Speed up rendering with framebuffer delta updates

Author: GMH-Code

scchip/constants.py

@@ -5,7 +5,7 @@
 
 # App identification
 APP_NAME = "SuperChocChip Emulator"
-APP_VERSION = "1.3.0"
+APP_VERSION = "1.3.1"
 APP_COPYRIGHT = "Copyright (C) 2022 Gregory Maynard-Hoare, licensed under GNU Affero General Public License v3.0"
 APP_INTRO = "{} V{} -- ".format(APP_NAME, APP_VERSION)
 

scchip/framebuffer.py

@@ -45,6 +45,7 @@ def __init__(self, renderer, num_planes=1, allow_wrapping=True):
         self.vid_size = 0
         self.vid_cache = RAM()
         self.ram_banks = []
+        self.frame_delta = {}
         self.report_perf()
 
         for _ in range(num_planes):
@@ -85,9 +86,7 @@ def clear(self):
         for plane in self.affect_planes:
             plane.clear()
 
-        for y in range(self.vid_height):
-            for x in range(self.vid_width):
-                self._render_pixel(x, y)
+        self._redraw_all()
 
     def get_affected_planes(self):
         return self.affect_planes
@@ -120,7 +119,7 @@ def _render_pixel(self, x, y):
                 colour += 2 ** plane_num
 
         if self.vid_cache.read(vram_loc) != colour:
-            self.renderer.set_pixel(x, y, colour)
+            self.frame_delta[(x, y)] = colour
             self.vid_cache.write(vram_loc, colour)
 
     # Half-pixel vertical scrolling is unsupported in 64x32 pixel mode
@@ -137,7 +136,7 @@ def scroll_up(self, rows):
             plane.move_mem(-mem_offset)  # Usually moves contents up by 1 pixel, or 0.5 on low resolution
             plane.zero_block(vid_size - mem_offset, mem_offset)  # Erase the bottom strips
 
-        self._post_scroll()
+        self._redraw_all()
 
     def scroll_left(self, cols):
         if not self.affect_planes:
@@ -153,7 +152,7 @@ def scroll_left(self, cols):
                 # Erase 4-pixel block to right of line in high resolution, 2 on low resolution
                 plane.zero_block(vid_width * y - cols, cols)
 
-        self._post_scroll()
+        self._redraw_all()
 
     def scroll_right(self, cols):
         if not self.affect_planes:
@@ -169,7 +168,7 @@ def scroll_right(self, cols):
                 # Erase 4-pixel block to left of line in high resolution, 2 on low resolution
                 plane.zero_block(vid_width * y, cols)
 
-        self._post_scroll()
+        self._redraw_all()
 
     def scroll_down(self, rows):
         if not self.affect_planes:
@@ -181,16 +180,23 @@ def scroll_down(self, rows):
             plane.move_mem(mem_offset)  # Usually moves contents down by 1 pixel, 0.5 on low resolution
             plane.zero_block(0, mem_offset)  # Erase the top strips
 
-        self._post_scroll()
+        self._redraw_all()
 
-    def _post_scroll(self):
+    def _redraw_all(self):
         # Redraw whole screen after a scroll.  The video cache should take the load off the renderer a bit
         for y in range(self.vid_height):
             for x in range(self.vid_width):
                 self._render_pixel(x, y)
 
     def refresh_display(self):
-        self.renderer.refresh_display()
+        # Request the renderer updates altered pixels and then refreshes the display.  This method results in a huge
+        # (around 5x) speed up when using PyPy with graphically-intensive games, and a tiny improvement with CPython.
+        for xy, colour in self.frame_delta.items():
+            self.renderer.set_pixel(*xy, colour)
+
+        content_changed = bool(self.frame_delta)
+        self.frame_delta.clear()
+        self.renderer.refresh_display(content_changed)
 
     def switch_planes(self, mask):
         try:

scchip/renderers/r_curses.py

@@ -21,6 +21,7 @@
 import curses
 import _curses
 from .r_null import RendererError, Renderer as RendererBase
+from ..constants import APP_NAME
 
 
 class Renderer(RendererBase):
@@ -92,6 +93,7 @@ def set_resolution(self, width, height):
             self.pad.bkgd(" ", curses.color_pair(self.palette_index[0]))
 
         super().set_resolution(width, height)
+        self.set_title(APP_NAME)
 
     def set_pixel(self, x, y, colour):
         if self.palette_index:
@@ -100,14 +102,13 @@ def set_pixel(self, x, y, colour):
             curses_colour = curses.A_REVERSE if colour else curses.A_NORMAL
 
         self.pad.addstr(y + 1, x * self.scale, self.pixel_char, curses_colour)
-        super().set_pixel(x, y, colour)
 
