From bc6ec37e87d81367f97157dfd3366f4938c8af00 Mon Sep 17 00:00:00 2001
From: Walter Bender <walter@sugarlabs.org>
Date: Thu, 12 Aug 2010 22:41:29 +0000
Subject: Turtle 'sees'

---
(limited to 'TurtleArt')

diff --git a/TurtleArt/tacanvas.py b/TurtleArt/tacanvas.py
index 667cc0f..72c1c7d 100644
--- a/TurtleArt/tacanvas.py
+++ b/TurtleArt/tacanvas.py
@@ -566,6 +566,24 @@ class TurtleGraphics:
                                                            int(w), int(h)),
                                          False)
 
+    def get_color_index(self, r, g, b, a=0):
+        """ Find the closest palette entry to the rgb triplet """
+        # TODO: Take into account gray and shade levels
+        min_distance = 1000000
+        closest_color = -1
+        for i, c in enumerate(color_table):
+            cr = int((c & 0xff0000) >> 16)
+            cg = int((c & 0x00ff00) >> 8)
+            cb = int((c & 0x0000ff))
+            distance_squared = ((cr - r) ** 2) + ((cg - g) ** 2) + \
+                ((cb - b) ** 2)
+            if distance_squared == 0:
+                return i
+            if distance_squared < min_distance:
+                min_distance = distance_squared
+                closest_color = i
+        return closest_color
+
     def get_pixel(self):
         """ Read the pixel at x, y """
         if self.tw.interactive_mode:
diff --git a/TurtleArt/taconstants.py b/TurtleArt/taconstants.py
index 5088b8f..b20948d 100644
--- a/TurtleArt/taconstants.py
+++ b/TurtleArt/taconstants.py
@@ -135,7 +135,7 @@ PALETTES = [['clean', 'forward', 'back', 'show', 'left', 'right',
             ['kbinput', 'push', 'printheap', 'keyboard', 'pop', 'clearheap',
              'myfunc1arg',  'userdefined', 'addturtle', 'comment', 'print',
              'cartesian', 'width', 'height', 'polar', 'sandwichtop',
-             'sandwichbottom', 'readpixel'],
+             'sandwichbottom', 'readpixel', 'see'],
             ['journal', 'audio', 'description', 'hideblocks', 'showblocks',
              'fullscreen', 'savepix', 'savesvg', 'picturelist',
              'picture1x1a', 'picture1x1', 'picture2x2', 'picture2x1',
@@ -199,7 +199,7 @@ BOX_STYLE = ['number', 'xcor', 'ycor', 'heading', 'pensize', 'color', 'shade',
     'toppos', 'rightpos', 'bottompos', 'width', 'height', 'pop', 'keyboard',
     'red', 'orange', 'yellow', 'green', 'cyan', 'blue', 'purple', 'white',
     'black', 'titlex', 'titley', 'leftx', 'topy', 'rightx', 'bottomy',
-    'volume', 'pitch', 'voltage', 'resistance', 'gray']
+    'volume', 'pitch', 'voltage', 'resistance', 'gray', 'see']
 BOX_STYLE_MEDIA =  ['description', 'audio', 'journal']
 NUMBER_STYLE = ['plus2', 'product2', 'myfunc']
 NUMBER_STYLE_VAR_ARG = ['myfunc1arg', 'myfunc2arg', 'myfunc3arg']
@@ -354,6 +354,7 @@ BLOCK_NAMES = {
     'sandwichtop':[_('top of stack')],
     'sandwichtop2':[_('top of stack')],
     'scale':[_('scale')],
+    'see':[_('turtle sees')],
     'setcolor':[_('set color')],
     'setgray':[_('set gray')],
     'seth':[_('set heading')],
@@ -493,6 +494,7 @@ PRIMITIVES = {
     'sandwichcollapsed':'nop',
     'savepix':'savepix',
     'savesvg':'savesvg',
+    'see':'see',
     'scale':'scale',
     'setcolor':'setcolor',
     'setgray':'setgray',
@@ -802,6 +804,7 @@ HELP_STRINGS = {
     'savepix':_("saves a picture to the Sugar Journal"),
     'savesvg':_("saves turtle graphics as an SVG file in the Sugar Journal"),
     'scale':_("holds current scale value"),
+    'see':_('returns the color that the turtle "sees"'),
     'setcolor':_("sets color of the line drawn by the turtle"),
     'setgray':_("sets gray level of the line drawn by the turtle"),
     'seth':_("sets the heading of the turtle (0 is towards the top of the screen.)"),
diff --git a/TurtleArt/talogo.py b/TurtleArt/talogo.py
index 84da6d3..5f2a6d5 100644
--- a/TurtleArt/talogo.py
+++ b/TurtleArt/talogo.py
@@ -324,6 +324,7 @@ class LogoCode:
         'savepix':[1, lambda self, x: self.save_picture(x)],
         'savesvg':[1, lambda self, x: self.save_svg(x)],
         'scale':[0, lambda self: self.scale],
+        'see':[0, lambda self: self.see()],
         'setcolor':[1, lambda self, x: self.tw.canvas.setcolor(x)],
         'setgray':[1, lambda self, x: self.tw.canvas.setgray(x)],
         'seth':[1, lambda self, x: self.tw.canvas.seth(x)],
@@ -1171,6 +1172,12 @@ class LogoCode:
                 self.tw.canvas.draw_text(text, int(x), int(y),
                                          self.body_height, int(w))
 
+    def see(self):
+        """ Read r, g, b from the canvas and return a corresponding palette
+        color """
+        r, g, b, a = self.tw.canvas.get_pixel()
+        return self.tw.canvas.get_color_index(r, g, b)
+
     def read_pixel(self):
         """ Read r, g, b, a from the canvas and push b, g, r to the stack """
         r, g, b, a = self.tw.canvas.get_pixel()
--
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