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Overview
Comment:more tests and improvements on cairo
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SHA1: 6ea4d2df39e2ea26795d1932e887cc14fd953566
User & Date: ovenpasta@pizzahack.eu 2016-07-24 21:23:10
Context
2016-07-24
21:24
add romeladen.png for cairo tests check-in: 647578553e user: ovenpasta@pizzahack.eu tags: trunk
21:23
more tests and improvements on cairo check-in: 6ea4d2df39 user: ovenpasta@pizzahack.eu tags: trunk
2016-07-23
07:46
cairo improvements, added some tests check-in: ecd5997790 user: ovenpasta@pizzahack.eu tags: trunk
Changes
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Changes to cairo-test.scm.

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(import (cairo))

(cairo-library-init)


(define (test-cairo name proc) 
  (let* ([surface (cairo-image-surface-create (cairo-format 'argb-32) 120 120)]
	 [cr (cairo-create surface)])
    (cairo-scale cr 120. 120.)
    (proc surface cr)
    (cairo-surface-write-to-png surface (string-append name ".png"))))









(test-cairo "stroke"
	    (lambda (surface cr)
	      (cairo-set-line-width cr 0.1)
	      (cairo-set-source-rgb cr 0. 0. 0.)
	      (cairo-rectangle cr 0.25 0.25 0.25 0.25)
	      (cairo-stroke cr)))

(test-cairo "showtext"
	    (lambda (surface cr)
	      (cairo-scale cr 120. 120.)
	      (cairo-set-source-rgb cr 0. 0. 0.)
	      (cairo-select-font-face cr "Georgia" (cairo-font-slant 'normal) (cairo-font-weight 'bold))
	      (cairo-set-font-size cr 1.2)
	      (let ([extents (cairo-text-extents-create)])	
		(cairo-text-extents cr "a" extents)
		(cairo-move-to cr 
			       (- 0.5 (/ (ftype-ref cairo-text-extents-t (width) extents) 2) (ftype-ref cairo-text-extents-t (x-bearing) extents))
................................................................................

		(cairo-rectangle cr 0.0 0.0 1. 1.)
		(cairo-set-source cr linpat)
		(cairo-fill cr))))

(test-cairo "tips-ellipse" 
	    (lambda (surface cr)
	      (define pi 3.1415926536)
	      (cairo-set-line-width cr 0.1)
	      
	      (cairo-save cr)
	      (cairo-scale cr 0.5 1.)
	      (cairo-arc cr 0.5 0.5 0.40 0. (* 2. pi))
	      (cairo-stroke cr)
	      
	      (cairo-translate cr 1. 0.)
	      (cairo-arc cr 0.5 0.5 0.40 0. (* 2. pi))
	      (cairo-restore cr)
	      (cairo-stroke cr)))

















































































































































































































































































































































































































































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(import (cairo))

(cairo-library-init)
(define pi 3.1415926536)

(define (test-cairo name proc) 
  (let* ([surface (cairo-image-surface-create (cairo-format 'argb-32) 120 120)]
	 [cr (cairo-create surface)])
    (cairo-scale cr 120. 120.)
    (proc surface cr)
    (cairo-surface-write-to-png surface (string-append name ".png"))))

(define (sample-cairo name proc) 
  (let* ([surface (cairo-image-surface-create (cairo-format 'argb-32) 256 256)]
	 [cr (cairo-create surface)])
    (proc surface cr)
    (cairo-surface-write-to-png surface (string-append name ".png"))))

;; FROM https://www.cairographics.org/tutorial/

(test-cairo "stroke"
	    (lambda (surface cr)
	      (cairo-set-line-width cr 0.1)
	      (cairo-set-source-rgb cr 0. 0. 0.)
	      (cairo-rectangle cr 0.25 0.25 0.25 0.25)
	      (cairo-stroke cr)))

(test-cairo "showtext"
	    (lambda (surface cr)

	      (cairo-set-source-rgb cr 0. 0. 0.)
	      (cairo-select-font-face cr "Georgia" (cairo-font-slant 'normal) (cairo-font-weight 'bold))
	      (cairo-set-font-size cr 1.2)
	      (let ([extents (cairo-text-extents-create)])	
		(cairo-text-extents cr "a" extents)
		(cairo-move-to cr 
			       (- 0.5 (/ (ftype-ref cairo-text-extents-t (width) extents) 2) (ftype-ref cairo-text-extents-t (x-bearing) extents))
................................................................................

