Extract stroke mix request wiring

src/legacy_canvas_stroke_execution_services.h

@@ -340,6 +340,38 @@ struct LegacyCanvasStrokeMixPassResult {
     std::size_t composed_planes = 0;
 };
 
+[[nodiscard]] inline LegacyCanvasStrokeMixPassRequest make_legacy_canvas_stroke_mix_pass_request(
+    std::string_view context,
+    glm::vec2 resolution,
+    std::span<const LegacyCanvasStrokeMixPassPlane> planes,
+    std::function<void()> bind_mix_samplers,
+    std::function<void()> unbind_mix_samplers,
+    std::function<void(int, const glm::mat4&)> setup_plane_shader,
+    std::function<void(int)> bind_layer_texture,
+    std::function<void(int)> bind_stroke_texture,
+    std::function<void(int)> bind_mask_texture,
+    std::function<void()> draw_plane,
+    std::function<void(int)> unbind_mask_texture,
+    std::function<void(int)> unbind_stroke_texture,
+    std::function<void(int)> unbind_layer_texture)
+{
+    return LegacyCanvasStrokeMixPassRequest {
+        .context = context,
+        .resolution = resolution,
+        .planes = planes,
+        .bind_mix_samplers = std::move(bind_mix_samplers),
+        .unbind_mix_samplers = std::move(unbind_mix_samplers),
+        .setup_plane_shader = std::move(setup_plane_shader),
+        .bind_layer_texture = std::move(bind_layer_texture),
+        .bind_stroke_texture = std::move(bind_stroke_texture),
+        .bind_mask_texture = std::move(bind_mask_texture),
+        .draw_plane = std::move(draw_plane),
+        .unbind_mask_texture = std::move(unbind_mask_texture),
+        .unbind_stroke_texture = std::move(unbind_stroke_texture),
+        .unbind_layer_texture = std::move(unbind_layer_texture),
+    };
+}
+
 struct LegacyCanvasStrokeDualPassRequest {
     std::string_view context;
     std::function<void()> bind_brush_tip;