CODEWITHSUNDEEP
bitmapracket
Bryan Abrams
Bryan Abrams

Reputation: 337

Drawing Context and Bitmap

I've been trying to make a user application for drawing tileset bitmaps, so something a bit like this (multiple layers of fg color/alpha, bg color/alpha, and characters):

enter image description here

Creating the bitmap isn't a problem, but now I'm at the part where I'd like to edit and make modifications to it. I'm satisifed with the bitmap output but I notice if I've already printed a bitmap once I can no longer make changes to it

enter image description here

I've already checked the documentation for bitmap%, bitmap-dc%, and dc% but I couldn't find any information if this is intentional. Am I missing a step inbetween?

Update: I notice that if I copy the bitmap to another bitmap after drawing than the changes will visible in the new bitmap but the old one doesn't

enter image description here

Here is the sample code

#lang racket

(require racket/draw)

(define bmp1 (make-bitmap 128 128))
(define bdc1 (new bitmap-dc% [bitmap bmp1]))
(send bdc1 set-pen "yellow" 1 'solid)
(send bdc1 set-brush "black" 'solid)
(send bdc1 draw-rectangle 0 0 128 128)
(send bdc1 draw-rectangle 0 0 64 64)
(send bdc1 draw-line 0 0 128 128)
bmp1
(send bdc1 set-pen "red" 4 'solid)
(send bdc1 draw-line 128 0 0 128)
bmp1

(define bmp2 (make-bitmap 128 128))
(define bdc2 (new bitmap-dc% [bitmap bmp2]))
(define d (send bdc2 draw-bitmap bmp1 0 0))
bmp2
bmp1

Upvotes: 4

Views: 306

Answers (1)

soegaard
soegaard

Reputation: 31145

I am 90% sure that you are seeing the results of a bug in DrRacket. And I am almost sure that the bug has been fixed already.

https://www.cs.utah.edu/plt/snapshots/

Can I talk you into installing the development version from the above link?

The bug in question: https://github.com/racket/drracket/commit/2d3205571cb4d1d38335c4bac84810e72777c769

Upvotes: 1

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