		(cairo-rectangle cr 0.0 0.0 1. 1.)
		(cairo-set-source cr linpat)
		(cairo-fill cr))))

(test-cairo "tips-ellipse" 
	    (lambda (surface cr)

	      (cairo-set-line-width cr 0.1)
	      
	      (cairo-save cr)
	      (cairo-scale cr 0.5 1.)
	      (cairo-arc cr 0.5 0.5 0.40 0. (* 2. pi))
	      (cairo-stroke cr)
	      
	      (cairo-translate cr 1. 0.)
	      (cairo-arc cr 0.5 0.5 0.40 0. (* 2. pi))
	      (cairo-restore cr)
	      (cairo-stroke cr)))



;; FROM https://www.cairographics.org/samples/

(sample-cairo "arc" 
	    (lambda (surface cr)
	      (let ([xc 128.] [yc 128.] [radius 100.] 
		    [angle1 (* 45. (/ pi 180.))] [angle2 (* 180. (/ pi 180.))])
		(cairo-set-line-width cr 10.0)
		(cairo-arc cr xc yc radius angle1 angle2)
		(cairo-stroke cr)

		;;/* draw helping lines */
		(cairo-set-source-rgba cr 1. 0.2 0.2 0.6)
		(cairo-set-line-width cr 6.0)

		(cairo-arc cr xc yc 10.0 0. (* 2 pi))
		(cairo-fill cr)
		
		(cairo-arc cr xc yc radius angle1 angle1)
		(cairo-line-to cr xc yc)
		(cairo-arc cr xc yc radius angle2 angle2)
		(cairo-line-to cr xc yc)
		(cairo-stroke cr))))
		
(sample-cairo "arc-negative" 
	    (lambda (surface cr)
	      (let ([xc 128.] [yc 128.] [radius 100.] 
		    [angle1 (* 45. (/ pi 180.))] [angle2 (* 180. (/ pi 180.))])
		(cairo-set-line-width cr 10.0)
		(cairo-arc-negative cr xc yc radius angle1 angle2)
		(cairo-stroke cr)

		;;/* draw helping lines */
		(cairo-set-source-rgba cr 1. 0.2 0.2 0.6)
		(cairo-set-line-width cr 6.0)

		(cairo-arc cr xc yc 10.0 0. (* 2 pi))
		(cairo-fill cr)
		
		(cairo-arc cr xc yc radius angle1 angle1)
		(cairo-line-to cr xc yc)
		(cairo-arc cr xc yc radius angle2 angle2)
		(cairo-line-to cr xc yc)
		(cairo-stroke cr))))
		

(sample-cairo "clip" 
	    (lambda (surface cr)
	      (cairo-arc cr 128.0 128.0 76.8 0. (* 2. pi))
	      (cairo-clip cr)

	      (cairo-new-path cr)       ;  /* current path is not
			         	;     consumed by (cairo-clip() */
	      (cairo-rectangle cr 0. 0. 256. 256.)
	      (cairo-fill cr)
	      (cairo-set-source-rgb cr 0. 1. 0.)
	      (cairo-move-to cr 0. 0.)
	      (cairo-line-to cr 256. 256.)
	      (cairo-move-to cr 256. 0.)
	      (cairo-line-to cr 0. 256.)
	      (cairo-set-line-width cr 10.0)
	      (cairo-stroke cr)))

(sample-cairo "clip-image"
	      (lambda (surface cr)
		(cairo-arc cr 128.0 128.0 76.8 0. (* 2 pi))
		(cairo-clip cr)
		(cairo-new-path cr); /* path not consumed by clip()*/

		(let* ([image (cairo-image-surface-create-from-png "romedalen.png")]
		       [w (cairo-image-surface-get-width image)]
		       [h (cairo-image-surface-get-height image)])

		  (cairo-scale cr (/ 256.0 w) (/ 256.0 h))
		  (cairo-set-source-surface cr image 0. 0.)
		  (cairo-paint cr))))

(sample-cairo "curve-rectangle"
	      (lambda (surface cr)
		; a custom shape that could be wrapped in a function
		(let* ([x0 25.6] ;   parameters like cairo_rectangle 
		       [y0 25.6]
		       [rect-width 204.8]
		       [rect-height 204.8]
		       [radius  102.4] ;   and an approximate curvature radius 
		       
