Re: [racket-users] Image Transparency Detection

2016-09-09 Thread Matthew Flatt
I don't think there's currently a way to make a loaded bitmap have an alpha channel only if the source stream has one. You could use 'unknown/mask, which should create a mask bitmap only if the source stream has an alpha channel, but at the expense of parsing the file an extra time. At Fri, 9 Sep

[racket-users] Image Transparency Detection

2016-09-09 Thread Lehi Toskin
Is there a way to detect if an image has a transparency/alpha channel? I've been looking around and `(send bmp has-alpha-channel?)` really only works if `bmp` has been loaded or created specifically with an alpha channel. What I want to know is if a given path-string has such properties, not if

RE: [racket-users] typed racket confusion

2016-09-09 Thread Jos Koot
Thanks, I already had a hunch in the direction of your answer. In function b the problem seems to be that subexpression (if (even? n) add1 sub1) seems to be reduced without info to which the argument it will be applied. Nevertheless I wonder whether or not it would be possible to have the typecheck

Re: [racket-users] typed racket confusion

2016-09-09 Thread WarGrey Gyoudmon Ju
Because in function `b`, the type of the `lambda` that `n` actually be passed to is the union of `add1` and `sub1` in the context, hence, the info on parity of `n` are lost before this `lambda` is evaluated. On Sat, Sep 10, 2016 at 3:42 AM, Jos Koot wrote: > #lang typed/racket > > (define (a (n

[racket-users] typed racket confusion

2016-09-09 Thread Jos Koot
#lang typed/racket (define (a (n : Exact-Nonnegative-Integer)) : Exact-Nonnegative-Integer (if (even? n) (add1 n) (sub1 n))) (define (b (n : Exact-Nonnegative-Integer)) : Exact-Nonnegative-Integer ((if (even? n) add1 sub1) n)) Function a goes well, but function b gives an error during expansio

Re: [racket-users] SVG as pict

2016-09-09 Thread Byron Davies
Yes, that does exactly what I needed — a fully scalable svg pict. Thank you! And the other discussants. Byron > On Sep 3, 2016, at 6:29 PM, Asumu Takikawa wrote: > > On 2016-09-03 20:53:59 +0200, Jens Axel Søgaard wrote: >> I took a quick look at the code of rsvg. It seems svg-bytes->pict does

Re: [racket-users] Re: List-box% using percentages to resize multiple columns

2016-09-09 Thread Erich Rast
You are right. I've checked it and it was a simple case of arguments switched - 120 pixel min-width was inadvertently switched for 20%. It works fine now, and on-size seems to be the right place for calculation, too. Thanks! Best, Erich On Thu, 8 Sep 2016 17:56:38 -0700 (PDT) Alex Harsanyi w