How to use the draw function

How to use the draw function

In the previous examples, we used the draw facet of a face to apply geometrical transformations on image such as translations or rotations. But draw also designs a powerful Red function that can be used to modify the content of an image. Any Red image can be passed as parameter to the draw function. 

The idea is simple. First copy into a block the modifications you want apply to the image as a list of draw operations.

plot: copy [line-width 2 pen red line 0x0 512x512 pen off pen green line 0x512 512x0 box 10x10 50x50 box 55x55 75X75 text 210x5 "Hello Lena"]

Then ask the image container to draw the image and the modifications you defined.

canvas/image: draw img plot

Code example

Red [

    Title:   "Draw tests "

    Author:  "Francois Jouen"

    File:    %DrawOnImage.red

    Needs:   'View

]

;How to use the draw function and not draw facet!

img: load %lena.jpg

margins: 5x5

plot: copy [line-width 2 pen red line 0x0 512x512 pen off pen green line 0x512 512x0  box 10x10 50x50 box 55x55 75X75 text 210x5 "Hello Lena"

]

view win: layout [

        title "Image Tests"

        origin margins space margins

        button 60 "Draw"    [canvas/image: draw img plot]

        button 60 "Quit"    [Quit]

        return 

        canvas: base 512x512 img

        return

        sbar: field 250

        do [sbar/data: length? img/rgb]

]

and the result