Improve performance by creating in-memory gifs

Gui.py

@@ -393,38 +393,106 @@ class SpriteSelector(object):
     def local_unofficial_sprite_dir(site):
         return local_path("data/sprites/unofficial")
 
+
 def get_image_for_sprite(filename):
     sprite = Sprite(filename)
-    image = PhotoImage(height=24, width=16, palette="256/256/256")
+    if not sprite.valid:
+        return None
+    height = 24
+    width = 16
 
-    def color_to_hex(color):
-        return "#{0:02X}{1:02X}{2:02X}".format(*color)
+    def draw_sprite_into_gif(add_palette_color, set_pixel_color_index):
 
-    def drawsprite(spr, pal_as_colors, offset):
-        for y in range(len(spr)):
-            for x in range(len(spr[y])):
-                pal_index = spr[y][x]
-                if pal_index:
-                    color = pal_as_colors[pal_index - 1]
-                    image.put(color_to_hex(color), to=(x + offset[0], y + offset[1]))
+        def drawsprite(spr, pal_as_colors, offset):
+            for y in range(len(spr)):
+                for x in range(len(spr[y])):
+                    pal_index = spr[y][x]
+                    if pal_index:
+                        color = pal_as_colors[pal_index - 1]
+                        set_pixel_color_index(x + offset[0], y + offset[1], color)
 
-    shadow_palette = [(40, 40, 40)]
-    shadow = [
-        [0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0],
-        [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
-        [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
-        [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
-        [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
-        [0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0],
-    ]
+        add_palette_color(16, (40, 40, 40))
+        shadow = [
+            [0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0],
+            [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
+            [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
+            [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
+            [0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
+            [0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0],
+        ]
 
-    drawsprite(shadow, shadow_palette, (2, 17))
+        drawsprite(shadow, [16], (2, 17))
 
-    palettes = sprite.decode_palette()
-    body = sprite.decode16(0x4C0)
-    drawsprite(body, palettes[0], (0, 8))
-    head = sprite.decode16(0x40)
-    drawsprite(head, palettes[0], (0, 0))
+        palettes = sprite.decode_palette()
+        for i in range(15):
+            add_palette_color(i + 1, palettes[0][i])
+
+        body = sprite.decode16(0x4C0)
+        drawsprite(body, list(range(1, 16)), (0, 8))
+        head = sprite.decode16(0x40)
+        drawsprite(head, list(range(1, 16)), (0, 0))
+
+    def make_gif(callback):
+        gif_header = b'GIF89a'
+
+        gif_lsd = bytearray(7)
+        gif_lsd[0] = width
+        gif_lsd[2] = height
+        gif_lsd[4] = 0xF4  # 32 color palette follows.  transparant + 15 for sprite + 1 for shadow=17 which rounds up to 32 as nearest power of 2
+        gif_lsd[5] = 0  # background color is zero
+        gif_lsd[6] = 0  # aspect raio not specified
+        gif_gct = bytearray(3 * 32)
+
+        gif_gce = bytearray(8)
+        gif_gce[0] = 0x21  # start of extention blocked
+        gif_gce[1] = 0xF9  # identifies this as the Graphics Control extension
+        gif_gce[2] = 4  # we are suppling only the 4 four bytes
+        gif_gce[3] = 0x01  # this gif includes transparency
+        gif_gce[4] = gif_gce[5] = 0  # animation frrame delay (unused)
+        gif_gce[6] = 0  # transparent color is index 0
+        gif_gce[7] = 0  # end of gif_gce
+        gif_id = bytearray(10)
+        gif_id[0] = 0x2c
+        # byte 1,2 are image left. 3,4 are image top both are left as zerosuitsamus
+        gif_id[5] = width
+        gif_id[7] = height
+        gif_id[9] = 0  # no local color table
+
+        gif_img_minimum_code_size = bytes([7])  # we choose 7 bits, so that each pixel is represented by a byte, for conviennce.
+
+        clear = 0x80
+        stop = 0x81
+
+        unchunked_image_data = bytearray(height * (width + 1) + 1)
+        # we technically need a Clear code once every 125 bytes, but we do it at the start of every row for simplicity
+        for row in range(height):
+            unchunked_image_data[row * (width + 1)] = clear
+        unchunked_image_data[-1] = stop
+
+        def add_palette_color(index, color):
+            gif_gct[3 * index] = color[0]
+            gif_gct[3 * index + 1] = color[1]
+            gif_gct[3 * index + 2] = color[2]
+
+        def set_pixel_color_index(x, y, color):
+            unchunked_image_data[y * (width + 1) + x + 1] = color
+
+        callback(add_palette_color, set_pixel_color_index)
+
+        def chunk_image(img):
+            for i in range(0, len(img), 255):
+                chunk = img[i:i + 255]
+                yield bytes([len(chunk)])
+                yield chunk
+
+        gif_img = b''.join([gif_img_minimum_code_size] + list(chunk_image(unchunked_image_data)) + [b'\x00'])
+
+        gif = b''.join([gif_header, gif_lsd, gif_gct, gif_gce, gif_id, gif_img, b'\x3b'])
+
+        return gif
+
+    gif_data = make_gif(draw_sprite_into_gif)
+    image = PhotoImage(data=gif_data)
 
     return image.zoom(2)