Draw

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Draw

Draws a figure from a string of pen commands such as "U10 R10".

Syntax

Draw [target,] cmd

Parameters

• target
• cmd

Description

Drawing will take place onto the current work page set via ScreenSet or onto the target Get/Put buffer if specified.
The Draw statement can be used to issue several drawing commands all at once; it is useful to quickly draw figures. The command string accepts the following commands:

Commands to plot pixels:

Command	Description
	Commands to plot pixels:
B	Optional prefix: move but do not draw.
N	Optional prefix: draw but do not move.
M x,y	Move to specified screen location. if a '+' or '-' sign precedes x, movement is relative to current cursor position. x's sign has no effect on the sign of y.
U [n]	Move n units up. If n is omitted, 1 is assumed.
D [n]	Move n units down. If n is omitted, 1 is assumed.
L [n]	Move n units left. If n is omitted, 1 is assumed.
R [n]	Move n units right. If n is omitted, 1 is assumed.
E [n]	Move n units up and right. If n is omitted, 1 is assumed.
F [n]	Move n units down and right. If n is omitted, 1 is assumed.
G [n]	Move n units down and left. If n is omitted, 1 is assumed.
H [n]	Move n units up and left. If n is omitted, 1 is assumed.
	Commands to color:
C n	Changes current foreground color to n.
P p,b	PAINTs (flood fills) region of border color b with color p.
	Commands to scale and rotate:
S n	Sets the current unit length, default is 4. A unit length of 4 is equal to 1 pixel.
A n	Rotate n*90 degrees (n ranges 0-3).
TA n	Rotate n degrees (n ranges 0-359).
	Extra commands:
X p	Executes commands at p, where p is a STRING PTR.

Commands to set the color, size and angle will take affect all subsequent Draw operations.

Draw respects the current clipping region as set by the View (Graphics) statement, but its coordinates are not affected by the custom coordinates system.

Remarks

Differences from QB

• target is new to FreeBASIC
• QB used the special pointer keyword VARPTR$ with the X p command.
• FB does not currently allow sub-pixel movements: all movements are rounded to the nearest integer coordinate.

See also

• Draw String
• Screen (Graphics)
• VarPtr
• Paint

Examples

Screen 13

'Move to (50,50) without drawing

Draw "BM 50,50"

'Set drawing color to 2 (green)

Draw "C2"

'Draw a box

Draw "R50 D30 L50 U30"

'Move inside the box

Draw "BM +1,1"

'Flood fill with color 1 (blue) up to border color 2

Draw "P 1,2"

Sleep

'' Draws a flower on-screen

Dim As Integer i, a, c

Dim As String fill, setangle

'' pattern for each petal

Dim As Const String petal = _

    _

    ("X" & VarPtr(setangle)) _ '' link to angle-setting string

    _

    & "C15" _       '' set outline color (white)

    & "M+100,+10" _ '' draw outline

    "M +15,-10" _

    "M -15,-10" _

    "M-100,+10" _

    _

    & "BM+100,0" _              '' move inside petal

    & ("X" & VarPtr(fill)) _    '' flood-fill petal (by linking to fill string)

    & "BM-100,0"                '' move back out

'' set screen

ScreenRes 320, 240, 8

'' move to center

Draw "BM 160, 120"

'' set initial angle and color number

a = 0: c = 32

For i = 1 To 24

    '' make angle-setting and filling command strings

    setangle = "TA" & a

    fill = "P" & c & ",15"

    '' draw the petal pattern, which links to angle-setting and filling strings

    Draw petal

    '' short delay

    Sleep 100

    '' increment angle and color number

    a += 15: c += 1

Next i

Sleep

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Category: Screen Functions
Kind: keyword

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Reproduced from the FreeBASIC Wiki Manual under the GNU Free Documentation License 1.3 — with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. Copyright © the FreeBASIC project and wiki contributors. See License.