Share retained stroke frame execution helpers

src/node_stroke_preview.cpp

@@ -289,61 +289,40 @@ glm::vec4 NodeStrokePreview::stroke_draw_samples(
 
 std::vector<NodeStrokePreview::StrokeFrame> NodeStrokePreview::stroke_draw_compute(Stroke& stroke, float zoom) const
 {
-    std::vector<StrokeFrame> ret;
-    StrokeSample prev = stroke.m_prev_sample;
     auto samples = stroke.compute_samples();
-    std::array<vertex_t, 4> B = {
-        vertex_t{ {0, 0, 1, 1}, {0, 0}, {0, 0} },
-        vertex_t{ {0, 0, 1, 1}, {0, 1}, {0, 1} },
-        vertex_t{ {0, 0, 1, 1}, {1, 1}, {1, 1} },
-        vertex_t{ {0, 0, 1, 1}, {1, 0}, {1, 0} },
-    };
-    for (const auto& s : samples)
-    {
-        if (!s.valid())
-            continue;
-
-        ret.emplace_back();
-        auto& f = ret.back();
-
-        glm::vec2 dx_mix(prev.size * 0.5f, 0), dy_mix(0, prev.size * 0.5f);
-        glm::vec2 off_mix[4] = {
-            -dx_mix - dy_mix, // A - bottom-left
-            -dx_mix + dy_mix, // B - top-left
-            +dx_mix + dy_mix, // C - top-right
-            +dx_mix - dy_mix, // D - bottom-right
-        };
-        // P is the initial square centered at the cursor location 
-        glm::vec2 dx(s.size * 0.5f, 0), dy(0, s.size * 0.5f);
-        glm::vec2 off[4] = {
-            -dx - dy, // A - bottom-left
-            -dx + dy, // B - top-left
-            +dx + dy, // C - top-right
-            +dx - dy, // D - bottom-right
-        };
-
-        glm::vec2 mixer_sz(m_rtt.getWidth(), m_rtt.getHeight());
-        glm::vec2 mixer_bb_min(mixer_sz);
-        glm::vec2 mixer_bb_max(0, 0);
-        for (int j = 0; j < 4; j++)
-        {
-            auto p = (xy(prev.pos) + zoom * s.scale * off_mix[j] * glm::orientate2(-s.angle));
-            mixer_bb_min = glm::max({ 0, 0 }, glm::min(mixer_bb_min, p));
-            mixer_bb_max = glm::min(mixer_sz, glm::max(mixer_bb_max, p));
-
-            B[j].pos = glm::vec4(xy(s.pos) + zoom * s.scale * off[j] * glm::orientate2(-s.angle) - glm::vec2(0, 1), 1, 1);
-            B[j].uvs2 = p / mixer_sz;
-        }
-
-        f.m_mixer_rect = { glm::floor(mixer_bb_min), glm::ceil(mixer_bb_max - mixer_bb_min) };
-        f.col = glm::vec4(s.col, 1);
-        f.flow = s.flow;
-        f.opacity = s.opacity;
-        f.shapes = B;
-
-        prev = s;
+    StrokeSample previous_sample = stroke.m_prev_sample;
+    previous_sample.size *= zoom;
+    for (auto& sample : samples) {
+        sample.size *= zoom;
     }
-    return ret;
+
+    return pp::panopainter::plan_legacy_canvas_stroke_frames(
+        pp::panopainter::LegacyCanvasStrokeComputeRequest {
+            .previous_sample = previous_sample,
+            .samples = samples,
+            .zoom = 1.0f,
+            .mixer_size = glm::vec2(m_rtt.getWidth(), m_rtt.getHeight()),
+        },
+        [](
+            std::array<vertex_t, 4>& brush_quad,
+            bool /*project_3d*/,
+            glm::mat4 /*model_view*/) {
+            return brush_quad;
+        },
+        [](
+            glm::vec4 mixer_rect,
+            glm::vec4 color,
+            float flow,
+            float opacity,
+            std::array<vertex_t, 4>&& shapes) {
+            return StrokeFrame {
+                .col = color,
+                .flow = flow,
+                .opacity = opacity,
+                .shapes = std::move(shapes),
+                .m_mixer_rect = mixer_rect,
+            };
+        });
 }
 
 void NodeStrokePreview::draw_stroke_immediate()