Extract live stroke face framebuffer helper

tests/paint_renderer/stroke_execution_tests.cpp

@@ -383,6 +383,101 @@ void retained_stroke_destination_texture_dispatch_helper_builds_expected_callbac
     PP_EXPECT(h, events == expected_events);
 }
 
+void retained_stroke_live_pass_face_framebuffers_helper_preserves_callback_order(pp::tests::Harness& h)
+{
+    struct Frame {
+        int id = -1;
+        std::array<std::vector<vertex_t>, 6> shapes {};
+    };
+    struct Framebuffer {
+        std::vector<std::string>* events = nullptr;
+        int face_index = -1;
+
+        void bindFramebuffer()
+        {
+            events->push_back("bind:" + std::to_string(face_index));
+        }
+
+        void unbindFramebuffer()
+        {
+            events->push_back("unbind:" + std::to_string(face_index));
+        }
+    };
+    auto make_frame = [](int id, int face_index) {
+        Frame frame { .id = id };
+        frame.shapes[face_index] = {
+            vertex_t(glm::vec2(0.0F, 0.0F)),
+            vertex_t(glm::vec2(1.0F, 0.0F)),
+            vertex_t(glm::vec2(0.5F, 1.0F)),
+        };
+        return frame;
+    };
+    const std::array<Frame, 2> frames {
+        make_frame(0, 0),
+        make_frame(1, 1),
+    };
+    std::array<Framebuffer, 2> framebuffers {
+        Framebuffer { .events = nullptr, .face_index = 0 },
+        Framebuffer { .events = nullptr, .face_index = 1 },
+    };
+
+    std::vector<std::string> events;
+    framebuffers[0].events = &events;
+    framebuffers[1].events = &events;
+
+    std::array<glm::vec4, 2> accumulated_dirty_boxes {
+        glm::vec4(0.0F),
+        glm::vec4(0.0F),
+    };
+    std::array<glm::vec4, 2> pass_dirty_boxes {
+        glm::vec4(0.0F),
+        glm::vec4(0.0F),
+    };
+    const std::array<bool, 2> include_dirty_faces { true, true };
+    std::array<bool, 2> committed_dirty_faces { false, false };
+    std::array<bool, 2> pass_dirty_faces { false, false };
+
+    const auto executed_faces = pp::panopainter::execute_legacy_canvas_stroke_live_pass_face_framebuffers(
+        frames,
+        pp::renderer::Extent2D { 64U, 32U },
+        accumulated_dirty_boxes,
+        pass_dirty_boxes,
+        include_dirty_faces,
+        [&](auto& frame) {
+            events.emplace_back("begin-frame:" + std::to_string(frame.id));
+        },
+        [&](auto& frame, int face_index, auto&) {
+            events.emplace_back("begin-face:" + std::to_string(frame.id) + ":" + std::to_string(face_index));
+        },
+        [&](auto& frame, int face_index, auto&) {
+            events.emplace_back("sample:" + std::to_string(frame.id) + ":" + std::to_string(face_index));
+            return glm::vec4(0.0F);
+        },
+        framebuffers,
+        true,
+        committed_dirty_faces,
+        pass_dirty_faces);
+
+    const std::vector<std::string> expected_events {
+        "begin-frame:0",
+        "begin-face:0:0",
+        "bind:0",
+        "sample:0:0",
+        "unbind:0",
+        "begin-frame:1",
+        "begin-face:1:1",
+        "bind:1",
+        "sample:1:1",
+        "unbind:1",
+    };
+    PP_EXPECT(h, executed_faces == 2U);
+    PP_EXPECT(h, events == expected_events);
+    PP_EXPECT(h, committed_dirty_faces[0]);
+    PP_EXPECT(h, committed_dirty_faces[1]);
+    PP_EXPECT(h, pass_dirty_faces[0]);
+    PP_EXPECT(h, pass_dirty_faces[1]);
+}
+
 void retained_stroke_sample_executor_copies_destination_and_expands_quads(pp::tests::Harness& h)
 {
     const auto vertices = make_quad_vertices();
@@ -1475,6 +1570,9 @@ int main()
     harness.run(
         "retained_stroke_destination_texture_dispatch_helper_builds_expected_callback_wiring",
         retained_stroke_destination_texture_dispatch_helper_builds_expected_callback_wiring);
+    harness.run(
+        "retained_stroke_live_pass_face_framebuffers_helper_preserves_callback_order",
+        retained_stroke_live_pass_face_framebuffers_helper_preserves_callback_order);
     harness.run(
         "retained_stroke_live_pass_sampler_dispatch_helper_builds_expected_callback_wiring",
         retained_stroke_live_pass_sampler_dispatch_helper_builds_expected_callback_wiring);