render stroke preview to image

src/node_stroke_preview.cpp

@@ -9,6 +9,7 @@
 
 std::atomic_int NodeStrokePreview::s_instances{ 0 };
 std::atomic_bool NodeStrokePreview::s_running{ false };
+std::mutex NodeStrokePreview::s_render_mutex;
 std::thread NodeStrokePreview::s_renderer;
 BlockingQueue<std::shared_ptr<NodeStrokePreview>> NodeStrokePreview::s_queue;
 
@@ -498,6 +499,27 @@ void NodeStrokePreview::draw_stroke_immediate()
     glClearColor(cc[0], cc[1], cc[2], cc[3]);
 }
 
+Image NodeStrokePreview::render_to_image()
+{
+    std::lock_guard<std::mutex> _lock(s_render_mutex);
+
+    App::I->render_task([this] {
+        auto new_size = m_preview_size;
+        if (!m_tex_preview.ready() || m_tex_preview.size() != new_size)
+            m_tex_preview.create((int)new_size.x, (int)new_size.y);
+        if (m_tex.size() != new_size)
+        {
+            m_rtt.create((int)new_size.x, (int)new_size.y);
+            m_rtt_mixer.create((int)new_size.x, (int)new_size.y);
+            m_tex.create((int)new_size.x, (int)new_size.y);
+            m_tex_dual.create((int)new_size.x, (int)new_size.y);
+            m_tex_background.create((int)new_size.x, (int)new_size.y);
+        }
+        draw_stroke_immediate();
+    });
+    return m_tex_preview.get_image();
+}
+
 void NodeStrokePreview::draw_stroke()
 {
     if (m_size.x == 0 || m_size.y == 0)
@@ -519,6 +541,8 @@ void NodeStrokePreview::draw_stroke()
                 auto node = s_queue.Get();
                 if (node)
                 {
+                    std::lock_guard<std::mutex> _lock(s_render_mutex);
+
                     // if the brush is not already loaded, load it and then destroy it
                     bool to_unload = (node->m_brush->m_tip_texture == nullptr);
                     node->m_brush->preload();

src/node_stroke_preview.h

@@ -29,6 +29,7 @@ public:
     using parent = NodeBorder;
     static std::atomic_int s_instances;
     static std::atomic_bool s_running;
+    static std::mutex s_render_mutex;
     static std::thread s_renderer;
     static BlockingQueue<std::shared_ptr<NodeStrokePreview>> s_queue;
     static void terminate_renderer();
@@ -52,6 +53,7 @@ public:
     std::vector<StrokeFrame> stroke_draw_compute(Stroke& stroke) const;
     void draw_stroke();
     void draw_stroke_immediate();
+    Image render_to_image();
     virtual void draw() override;
     virtual void handle_resize(glm::vec2 old_size, glm::vec2 new_size, float zoom) override;
     virtual void destroy() override;