Rgb

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RGB

Returns an opaque colour value from red, green and blue parts of 0 to 255.

Syntax

#define RGB(r,g,b) CULng((CUByte(r) Shl 16) Or (CUByte(g) Shl 8) Or CUByte(b) Or (&hFF000000ul))

Parameters

• red
• green
• blue

Description

red, green and blue are components ranging 0-255.

The RGB function can be used to compute a valid color value for use while in hi/truecolor modes. It returns an unsigned long, in the format &hAARRGGBB, where RR, GG and BB equal the values passed to this function, in hexadecimal format. AA is the implicit alpha value and is automatically set to &hFF (opaque).
It is possible to retrieve the red, green, blue and alpha values from a color value, by using a combination of And and Shr. The second example below shows how to #define and use macros to do this.

Note for Windows API programmers: The macro named RGB in the Windows references has been renamed BGR in the FB headers for Windows to avoid collisions.

Return Value

The combined color.

Remarks

Usage

result = RGB(red, green, blue)

Dialect Differences

• Not available in the -lang qb dialect unless referenced with the alias __Rgb.

Differences from QB

• New to FreeBASIC

See also

• RGBA
• Color
• #define

Examples

See Put (Graphics) example in addition.

ScreenRes 640,480,32  '32 bit color

Line(0,0)-(319,479), RGB(255,0,0) 'draws a bright red box on the left side of the window

Line(639,0)-(320,479), RGB(0,0,255) 'draws a bright blue box on the right side of the window

Sleep 'wait before exiting

'' setting and retrieving Red, Green, Blue and Alpha values

#define RGBA_R( c ) ( CULng( c ) Shr 16 And 255 )

#define RGBA_G( c ) ( CULng( c ) Shr  8 And 255 )

#define RGBA_B( c ) ( CULng( c )        And 255 )

#define RGBA_A( c ) ( CULng( c ) Shr 24         )

Dim As UByte r, g, b, a

Dim As ULong col = RGB(128, 192, 64)

Print Using "Color: _&H\      \"; Hex(col, 8)

r = RGBA_R( col )

g = RGBA_G( col )

b = RGBA_B( col )

a = RGBA_A( col )

Print

Print Using "Red:         _&H\\ = ###"; Hex(r, 2); r

Print Using "Green:       _&H\\ = ###"; Hex(g, 2); g

Print Using "Blue:        _&H\\ = ###"; Hex(b, 2); b

Print Using "Alpha:       _&H\\ = ###"; Hex(a, 2); a

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Category: 2D Drawing 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.