What do you think about a variant on center-crop called crop/align that accepts a width, a height, an image, and an x-place and a y-place?
That would seem to fit better into the library the way it's currently constructed. For working around the frame issue, how about just a color-frame function that controls the color for now? Robby Robby On Sat, Jun 21, 2014 at 1:42 PM, Kevin Forchione <lyss...@gmail.com> wrote: > Hi guys, > I’ve been working with 2htdp/image and been struck by its monitor-oriented > coordinate system and its image-centric perspective, both of which have > proven a rich bed for new tools. I’ve found these two functions have been > useful to me and might be useful for others. I’ve particularly found them > useful as my racket sessions use the “white on black” color schemes, and with > my eyesight a pixel’s contrast makes a difference. > > The center-crop function facilitates the image-cntric perspective of the > library by centering the cropping rectangle on the image center. The frame > function replaces the library’s existing function with one that does the same > thing, but also provides parameters for setting the pixel frame coloring, > background coloring within the frame, and x/y offsets that work with > center-crop to expand or shrink the framing of the image. > > ;; center-crop: width height image -> image? > ;; crops image in a rectangle of width x height whose center is image center. > (define (center-crop width height img) > (crop (- (quotient (image-width img) 2) (quotient width 2)) > (- (quotient (image-height img) 2) (quotient height 2)) > width > height > img)) > > ;; frame: image frame-option ... -> image? > ;; Returns an image just like image, except with a frame-color'd, single > pixel frame > ;; around the bounding box of the image. The background-color indicates the > color > ;; inside the frame over which the image is laid. If an offset is provided it > ;; indicates a center-crop in that dimension. A positive value extends the > crop > ;; beyond the image bounding box, a negative value center-crops the image > within > ;; the bounding box. > (define (frame img > #:frame-color (frame-color 'black) > #:background-color (background-color 'transparent) > #:frame-offset (frame-offset 0) > #:frame-x-offset (frame-x-offset frame-offset) > #:frame-y-offset (frame-y-offset frame-offset)) > (let ([width (+ (image-width img) frame-x-offset)] > [height (+ (image-height img) frame-y-offset)]) > (overlay (rectangle width height 'outline frame-color) > (center-crop width height img) > (rectangle width height 'solid background-color)))) > > -Kevin > _________________________ > Racket Developers list: > http://lists.racket-lang.org/dev _________________________ Racket Developers list: http://lists.racket-lang.org/dev
