Thanks. Yes, they want to (say) draw a solid green circle next to the name of someone who has been active in the last five minutes. As I understand it, they followed the GUI Toolkit intro and arrived at the point where they have a canvas% with the on-paint method specified in its constructor. The on-paint method then needs to draw the green circle. They are familiar with (circle 20 "solid" "green"), so they just want to do the equivalent of (place-image green-circle x y ?dc?).
I think the image->bitmap function Alexander provided looks like what they need, and then they can use the draw-bitmap message. I didn't know how to pull the functions from different packages to make them usable one file. Thanks for the help. Andrew Andrew Mauer-Oats Mathematics Ph.D. Chicago Public Schools: Whitney Young On Thu, Mar 19, 2015 at 8:15 PM, Alexander D. Knauth <alexan...@knauth.org> wrote: > Here’s one way, if you mean a bitmap% object: > > #lang racket/base > > (provide image->bitmap) > > (require racket/class > (only-in racket/draw make-bitmap bitmap-dc%) > (only-in 2htdp/image image-width image-height) > (only-in mrlib/image-core render-image)) > > (define (image->bitmap image) > (let* ([width (image-width image)] > [height (image-height image)] > [bm (make-bitmap width height)] > [dc (make-object bitmap-dc% bm)]) > (send dc clear) > (render-image image dc 0 0) > bm)) > > > On Mar 19, 2015, at 7:05 PM, Robby Findler <ro...@eecs.northwestern.edu> > wrote: > > > When you say "bitmap" do you mean "bitmap% object"? And if so, why do > > they want to do that? If not, do you mean something else? > > > > Robby > > > > > > On Thu, Mar 19, 2015 at 5:24 PM, Andrew Mauer-Oats <mauero...@gmail.com> > wrote: > >> Is there a public way to change an image created using the 2htdp/image > >> library into a bitmap? > >> > >> My students are used to those functions and it would be easier for some > of > >> them to go and build the GUI they want if they didn't have to change > over to > >> explicitly using drawing contexts. > >> > >> I have looked at the source for mrlib/image-core, > 2htdp/private/image-more, > >> and 2htdp/image. It looks like no exported functions can change an > image to > >> a bitmap. > >> > >> The only thing they want to do is be able to render an image onto a dc. > >> Presumably the render-image function would do that, were it exported. > >> > >> What should I do? > >> > >> Thanks for your help, > >> > >> Andrew Mauer-Oats > >> Mathematics Ph.D. > >> Chicago Public Schools: Whitney Young > >> > >> ____________________ > >> Racket Users list: > >> http://lists.racket-lang.org/users > >> > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > >
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