added some more options to knob_scale and fixed some 0 division error in

vertical scale

extensions/fablabchemnitz/knob_scale/knob_scale.inx

@@ -7,11 +7,13 @@
             <param name="x" type="float" min="-1000" max="10000" precision="3" gui-text="Center X:">0</param>
             <param name="y" type="float" min="-1000" max="10000" precision="3" gui-text="Center Y:">0</param>
             <param name="radius" type="float" min="0.001" max="10000" precision="3" gui-text="Knob radius:">100</param>
-            <param name="angle" type="float" min="90.0" max="360.0" precision="3" gui-text="Angle">300</param>
+            <param name="angle" type="float" min="1.0" max="360.0" precision="3" gui-text="Angle (°)">300</param>
+            <param name="angle_shifting" type="float" min="0.0" max="360.0" precision="3" gui-text="Angle shifting (°)">300</param>
             <param name="linewidth" type="float" min="0.001" max="100" precision="3" gui-text="Line width">1</param>
             <param name="draw_arc" type="bool" gui-text="Draw Arc">true</param>
             <param name="draw_centering_circle" type="bool" gui-text="Draw Centering Circle">false</param>
             <param name="logarithmic_scale" type="bool" gui-text="Logarithmic Scale">false</param>
+            <param name="invert" type="bool" gui-text="Invert direction">false</param>
             <param name="units" type="optiongroup" gui-text="Units" appearance="combo">
                 <option value="px">px</option>
                 <option value="mm">mm</option>

extensions/fablabchemnitz/knob_scale/knob_scale.py

@@ -32,9 +32,11 @@ class KnobScale(inkex.EffectExtension):
         pars.add_argument("--radius", type=float, default=100.0, help="Knob radius")
         pars.add_argument("--linewidth", type=float, default=1)
         pars.add_argument("--angle", type=float, default=260.0, help="Angle of the knob scale in degrees")
+        pars.add_argument("--angle_shifting", type=float, default=0.0, help="Angle shifting")
         pars.add_argument("--draw_arc", type=inkex.Boolean, default='True')
         pars.add_argument("--draw_centering_circle", type=inkex.Boolean, default='False')
         pars.add_argument("--logarithmic_scale", type=inkex.Boolean, default='False', help="")
+        pars.add_argument("--invert", type=inkex.Boolean, default='False', help="")
         pars.add_argument("-u", "--units", default="px", help="units to measure size of knob")
 
         # Tick settings
@@ -74,10 +76,10 @@ class KnobScale(inkex.EffectExtension):
 
         text.set('style', str(inkex.Style(style)))
         parent.append(text)
-    def draw_knob_arc(self, radius, parent, angle, transform='' ):
+    def draw_knob_arc(self, radius, parent, angle, angle_shifting, transform='' ):
 
-        start_point_angle = (angle - pi)/2.0
+        start_point_angle = angle_shifting + (angle - pi)/2.0
-        end_point_angle = pi - start_point_angle
+        end_point_angle = pi - start_point_angle + angle_shifting*2
 
         style = {   'stroke'        : '#000000',
                     'stroke-width'  : str(self.options.linewidth),
@@ -161,6 +163,7 @@ class KnobScale(inkex.EffectExtension):
         self.x_offset = self.svg.unittouu(str(self.options.x) + self.options.units)
         self.y_offset = self.svg.unittouu(str(self.options.y) + self.options.units)
         angle = self.options.angle*pi/180.0
+        angle_shifting = self.options.angle_shifting*pi/180.0
         n_ticks = self.options.n_ticks
         n_subticks = self.options.n_subticks
         is_outer = True
@@ -173,8 +176,12 @@ class KnobScale(inkex.EffectExtension):
 
 
         # Labeling settings
-        start_num = self.options.start_value
+        if self.options.invert is True:
-        end_num = self.options.stop_value
+            end_num = self.options.start_value
+            start_num = self.options.stop_value    
+        else:
+            start_num = self.options.start_value
+            end_num = self.options.stop_value
         text_spacing = self.svg.unittouu(str(self.options.text_offset) + self.options.units)
         text_size = self.svg.unittouu(str(self.options.text_size) + self.options.units)
 
@@ -186,13 +193,13 @@ class KnobScale(inkex.EffectExtension):
             arc_radius = radius
 
         if self.options.draw_arc:
-            self.draw_knob_arc(arc_radius, parent, angle)
+            self.draw_knob_arc(arc_radius, parent, angle, angle_shifting)
 
         if self.options.draw_centering_circle:
             self.draw_centering_circle(arc_radius + tick_length + text_size + text_spacing, parent)
 
         if self.options.logarithmic_scale:
-            start_ticks_angle = 1.5*pi - 0.5*angle
+            start_ticks_angle = 1.5*pi - 0.5*angle + angle_shifting
             for tick in range(n_ticks):
                 self.draw_tick(radius, start_ticks_angle + angle*log(tick+1)/log(n_ticks),
                                     tick_length, parent)
@@ -218,7 +225,7 @@ class KnobScale(inkex.EffectExtension):
                                  subtick_length, parent)        
         else:
             ticks_delta = angle / (n_ticks - 1)
-            start_ticks_angle = 1.5*pi - 0.5*angle
+            start_ticks_angle = 1.5*pi - 0.5*angle + angle_shifting
 
             for tick in range(n_ticks):
                 self.draw_tick(radius, start_ticks_angle + ticks_delta*tick,

extensions/fablabchemnitz/vertical_horizontal_scale/vertical_horizontal_scale.py

@@ -441,6 +441,10 @@ class VerticalHorizontalScale(inkex.EffectExtension):
     def effect(self):
         scalefrom = self.options.scalefrom
         scaleto = self.options.scaleto
+        
+        if scalefrom - scaleto == 0:
+            inkex.utils.debug("Offset between number labels needs to be at least 1")
+            exit()
 
         scaleGroup = self.svg.get_current_layer().add(inkex.Group())
         groups = [None, None, None, None]