Route stroke pad planning through helper

src/legacy_canvas_stroke_execution_services.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "paint_renderer/compositor.h"
+#include "../libs/glm/glm/glm.hpp"
 #include "util.h"
 
 #include <array>
@@ -46,6 +47,17 @@ struct LegacyCanvasStrokeFaceDirtyResult {
     bool pass_dirty = false;
 };
 
+struct LegacyCanvasStrokePadRegionRequest {
+    pp::renderer::Extent2D extent {};
+    glm::vec4 pass_dirty_box {};
+};
+
+struct LegacyCanvasStrokePadRegionResult {
+    bool has_pixels = false;
+    pp::paint_renderer::CanvasStrokeCopyRegion copy_region {};
+    std::array<pp::paint_renderer::CanvasStrokePoint, 6> ndc_quad {};
+};
+
 [[nodiscard]] inline pp::paint_renderer::CanvasStrokeBox legacy_canvas_stroke_box(glm::vec4 box) noexcept
 {
     return pp::paint_renderer::CanvasStrokeBox {
@@ -62,6 +74,22 @@ struct LegacyCanvasStrokeFaceDirtyResult {
     return glm::vec4(box.min_x, box.min_y, box.max_x, box.max_y);
 }
 
+[[nodiscard]] inline LegacyCanvasStrokePadRegionResult plan_legacy_canvas_stroke_pad_region(
+    const LegacyCanvasStrokePadRegionRequest& request) noexcept
+{
+    const auto plan = pp::paint_renderer::plan_canvas_stroke_pad_region(
+        pp::paint_renderer::CanvasStrokePadRegionRequest {
+            .extent = request.extent,
+            .pass_dirty_box = legacy_canvas_stroke_box(request.pass_dirty_box),
+        });
+
+    return LegacyCanvasStrokePadRegionResult {
+        .has_pixels = plan.has_pixels,
+        .copy_region = plan.copy_region,
+        .ndc_quad = plan.ndc_quad,
+    };
+}
+
 [[nodiscard]] inline LegacyCanvasStrokeFaceDirtyResult plan_legacy_canvas_stroke_face_dirty_update(
     const LegacyCanvasStrokeFaceDirtyRequest& request) noexcept
 {