		       [x1 (+ x0 rect-width)]
		       [y1 (+ y0 rect-height)])
		  ;; WHAT IS THIS?
		  ;;if (!rect_width || !rect_height)
		  ;;return;

		  (cond [(< (/ rect-width 2) radius) 
			 (cond [(< (/ rect-height 2) radius)
				(cairo-move-to  cr x0 (/ (+ y0 y1) 2))
				(cairo-curve-to cr x0 y0 x0 y0 (/ (+ x0 x1) 2) y0)
				(cairo-curve-to cr x1 y0 x1 y0 x1 (/ (+ y0 y1) 2))
				(cairo-curve-to cr x1 y1 x1 y1 (/ (+ x1 x0) 2) y1)
				(cairo-curve-to cr x0 y1 x0 y1 x0 (/ (+ y0 y1) 2))]
			       [else
				(cairo-move-to  cr x0 (+ y0 radius))
				(cairo-curve-to cr x0 y0 x0 y0 (/ (+ x0 x1) 2) y0)
				(cairo-curve-to cr x1 y0 x1 y0 x1 (+ y0 radius))
				(cairo-line-to cr x1  y1 - radius)
				(cairo-curve-to cr x1 y1 x1 y1 (/ (+ x1 x0) 2) y1)
				(cairo-curve-to cr x0 y1 x0 y1 x0 (- y1 radius))])]
			[else
			 (cond  [(< (/ rect-height 2) radius)
				 (cairo-move-to  cr x0 (/ (+ y0 y1) 2))
				 (cairo-curve-to cr x0  y0 x0  y0 (+ x0 radius) y0)
				 (cairo-line-to cr (- x1 radius) y0)
				 (cairo-curve-to cr x1 y0 x1 y0 x1 (/ (+ y0 y1) 2))
				 (cairo-curve-to cr x1 y1 x1 y1 (- x1 radius) y1)
				 (cairo-line-to cr (+ x0 radius) y1)
				 (cairo-curve-to cr x0 y1 x0 y1 x0 (/ (+ y0 y1) 2))]
				[else
				 (cairo-move-to  cr x0 (+ y0 radius))
				 (cairo-curve-to cr x0  y0 x0  y0 (+ x0 radius) y0)
				 (cairo-line-to cr (- x1 radius) y0)
				 (cairo-curve-to cr x1 y0 x1 y0 x1 (+ y0 radius))
				 (cairo-line-to cr x1  (- y1 radius))
				 (cairo-curve-to cr x1 y1 x1 y1 (- x1 radius) y1)
				 (cairo-line-to cr (+ x0 radius) y1)
				 (cairo-curve-to cr x0 y1 x0 y1 x0 (- y1 radius))])])

			 (cairo-close-path cr)
			 (cairo-set-source-rgb cr 0.5 0.5 1.)
			 (cairo-fill-preserve cr)
			 (cairo-set-source-rgba cr 0.5 0. 0. 0.5)
			 (cairo-set-line-width cr 10.0)
			 (cairo-stroke cr))))

(sample-cairo "curve-to"
	      (lambda (surface cr)
		(let ([x 25.6] [y 128.0]
		      [x1 102.4] [y1 230.4]
		      [x2 153.6] [y2 25.6]
		      [x3 230.4] [y3 128.0])

		  (cairo-move-to cr x y)
		  (cairo-curve-to cr x1 y1 x2 y2 x3 y3)
		  
		  (cairo-set-line-width cr 10.0)
		  (cairo-stroke cr)
		  
		  (cairo-set-source-rgba cr 1. 0.2 0.2 0.6)
		  (cairo-set-line-width cr 6.0)
		  (cairo-move-to cr x y)   (cairo-line-to cr x1 y1)
		  (cairo-move-to cr x2 y2) (cairo-line-to cr x3 y3)
		  (cairo-stroke cr))))


(sample-cairo "dash"
	      (lambda (surface cr)
		(let ([dashes '#(50.0    ; ink 
				 10.0    ; skip
				 10.0    ; ink 
				 10.0)]  ; skip
		      [offset -50.])
	       
