Re: Is there any way to draw a line with arrow in wx?

Deepest appologies.   The above code has a bug.  Please use the following:

from math import atan2, sin, cos, pi
def DrawArrowLine( dc, x0, y0, x1, y1, arrowFrom=True, arrowTo=True, 
arrowLength=16, arrowWidth=8 ):
    '''
        Draws a line with arrows in a regular wxPython DC.
        The line is drawn with the dc's wx.Pen.  The arrows are filled with 
the current Pen's colour.
        Edward Sitarski 2021.
    '''
    dc.DrawLine( x0, y0, x1, y1 )
    if x0 == x1 and y0 == y1:
        return
    
    # Set up the dc for drawing the arrows.
    penSave, brushSave = dc.GetPen(), dc.GetBrush()
    dc.SetPen( wx.TRANSPARENT_PEN )
    dc.SetBrush( wx.Brush(penSave.GetColour()) )
    
    # Compute the "to" arrow polygon.
    angle = atan2( y1 - y0, x1 - x0 )
    toCosAngle, toSinAngle = -cos(angle), -sin(angle)
    toArrowPoly = [
        (int(xp*toCosAngle - yp*toSinAngle), int(yp*toCosAngle + 
xp*toSinAngle)) for xp, yp in (
            (0,0),
            (arrowLength, arrowWidth/2),
            (arrowLength, -arrowWidth/2),
        )
    ]
    
    # Draw the arrows.
    if arrowTo:
        dc.DrawPolygon( toArrowPoly, x1, y1 )
    if arrowFrom:
        dc.DrawPolygon( [(-x,-y) for x,y in toArrowPoly], x0, y0 )
    
    # Restore the dc.
    dc.SetPen( penSave )
    dc.SetBrush( brushSave )


On Saturday, September 11, 2021 at 11:55:12 AM UTC-4 Edward Sitarski wrote:

> I realize this question was asked a long time ago.
> Sometimes you simply want to draw an arrow in a dc.
> I recently ran into this problem.  See below:
>
> from math import atan2, sin, cos, pi
> def DrawArrowLine( dc, x0, y0, x1, y1, arrowFrom=True, arrowTo=True, 
> arrowLength=16, arrowWidth=8 ):
>     '''
>         Draws a line with arrows in a regular wxPython DC.
>         The line is drawn with the dc's wx.Pen.  The arrows are filled 
> with the current Pen's colour.
>         Edward Sitarski 2021.
>     '''
>     dc.DrawLine( x0, y0, x1, y1 )
>     if x0 == x1 and y0 == y1:
>         return
>     
>     # Set up the dc for drawing the arrows.
>     penSave, brushSave = dc.GetPen(), dc.GetBrush()
>     dc.SetPen( wx.TRANSPARENT_PEN )
>     dc.SetBrush( wx.Brush(dc.GetPen().GetColour()) )
>     
>     # Compute the "to" arrow polygon.
>     angle = atan2( y1 - y0, x1 - x0 )
>     toCosAngle, toSinAngle = -cos(angle), -sin(angle)
>     toArrowPoly = [
>         (int(xp*toCosAngle - yp*toSinAngle), int(yp*toCosAngle + 
> xp*toSinAngle)) for xp, yp in (
>             (0,0),
>             (arrowLength, arrowWidth/2),
>             (arrowLength, -arrowWidth/2),
>         )
>     ]
>     
>     # Draw the arrows.
>     if arrowTo:
>         dc.DrawPolygon( toArrowPoly, x1, y1 )
>     if arrowFrom:
>         dc.DrawPolygon( [(-x,-y) for x,y in toArrowPoly], x0, y0 )
>     
>     # Restore the dc.
>     dc.SetPen( penSave )
>     dc.SetBrush( brushSave )
> On Friday, February 22, 2013 at 12:06:08 PM UTC-5 [email protected] 
> wrote:
>
>> On Thu, Feb 21, 2013 at 1:21 PM, Vlastimil Brom 
>> <[email protected]> wrote: 
>> > 2013/2/21 Shannon <[email protected]>: 
>> >> I was wondering is there any way to draw a line with an arrow, which 
>> can 
>> >> indicate the from 'point 1' point to 'point 2'. 
>>
>> > I haven't used any of these myself, but OGL and FloatCanvas come to 
>> > mind in this context; see the wxpython demo: 
>> > More windows/controls: FloatCanvas 
>>
>> Indeed -- for FloatCanvas, look at the main Demo, look at the "Arrows" 
>> demo under the "Tests" Menu - the arrows are not particularly pretty, 
>> but you could make your own DrawObject with prettier ones if you want. 
>>
>> There are also bunch more little FloatCanvas demos in SVN also: 
>>
>> http://svn.wxwidgets.org/svn/wx/wxPython/3rdParty/FloatCanvas/Demos/ 
>>
>> The VectPlot.py demo uses arrows. 
>>
>> -Chris 
>>
>>
>> -- 
>>
>> Christopher Barker, Ph.D. 
>> Oceanographer 
>>
>> Emergency Response Division 
>> NOAA/NOS/OR&R (206) 526-6959 voice 
>> 7600 Sand Point Way NE (206) 526-6329 fax 
>> Seattle, WA 98115 (206) 526-6317 main reception 
>>
>> [email protected] 
>>
>

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