Paint

FreeBASIC

Paint
 
Fills an area delimited by a border of a specified color

Syntax

Paint [target,] [STEP] (x, y)[, [paint][, [border_color]]]

Parameters

target
specifies buffer to draw on.
STEP
indicates that coordinates are relative
(x, y)
coordinates of the pixel on which to start the flood fill (paint)
paint
the color attribute or fill pattern
a numeric value indicates a color, while a string indicates a fill pattern
border_color
boundary color for the fill

Description

Graphics command to fill an area delimited by a border of specified color. Also known as 'flood-fill' or 'paint bucket'.

Paint can operate on the current work page as set by the ScreenSet statement or on the target Get/Put buffer, if specified.

Filling starts at specified (x,y) coordinates; if STEP is specified, these are relative to the last graphics cursor position. Coordinates are also affected by custom coordinates system set up by Window and/or View (Graphics) statements; clipping set by View also applies.

If the paint argument is a number, it is assumed a color in the same format used by the Color statement, and the region is flood-filled using that color. If paint is a String, the region will be filled using a pattern; the pattern is always 8*8 pixels, and the passed string must hold pixels data in a format dependent on the current color depth. The string holds pattern pixels row by row, and its size should be as follows:

For color depths 1, 2, 4 and 8:
size = 8 * 8 = 64
For color depths 15 and 16:
size = (8 * 8) * 2 = 128
For color depths 24 and 32:
size = (8 * 8) * 4 = 256

If the passed string is smaller, missing pixels will be 0. If the paint argument is omitted, normal filling is performed using the current foreground color set by Color. Flood-filling continues until pixels of the specified border color are found; if border_color is omitted, the current background color is assumed.

Example

' draws a white circle painted blue inside
Screen 13
Circle (160, 100), 30, 15
Paint (160, 100), 1, 15
Sleep


' draws a circle and fills it with a checkered pattern

'' choose the bit depth for the Screen
'' try setting this to other values: 8, 16 or 32

Const bit_depth = 8

'' function for returning a pixel color, represented as a string
'' returns a the string in the appropriate format for the current bit depth
Function paint_pixel( ByVal c As UInteger, ByVal bit_depth_ As Integer ) As String
    
    If bit_depth_ <= 8 Then '' 8-bit:
        Function =  Chr( CUByte(c) )
        
    ElseIf bit_depth_ <= 16 Then '' 16-bit:
        Function = MKShort( c Shr 3 And &h1f Or _
                            c Shr 5 And &h7e0 Or _
                            c Shr 8 And &hf800 )
        
    ElseIf bit_depth_ <= 32 Then '' 32-bit:
        Function = MKL(c)
        
    End If
    
End Function


'' open a graphics window at the chosen bit depth
ScreenRes 320, 200, bit_depth

'' declare variables for holding colors
Dim As UInteger c, c1, c2, cb

'' declare string variable for holding the pattern used in Paint
Dim As String paint_pattern = ""

'' set colors
If bit_depth <= 8 Then
    c1 = 7  ''pattern color 1
    c2 = 8  ''pattern color 2
    cb = 15 ''border color
Else
    c1 = RGB(192, 192, 192) '' pattern color 1
    c2 = RGB(128, 128, 128) '' pattern color 2
    cb = RGB(255, 255, 255) '' border color
End If

'' make the pattern to be used in Paint
For y As UInteger = 0 To 7
    For x As UInteger = 0 To 7
        
        '' choose the color of the pixel (c)
        If (x \ 4 + y \ 4) Mod 2 > 0 Then
            c = c1
        Else
            c = c2
        End If
        
        '' add the pixel to the pattern
        paint_pattern = paint_pattern + paint_pixel(c, bit_depth)
        
        '' the following line can be used if you want to draw the 
        '' pattern tile in the top left hand corner of the screen:
        
        ' pset (x, y), c
        
    Next x
Next y

'' draw a circle with the border color
Circle (160, 100), 50, cb, , , 1.0

'' paint the circle region with paint_pattern, stopping at the border color
Paint (160, 100), paint_pattern, cb

'' pause before ending the program
Sleep


Differences from QB

  • target is new to FreeBASIC
  • In QB, the fill pattern was always 8-bits wide, and the height was the length of the string (up to 64). In FreeBASIC, the fill pattern is 8 pixels wide, independent of the color depth, and the height is always 8
  • The background color parameter supported by QB is not supported by the FreeBASIC version

See also