Extract preview final composite orchestration

src/legacy_node_stroke_preview_execution_services.h

@@ -6,6 +6,7 @@
 #include "legacy_canvas_stroke_shader_services.h"
 #include "legacy_canvas_stroke_services.h"
 #include "paint_renderer/compositor.h"
+#include "texture.h"
 
 #include <algorithm>
 #include <cmath>
@@ -242,6 +243,69 @@ struct LegacyNodeStrokePreviewMainPassTextureDispatch {
     std::function<void()> bind_mixer;
 };
 
+struct LegacyNodeStrokePreviewFinalCompositeRequest {
+    glm::vec2 resolution {};
+    glm::vec2 pattern_scale {};
+    const Brush* brush = nullptr;
+    const pp::paint_renderer::CanvasStrokeCompositePassPlan* composite_pass = nullptr;
+    std::function<void()> setup_composite_shader;
+    std::function<void()> bind_composite_samplers;
+    std::function<void()> bind_composite_inputs;
+    std::function<void()> draw_composite;
+};
+
+[[nodiscard]] inline bool execute_legacy_node_stroke_preview_final_composite(
+    const LegacyNodeStrokePreviewFinalCompositeRequest& request)
+{
+    if (!request.brush ||
+        !request.composite_pass ||
+        !request.setup_composite_shader ||
+        !request.bind_composite_samplers ||
+        !request.bind_composite_inputs ||
+        !request.draw_composite) {
+        return false;
+    }
+
+    pp::panopainter::execute_legacy_stroke_preview_final_composite(
+        [&] {
+            request.setup_composite_shader();
+        },
+        [&] {
+            request.bind_composite_samplers();
+        },
+        [&] {
+            request.bind_composite_inputs();
+        },
+        [&] {
+            request.draw_composite();
+        });
+    return true;
+}
+
+struct LegacyNodeStrokePreviewCopyResultRequest {
+    Texture2D* preview_texture = nullptr;
+    glm::vec2 size {};
+    std::function<void(int, int, int, int, int, int)> copy_framebuffer_to_texture;
+};
+
+[[nodiscard]] inline bool copy_legacy_node_stroke_preview_result(
+    const LegacyNodeStrokePreviewCopyResultRequest& request)
+{
+    if (!request.preview_texture || !request.copy_framebuffer_to_texture) {
+        return false;
+    }
+    pp::panopainter::copy_legacy_stroke_preview_texture(
+        [&] {
+            request.preview_texture->bind();
+        },
+        request.copy_framebuffer_to_texture,
+        pp::panopainter::LegacyStrokePreviewCopySize {
+            .width = static_cast<int>(request.size.x),
+            .height = static_cast<int>(request.size.y),
+        });
+    return true;
+}
+
 [[nodiscard]] inline LegacyNodeStrokePreviewMainPassTextureDispatch make_legacy_node_stroke_preview_main_pass_texture_dispatch(
     std::function<void(int)> activate_texture_unit,
     std::function<void()> bind_brush_tip,