Route stroke frame-face traversal through helper

src/canvas.cpp

@@ -690,24 +690,21 @@ void Canvas::stroke_draw()
     std::array<glm::vec4, 6> box_face = SIXPLETTE(glm::vec4(m_size, 0, 0));
     std::array<bool, 6> box_dirty = SIXPLETTE(false);
     glm::vec4 pad_color;
-    for (auto& f : frames)
-    {
-        if (brush->m_tip_mix > 0.f)
-        {
-            stroke_draw_mix(xy(f.m_mixer_rect), zw(f.m_mixer_rect));
-        }
-
-        for (int i = 0; i < 6; i++)
-        {
-            auto& P = f.shapes[i];
-            if (P.size() < 3)
-                continue;
+    pp::panopainter::execute_legacy_canvas_stroke_frame_faces(
+        frames,
+        [&](auto& f) {
+            if (brush->m_tip_mix > 0.f)
+            {
+                stroke_draw_mix(xy(f.m_mixer_rect), zw(f.m_mixer_rect));
+            }
+        },
+        [&](auto& f, int i, auto& P) {
             m_dirty_face[i] = true;
             merge_faces[i] = true;
             box_dirty[i] = true;
 
             m_tmp[i].bindFramebuffer();
-            
+
             pp::panopainter::use_legacy_stroke_shader();
             pp::panopainter::apply_legacy_stroke_sample_uniforms(
                 pp::panopainter::LegacyStrokeSampleUniforms {
@@ -718,7 +715,7 @@ void Canvas::stroke_draw()
             auto box_sample = stroke_draw_samples(i, P, copy_stroke_destination);
 
             m_tmp[i].unbindFramebuffer();
-            
+
             const auto dirty_update = pp::panopainter::plan_legacy_canvas_stroke_face_dirty_update(
                 pp::panopainter::LegacyCanvasStrokeFaceDirtyRequest {
                     .extent = stroke_extent,
@@ -731,8 +728,7 @@ void Canvas::stroke_draw()
             box_face[i] = dirty_update.pass_dirty_box;
             // TODO: maybe average color?
             pad_color = f.col;
-        }
-    }
+        });
 
     set_active_texture_unit(3);
     m_mixer.unbindTexture();
@@ -812,19 +808,17 @@ void Canvas::stroke_draw()
             dual_brush->m_tip_texture->bind() :
             unbind_texture_2d();
         auto frames_dual = stroke_draw_compute(*m_dual_stroke);
-        for (auto& f : frames_dual)
-        {
-            pp::panopainter::apply_legacy_stroke_sample_uniforms(
-                pp::panopainter::LegacyStrokeSampleUniforms {
-                    .color = f.col,
-                    .alpha = f.flow,
-                    .opacity = f.opacity,
-                });
-            for (int i = 0; i < 6; i++)
-            {
-                auto& P = f.shapes[i];
-                if (P.size() < 3)
-                    continue;
+        pp::panopainter::execute_legacy_canvas_stroke_frame_faces(
+            frames_dual,
+            [&](auto& f) {
+                pp::panopainter::apply_legacy_stroke_sample_uniforms(
+                    pp::panopainter::LegacyStrokeSampleUniforms {
+                        .color = f.col,
+                        .alpha = f.flow,
+                        .opacity = f.opacity,
+                    });
+            },
+            [&](auto&, int i, auto& P) {
                 m_tmp_dual[i].bindFramebuffer();
                 auto box_sample = stroke_draw_samples(i, P, copy_stroke_destination);
                 m_tmp_dual[i].unbindFramebuffer();
@@ -840,8 +834,7 @@ void Canvas::stroke_draw()
                             stroke_material.composite_pass.dual_blend_mode == 0,
                     });
                 m_dirty_box[i] = dirty_update.accumulated_dirty_box;
-            }
-        }
+            });
     }
 
     m_sampler_brush.unbind();

src/legacy_canvas_stroke_execution_services.h

@@ -8,6 +8,7 @@
 #include "util.h"
 
 #include <array>
+#include <cstddef>
 #include <functional>
 #include <span>
 #include <string_view>
@@ -152,6 +153,27 @@ template <typename ProjectStroke, typename MakeFrame>
     return frames;
 }
 
+template <typename Frames, typename BeginFrame, typename ExecuteFace>
+std::size_t execute_legacy_canvas_stroke_frame_faces(
+    Frames&& frames,
+    BeginFrame&& begin_frame,
+    ExecuteFace&& execute_face)
+{
+    std::size_t executed_faces = 0;
+    for (auto& frame : frames) {
+        begin_frame(frame);
+        for (int face_index = 0; face_index < 6; ++face_index) {
+            auto& vertices = frame.shapes[face_index];
+            if (vertices.size() < 3) {
+                continue;
+            }
+            execute_face(frame, face_index, vertices);
+            ++executed_faces;
+        }
+    }
+    return executed_faces;
+}
+
 [[nodiscard]] inline pp::paint_renderer::CanvasStrokeBox legacy_canvas_stroke_box(glm::vec4 box) noexcept
 {
     return pp::paint_renderer::CanvasStrokeBox {