From 0617b4e0f54018fbb0ad786ac3c0d0bd6a8ee9c3 Mon Sep 17 00:00:00 2001
From: Arnaud Botella <arnaud.botella@geode-solutions.com>
Date: Wed, 21 Oct 2026 09:09:49 +0200
Subject: [PATCH] feat(RasterImage): contiguous access to all the colors

colors() and modifiable_colors() expose the color storage as spans so
readers and writers can process whole images without a function call
per cell.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 include/geode/image/core/raster_image.hpp | 13 ++++++++++
 src/geode/image/core/raster_image.cpp     | 22 ++++++++++++++++
 tests/image/test-raster-image.cpp         | 31 +++++++++++++++++++++++
 3 files changed, 66 insertions(+)

diff --git a/include/geode/image/core/raster_image.hpp b/include/geode/image/core/raster_image.hpp
index 844d78251..9d91f8139 100644
--- a/include/geode/image/core/raster_image.hpp
+++ b/include/geode/image/core/raster_image.hpp
@@ -23,6 +23,8 @@
 
 #pragma once
 
+#include <absl/types/span.h>
+
 #include <geode/basic/cell_array.hpp>
 #include <geode/basic/identifier.hpp>
 #include <geode/basic/pimpl.hpp>
@@ -72,6 +74,17 @@ namespace geode
 
         void set_color( index_t index, RGBColor color );
 
+        /*!
+         * All the cell colors, stored contiguously in cell index order
+         */
+        [[nodiscard]] absl::Span< const RGBColor > colors() const;
+
+        /*!
+         * All the cell colors, stored contiguously in cell index order, for
+         * bulk modifications
+         */
+        [[nodiscard]] absl::Span< RGBColor > modifiable_colors();
+
         [[nodiscard]] RasterImage clone() const;
 
     private:
diff --git a/src/geode/image/core/raster_image.cpp b/src/geode/image/core/raster_image.cpp
index 117de7734..f9b6f7770 100644
--- a/src/geode/image/core/raster_image.cpp
+++ b/src/geode/image/core/raster_image.cpp
@@ -55,6 +55,16 @@ namespace geode
             colors_[index] = std::move( color );
         }
 
+        [[nodiscard]] absl::Span< const RGBColor > colors() const
+        {
+            return colors_;
+        }
+
+        [[nodiscard]] absl::Span< RGBColor > modifiable_colors()
+        {
+            return absl::MakeSpan( colors_ );
+        }
+
         [[nodiscard]] index_t nb_colors() const
         {
             return static_cast< index_t >( colors_.size() );
@@ -150,6 +160,18 @@ namespace geode
         impl_->set_color( index, std::move( color ) );
     }
 
+    template < index_t dimension >
+    absl::Span< const RGBColor > RasterImage< dimension >::colors() const
+    {
+        return impl_->colors();
+    }
+
+    template < index_t dimension >
+    absl::Span< RGBColor > RasterImage< dimension >::modifiable_colors()
+    {
+        return impl_->modifiable_colors();
+    }
+
     template < index_t dimension >
     RasterImage< dimension > RasterImage< dimension >::clone() const
     {
diff --git a/tests/image/test-raster-image.cpp b/tests/image/test-raster-image.cpp
index a5b3e1bf0..fa2d2ffab 100644
--- a/tests/image/test-raster-image.cpp
+++ b/tests/image/test-raster-image.cpp
@@ -135,6 +135,36 @@ void test_extra_colors()
         "[TEST] Loading more colors than cells should throw" );
 }
 
+void test_colors_access()
+{
+    geode::RasterImage2D raster{ { 4, 3 } };
+    auto colors = raster.modifiable_colors();
+    geode::OpenGeodeImageException::test( colors.size() == raster.nb_cells(),
+        "[TEST] Wrong number of modifiable colors" );
+    for( const auto i : geode::Indices{ colors } )
+    {
+        const auto value = static_cast< geode::local_index_t >( 10 * i );
+        colors[i] = { value, static_cast< geode::local_index_t >( value + 1 ),
+            static_cast< geode::local_index_t >( value + 2 ) };
+    }
+    const auto& const_raster = raster;
+    const auto stored_colors = const_raster.colors();
+    geode::OpenGeodeImageException::test(
+        stored_colors.size() == raster.nb_cells(),
+        "[TEST] Wrong number of colors" );
+    for( const auto i : geode::Range{ raster.nb_cells() } )
+    {
+        const auto value = static_cast< geode::local_index_t >( 10 * i );
+        const geode::RGBColor expected{ value,
+            static_cast< geode::local_index_t >( value + 1 ),
+            static_cast< geode::local_index_t >( value + 2 ) };
+        geode::OpenGeodeImageException::test( raster.color( i ) == expected,
+            "[TEST] Wrong color set through modifiable colors for ", i );
+        geode::OpenGeodeImageException::test(
+            stored_colors[i] == expected, "[TEST] Wrong stored color for ", i );
+    }
+}
+
 template < geode::index_t dimension >
 void test_io( std::array< geode::index_t, dimension > cells_number )
 {
@@ -190,6 +220,7 @@ void test()
     test_missing_colors();
     test_too_many_cells();
     test_extra_colors();
+    test_colors_access();
     auto raster2 = std::move( raster );
     geode::OpenGeodeImageException::test(
         raster2.nb_cells() == 100, "Wrong number of cells after move" );