[ALLY] Re: View Docs - draw
From: allenk:powerup:au at: 10-Apr-2001 19:31
Hi Phil,
Not sure if this is uptodate or not for the View version, but it should get
you started.
Docs copyright RT etc...
Cheers,
Allen K
DRAW Dialect for REBOL Faces
----------------------------
Updated: 20-Jan-2001/19:24
NOTE: Add your own short/interesting/insightful examples to the tail of
this document.
The DRAW dialect is part of the EFFECTS block of a face. For example:
view layout [
box black 100x100 effect [
draw [
pen red
line 30x30 50x20 70x70 40x50
pen blue
box 20x20 80x80
fill-pen leaf
box 20x60 40x80
polygon 10x10 40x40 40x80 10x0
pen white
text 8x25 "Example"
fill-pen gold
flood 2x2
]
]
]
The DRAW dialect accepts the following keywords, followed by their
optional arguments.
Arguments of different datatypes can appear in alternate order.
For example, text can be specified as:
text 8x25 "Example"
or:
text "Example" 8x25
Draw Attribute Words:
---------------------
pen [foreground-color [tuple! none!]] [background-color [tuple! none!]]
Set the current foreground color and background color for outline
rendering (line, circle, polygon, box). A color of none is equivalent
to transparent. The defaults are: foreground: inverse of face color,
background: none. (Note: instead of a tuple or none this function should
also accept the words 'inverse and 'reverse, with 'inverse meaning
"rendering by complementing the image", i.e. without a given color,
and with 'reverse meaning "reverse the meaning of foreground and
background" -- to be implemented).
fill-pen [foreground-color [tuple! none!]] [background-color [tuple! none!]]
Set the current foreground color and background color for area filling
(circle, box, flood, to be implemented: polygon). A color of none is
equivalent to transparent. (Note: area fill patterns are not supported
yet, so the background color is not used at this time). The defaults
are none. (Note: 'inverse and 'reverse to be added. See above).
line-pattern [len1 [integer!]] [len2 [integer!]] ... [lenn [integer!]]
Set the line pattern. Each len parameter defines the length of a
set (foreground) or unset (background) segment of the line, Set and
unset segments alternate. For instance "line-patten 1 5" defines a
dotted line, with dots 5 pixels apart, "line-pattern 8 8" defines a
dashed line, "line-pattern 1 4 4 4" defines a morse-code-style line
(alternating between dotted and dashed). Up to 8 segments can be
defined.
An empty line-pattern call (without parameters following) resets to
the default: a solid line.
font [textfont [object!]]
Set the font to be used in subsequent text calls. The default is the
font used by the face. (Note: this function should probably accept other
types of parameters as well, e.g. a font name or size, and clone the
current face font object, if necessary -- to be implemented).
Draw Object Words:
------------------
line [point1 [pair!]] [point2 [pair!]] ... [pointn [pair!]]
Draw a line from point1 to point2, from point 2 to point 3, ... to point
n.
Points n and 1 are NOT connected by an additional line. The current pen
colors and line pattern are observed.
polygon [point1 [pair!]] [point2 [pair!]] ... [pointn [pair!]]
Similar to line, except that points n and 1 are connected afterwards, to
create a closed polygon. (Note that simply adding point1 at the end of
a call to line does NOT create the same effect, because then point1
would
be rendered twice, which causes undesired effects in some rendering
modes).
If the fill-pen is different from none then the polygon is filled in the
specified color.
circle [center [pair!]] [radius [integer!]]
Draw a circle at the given point, with the given radius. Both the
outline pen colors and the fill colors are observed. The line pattern
is NOT observed.
box [point1 [pair!]] [point2 [pair!]]
Draw a rectangle, parallel to the x/y axes, through the two diagonal
endpoints specified. Both the outline pen colors and the fill colors
are observed. The line pattern is observed for the box outline.
text [point [pair!]] [text [string!]]