		  (cairo-set-dash cr dashes (vector-length dashes) offset)
		  (cairo-set-line-width cr 10.0)

		  (cairo-move-to cr 128.0 25.6)
		  (cairo-line-to cr 230.4 230.4)
		  (cairo-rel-line-to cr -102.4 0.0)
		  (cairo-curve-to cr 51.2 230.4 51.2 128.0 128.0 128.0)

		  (cairo-stroke cr))))


(sample-cairo "fill-and-stroke2"
	      (lambda (surface cr)
		(cairo-move-to cr 128.0 25.6)
		(cairo-line-to cr 230.4 230.4)
		(cairo-rel-line-to cr -102.4 0.0)
		(cairo-curve-to cr 51.2 230.4 51.2 128.0 128.0 128.0)
		(cairo-close-path cr)
		
		(cairo-move-to cr 64.0 25.6)
		(cairo-rel-line-to cr 51.2 51.2)
		(cairo-rel-line-to cr -51.2 51.2)
		(cairo-rel-line-to cr -51.2 -51.2)
		(cairo-close-path cr)
		
		(cairo-set-line-width cr 10.0)
		(cairo-set-source-rgb cr 0. 0. 1.)
		(cairo-fill-preserve cr)
		(cairo-set-source-rgb cr 0. 0. 0.)
		(cairo-stroke cr)))

(sample-cairo "fill style"
	      (lambda (surface cr)
		
		(cairo-set-line-width cr 6.)
		
		(cairo-rectangle cr 12. 12. 232. 70.)
		(cairo-new-sub-path cr) (cairo-arc cr 64. 64. 40. 0. (* 2 pi))
		(cairo-new-sub-path cr) (cairo-arc-negative cr 192. 64. 40. 0. (* -2 pi))

		(cairo-set-fill-rule cr (cairo-fill-rule 'even-odd))
		(cairo-set-source-rgb cr 0. 0.7 0.) (cairo-fill-preserve cr)
		(cairo-set-source-rgb cr 0. 0. 0.) (cairo-stroke cr)

		(cairo-translate cr 0. 128.)
		(cairo-rectangle cr 12. 12. 232. 70.)
		(cairo-new-sub-path cr) (cairo-arc cr 64. 64. 40. 0. (* 2 pi))
		(cairo-new-sub-path cr) (cairo-arc-negative cr 192. 64. 40. 0. (* -2 pi))

		(cairo-set-fill-rule cr (cairo-fill-rule 'winding))
		(cairo-set-source-rgb cr 0. 0. 0.9) (cairo-fill-preserve cr)
		(cairo-set-source-rgb cr 0. 0. 0.) (cairo-stroke cr)))

(sample-cairo "gradient"
	      (lambda (surface cr)
		(let ([pat (cairo-pattern-create-linear 0.0 0.0  0.0 256.0)])
		  (cairo-pattern-add-color-stop-rgba pat 1 0 0 0 1)
		  (cairo-pattern-add-color-stop-rgba pat 0 1 1 1 1)
		  (cairo-rectangle cr 0 0 256 256)
		  (cairo-set-source cr pat)
		  (cairo-fill cr))
		(let ([pat (cairo-pattern-create-radial 115.2 102.4 25.6 102.4  102.4 128.0)])
		  (cairo-pattern-add-color-stop-rgba pat 0 1 1 1 1)
		  (cairo-pattern-add-color-stop-rgba pat 1 0 0 0 1)
		  (cairo-set-source cr pat)
		  (cairo-arc cr 128.0 128.0 76.8 0 (* 2 pi))
		  (cairo-fill cr))))

(sample-cairo "image"
	      (lambda (surface cr)
		(let* ([image (cairo-image-surface-create-from-png "romedalen.png")]
		       [w (cairo-image-surface-get-width image)]
		       [h (cairo-image-surface-get-height image)])

		  (cairo-translate cr 128.0 128.0)
		  (cairo-rotate cr (* 45 (/ pi 180)))
		  (cairo-scale  cr (/ 256.0 w) (/ 256.0 h))
		  (cairo-translate cr (* -0.5 w) (* -0.5 h))
		  
		  (cairo-set-source-surface cr image 0 0)
		  (cairo-paint cr))))

(sample-cairo "image-pattern"
	      (lambda (surface cr)
		(let* ([image (cairo-image-surface-create-from-png "romedalen.png")]
		       [w (cairo-image-surface-get-width image)]
		       [h (cairo-image-surface-get-height image)])
		  (let ([pattern (cairo-pattern-create-for-surface image)]
			[matrix (cairo-matrix-create)])
		    (cairo-pattern-set-extend pattern (cairo-extend 'repeat))

