scaling arrow heads

[Christof Ecker]

The following patch changes the line dialog to allow scaling of arrow
heads.

As sketch is representing arrow heads as paths, it is not possible, to
introduce a separete scaling factor without changing the whole concept
(e.g. the fileformat).

My solution is to introduce a "standart size" for arrow heads, which
corresponds to the arrow drawn in a certain thickness and scaling. The
scaling factor is then defined as the ratio of the height of the arrow
head and its standart height.

Cheers,
Christof

diff -r sketch-0.6.14/Sketch/UI/linedlg.py 
sketch-0.6.14_hack/Sketch/UI/linedlg.py
30,34c30,31
<      StandardDashes, StandardArrows, StandardColors
<
<
< from Tkinter import Frame, Label, IntVar, LEFT, X, E, W, GROOVE
< from tkext import ColorButton, UpdatedCheckbutton, MyOptionMenu2
---
>      StandardDashes, StandardArrows, StandardColors, Scale, Point, \
>      Arrow
35a33,37
> from Tkinter import Frame, Label, IntVar, LEFT, RIGHT, TOP, X, Y, E, \
>      W, GROOVE, DoubleVar
> from tkext import ColorButton, UpdatedCheckbutton, MyOptionMenu2, \
>      MyEntry
> from miniscroll import MiniScroller
41a44,64
> class RoundedFloat:
>     def __init__(self, var, precision=2):
>         self.var = var
>         self.precision = precision
>     def get(self):
>         return self.var.get()
>     def set(self, value):
>         self.var.set(round(value, self.precision))
>
> def create_scale_entry(top, master, command, args = (), scroll_pad = 2):
>     var = DoubleVar(top)
>     var.set(100.0)
>     rounded_var = RoundedFloat(var, precision=2)
>     entry = MyEntry(master, textvariable = var, justify = RIGHT,
>                     width = 6, command = command, args = args)
>     scroll = MiniScroller(master, variable = var, min = 0, max = None,
>                         step = 10)
>     entry.pack(side = LEFT, expand = 1, fill = X, anchor = E)
>     scroll.pack(side = LEFT, fill = Y, pady = scroll_pad)
>     return rounded_var
>
83c106,107
< _arrow_height = 25
---
> _arrow_height = 20
> _scalefactor = 20.
121a146,162
> def set_scalefactor(arrow, scale):
>     ascale = get_scalefactor(arrow)
>     if ascale == 0:
>         return arrow
>     path = arrow.path.Duplicate()
>     path.Transform(Scale(scale/ascale))
>     arrow = Arrow(path)
>     return arrow
>
> def get_scalefactor(arrow):
>     if arrow is None:
>         return 0
>     p = Point(1,0)
>     x1, y1, x2, y2 = arrow.BoundingRect(p, p, _thickness)
>     return (y2-y1)/_scalefactor *100
>
>
134c175
<         button_frame.grid(row = 5, columnspan = 2, sticky = 'ew')
---
>         button_frame.grid(row = 6, columnspan = 2, sticky = 'ew')
171c212
<         self.opt_arrow1 = MyOptionMenu2(top, arrow1, command = self.set_arrow,
---
>         self.opt_arrow1 = MyOptionMenu2(top, arrow1, command = 
> self.set_arrowshape,
175c216
<         self.opt_arrow2 = MyOptionMenu2(top, arrow2, command = self.set_arrow,
---
>         self.opt_arrow2 = MyOptionMenu2(top, arrow2, command = 
> self.set_arrowshape,
181a223,238
>         scale_frame = Frame(top, relief = GROOVE, bd = 2)
>         scale_frame.grid(row = 4, columnspan = 2, sticky = 'ew')
>
>       label = Label(scale_frame, text = "Arrow Scale")
>       label.pack(side = TOP, expand = 1, fill=X, anchor = W)
>
>       self.var_scale1 = create_scale_entry(top, scale_frame,
>                                              self.set_arrowscale,
>                                              args = 1,
>                                              scroll_pad = 0)
>
>       self.var_scale2 = create_scale_entry(top, scale_frame,
>                                             self.set_arrowscale,
>                                             args = 2,
>                                             scroll_pad = 0)
>
188c245
<         self.opt_join.grid(row = 4, column = 0, sticky = 'ew')
---
>         self.opt_join.grid(row = 5, column = 0, sticky = 'ew')
197c254
<         self.opt_cap.grid(row = 4, column = 1, sticky = 'ew')
---
>         self.opt_cap.grid(row = 5, column = 1, sticky = 'ew')
224c281,291
<
---
>
>     def _get_arrow(self, which):
>         if which == 1:
>             scale = self.var_scale1.get()
>             arrow = self.opt_arrow1.GetValue()
>         else:
>             scale = self.var_scale2.get()
>             arrow = self.opt_arrow2.GetValue()
>
>         return set_scalefactor(arrow, scale)
>
234,235c301,302
<             kw["line_arrow1"] = self.opt_arrow1.GetValue()
<             kw["line_arrow2"] = self.opt_arrow2.GetValue()
---
>             kw["line_arrow1"] = self._get_arrow(1)
>             kw["line_arrow2"] = self._get_arrow(2)
266c333
<     def set_arrow(self, arrow, which):
---
>     def set_arrow(self, arrow=None, scale=None, which=1):
267a335,339
>             if scale is None:
>                 scale = self.var_scale1.get()
>             if arrow is None:
>                 arrow = self.opt_arrow1.GetValue()
>             arrow = set_scalefactor(arrow, scale)
270a343,347
>             if scale is None:
>                 scale = self.var_scale2.get()
>             if arrow is None:
>                 arrow = self.opt_arrow2.GetValue()
>             arrow = set_scalefactor(arrow, scale)
273c350,356
<
---
>
>     def set_arrowshape(self, arrow, which):
>         self.set_arrow(arrow = arrow, which = which)
>
>     def set_arrowscale(self, scale, which):
>         self.set_arrow(scale = scale, which = which)
>
275a359,361
>         scale = get_scalefactor(arrow)
>         arrow = set_scalefactor(arrow, 100.)
>
279a366,367
>         if arrow is not None:
>             self.var_scale1.set(scale)
281a370,372
>         scale = get_scalefactor(arrow)
>         arrow = set_scalefactor(arrow, 100.)
>
286c377,379
<
---
>         if arrow is not None:
>             self.var_scale2.set(scale)
>