-    def refresh_display(self):
+    def refresh_display(self, content_changed=False):
         screen_height, screen_width = self.screen.getmaxyx()  # This doesn't seem to ever change/work on Windows?!
 
         if screen_height == self.last_screen_height and screen_width == self.last_screen_width:
             # Fast delta update
-            if self.refresh_needed:
+            if content_changed:
                 self.pad.refresh(0, 0, 0, 0, screen_height - 1, screen_width - 1)
         else:
             # Screen resolution changed, redraw everything
@@ -121,17 +122,13 @@ def refresh_display(self):
             self.last_screen_height = screen_height
             self.last_screen_width = screen_width
 
-        super().refresh_display()
-
     def set_title(self, title):
         if self.pad:
             title_len = len(title)
 
             if self.width > title_len:
                 self.pad.addstr(0, 0, "".join((title, " " * (self.width * self.scale - title_len))), curses.A_REVERSE)
-                self.refresh_needed = True
-
-        super().set_title(title)
+                self.refresh_display(True)
 
     def shutdown(self):
         if self.screen:

scchip/renderers/r_null.py

@@ -22,18 +22,16 @@ def __init__(self, scale=None, use_colour=True, **kwargs):  # pylint: disable=un
         self.scale = 1 if scale is None else scale
         self.use_colour = use_colour
         self.set_resolution(0, 0)
-        self.refresh_needed = False
 
     def set_resolution(self, width, height):
         self.width = width
         self.height = height
-        self.refresh_needed = False
 
     def set_pixel(self, x, y, colour):  # pylint: disable=unused-argument
-        self.refresh_needed = True
+        pass
 
-    def refresh_display(self):
-        self.refresh_needed = False
+    def refresh_display(self, content_changed=False):
+        pass
 
     def set_title(self, title):
         pass

scchip/renderers/r_pygame.py

@@ -20,6 +20,7 @@
 
 import pygame
 from .r_null import RendererError, Renderer as RendererBase
+from ..constants import APP_NAME
 
 
 class Renderer(RendererBase):
@@ -28,7 +29,7 @@ def __init__(self, scale=None, use_colour=True, pygame_palette=None, smoothing=0
             scale = 512  # Default window width if not supplied, or set to default
 
         pygame.display.init()
-        self.set_title("Starting...")  # Perhaps an icon would be nice, too?
+        self.set_title(APP_NAME)  # Perhaps an icon would be nice, too?
         self.pixel_array = None
         self.scaled_size = (scale, scale // 2)
         self.display_surface = pygame.display.set_mode(self.scaled_size, 0, 8)
@@ -72,10 +73,9 @@ def set_resolution(self, width, height):
 
     def set_pixel(self, x, y, colour):
         self.pixel_array[x][y] = self.colour_map[colour]
-        super().set_pixel(x, y, colour)
 
-    def refresh_display(self):
-        if self.refresh_needed and self.pixel_array:
+    def refresh_display(self, content_changed=False):
+        if content_changed and self.pixel_array:
             self.pixel_array.close()
             del self.pixel_array
             render_surface = self.render_surface
@@ -89,11 +89,8 @@ def refresh_display(self):
             pygame.display.flip()
             self._set_pixel_array()
 
-        super().refresh_display()
-
     def set_title(self, title):
         pygame.display.set_caption(title)
-        super().set_title(title)
 
     def _set_pixel_array(self):
         self.pixel_array = pygame.PixelArray(self.render_surface)

superchocchip.py

@@ -3,7 +3,7 @@
 __author__ = "Gregory Maynard-Hoare"
 __copyright__ = "Copyright (C) 2022 Gregory Maynard-Hoare"
 __license__ = "GNU Affero General Public License v3.0"
-__version__ = "1.3.0"
+__version__ = "1.3.1"
 
 from argparse import ArgumentParser
 from scchip import main