Scheme Slides 101 by Paulo Jorge Matos May 4th,

Transcription

1 Scheme Slides 101 by Paulo Jorge Matos May 4th,

2 Scheme Slides 101 by Paulo Jorge Matos May 4th, Welcome my -friends... Let's get it started! 2

3 Welcome What's the fuss all about? Slideshows as Scheme programs! The result of your program is a slideshow. 3

4 Welcome But... I'll not talk about presention design or Scheme 4

5 Slideshow is a module (module presentation (lib "slideshow.ss" "slideshow") (slide (t "Hello World!"))) This would result in... 5

6 Hello World! 6

7 Relatives... There are some more functions: (slide/title...) (slide/title/tall...) (slide/title/center...) (slide/center...) etc... These are all functions which generate slides as a side-effect. Slides with special properties (title, centered text, etc) 7

8 & Languages Slideshows are inside module declarations. (module <name> (lib "slideshow.ss" "slideshow") <slides>) In DrScheme, if you run the module inside the module language, you'll trigger the slideshow to start! Problems: DrScheme takes time to load. issues might come up.... might scare your audience even before the presentation starts! Still, it is good for testing! 8

9 What's pict? pict is a structure representing a picture! (defined in texpict.ss) (define-struct pict (draw width height ascent descent children panbox)) (define-struct child (pict dx dy sx sy)) Ascent and descent are useful for textlines. 9

10 directly from the REPL Blank picts (blank) Lines ([h v]line, dash-[h v]line) Text Strings (text) Image Loading (bitmap) I love lambda! (transparency just works!) Geometric Shapes (circle, ellipse, rectangle, etc) 10

11 So... Let your imagination flow... And compose them! 11

12 Pict Composition and Modification Frame Creation Pict Appending Pict Superimposition 12

13 Pict Composition and Modification Pict Insets Let's just review carefully! 13

14 Appending picts We can append picts horizontally of vertically and also along their base lines. The first letters of the function say it all. (dp-append [d 0] pict...) d = {h, v} specifies horizontal or vertical. p = {l, c, r} for vertical, specifies left, center, right. p = {t, c, b} for top, center, bottom. And we still have htl-append and hbl-append to align bottom of ascents and top of descents. 14

15 Appending examples ht-append: vl-append: hc-append: vr-append: 15

16 Pict Superimposition Superimposes picts onto one another based on bounding box references. (dp-superimpose pict...) Now, d = {l, r, c}, for left, right, center. and, p = {t, b, c, tl, bl}, for top, bottom, center, bottom of ascents, and bottom of descents. 16

17 Superimposition examples cc-superimpose: lt-superimpose: rt-superimpose: cb-superimpose: 17

18 Pict Inset Insets are powerful in combination with superimposes and appending. But still, they only extend pict margins! More on this later! 18

19 LaTeX works! One of the initial problems I had was with Math content but... We are in Scheme, remember! So I just developed a plugin which renders LaTeX. 10 minutes later, about 20 loc... 19

20 And here it is... As large as you want! Soon in my webpage. Want it now? Contact me! 20

21 Types Two animation types: Scroll s Object s Both handled by scroll-transition 21

22 Scroll s You can use: (scroll-transition x y w h dx dy [secs steps-k]) With: (scroll-transition ) You scroll from here... 22

23 Scroll s to here... 23

24 Object s You can also move objects around! But there are problems with the way this works... 24

25 Back to the beginning! Facts: We are using Scheme! We can access Scheme libraries Or even the FFI for that matter. We can make programmable slides This is where the power lies! 25

26 Programmable Slides (module hello-world (lib "slideshow.ss" "slideshow") (define (make-slide-n n) (slide/title "How to Generalize Slides" (page-item "This is slide number" (number->string n)))) (make-slide-n 1) (make-slide-n 2) (make-slide-n 3)) Runs the slideshow: 26

27 How to Generalize Slides This is slide number 1 27

28 How to Generalize Slides This is slide number 2 28

29 How to Generalize Slides This is slide number 3 29

30 Nice application: Algorithm Explanation We can explain algorithms through the use of stepping through slides and nodes. Let me explain you what you, obviously, already know... DFS on a tree:

