Re: [gef-dev] Why is converting from double to int done using the Math.f

[Alexander Nyßen <alexander.nyssen@xxxxxxxxx>]

Hi Jan,

you are right, what you are facing here is one of the several inconsistencies within the current Draw2d geometry API, and one of the reasons we started to build a new one in GEF4. You would actually have to switch to integer-based precision when performing the calculation of the drawing position (i.e. y = line.y() - rect.height()) for the rectangle. I agree that in general rounding would probably lead to better results, so that's what we will do when rendering GEF4 geometries (which are completely based on double-precision) within a GEF4 Graphics.

Cheers

Alexander

Am 17.04.2013 um 12:16 schrieb Jan Krakora <jan.krakora.cz@xxxxxxxxx>:

Hi all,

since the GEF forum is basically dead I would like to ask you here. Why is used Math.floor in all Precision* classes?

Let me give you an example:

First of all, I use PrecisionPoint, PrecisionRectangle, PrecisionDimension everywhere.

So there is a line with y coordinate 31.14. You have a rectangle with height 18.315 that you would like to draw exactly above the line
so its bottom edge overlaps the line. But since the converting from double to int is done using Math.floor the coordinates
are as such:

the line:
   y: 31.14 -> 31
the rectangle
   y: 31.14 - 18.315 =  12.825 -> 12
   height: 18.315 -> 18

As you can see the rectangle will be rendered above the line. They don't overlap. Why aren't double coordinates rounded?
Do I compute the y of the rectangle in wrong way?

Thanks, Jan Krakora.
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