Add application file

backend.py

@@ -0,0 +1,64 @@
+import json
+from flask import Flask
+from flask_cors import CORS
+
+from PIL import Image
+import numpy as np
+import potrace
+
+app = Flask(__name__)
+CORS(app)
+
+FRAMES = 5258
+
+def png_to_np_array(filename):
+    img = Image.open(filename)
+    data = np.array(img.getdata()).reshape(img.size[1], img.size[0], 3)
+    bindata = np.zeros((img.size[1], img.size[0]), np.uint32)
+    for i, row in enumerate(data):
+        for j, byte in enumerate(row):
+            bindata[img.size[1]-i-1, j] = 1 if sum(byte) < 127*3 else 0
+        #     print('###' if bindata[i, j] == 1 else '   ', end='')
+        # print()
+    return bindata
+
+def png_to_svg(filename):
+    data = png_to_np_array(filename)
+    bmp = potrace.Bitmap(data)
+    path = bmp.trace()
+    return path
+
+frame_coords = []
+
+for i in range(FRAMES):
+
+    latex = []
+
+    path = png_to_svg('frames/frame%d.png' % (i+1))
+
+    for curve in path.curves:
+        segments = curve.segments
+        start = curve.start_point
+        for segment in segments:
+            x0, y0 = start
+            if segment.is_corner:
+                x1, y1 = segment.c
+                x2, y2 = segment.end_point
+                latex.append('((1-t)%f+t%f,(1-t)%f+t%f)' % (x0, x1, y0, y1))
+                latex.append('((1-t)%f+t%f,(1-t)%f+t%f)' % (x1, x2, y1, y2))
+            else:
+                x1, y1 = segment.c1
+                x2, y2 = segment.c2
+                x3, y3 = segment.end_point
+                latex.append('((1-t)((1-t)((1-t)%f+t%f)+t((1-t)%f+t%f))+t((1-t)((1-t)%f+t%f)+t((1-t)%f+t%f)),\
+                (1-t)((1-t)((1-t)%f+t%f)+t((1-t)%f+t%f))+t((1-t)((1-t)%f+t%f)+t((1-t)%f+t%f)))' % \
+                (x0, x1, x1, x2, x1, x2, x2, x3, y0, y1, y1, y2, y1, y2, y2, y3))
+            start = segment.end_point
+
+    frame_coords.append(latex)
+
+@app.route('/')
+def index():
+    return json.dumps(frame_coords)
+
+app.run()