lazy stroke preview rendering

src/node_stroke_preview.cpp

@@ -38,6 +38,8 @@ void NodeStrokePreview::empty_queue()
     s_queue.q.clear();
 }
 
+int NodeStrokePreview::instances = 0;
+
 Node* NodeStrokePreview::clone_instantiate() const
 {
     return new NodeStrokePreview();
@@ -271,7 +273,10 @@ void NodeStrokePreview::draw_stroke_immediate()
     m_sampler_linear.bind(4);
 
     const auto& b = m_brush;
-    
+
+    Stroke m_stroke;
+    Stroke m_dual_stroke;
+
     m_stroke.m_filter_points = false;
     m_stroke.m_max_size = m_max_size > 0 ? m_max_size : m_size.y * .75f;
     m_stroke.m_camera.fov = Canvas::I->m_cam_fov;
@@ -518,10 +523,13 @@ void NodeStrokePreview::draw_stroke()
                     node->m_brush->preload();
 
                     node->async_start();
+
                     gl_state gl;
                     gl.save();
 
-                    auto new_size = node->m_tex_preview.size();
+                    auto new_size = node->m_preview_size;
+                    if (!node->m_tex_preview.ready() || node->m_tex_preview.size() != new_size)
+                        node->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);
@@ -558,7 +566,6 @@ void NodeStrokePreview::draw_stroke()
 
 void NodeStrokePreview::draw()
 {
-    //glEnable(GL_BLEND);
     ShaderManager::use(kShader::Texture);
     ShaderManager::u_mat4(kShaderUniform::MVP, m_mvp);
     ShaderManager::u_int(kShaderUniform::Tex, 0);
@@ -574,11 +581,10 @@ void NodeStrokePreview::handle_resize(glm::vec2 old_size, glm::vec2 new_size)
     if (m_tex_preview.size() == new_size || !m_brush)
         return;
 
-    new_size *= root()->m_zoom;
+    m_preview_size = new_size * root()->m_zoom;
 
-    m_tex_preview.create((int)new_size.x, (int)new_size.y);
-
-    draw_stroke();
+    if (m_on_screen)
+        draw_stroke();
 }
 
 void NodeStrokePreview::destroy_immediate()
@@ -586,3 +592,17 @@ void NodeStrokePreview::destroy_immediate()
     Node::destroy_immediate();
     m_tex_preview.destroy();
 }
+
+void NodeStrokePreview::handle_on_screen(bool old_visibility, bool new_visibility)
+{
+    parent::handle_on_screen(old_visibility, new_visibility);
+    if (new_visibility)
+    {
+        draw_stroke();
+    }
+    else
+    {
+        s_queue.Remove(std::static_pointer_cast<NodeStrokePreview>(shared_from_this()));
+        m_tex_preview.destroy();
+    }
+}