At Thu, 6 Oct 2011 08:31:39 -0400, Sam Tobin-Hochstadt wrote: > On Thu, Oct 6, 2011 at 8:16 AM, Paulo J. Matos <[email protected]> wrote: > > On 05/10/11 15:26, Stephen Bloch wrote: > >>> > >>> I am wondering if there's anything in place already to create an image > >>> thumbnail. This is basically resizing an image. > >> > >> In the student graphics libraries (2htdp/image and picturing-programs, > >> which is derived from 2htdp/image), you can use "scale" to scale an image > >> up > >> or down by a specified ratio. For that matter, if you want to scale the x > >> and y dimensions differently, you can use "scale/xy". I believe this is a > >> constant-time operation; the number-crunching comes later, when you render > >> it to a bitmap for display on the screen or saving to a PNG file. > >> > >> > > > > Thanks, I can't seem find a way to open image files (jpeg, png, bmp, etc). > > Is there anything like that in Racket currently? Or do we need ffi to > > libjpeg, libpng, etc.? > > See the various options to `load-bitmap' here: > > http://docs.racket-lang.org/draw/bitmap_.html?q=png#%28meth._%28%28%28lib._rack > et/draw..rkt%29._bitmap~25%29._load-file%29%29
With `2htdp/image', though, probably you just want `bitmap': http://docs.racket-lang.org/teachpack/2htdpimage.html?q=bitmap#(form._((lib._2htdp/image..rkt)._bitmap)) And then `save-bitmap' to write an image to a PNG file: http://docs.racket-lang.org/teachpack/2htdpimage.html?q=save-image&q=bitmap#(def._((lib._2htdp/image..rkt)._save-image)) _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
