterator_.out_row_end_ = iterator_.out + (intptr_t)BLI_rcti_size_x(&area) * elem_stride;
iterator_.out_end_ = iterator_.out_row_end_ +
(intptr_t)iterator_.out_row_stride_ * (BLI_rcti_size_y(&area) - 1);
}
/**
* Create a buffers iterator builder to iterate given output buffer with no offsets.
*/
BuffersIteratorBuilder(T *output, int buffer_width, int buffer_height, int elem_stride = 1)
: BuffersIteratorBuilder(
output, buffer_width, {0, buffer_width, 0, buffer_height}, elem_stride)
{
}
/**
* Add an input buffer to be iterated. Its coordinates must be correlated with the output.
*/
void add_input(const T *input, int buffer_width, int elem_stride = 1)
{
BLI_assert(!is_built_);
typename Iterator::In in;
in.elem_stride = elem_stride;
in.rows_gap = buffer_width * elem_stride - BLI_rcti_size_x(&area_) * elem_stride;
in.in = input + area_.ymin * buffer_width * elem_stride + area_.xmin * elem_stride;
iterator_.ins_.append(std::move(in));
}
/**
* Build the iterator.
*/
BuffersIteratorBuilder::Iterator build()
{
is_built_ = true;
return iterator_;
}
};
template<typename T> using BuffersIterator = typename BuffersIteratorBuilder<T>::Iterator;
} // namespace blender::compositor
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