		    (cairo-translate cr 128.0 128.0)
		    (cairo-rotate cr (/ pi 4))
		    (cairo-scale cr (/ 1 (sqrt 2)) (/ 1 (sqrt 2)))
		    (cairo-translate cr -128.0 -128.0)
		    
		    (cairo-matrix-init-scale matrix (* (/ w 256.0) 5.0) (* (/ h 256.0) 5.0))
		    (cairo-pattern-set-matrix pattern matrix)

		    (cairo-set-source cr pattern)

		    (cairo-rectangle cr 0 0 256.0 256.0)
		    (cairo-fill cr)))))


(sample-cairo "multi-segment-caps"
	      (lambda (surface cr)
		(cairo-move-to cr 50.0 75.0)
		(cairo-line-to cr 200.0 75.0)
		
		(cairo-move-to cr 50.0 125.0)
		(cairo-line-to cr 200.0 125.0)
		
		(cairo-move-to cr 50.0 175.0)
		(cairo-line-to cr 200.0 175.0)
		
		(cairo-set-line-width cr 30.0)
		(cairo-set-line-cap cr (cairo-line-cap 'round))
		(cairo-stroke cr)))

(sample-cairo "rounded-rectangle"
	      (lambda (surface cr)
		;/* a custom shape that could be wrapped in a function */
		(let* ([x 25.6] ;/* parameters like (cairo-rectangle */
		       [y 25.6]
		       [width 204.8]
		       [height 204.8]
		       [aspect 1.0] ;     /* aspect ratio */
		       [corner-radius (/ height 10.0)] ;   /* and corner curvature radius */
		       [radius (/ corner-radius aspect)]
		       [degrees (/ pi 180.0)])

		  (cairo-new-sub-path cr)
		  (cairo-arc cr (- (+ x  width) radius) (+ y radius) radius (* -90 degrees) (* 0 degrees))
		  (cairo-arc cr (- (+ x width) radius) (- (+ y height) radius) radius (* 0 degrees) (* 90 degrees))
		  (cairo-arc cr (+ x radius) (- (+ y height) radius) radius (* 90 degrees) (* 180 degrees))
		  (cairo-arc cr (+ x radius) (+ y radius) radius (* 180 degrees) (* 270 degrees))
		  (cairo-close-path cr)
		  
		  (cairo-set-source-rgb cr 0.5 0.5 1)
		  (cairo-fill-preserve cr)
		  (cairo-set-source-rgba cr 0.5 0 0 0.5)
		  (cairo-set-line-width cr 10.0)
		  (cairo-stroke cr))))

(sample-cairo "set-line-cap"
	      (lambda (surface cr)


(cairo-set-line-width cr 30.0)
(cairo-set-line-cap  cr (CAIRO-LINE-CAP-BUTT) /* default */
(cairo-move-to cr 64.0 50.0) (cairo-line-to cr 64.0 200.0)
(cairo-stroke cr)
(cairo-set-line-cap  cr (CAIRO-LINE-CAP-ROUND)
(cairo-move-to cr 128.0 50.0) (cairo-line-to cr 128.0 200.0)
(cairo-stroke cr)
(cairo-set-line-cap  cr (CAIRO-LINE-CAP-SQUARE)
(cairo-move-to cr 192.0 50.0) (cairo-line-to cr 192.0 200.0)
(cairo-stroke cr)

/* draw helping lines */
(cairo-set-source-rgb cr 1 0.2 0.2)
(cairo-set-line-width cr 2.56)
(cairo-move-to cr 64.0 50.0) (cairo-line-to cr 64.0 200.0)
(cairo-move-to cr 128.0 50.0)  (cairo-line-to cr 128.0 200.0)
(cairo-move-to cr 192.0 50.0) (cairo-line-to cr 192.0 200.0)
(cairo-stroke cr)

(sample-cairo "set-line-join"
	      (lambda (surface cr)


(cairo-set-line-width cr 40.96)
(cairo-move-to cr 76.8 84.48)
(cairo-rel-line-to cr 51.2 -51.2)
(cairo-rel-line-to cr 51.2 51.2)
(cairo-set-line-join cr (CAIRO-LINE-JOIN-MITER) /* default */
(cairo-stroke cr)

