message: Issue draw calls only when necessary
diff: @@ -294,6 +294,7 @@ impl Renderer {
  let translated = transformation
  * Transformation::translate(0.0, -(layer.y_offset as f32));
  + if layer.quads.len() > 0 {
  self.quad_pipeline.draw(
  &mut self.device,
  encoder,
  @@ -302,7 +303,9 @@ impl Renderer {
  layer.bounds,
  target,
  );
  + }
  + if layer.images.len() > 0 {
  self.image_pipeline.draw(
  &mut self.device,
  encoder,
  @@ -311,8 +314,9 @@ impl Renderer {
  layer.bounds,
  target,
  );
  + }
  - {
  + if layer.text.len() > 0 {
  let mut glyph_brush = self.glyph_brush.borrow_mut();
  for text in layer.text.iter() {
  