31 Tree Definition Tree structure are lists: '("1" ("2" ("4") ("5")) ("3" ("6") ("7"))) Making tree nodes: (define (make-node name) (let ([name-pict (t name)]) (cc-superimpose name-pict (circle (+ 10 (max (pict-height name-pict) (pict-width name-pict))))))) Make tree with picts instead of strings: (define (make-node-picts tree) (if (null? tree) null (cons (make-node (car tree)) (map make-node-picts (cdr tree))))) Have you tried to interact with DrScheme by using this function. Uh, it's nice! 31

32 Tree transversal (define (make-tree-pict tree node-sep level-sep) (letrec ([ext-bfs (lambda (lst) (if (null? lst) null (cons (s1:filter (lambda (e) (not (list? e))) lst) (ext-bfs (apply append (s1:filter list? lst))))))]) (let ([sep-node-pict (blank node-sep 1)] [sep-level-pict (blank 1 level-sep)]) (apply vc-append (interpose (map (lambda (lev) (apply hc-append (interpose lev sep-node-pict)) (ext-bfs tree)) sep-level-pict))))) interpose intercalates each element on a list with another one. 32

33 Node Connection and find! We haven't mentioned the powerful find. It's easier to understand who it works with example. (define (connect tree node1 node2) (pin-arrow-line 5 tree node1 cb-find node2 ct-find)) 33

34 Tree List Generation Generates a list of picts for slide showing: (define (make-all-dfs-picts tree node-sep level-sep) (let* ([node-picts (make-node-picts tree)] [tree-pict (make-tree-pict node-picts node-sep level-sep)] [anim-picts (list tree-pict)]) (let loop ([t node-picts]) (for-each (lambda (child) (set! anim-picts (cons (connect (car anim-picts) (car t) (car child)) anim-picts)) (loop child)) (cdr t)) (reverse anim-picts)))) 34

35 The slideshow Now a simple slideshow can be generated: (define (dfs-slideshow tree node-sep level-sep) (let ([picts (make-all-dfs-picts tree node-sep level-sep)]) (slide/title/center "DFS Demo" 'ALTS (map list picts)))) When run we get: 35

36 DFS Demo

37 DFS Demo

38 DFS Demo

39 DFS Demo

40 DFS Demo

41 DFS Demo

42 DFS Demo

43 How is assembling done? Slide assembling is done through parameter current-slide-assembler This is a function which receives a title, a separator and a pict with the slide content. Slides are by default 1024x768. If resolution is different, everything gets scaled. Here's how to include a background for example (parameter for this cover) (define 1stbg (bitmap "./1stslide.png")) (current-slide-assembler (lambda (title sep content) (cc-superimpose full-page 1stbg content))) 43

44 Slide design Most of slide design occurs here. You can have higher-level assemblers, but still the last one is the defined by current-slide-assembler Most of the problem lies in your imagination, after that is pict management and scheme programming! 44

45 The slideshow executable The fact that you can access all of PLT-Scheme during slideshow raises security issues. File Deletion, Net access, etc. So, for slideshow distribution, it is best to run the slideshow through the slideshow executable. It won't let you access problematic functions unless you enable the --trust flag. It also has other goodies like timing your slideshows pratice, exporting to postscript, seeing comments or previews. 45

46 Slideshow design Slideshow design with picts requires practice. It's not point and click but it is much more powerful. Since slideshows will be 1024x768, make sure you change your PC resolution before presentation. Preview slideshow with 1024x768, by setting flag "-s ". For nice backgrounds, since PLT-Scheme doesn't support opacity yet, use inkscape for background design. Support for png export, vector graphics design, etc. 46

47 Working with picts Remember you're inside PLT-Scheme so you can have higher-level slide generating functions. For example, this presentation does not use slide/title standard functions. Defines a sslide function which gets the content of the slide and automaticly includes a subtitle and the left side menu. Only then calls the standard functions. 47

48 Practice, practice, practice Generating simple slides is really simple, harder slides are more complex but the result is rewarding. Abstractions for one slideshow can easily be reused for the next. 48

49 So, why Scheme? Easy to define abstractions. Easy to design nice slides and reuse them. For the portability freaks, runs on all PLT-Scheme supported archs (Linux, Mac, Win..., hey, it's in alphabetic order... NO FIGHTS!) Even exports for PS, which can then be converted to PDF. Excellent support from the PLT libraries. 49

50 But why? It's Scheme!!! Ah, now I understand! 50

51 So, I know it all? NO! Reactive slideshows with cdrswift A lot more functions on slides and picts. Knowing MrEd helps for font management, color management, etc. And, Practice makes perfect! 51

52 Can I peak? The End Continue with caution... 52