Legend icons - extra pixel in bottom-right corner
This was reported on the maplab-users list.
I think I have noticed this problem too before. We should investigate this at
some point, maybe a GD issue?
Peter.Bruton@ccrs.nrcan.gc.ca wrote:
>
> Hello;
>
> For some reason when I classify polygons, the class symbol in the legend has
> an extra pixel located in the bottom right-hand side of the symbol/image
> (see attached file). When I set the Class's Outline colour, the extra pixel
> does not appear. I am using the HTML legend.
>
> Does anyone know why this occurs and how to get rid of it?
>
> Thanks in advance.
>
> Peter Bruton
>
Fred Warnock wrote:
>
> Peter,
>
> I took a closer look at those two symbols, and I assume you set the
> symbol size to 20x10. It's not that the one with no outline has a tail,
> it seems that there is a white line at the bottom of the icon covering
> all but the rightmost pixel.
>
> I'm not sure what the problem is, but one of the developers is sure to
> read this ;)
>
Change History
(5)
| Resolution: |
→ fixed
|
| Status: |
assigned → closed
|
It's a problem in the polygon fill code. That code is real old. Last modification I know of was to address performance. Can't recall who made the changes. I'll check CVS. Anyway the problem is on the last scanline for regularly shaped polygons. Consider the output below that you get when rendering a rectangle as defined in maplegend.c. Scanline 16 *should* run from 5 to 22 but doesn't for some reason. Instead only the last pixel in that line gets colored, hence the seemingly extra pixel. In reality that's the only one in the row that's correct. Now what's interesting is that the last line of the output has x2<x1 which screws up the scanline writing function. If those values were reversed then all would be well since the missing pixels would then be filled in. I don't want to just fix the scanline function to order x1 and x2 correctly just yet since there would be a bit of a performance hit (not much though). Instead I'll check the fill code to see why x1 isn't always less than x2. More soon... Shape contains 1 parts. Part 0 contains 5 points. 0: (5.000000, 5.000000) 1: (22.000000, 5.000000) 2: (22.000000, 16.000000) 3: (5.000000, 16.000000) 4: (5.000000, 5.000000) scanline y=5, x1=5, x2=5 scanline y=6, x1=5, x2=22 scanline y=7, x1=5, x2=22 scanline y=8, x1=5, x2=22 scanline y=9, x1=5, x2=22 scanline y=10, x1=5, x2=22 scanline y=11, x1=5, x2=22 scanline y=12, x1=5, x2=22 scanline y=13, x1=5, x2=22 scanline y=14, x1=5, x2=22 scanline y=15, x1=5, x2=22 scanline y=16, x1=22, x2=22 scanline y=5, x1=5, x2=5 scanline y=5, x1=5, x2=22 scanline y=16, x1=22, x2=5