[pygtk] Cairo Line Width

[Laszlo Pandy]

In Cairo, the coordinates do not refer to a particular pixel. Instead
"...integer coordinates map to points half way between sample point
locations."

http://www.cairographics.org/FAQ/#sharp_lines

Laszlo

2008/9/26 Jeffrey Drake <jeffd at techsociety.ca>:
> In my code below, I set a line width of 1 and then when I go to draw a
> grid, what appears is an antialiased line of still width of 2. I need a
> single pixel, not the ugly 2 width beast as shown before.
>
> The problem is when drawing the horizontal grid below.
>
> Any ideas on how to fix this?
>
> My original code (without the set_line_width(1) is available at
> https://launchpad.net/starz/demo1
>
>
> - Jeff.
>
>    def draw(self, context):
>        rect = self.get_allocation()
> #        x = rect.x + rect.width / 2
> #        y = rect.y + rect.height / 2
>        cx = rect.width
>        cy = rect.height
>
>        context.set_line_width(1)
>
>        # white background
>        context.set_source_rgb(1,1,1)
>        context.rectangle(0, 0, cx, cy)
>        context.fill()
>
>        context.stroke()
>
>        # no grid if no model
>        if self.model == None:
>            return
>
>        cx = self.width
>        cy = self.height
>
>        # black grid
>        context.set_source_rgb(0,0,0)
>
>        # horizontal lines
>        for i in xrange(self.model.cy+1):
>            context.move_to(0, i * 33)
>            context.line_to(cx, i * 33)
>            print i*33
>
>        for i in xrange(self.model.cx+1):
>            context.move_to(i * 33, 0)
>            context.line_to(i * 33, cy)
>
>        context.stroke()
>
>        # draw planets
>        context.set_source_rgb(0.5, 0.5, 0.5)
>
>        for x,y in self.model.map:
>            context.arc(x * 33 + 10, y * 33 + 10, 8, 0, 2 * math.pi)
>            context.fill()
>            context.stroke()
>
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