From a6417742e6e7688f215d91184355e399745c02aa Mon Sep 17 00:00:00 2001
From: Anurag Chowdhury <anurag@seeta.in>
Date: Fri, 22 Oct 2010 03:04:11 +0000
Subject: New suggestion for arrow drawing in Paint

activity.olpc4170

In the paint activity's shape tool we were able to make only horizontal arrows,
so now we have modified the arrow tool which will now make arrows in all
directions.
---
diff --git a/Desenho.py b/Desenho.py
index 17525e5..ec464af 100644
--- a/Desenho.py
+++ b/Desenho.py
@@ -294,18 +294,31 @@ class Desenho:
 
         x = coords[0] - widget.oldx
         y = coords[1] - widget.oldy
-        points = [(widget.oldx, widget.oldy),\
-            (widget.oldx + int(x / 6), widget.oldy + y), \
-            (widget.oldx + int(x / 6), widget.oldy + int(y / 3)), \
-            (widget.oldx + x, widget.oldy + int(y / 3)), \
-            (widget.oldx + x, widget.oldy - int(y / 3)), \
-            (widget.oldx + int(x / 6), widget.oldy - int(y / 3)),\
-            (widget.oldx + int(x / 6), widget.oldy - y)]
+        A = math.atan2(y, x)
+        dA = 2 * math.pi / 2
+        r = math.hypot(y, x)
+        m = math.sin(A)
+        p = [(widget.oldx, widget.oldy)]
+        p.append((widget.oldx + int(r * math.cos(A)),\
+                  widget.oldy + int(r * math.sin(A))))
+        p.append((widget.oldx + int(0.74 * r * math.cos(A + dA / 6)),\
+                  widget.oldy + int(0.74 * r * math.sin(A + dA / 6))))
+        p.append((widget.oldx + int(2 * r * math.cos(A + dA / 6 + dA / 20)),\
+                  widget.oldy + int(2 * r * math.sin(A + dA / 6 + dA / 20))))
+        p.append((widget.oldx +\
+                  int(2 * r * math.cos(A + dA / 6 - dA / 20 + dA / 6)),\
+                  widget.oldy +\
+                  int(2 * r * math.sin(A + dA / 6 - dA / 20 + dA / 6))))
+        p.append((widget.oldx + int(0.74 * r * math.cos(A + dA / 6 + dA / 6)),\
+                  widget.oldy + int(0.74 * r * math.sin(A + dA / 6 + dA / 6))))
+        p.append((widget.oldx + int(r * math.cos(A + dA / 2)),\
+                  widget.oldy + int(r * math.sin(A + dA / 2))))
         pixmap.draw_drawable(widget.gc, widget.pixmap, 0, 0, 0, 0,
             width, height)
+        tp = tuple(p)
         if fill == True:
-            pixmap.draw_polygon(widget.gc, True, points)
-        pixmap.draw_polygon(widget.gc_line, False, points)
+            pixmap.draw_polygon(widget.gc, True, tp)
+        pixmap.draw_polygon(widget.gc_line, False, tp)
         widget.queue_draw()
 
     def parallelogram(self, widget, coords, temp, fill):
--
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