Renders the specified text at the specified position, using the current
font setting, foreground and background color.
image [[point [pair!]] image [image!]] [transp-color [tuple!]]
Renders the specified image at the specified position. If
transp-color is specified then this color (in the image) is
considered to be transparent.
Draw Function Words:
--------------------
flood [point [pair!]] [border-color [tuple!]]
Flood-fills the area around the specified point with the current
foreground fill color. If border-color is not specified then any
pixel with a color different from the color of the starting point
is considered to be part of the border. Otherwise all pixels with
a color of border-color define the border.
Examples:
---------
Draw a single red line into a face and display it:
view/new make face [
size: 200x200
effect: [draw [pen 200.0.0 line 20x20 180x180]]
]
Draw a few connected red lines and a blue box:
view make face [
size: 200x200
effect: [
draw [
pen 200.0.0
line 50x50 150x150 50x150 150x50 50x50
pen 0.0.200
box 20x20 180x180
]
]
]
Draw a circle:
view/new make face [
size: 200x200
effect: [
draw [
pen 200.0.0
circle 100x100 50
]
]
]
Draw a filled circle:
view make face [
size: 200x200
effect: [
draw [
pen 200.0.0
fill-pen 50.50.100
circle 100x100 50
]
]
]
Draw a box and a circle, then use a flood fill:
view make face [
size: 200x200
color: black
effect: [
draw [
pen white
box 20x20 180x180
pen red
circle 100x100 100
fill-pen blue
flood 100x100
]
]
]
Draws text in a maroon color:
view make face [
size: 200x200
effect: [
draw [
pen maroon
text "Hello" 20x20
]
]
]
Using other fonts for text:
italic-font: make face/font [
size: 10
style: 'italic
name: font-serif
]
view layout [
image 150x150 gold effect [
draw [
pen blue
text 0x20 "Default Font"
font italic-font
text 0x40 "Small Times Italic Font"
]
]
]
Other face effects can be done before the DRAW operation. This
example draws 100 random lines in random colors on a gradient
backdrop effect:
fx: [gradient 1x1 0.150.0 0.0.150 draw []]
lines: select fx 'draw
loop 100 [
repend lines [
'pen random 250.50.50
'line random 200x200 random 200x200
]
]
view make face [size: 200x200 effect: fx]
Other face effects can follow the DRAW operation. This example
draws a line and a box then inverts and blurs them:
view make face [
size: 200x200
effect: [
draw [
pen 200.0.0
line 50x50 150x150 50x150 150x50 50x50
pen 0.0.200
box 20x20 180x180
]
invert blur
]
]
Perform a pre-effect and a post-effect. A gradient is created,
then 100 random circles are drawn, then the result is color
differenced with an image bitmap.
fx: [gradient 1x1 0.150.0 0.0.150 draw []]
lines: select fx 'draw
loop 100 [
repend lines [
'pen random 250.50.50
'circle random 200x200 random 100
]
]
repend fx ['difference load link-root/apps/demos/bay.jpg]
view make face [size: 200x200 effect: fx]
Draw an image twice. The first includes all of its colors. The
second makes one of its colors transparent.
i: load link-root/desktop/ico_console.gif
view make face [
size: 200x200
effect: [
draw [
image i 20x20
image i 80x80 174.154.122
]
]
]
Draws lines when you hold the mouse button down and move it.
f: make face [
size: 400x400
effect: copy/deep [draw [pen black line]]
line: second effect
feel: make feel [
engage: func [f a e] [
if find [down over] a [
append f/line e/offset
show f
]
if a = 'up [append f/line 'line]
]
]
]
view make face [size: f/size pane: f]
Draws filled circles as the mouse is moved with the button down:
f: make face [
size: 400x400
effect: copy/deep [draw [pen black]]
line: second effect
feel: make feel [
engage: func [f a e] [
if find [down over] a [
repend f/line [
'fill-pen random 0.255.0
'circle e/offset 20
]
show f
]
]
]
]
view make face [size: f/size pane: f]
