From d543a09bcfaf3d8a28541423baa65ad0ef2b72a4 Mon Sep 17 00:00:00 2001
From: Daniel Dresser <danield@image-engine.com>
Date: Sun, 22 Jan 2023 22:10:22 -0800
Subject: [PATCH] RankFilter : Use Sampler::visitPixels to improve performance

---
 src/GafferImage/RankFilter.cpp | 40 +++++++++++++++-------------------
 1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/src/GafferImage/RankFilter.cpp b/src/GafferImage/RankFilter.cpp
index 72b97544fd1..cc72d3a8a6d 100644
--- a/src/GafferImage/RankFilter.cpp
+++ b/src/GafferImage/RankFilter.cpp
@@ -225,8 +225,9 @@ void RankFilter::compute( Gaffer::ValuePlug *output, const Gaffer::Context *cont
 		vector<V2i> &result = resultData->writable();
 		result.reserve( ImagePlug::tileSize() * ImagePlug::tileSize() );
 
-		vector<float> pixels( ( 1 + 2 * radius.x ) * ( 1 + 2 * radius.y ) );
-		vector<float> sortPixels( ( 1 + 2 * radius.x ) * ( 1 + 2 * radius.y ) );
+		int supportSize = 1 + 2 * radius.x;
+		vector<float> pixels( supportSize * supportSize );
+		vector<float> sortPixels( supportSize * supportSize );
 		vector<float>::iterator resultIt = sortPixels.begin() + sortPixels.size() / 2;
 
 		V2i p;
@@ -237,15 +238,11 @@ void RankFilter::compute( Gaffer::ValuePlug *output, const Gaffer::Context *cont
 				IECore::Canceller::check( context->canceller() );
 
 				// Fill array with all nearby samples
-				V2i o;
-				vector<float>::iterator pixelsIt = pixels.begin();
-				for( o.y = -radius.y; o.y <= radius.y; ++o.y )
-				{
-					for( o.x = -radius.x; o.x <= radius.x; ++o.x )
-					{
-						*pixelsIt++ = sampler.sample( p.x + o.x, p.y + o.y );
-					}
-				}
+				V2i corner = p - radius;
+				sampler.visitPixels(
+					Imath::Box2i( p - radius, p + radius + Imath::V2i( 1 ) ),
+					[corner, supportSize, &pixels]( float v, int x, int y ){ pixels[ ( y - corner.y ) * supportSize + x - corner.x ] = v; }
+				);
 
 				switch( m_mode )
 				{
@@ -268,7 +265,8 @@ void RankFilter::compute( Gaffer::ValuePlug *output, const Gaffer::Context *cont
 				V2i r( INT_MAX, INT_MAX );
 
 				int closestMatch = INT_MAX;
-				pixelsIt = pixels.begin();
+				vector<float>::iterator pixelsIt = pixels.begin();
+				V2i o;
 				for( o.y = -radius.y; o.y <= radius.y; ++o.y )
 				{
 					for( o.x = -radius.x; o.x <= radius.x; ++o.x )
@@ -398,7 +396,8 @@ IECore::ConstFloatVectorDataPtr RankFilter::computeChannelData( const std::strin
 		return resultData;
 	}
 
-	vector<float> pixels( ( 1 + 2 * radius.x ) * ( 1 + 2 * radius.y ) );
+	int supportSize = 1 + 2 * radius.x;
+	vector<float> pixels( supportSize * supportSize );
 	vector<float>::iterator resultIt = pixels.begin() + pixels.size() / 2;
 
 	V2i p;
@@ -408,15 +407,12 @@ IECore::ConstFloatVectorDataPtr RankFilter::computeChannelData( const std::strin
 		{
 			IECore::Canceller::check( context->canceller() );
 
-			V2i o;
-			vector<float>::iterator pixelsIt = pixels.begin();
-			for( o.y = -radius.y; o.y <= radius.y; ++o.y )
-			{
-				for( o.x = -radius.x; o.x <= radius.x; ++o.x )
-				{
-					*pixelsIt++ = sampler.sample( p.x + o.x, p.y + o.y );
-				}
-			}
+			V2i corner = p - radius;
+			sampler.visitPixels(
+				Imath::Box2i( p - radius, p + radius + Imath::V2i( 1 ) ),
+				[corner, supportSize, &pixels]( float v, int x, int y ){ pixels[ ( y - corner.y ) * supportSize + x - corner.x ] = v; }
+			);
+
 			switch( m_mode )
 			{
 				case MedianRank: