Smooth starting animation

Author: onelife

README.md

@@ -1,2 +1,10 @@
-# termslides
-Terminal slideshow
+# TermSlides
+Script your slides in a YAML file and show it in terminal.
+
+## Install
+`pip install termslides`
+
+## Example
+
+![sample.yaml](docs/termslides_sample.gif)
+

docs/termslides_sample.gif

@@ -1,9 +1,10 @@
 # -*- coding: utf-8 -*-
 
 import sys
+from types import MethodType
 
 import yaml
-from asciimatics.exceptions import ResizeScreenError
+from asciimatics.exceptions import NextScene, ResizeScreenError
 from asciimatics.effects import Stars, Snow
 from asciimatics.scene import Scene
 from asciimatics.screen import Screen
@@ -17,6 +18,89 @@
 __all__ = ['termslides']
 
 
+def patch_draw_next_frame(self, repeat=True):
+    """
+    Draw the next frame in the currently configured Scenes. You must call
+    :py:meth:`.set_scenes` before using this for the first time.
+
+    :param repeat: Whether to repeat the Scenes once it has reached the end.
+        Defaults to True.
+
+    :raises StopApplication: if the application should be terminated.
+    """
+    scene = self._scenes[self._scene_index]
+    try:
+        # Check for an event now and remember for refresh reasons.
+        event = self.get_event()
+        got_event = event is not None
+
+        # Now process all the input events
+        while event is not None:
+            event = scene.process_event(event)
+            if event is not None and self._unhandled_input is not None:
+                self._unhandled_input(event)
+            event = self.get_event()
+
+        # Only bother with a refresh if there was an event to process or
+        # we have to refresh due to the refresh limit required for an
+        # Effect.
+        self._frame += 1
+        self._idle_frame_count -= 1
+        if got_event or self._idle_frame_count <= 0 or self._forced_update:
+            self._forced_update = False
+            self._idle_frame_count = 1000000
+            for effect in scene.effects:
+                # Update the effect and delete if needed.
+                effect.update(self._frame)
+                if effect.delete_count is not None:
+                    effect.delete_count -= 1
+                    if effect.delete_count <= 0:
+                        scene.remove_effect(effect)
+
+                # Sort out when we next _need_ to do a refresh.
+                if effect.frame_update_count > 0:
+                    self._idle_frame_count = min(self._idle_frame_count,
+                                                 effect.frame_update_count)
+            self.refresh()
+
+        if 0 < scene.duration <= self._frame:
+            raise NextScene()
+    except NextScene as e:
+        # Tidy up the current scene.
+        scene.exit()
+
+        # Find the specified next Scene
+        if e.name is None:
+            # Just allow next iteration of loop
+            self._scene_index += 1
+            if self._scene_index >= len(self._scenes):
+                if repeat:
+                    self._scene_index = 0
+                else:
+                    raise StopApplication("Repeat disabled")
+        else:
+            # Find the required scene.
+            for i, scene in enumerate(self._scenes):
+                if scene.name == e.name:
+                    self._scene_index = i
+                    break
+            else:
+                raise RuntimeError(
+                    "Could not find Scene: '{}'".format(e.name))
+
+        # Reset the screen if needed.
+        scene = self._scenes[self._scene_index]
+        scene.reset()
+        self._frame = 0
+        self._idle_frame_count = 0
+        if scene.clear:
+            self.clear()
+        else:
+            self._start_line = 0
+            self._x = self._y = None
+            self._reset()
+
+
 @group()
 def cli():
     pass
@@ -31,6 +115,7 @@ def termslides(file):
     def slides_show(screen, scene):
         scenes = []
         screen.set_title(slides.pop('title', 'TermSlides'))
+        screen.draw_next_frame = MethodType(patch_draw_next_frame, screen)
 
         # list view
         slide_view = SlideView(screen, slides)
@@ -67,7 +152,7 @@ def slides_show(screen, scene):
             # input handler
             effects.insert(0, InputHandler(screen, list_view))
             # add to scenes
-            scenes.append(Scene(effects, duration, name=name))
+            scenes.append(Scene(effects, duration, name=name, clear=(start is None)))
 
         screen.play(scenes, stop_on_resize=True, start_scene=scene)