(cairo-move-to cr 76.8 161.28)
(cairo-rel-line-to cr 51.2 -51.2)
(cairo-rel-line-to cr 51.2 51.2)
(cairo-set-line-join cr (CAIRO-LINE-JOIN-BEVEL)
(cairo-stroke cr)

(cairo-move-to cr 76.8 238.08)
(cairo-rel-line-to cr 51.2 -51.2)
(cairo-rel-line-to cr 51.2 51.2)
(cairo-set-line-join cr (CAIRO-LINE-JOIN-ROUND)
(cairo-stroke cr)


(sample-cairo "text"
	      (lambda (surface cr)


(cairo-select-font-face cr "Sans" (CAIRO-FONT-SLANT-NORMAL
                               (CAIRO-FONT-WEIGHT-BOLD)
(cairo-set-font-size cr 90.0)

(cairo-move-to cr 10.0 135.0)
(cairo-show-text cr "Hello")

(cairo-move-to cr 70.0 165.0)
(cairo-text-path cr "void")
(cairo-set-source-rgb cr 0.5 0.5 1)
(cairo-fill-preserve cr)
(cairo-set-source-rgb cr 0 0 0)
(cairo-set-line-width cr 2.56)
(cairo-stroke cr)

/* draw helping lines */
(cairo-set-source-rgba cr 1 0.2 0.2 0.6)
(cairo-arc cr 10.0 135.0 5.12 0 2*M-PI)
(cairo-close-path cr)
(cairo-arc cr 70.0 165.0 5.12 0 2*M-PI)
(cairo-fill cr)



(sample-cairo "text-align-center"
	      (lambda (surface cr)
		(let ([utf8 "cairo"]
		      [extents (cairo-text-extents-create)])
		  (cairo-select-font-face cr "Sans" (cairo-font-slant 'normal) (cairo-font-weight 'normal))
		  (cairo-set-font-size cr 52.0)
		  (cairo-text-extents cr utf8 extents)
		  (let ([x (- 128.0 (+ (/ (ftype-ref cairo-text-extents-t (width) extents) 2) (ftype-ref cairo-text-extents-t (x-bearing) extents)))]
			[y (- 128.0 (+ (/ (ftype-ref cairo-text-extents-t (height) extents) 2) (ftype-ref cairo-text-extents-t (y-bearing) extents)))])
		    (cairo-move-to cr x y)
		    (cairo-show-text cr utf8)

		    ;/* draw helping lines */
		    (cairo-set-source-rgba cr 1 0.2 0.2 0.6)
		    (cairo-set-line-width cr 6.0)
		    (cairo-arc cr x y 10.0 0 (* 2 pi))
		    (cairo-fill cr)
		    (cairo-move-to cr 128.0 0)
		    (cairo-rel-line-to cr 0 256)
		    (cairo-move-to cr 0 128.0)
		    (cairo-rel-line-to cr 256 0)
		    (cairo-stroke cr)))))


(sample-cairo "text-extents"
	      (lambda (surface cr)
		(let ([utf8 "cairo"]
		      [extents (cairo-text-extents-create)]
		      [x 25] [y 150])

		  (cairo-select-font-face cr "Sans" (cairo-font-slant 'normal) (cairo-font-weight 'normal))
		  (cairo-set-font-size cr 100.0)
		  (cairo-text-extents cr utf8 extents)

		  (cairo-move-to cr x y)
		  (cairo-show-text cr utf8)

		  ;/* draw helping lines */
		  
		 (cairo-set-source-rgba cr 1 0.2 0.2 0.6)
		 (cairo-set-line-width cr 6.0)
		 (cairo-arc cr x y 10.0 0 (* 2 pi))
		 (cairo-fill cr)
		 (cairo-move-to cr x y)
		 (cairo-rel-line-to cr 0 (- (ftype-ref cairo-text-extents-t (height) extents)))
		 (cairo-rel-line-to cr (ftype-ref cairo-text-extents-t (width) extents) 0)
		 (cairo-rel-line-to cr (ftype-ref cairo-text-extents-t (x-bearing) extents) (- (ftype-ref cairo-text-extents-t (y-bearing) extents)))
		 (cairo-stroke cr))))



(system "eog .")

Changes to cairo.sls.

