Add command line color specification. (#38)

Author: craigthomas

README.md

@@ -25,6 +25,7 @@
       4. [Clip Quirks](#clip-quirks)
       5. [Logic Quirks](#logic-quirks)
    5. [Memory Size](#memory-size)
+   6. [Colors](#colors)
 5. [Customization](#customization)
    1. [Keys](#keys)
    2. [Debug Keys](#debug-keys)
@@ -304,6 +305,25 @@ but this behavior can be controlled with the `--mem_size` flag. Valid options ar
 `64K` or `4K` for historical purposes.
 
 
+### Colors
+
+The original Chip8 language specification called for pixels to be turned on or 
+off. It did not specify what color the pixel states had to be. The emulator 
+lets the user specify what colors they want to use when the emulator is running.
+Color values are specified by using HTML hex values such as `AABBCC` without the
+leading `#`. There are currently 4 color values that can be set:
+
+* `--color_0` specifies the background color. This defaults to `000000`.
+* `--color_1` specifies bitplane 1 color. This defaults to `666666`.
+* `--color_2` specifies bitplane 2 color. This defaults to `BBBBBB`.
+* `--color_3` specifies bitplane 1 and 2 overlap color. This defaults to `FFFFFF`.
+
+For Chip8 and SuperChip 8 programs, only the background color `color_0` (for pixels
+turned off) and the bitplane 1 color `color_1` (for pixels turned on) are used.
+Only XO Chip programs will use `color_2` and `color_3` when the additional bitplanes
+are potentially used.
+
+
 ## Customization
 
 The file `chip8/config.py` contains several variables that can be changed to

chip8/emulator.py

@@ -23,7 +23,13 @@ def main_loop(args):
     """
     delay_timer_event = 24
 
-    screen = Chip8Screen(scale_factor=args.scale)
+    screen = Chip8Screen(
+        scale_factor=args.scale,
+        color_0=args.color_0,
+        color_1=args.color_1,
+        color_2=args.color_2,
+        color_3=args.color_3,
+    )
     screen.init_display()
     cpu = Chip8CPU(
         screen,

chip8/screen.py

@@ -18,13 +18,6 @@
 # of a pixel.
 SCREEN_DEPTH = 8
 
-# The colors of the pixels to draw. The Chip 8 supports two colors: 0 (off)
-# and 1 (on). The format of the colors is in RGBA format.
-PIXEL_COLORS = {
-    0: Color(0, 0, 0, 255),
-    1: Color(250, 250, 250, 255)
-}
-
 # C L A S S E S ###############################################################
 
 
@@ -34,7 +27,14 @@ class Chip8Screen:
     with 2 colors. In this emulator, this translates to color 0 (off) and color
     1 (on).
     """
-    def __init__(self, scale_factor):
+    def __init__(
+            self,
+            scale_factor,
+            color_0="000000",
+            color_1="666666",
+            color_2="BBBBBB",
+            color_3="FFFFFF"
+    ):
         """
         Initializes the main screen. The scale factor is used to modify
         the size of the main screen, since the original resolution of the
@@ -47,6 +47,12 @@ def __init__(self, scale_factor):
         self.scale_factor = scale_factor
         self.surface = None
         self.mode = SCREEN_MODE_NORMAL
+        self.pixel_colors = {
+            0: Color(f"#{color_0}"),
+            1: Color(f"#{color_1}"),
+            2: Color(f"#{color_2}"),
+            3: Color(f"#{color_3}"),
+        }
 
     def init_display(self):
         """
@@ -81,7 +87,7 @@ def draw_pixel(self, x_pos, y_pos, turn_on):
         x_base = (x_pos * mode_scale) * self.scale_factor
         y_base = (y_pos * mode_scale) * self.scale_factor
         draw.rect(self.surface,
-                  PIXEL_COLORS[pixel_color],
+                  self.pixel_colors[pixel_color],
                   (x_base, y_base, mode_scale * self.scale_factor, mode_scale * self.scale_factor))
 
     def get_pixel(self, x_pos, y_pos):
@@ -97,7 +103,7 @@ def get_pixel(self, x_pos, y_pos):
         x_scale = (x_pos * mode_scale) * self.scale_factor
         y_scale = (y_pos * mode_scale) * self.scale_factor
         pixel_color = self.surface.get_at((x_scale, y_scale))
-        return pixel_color == PIXEL_COLORS[1]
+        return pixel_color == self.pixel_colors[1]
 
     def get_width(self):
         """
@@ -119,7 +125,7 @@ def clear_screen(self):
         """
         Turns off all the pixels on the screen (writes color 0 to all pixels).
         """
-        self.surface.fill(PIXEL_COLORS[0])
+        self.surface.fill(self.pixel_colors[0])
 
     @staticmethod
     def update():
@@ -152,7 +158,7 @@ def scroll_down(self, num_lines):
         mode_scale = 1 if self.mode == SCREEN_MODE_EXTENDED else 2
         actual_lines = num_lines * mode_scale * self.scale_factor
         self.surface.scroll(0, actual_lines)
-        self.surface.fill(PIXEL_COLORS[0], (0, 0, self.width * mode_scale * self.scale_factor, actual_lines))
+        self.surface.fill(self.pixel_colors[0], (0, 0, self.width * mode_scale * self.scale_factor, actual_lines))
         self.update()
 
     def scroll_left(self):
@@ -163,7 +169,7 @@ def scroll_left(self):
         actual_lines = 4 * mode_scale * self.scale_factor
         left = (self.width * mode_scale * self.scale_factor) - actual_lines
         self.surface.scroll(-actual_lines, 0)
-        self.surface.fill(PIXEL_COLORS[0], (left, 0, actual_lines, self.height * mode_scale * self.scale_factor))
+        self.surface.fill(self.pixel_colors[0], (left, 0, actual_lines, self.height * mode_scale * self.scale_factor))
         self.update()
 
     def scroll_right(self):
@@ -173,7 +179,7 @@ def scroll_right(self):
         mode_scale = 1 if self.mode == SCREEN_MODE_EXTENDED else 2
         actual_lines = 4 * mode_scale * self.scale_factor
         self.surface.scroll(actual_lines, 0)
-        self.surface.fill(PIXEL_COLORS[0], (0, 0, actual_lines, self.height * mode_scale * self.scale_factor))
+        self.surface.fill(self.pixel_colors[0], (0, 0, actual_lines, self.height * mode_scale * self.scale_factor))
         self.update()
 
 # E N D   O F   F I L E ########################################################

yac8e.py

@@ -64,6 +64,22 @@ def parse_arguments():
         "--trace", help="print registers and instructions to STDOUT",
         action="store_true", dest="trace"
     )
+    parser.add_argument(
+        "--color_0", help="the hex color to use for the background (default=000000)",
+        dest="color_0", default="000000"
+    )
+    parser.add_argument(
+        "--color_1", help="the hex color to use for bitplane 1 (default=666666)",
+        dest="color_1", default="666666"
+    )
+    parser.add_argument(
+        "--color_2", help="the hex color to use for bitplane 2 (default=BBBBBB)",
+        dest="color_2", default="BBBBBB"
+    )
+    parser.add_argument(
+        "--color_3", help="the hex color to use for bitplane overlaps (default=FFFFFF)",
+        dest="color_3", default="FFFFFF"
+    )
     return parser.parse_args()