Merge pull request #80 from tmontes/canvas-y-is-up

Canvas y is up

Author: tmontes

src/aturtle/canvas.py

@@ -0,0 +1,92 @@
+# ----------------------------------------------------------------------------
+# Python A-Turtle
+# ----------------------------------------------------------------------------
+# Copyright (c) Tiago Montes.
+# See LICENSE for details.
+# ----------------------------------------------------------------------------
+
+import tkinter
+
+
+
+class InvertedYCanvas:
+
+    """
+    Behaves like a tkinter.Canvas widget, where Y coordinates are negated such
+    that larger values are at the top of the screen.
+    """
+
+    def __init__(self, master, background):
+        """
+        Creates a Canvas widget with parent `master` and the given `background`
+        color. Sets the underlying tkinter.Canvas widget's highlightthickness
+        to zero such that no border/outline is visible.
+        """
+        self._canvas = tkinter.Canvas(
+            master,
+            highlightthickness=0,
+            background=background,
+        )
+
+    def _inverted_y(self, coords):
+
+        # `coords` is an iterable of (x0, y0, x1, y0, ..., xn, yn) numbers,
+        # where the ones in odd offsets/indices are Y values that are negated.
+
+        return [
+            -value if offset % 2 else value
+            for offset, value in enumerate(coords)
+        ]
+
+
+    def create_polygon(self, coords, *, fill, outline, width):
+        """
+        Creates a polygon item with given `coords` and visual attributes.
+        """
+        return self._canvas.create_polygon(
+            self._inverted_y(coords),
+            fill=fill,
+            outline=outline,
+            width=width,
+        )
+
+
+    def create_image(self, x, y, *, image, anchor):
+        """
+        Creates an image item at the given (`x`, `y`) position with the `image`
+        achored at `anchor`.
+        """
+        return self._canvas.create_image(x, -y, image=image, anchor=anchor)
+
+
+    def create_line(self, coords, *, fill, width, capstyle):
+        """
+        Creates a line item with given `coords` and visual attributes.
+        """
+        return self._canvas.create_line(
+            self._inverted_y(coords),
+            fill=fill,
+            width=width,
+            capstyle=capstyle,
+        )
+
+
+    def move(self, item_id, dx, dy):
+        """
+        Moves the item identified by `item_id` relatively by (`dx`, `dy`).
+        """
+        return self._canvas.move(item_id, dx, -dy)
+
+
+    def coords(self, item_id, coords):
+        """
+        Sets the coordinates of the item identified by `item_id` to `coords`.
+        """
+        return self._canvas.coords(item_id, self._inverted_y(coords))
+
+
+    def __getattr__(self, name):
+        """
+        Delegates attribute access to the wrapped tkinter.Canvas object.
+        """
+        return getattr(self._canvas, name)

src/aturtle/shapes/bitmap.py

@@ -106,20 +106,20 @@ def _rotated_tkinter(self, image, around, step, rotations):
 
         ax, ay = around
 
-        neg_theta = -math.pi * 2 * step / rotations
+        theta = math.pi * 2 * step / rotations
 
         pixel_rows = []
         transparency = {}
 
         for y in range(h):
             pixel_row = []
             for x in range(w):
-                cos_neg_theta = math.cos(neg_theta)
-                sin_neg_theta = math.sin(neg_theta)
+                cos_theta = math.cos(theta)
+                sin_theta = math.sin(theta)
                 off_x = x - ax
                 off_y = y - ay
-                src_x = int(off_x * cos_neg_theta - off_y * sin_neg_theta) + ax
-                src_y = int(off_x * sin_neg_theta + off_y * cos_neg_theta) + ay
+                src_x = int(off_x * cos_theta - off_y * sin_theta) + ax
+                src_y = int(off_x * sin_theta + off_y * cos_theta) + ay
                 if (0 <= src_x < w) and (0 <= src_y < h):
                     red, green, blue = image.get(src_x, src_y)
                     transp = image.transparency_get(src_x, src_y)
@@ -142,10 +142,10 @@ def _rotated_pil(self, pil_image, around, step, total):
 
         # PIL-based image rotation.
 
-        neg_theta = -360 * step / total
+        theta = 360 * step / total
 
         rotated_pil_image = pil_image.rotate(
-            neg_theta,
+            theta,
             resample=Image.BICUBIC,
             center=around,
         )

src/aturtle/sprites/bitmap.py

@@ -27,7 +27,7 @@ def __init__(self, canvas, shape, *, anchor=(0, 0), angle=0, speed=360,
             sprite_x - shape_x,
             sprite_y - shape_y,
             image=shape[angle],
-            anchor='nw',
+            anchor='sw',
         )
 
 

src/aturtle/turtle.py

@@ -176,7 +176,7 @@ async def async_left(self, angle, *, speed=None, easing=None, fps=None,
         underlying Sprite's animated movement operation.
         """
         await self._sprite.async_rotate(
-            -angle,
+            angle,
             speed=speed,
             easing=easing,
             fps=fps,
@@ -193,7 +193,7 @@ async def async_right(self, angle, *, speed=None, easing=None, fps=None,
         underlying Sprite's animated movement operation.
         """
         await self._sprite.async_rotate(
-            angle,
+            -angle,
             speed=speed,
             easing=easing,
             fps=fps,

src/aturtle/window.py

@@ -7,6 +7,8 @@
 
 import tkinter
 
+from . import canvas
+
 
 
 class Window:
@@ -18,7 +20,8 @@ class Window:
     _windows = []
 
     def __init__(self, width=320, height=320, x=None, y=None,
-                 fill_color='white', title='A-Turtle'):
+                 fill_color='white', title='A-Turtle',
+                 canvas_factory=canvas.InvertedYCanvas):
         """
         Initialize a Window with the given `width` and `height`, filled in
         `fill_color`, with the given `title`.
@@ -47,9 +50,8 @@ def __init__(self, width=320, height=320, x=None, y=None,
         y = (tk_window.winfo_screenheight() - height) // 2 if y is None else y
 
         tk_window.geometry(f'{width}x{height}+{x}+{y}')
-        canvas = tkinter.Canvas(
+        canvas = canvas_factory(
             tk_window,
-            highlightthickness=0,
             background=fill_color,
         )
         canvas.pack(expand=True, fill='both')

tests/test_bitmap_sprites.py

@@ -56,7 +56,7 @@ def test_create_calls_canvas_create_image(self):
             -10,
             -10,
             image='image-at-angle-0',
-            anchor='nw',
+            anchor='sw',
         )