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	 cairo-rectangle-int-t*
	 cairo-operator-t
	 cairo-antialias-t
	 cairo-fill-rule-t
	 cairo-line-cap-t
	 cairo-line-join-t
	 double*

	 cairo-rectangle-t
	 cairo-rectangle-t*
	 cairo-rectangle-list-t
	 cairo-rectangle-list-t*
	 cairo-scaled-font-t
	 cairo-font-face-t
	 cairo-glyph-t
................................................................................
	  cairo-rectangle-create
	  cairo-rectangle-list-create
	  cairo-glyph-create
	  cairo-text-cluster-create
	  cairo-text-extents-create
	  cairo-font-extents-create
	  cairo-path-create





	 cairo-guardian
	 cairo-free-garbage
	 cairo-guard-pointer


	 )
 (import (chezscheme) (ffi-utils))


 (define-syntax define-function*
   (lambda (x)
     (define (string-replace s x y)
................................................................................

     (define (convert-scheme->c function-name name type)
       (import (only (srfi s13 strings) 
		     string-delete string-suffix? string-prefix?))
       (define (remove-* x)
	 (string->symbol (string-delete #\* (symbol->string x))))
       
       (let ([t (syntax->datum (rename-scheme->c type))])

	 (cond 




	  [(and (string-prefix? "cairo-" (symbol->string t))
		(string-suffix? "*" (symbol->string t)))
	   #`(if (ftype-pointer? #,(datum->syntax type (remove-* t)) #,name) 
		 (ftype-pointer-address #,name) 
		 (assertion-violation 'convert-scheme->c "wrong pointer type for argument" (quote #,function-name) (quote #,name) (quote #,type) #,name))]
	  [else name])))

................................................................................
				   [(cairo-path-t*)           #'(cairo-guard-pointer (make-ftype-pointer cairo-path-t result))]
				   [(cairo-device-t*)         #'(cairo-guard-pointer (make-ftype-pointer cairo-device-t result))]
				   [else #'result]))))))])))

 (define-syntax define-ftype-allocator 
   (lambda (x)
     (syntax-case x () 


       [(_ name type) #'(define (name) (cairo-guard-pointer (make-ftype-pointer type (foreign-alloc (ftype-sizeof type)))))])))









 (define (cairo-library-init . t) (load-shared-object (if (null? t) "libcairo.so" (car t))))

 (define-ftype cairo-bool-t int)

 (define-ftype int* void*)
................................................................................
    [yx double]
    [xy double]
    [yy double]
    [x0 double]
    [y0 double]))

 (define-ftype cairo-matrix-t* void*)


 (define-ftype cairo-pattern-t (struct))
 (define-ftype cairo-pattern-t* void*)

 (define-ftype cairo-destroy-func-t (function (void*) void))

 (define-ftype cairo-destroy-func-t* void*)
................................................................................
   (function (void* void* unsigned-int) cairo-status-t))

 (define-ftype cairo-read-func-t* void*)

 (define-ftype cairo-rectangle-int-t
   (struct [x int] [y int] [width int] [height int]))

 (define-ftype-allocator make-cairo-rectangle-int cairo-rectangle-int-t)

 (define-ftype cairo-rectangle-int-t* void*)

 (define-enumeration* cairo-operator
   (clear source over in out atop dest dest-over dest-in
	  dest-out dest-atop xor add saturate multiply screen overlay
	  darken lighten color-dodge color-burn hard-light soft-light
................................................................................

 (define-enumeration* cairo-line-join 
   (miter round bevel))

 (define-ftype cairo-line-join-t int)

 (define-ftype double* void*)














 (define-ftype cairo-rectangle-t
   (struct
    [x double]
    [y double]
    [width double]
    [height double]))







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	 cairo-rectangle-int-t*
	 cairo-operator-t
	 cairo-antialias-t
	 cairo-fill-rule-t
	 cairo-line-cap-t
	 cairo-line-join-t
	 double*
	 double-array
	 cairo-rectangle-t
	 cairo-rectangle-t*
	 cairo-rectangle-list-t
	 cairo-rectangle-list-t*
	 cairo-scaled-font-t
	 cairo-font-face-t
	 cairo-glyph-t
................................................................................
	  cairo-rectangle-create
	  cairo-rectangle-list-create
	  cairo-glyph-create
	  cairo-text-cluster-create
	  cairo-text-extents-create
	  cairo-font-extents-create
	  cairo-path-create
	  double-array-create 
	  double-array-create-from-vector

	  cairo-matrix-create

	  cairo-guardian
	  cairo-free-garbage
	  cairo-guard-pointer


	 )
 (import (chezscheme) (ffi-utils))


 (define-syntax define-function*
   (lambda (x)
     (define (string-replace s x y)
................................................................................

