Added Checkerboard

extensions/fablabchemnitz_checkerboard.inx

@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<inkscape-extension xmlns="http://www.inkscape.org/namespace/inkscape/extension">
+  <_name>Checkerboard</_name>
+  <id>fablabchemnitz.de.checkerboard</id>
+  <param name="tab" type="notebook">
+    <page name="params" _gui-text="Params">
+      <param name="size" type="string" _gui-text="Cell size">50</param>
+      <param name="rows" type="int" min="0" max="1000" _gui-text="Rows">10</param>
+      <param name="cols" type="int" min="0" max="1000" _gui-text="Columns">10</param>
+      <param name="layer"  type="boolean" _gui-text="Create in current layer">true</param>
+    </page>
+    <page name="color1" _gui-text="1st color">
+      <param name="color1" type="color" _gui-text="Color 1">#000000ff</param>
+    </page>
+    <page name="color2" _gui-text="2nd color">
+      <param name="color2" type="color" _gui-text="Color 2">#ffffffff</param>
+    </page>
+    <page name="help" _gui-text="Help">
+        <param name="help_text" type="description">Create a checkerboard
+
+1. On the Params tab, choose the cell size
+    (size of the constituent squares), number
+    of rows and columns, and whether to add
+    the checkerboard to the current layer
+    (if unchecked, the checkerboard will be
+    added to the root layer)
+2. On the 1st color and 2nd color tabs,
+    select the colors for the two sets of
+    squares
+3. Click Apply
+
+More information and source code:
+https://github.com/jeffkayser/inkscape-checkerboard</param>
+    </page>
+  </param>
+  <effect>
+    <object-type>all</object-type>
+      <effects-menu>
+            <submenu _name="FabLab Chemnitz">
+                <submenu _name="Shape/Pattern from Generator" />
+            </submenu>
+      </effects-menu>
+  </effect>
+  <script>
+    <command reldir="extensions" interpreter="python">fablabchemnitz_checkerboard.py</command>
+  </script>
+</inkscape-extension>

extensions/fablabchemnitz_checkerboard.py

@@ -0,0 +1,94 @@
+#!/usr/bin/env python3
+
+"""
+Inkscape extension to create checkerboard patterns
+
+
+Copyright (C) 2011 Jeff Kayser
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+"""
+
+from gettext import gettext as _
+import inkex
+from lxml import etree
+import re
+from inkex import Color
+
+def rgbToHex(pickerColor):
+    longcolor = int(pickerColor)
+    if longcolor < 0:
+        longcolor = longcolor & 0xFFFFFFFF
+    return '#' + format(longcolor >> 8, '06X')
+
+def draw_square(x, y, w, h, color, parent, id_=None):
+    """Draw a w*h square at (x, y) having color color
+    """
+    if len(color) == 4:
+        opacity=color[3]
+    else:
+        opacity=1.0   
+    
+    style = {'stroke': 'none', 'stroke-width': '1', 'fill': rgbToHex(color), 'fill-opacity': opacity}
+    attribs = {'style': str(inkex.Style(style)), 'height': str(h), 'width': str(w), 'x': str(x), 'y': str(y)}
+    if id_ is not None:
+        attribs.update({'id': id_})
+    obj = etree.SubElement(parent, inkex.addNS('rect', 'svg'), attribs)
+
+def draw_grid(x, y, rows, cols, size, color1, color2, parent):
+    """Draw a rows*cols checkboard grid at (x, y) with square size of size*size,
+    with squares having alternating colors color1 and color2
+    """
+    # Group like-colors
+    group1 = etree.SubElement(parent, 'g', {'id': 'diagonal1'})
+    group2 = etree.SubElement(parent, 'g', {'id': 'diagonal2'})
+    for row in range(int(rows)):
+        for col in range(int(cols)):
+            alternate = (col + row) % 2 == 0
+            color = color1 if alternate else color2
+            group = group1 if alternate else group2
+            id_ = 'cell{0}x{1}'.format(col, row)
+            draw_square(x + col * size, y + row * size, size, size, color, group, id_)
+	
+class Checkerboard(inkex.Effect):
+    def __init__(self):
+        inkex.Effect.__init__(self)
+        self.arg_parser.add_argument("--tab")
+        self.arg_parser.add_argument("--color1", type=Color)
+        self.arg_parser.add_argument("--color2", type=Color)
+        self.arg_parser.add_argument("--size")
+        self.arg_parser.add_argument("--rows", type=int)
+        self.arg_parser.add_argument("--cols", type=int)
+        self.arg_parser.add_argument("--layer", type=inkex.Boolean)
+
+    def effect(self):
+        if self.svg.get_current_layer() is not None:
+            group = etree.SubElement(self.svg.get_current_layer(), 'g', {'id': 'checkerboard'})
+        else:
+            parent = self.document.getroot()
+            group = etree.SubElement(parent, 'g', {'id': 'checkerboard'})
+		  
+        rows = self.options.rows
+        cols = self.options.cols
+        # Convert to pixels
+        size = self.svg.unittouu(self.options.size)
+        color1 = self.options.color1
+        color2 = self.options.color2
+        # Center checkerboard within visible viewport
+        x, y = self.svg.namedview.center[0] - cols * size / 2, self.svg.namedview.center[1] - rows * size / 2
+        draw_grid(x, y, rows, cols, size, color1, color2, group)
+
+if __name__ == '__main__':
+    Checkerboard().run()