Lines with width 0 are not drawn

[vadz]

The lines screen in the drawing samples shows that the lines with 0 width are not drawn at all.

[alexpana]

This is intentional. If the width is 0, why should there be a line drawn? It is also the implicit behavior of Direct2D.

[vadz]

Width 0 means "use physical pen" for GDI, i.e. it always draws a line one pixel wide independently of the current scaling etc. If this is too difficult to implement with D2D, it should at least be the same as using width 1.

[alexpana]

Thanks for the explanation. Is this behavior consistent across platforms? In any case, I'll have a look at how to achieve the same effect in Direct2D.

[csomor]

yes, actually in graphics.cpp on OSX I fix it at 0.1 pt:
wxMacCoreGraphicsPenData::wxMacCoreGraphicsPenData( wxGraphicsRenderer* renderer, const wxPen& pen) I do
m_width = pen.GetWidth();
if (m_width <= 0.0)
m_width = (CGFloat) 0.1;

[alexpana]

But is that independent of scaling? If I use x20 scaling (x & y), wouldn't it draw a 2 pixel width line?

[csomor]

actually that's what I inteded, to have a 'fine line' the convention for dc was a pen with width 0,eg like in a technical drawing, so if things are scaled 20x having a 2pt is fine IMHO