From caec92ddd39443d4c88b4236297f63e9292e8a66 Mon Sep 17 00:00:00 2001
From: Hermet Park <hermet@lottiefiles.com>
Date: Mon, 23 Jun 2025 15:37:47 +0900
Subject: [PATCH] infra: add the partial rendering build option

allow users to set partial rendering as option to use,
enabled by deault.

-Dextra="partial_render, ..."
---
 meson.build                |  7 +++
 meson_options.txt          |  4 +-
 src/renderer/tvgRender.cpp |  6 ++-
 src/renderer/tvgRender.h   | 90 +++++++++++++++++++++++---------------
 4 files changed, 68 insertions(+), 39 deletions(-)

diff --git a/meson.build b/meson.build
index bf0ab450..4910acb3 100644
--- a/meson.build
+++ b/meson.build
@@ -126,6 +126,12 @@ endif
 
 
 #Extra
+partial_render = get_option('extra').contains('partial_render')
+
+if partial_render
+    config_h.set10('THORVG_PARTIAL_RENDER_SUPPORT', true)
+endif
+
 lottie_expressions = lottie_loader and get_option('extra').contains('lottie_expressions')
 
 if lottie_expressions
@@ -230,6 +236,7 @@ summary(
 
 summary(
   {
+    'Partial Rendering': partial_render,
     'Lottie Expressions': lottie_expressions,
     'OpenGL Variant': gl_variant,
   },
diff --git a/meson_options.txt b/meson_options.txt
index c143c3bf..9a0527f1 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -65,6 +65,6 @@ option('file',
 
 option('extra',
    type: 'array',
-   choices: ['', 'opengl_es', 'lottie_expressions'],
-   value: ['lottie_expressions'],
+   choices: ['', 'partial_render', 'opengl_es', 'lottie_expressions'],
+   value: ['partial_render', 'lottie_expressions'],
    description: '"Enable support for extra options')
diff --git a/src/renderer/tvgRender.cpp b/src/renderer/tvgRender.cpp
index 0c97f437..5b77a7d7 100644
--- a/src/renderer/tvgRender.cpp
+++ b/src/renderer/tvgRender.cpp
@@ -20,7 +20,6 @@
  * SOFTWARE.
  */
 
-#include <algorithm>
 #include "tvgMath.h"
 #include "tvgRender.h"
 
@@ -131,6 +130,9 @@ void RenderRegion::intersect(const RenderRegion& rhs)
     if (max.y < min.y) max.y = min.y;
 }
 
+#ifdef THORVG_PARTIAL_RENDER_SUPPORT
+
+#include <algorithm>
 
 void RenderDirtyRegion::init(uint32_t w, uint32_t h)
 {
@@ -311,6 +313,8 @@ void RenderDirtyRegion::commit()
     }
 }
 
+#endif
+
 /************************************************************************/
 /* RenderTrimPath Class Implementation                                  */
 /************************************************************************/
diff --git a/src/renderer/tvgRender.h b/src/renderer/tvgRender.h
index 938355ea..bf9c0b6e 100644
--- a/src/renderer/tvgRender.h
+++ b/src/renderer/tvgRender.h
@@ -155,51 +155,69 @@ struct RenderRegion
     uint32_t h() const { return (uint32_t) sh(); }
 };
 
-struct RenderDirtyRegion
-{
-public:
-    static constexpr const int PARTITIONING = 16;   //must be N*N
 
-    void init(uint32_t w, uint32_t h);
-    void commit();
-    void add(const RenderRegion* prv, const RenderRegion* cur);  //collect the old and new dirty regions together
-    void clear();
-
-    bool deactivate(bool on)
+#ifdef THORVG_PARTIAL_RENDER_SUPPORT
+    struct RenderDirtyRegion
     {
-        std::swap(on, disabled);
-        return on;
-    }
+    public:
+        static constexpr const int PARTITIONING = 16;   //must be N*N
 
-    bool deactivated()
-    {
-        return disabled;
-    }
+        void init(uint32_t w, uint32_t h);
+        void commit();
+        void add(const RenderRegion* prv, const RenderRegion* cur);  //collect the old and new dirty regions together
+        void clear();
 
-    const RenderRegion& partition(int idx)
-    {
-        return partitions[idx].region;
-    }
+        bool deactivate(bool on)
+        {
+            std::swap(on, disabled);
+            return on;
+        }
 
-    const Array<RenderRegion>& get(int idx)
-    {
-        return partitions[idx].list[partitions[idx].current];
-    }
+        bool deactivated()
+        {
+            return disabled;
+        }
 
-private:
-    void subdivide(Array<RenderRegion>& targets, uint32_t idx, RenderRegion& lhs, RenderRegion& rhs);
+        const RenderRegion& partition(int idx)
+        {
+            return partitions[idx].region;
+        }
 
-    struct Partition
-    {
-        RenderRegion region;
-        Array<RenderRegion> list[2];  //double buffer swapping
-        uint8_t current = 0;  //double buffer swapping list index. 0 or 1
+        const Array<RenderRegion>& get(int idx)
+        {
+            return partitions[idx].list[partitions[idx].current];
+        }
+
+    private:
+        void subdivide(Array<RenderRegion>& targets, uint32_t idx, RenderRegion& lhs, RenderRegion& rhs);
+
+        struct Partition
+        {
+            RenderRegion region;
+            Array<RenderRegion> list[2];  //double buffer swapping
+            uint8_t current = 0;  //double buffer swapping list index. 0 or 1
+        };
+
+        Key key;
+        Partition partitions[PARTITIONING];
+        bool disabled = false;
     };
+#else
+    struct RenderDirtyRegion
+    {
+        static constexpr const int PARTITIONING = 16;   //must be N*N
+
+        void init(uint32_t w, uint32_t h) {}
+        void commit() {}
+        void add(TVG_UNUSED const RenderRegion* prv, TVG_UNUSED const RenderRegion* cur) {}
+        void clear() {}
+        bool deactivate(TVG_UNUSED bool on) { return true; }
+        bool deactivated() { return true; }
+        const RenderRegion& partition(TVG_UNUSED int idx) { static RenderRegion tmp{}; return tmp; }
+        const Array<RenderRegion>& get(TVG_UNUSED int idx) { static Array<RenderRegion> tmp; return tmp; }
+    };
+#endif
 
-    Key key;
-    Partition partitions[PARTITIONING];
-    bool disabled = false;
-};
 
 struct RenderPath
 {