fix rendering of examples

doc/source/custom_directives.py

@@ -5,18 +5,19 @@
 import os
 import re
 from hashlib import sha1
-import traceback
 
 from sphinx.builders import Builder
 from sphinx.ext.autodoc import AutodocReporter
-from sphinx.util.console import bold
-
-import imgui
 
 try:
     from gen_example import render_snippet
-except ImportError:
+except ImportError as error:
     render_snippet = None
+    print (
+        "Could not import snippet renderer. "
+        "Will use static resources. Import error: %s" %
+        error
+    )
 
 
 VISUAL_EXAMPLES_DIR = "visual_examples"

doc/source/gen_example.py

@@ -146,7 +146,12 @@ def render_snippet(
 
             if auto_layout:
                 imgui.set_next_window_size(width - 10, height - 10)
-                imgui.set_next_window_position(impl.io.DisplaySize.x * 0.5, implio.DisplaySize.y * 0.5, 1, pivot_x = 0.5, pivot_y = 0.5)
+                imgui.set_next_window_position(
+                    impl.io.display_size.x * 0.5,
+                    impl.io.display_size.y * 0.5,
+                    pivot_x=0.5,
+                    pivot_y=0.5
+                )
 
             exec(code, locals(), globals())
 
@@ -156,6 +161,7 @@ def render_snippet(
         gl.glClear(gl.GL_COLOR_BUFFER_BIT)
 
         imgui.render()
+        impl.render(imgui.get_draw_data())
 
     # retrieve pixels from framebuffer and write to file
     pixels = gl.glReadPixels(0, 0, width, height, gl.GL_RGBA, gl.GL_UNSIGNED_BYTE)