     (define (convert-scheme->c function-name name type)
       (import (only (srfi s13 strings) 
		     string-delete string-suffix? string-prefix?))
       (define (remove-* x)
	 (string->symbol (string-delete #\* (symbol->string x))))
       
       (let ([t (syntax->datum (rename-scheme->c type))]
	     [t* (syntax->datum type)])
	 (cond 
	  [(eq? t* 'const-double*) 
	   #`(ftype-pointer-address 
	      (double-array-create-from-vector #,name))]
	  [(eq? t* 'double) #`(real->flonum #,name)]
	  [(and (string-prefix? "cairo-" (symbol->string t))
		(string-suffix? "*" (symbol->string t)))
	   #`(if (ftype-pointer? #,(datum->syntax type (remove-* t)) #,name) 
		 (ftype-pointer-address #,name) 
		 (assertion-violation 'convert-scheme->c "wrong pointer type for argument" (quote #,function-name) (quote #,name) (quote #,type) #,name))]
	  [else name])))

................................................................................
				   [(cairo-path-t*)           #'(cairo-guard-pointer (make-ftype-pointer cairo-path-t result))]
				   [(cairo-device-t*)         #'(cairo-guard-pointer (make-ftype-pointer cairo-device-t result))]
				   [else #'result]))))))])))

 (define-syntax define-ftype-allocator 
   (lambda (x)
     (syntax-case x () 
       [(_ name type) 
	#'(define (name) 
	    (cairo-guard-pointer (make-ftype-pointer type (foreign-alloc (ftype-sizeof type)))))])))

 (define-syntax define-ftype-array-allocator 
   (lambda (x)
     (syntax-case x () 
       [(_ name type element-type) 
	#'(define (name size) 
	    (cairo-guard-pointer (make-ftype-pointer type (foreign-alloc (* (ftype-sizeof element-type) size)))))])))


 (define (cairo-library-init . t) (load-shared-object (if (null? t) "libcairo.so" (car t))))

 (define-ftype cairo-bool-t int)

 (define-ftype int* void*)
................................................................................
    [yx double]
    [xy double]
    [yy double]
    [x0 double]
    [y0 double]))

 (define-ftype cairo-matrix-t* void*)
 (define-ftype-allocator cairo-matrix-create cairo-matrix-t)

 (define-ftype cairo-pattern-t (struct))
 (define-ftype cairo-pattern-t* void*)

 (define-ftype cairo-destroy-func-t (function (void*) void))

 (define-ftype cairo-destroy-func-t* void*)
................................................................................
   (function (void* void* unsigned-int) cairo-status-t))

 (define-ftype cairo-read-func-t* void*)

 (define-ftype cairo-rectangle-int-t
   (struct [x int] [y int] [width int] [height int]))

 (define-ftype-allocator cairo-rectangle-int-create cairo-rectangle-int-t)

 (define-ftype cairo-rectangle-int-t* void*)

 (define-enumeration* cairo-operator
   (clear source over in out atop dest dest-over dest-in
	  dest-out dest-atop xor add saturate multiply screen overlay
	  darken lighten color-dodge color-burn hard-light soft-light
................................................................................

 (define-enumeration* cairo-line-join 
   (miter round bevel))

 (define-ftype cairo-line-join-t int)

 (define-ftype double* void*)
 (define-ftype double-array (array 0 double))
 (define-ftype-array-allocator double-array-create double-array double)

 (define (double-array-create-from-vector l)
   (let* ([ls (vector->list l)]
	  [size (vector-length l)]
	  [array (double-array-create size)]) 
     (do ([i 0 (fx1+ i)]) 
	 ((fx>= i size))
       (let ([x (vector-ref l i)]
	     [r (ftype-&ref double-array (i) array)])
	 (ftype-set! double () r x)))
     array))

 (define-ftype cairo-rectangle-t
   (struct
    [x double]
    [y double]
    [width double]
    [height double]))