Compositor: Buffer iterators

Currently we mostly iterate buffer areas using x/y loops or through
utility methods extending from base classes.

To simplify code in simple operations this commit adds wrappers for
specifying buffer areas and their iterators for raw buffers with any
element stride:
- BufferRange: Specifies a range of contiguous buffer elements from a
 given element index.
- BufferRangeIterator: Iterates elements in a BufferRange.
- BufferArea: Specifies a rectangle area of elements in a 2D buffer.
- BufferAreaIterator: Iterates elements in a BufferArea.
- BuffersIterator: Simultaneously iterates an area of elements in an
 output buffer and any number of input buffers.
- BuffersIteratorBuilder: Helper for building BuffersIterator adding
 buffers one by one.
For iterating areas coordinates it adds `XRange` and `YRange` methods
that return `IndexRange`.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D11882

1 files changed, 29 insertions, 0 deletions

diff --git a/source/blender/compositor/intern/COM_MemoryBuffer.h b/source/blender/compositor/intern/COM_MemoryBuffer.h
index 4ad0872b0b7..048ed4c5d6e 100644
--- a/source/blender/compositor/intern/COM_MemoryBuffer.h
+++ b/source/blender/compositor/intern/COM_MemoryBuffer.h
@@ -18,6 +18,9 @@
 
 #pragma once
 
+#include "COM_BufferArea.h"
+#include "COM_BufferRange.h"
+#include "COM_BuffersIterator.h"
 #include "COM_ExecutionGroup.h"
 #include "COM_MemoryProxy.h"
 
@@ -239,6 +242,32 @@ class MemoryBuffer {
   }
 
   /**
+   * Get all buffer elements as a range with no offsets.
+   */
+  BufferRange<float> as_range()
+  {
+    return BufferRange<float>(m_buffer, 0, buffer_len(), elem_stride);
+  }
+
+  BufferRange<const float> as_range() const
+  {
+    return BufferRange<const float>(m_buffer, 0, buffer_len(), elem_stride);
+  }
+
+  BufferArea<float> get_buffer_area(const rcti &area)
+  {
+    return BufferArea<float>(m_buffer, getWidth(), area, elem_stride);
+  }
+
+  BufferArea<const float> get_buffer_area(const rcti &area) const
+  {
+    return BufferArea<const float>(m_buffer, getWidth(), area, elem_stride);
+  }
+
+  BuffersIterator<float> iterate_with(Span<MemoryBuffer *> inputs);
+  BuffersIterator<float> iterate_with(Span<MemoryBuffer *> inputs, const rcti &area);
+
+  /**
    * \brief get the data of this MemoryBuffer
    * \note buffer should already be available in memory
    */