COLOR - QB64Official/qb64 GitHub Wiki

The COLOR statement is used to change the foreground and background colors for printing text.

Syntax

COLOR [foreground&][, background&]

Description

  • background& colors are available in all QB64 color SCREEN modes.
  • SCREEN mode 10 has only 3 white foreground attributes including flashing.
  • To change the background& color only, use a comma and the desired color. Ex: COLOR , background&
  • Graphic drawing statements like PSET, PRESET, LINE, etc, also use the colors set by the COLOR statement if no color is passed when they are called.
  • The $COLOR metacommand adds named color constants for both text and 32-bit modes.
  • COLOR works when outputting text to $CONSOLE.
    • On macOS, colors in console mode will not match the VGA palette. See [https://en.wikipedia.org/wiki/ANSI_escape_code#8-bit 8-bit ANSI colors]

Screen Mode Attributes

  • SCREEN 0 background& colors 0 to 7 can be changed each text character without affecting other text. Use CLS after a background color statement to create a fullscreen background color. 64 DAC hues with 16 high intensity blinking foreground (16 to 31) color attributes. See _BLINK.
    • See example 7 below for more SCREEN 0 background colors.
  • SCREEN 1 has 4 background color attributes: 0 = black, 1 = blue, 2 = green, 3 = grey. White foreground color only.
  • SCREEN 2 is monochrome with white forecolor and black background.
  • SCREEN 7 can use 16 (DAC) colors with background colors. RGB settings can be changed in colors 0 to 7 using _PALETTECOLOR.
  • SCREEN 8 has 16 color attributes with 16 background colors.
  • SCREEN 9 can use up to 64 DAC color hues in 16 color attributes with background colors assigned to attribute 0 with a _PALETTECOLOR swap. RGB settings can be changed in colors 0 to 5 and 7 using _PALETTECOLOR.
  • SCREEN 10 has only 4 color attributes with black background. COLOR 0 = black, 1 = grey, 2 = flash white and 3 = bright white.
  • SCREEN 11 is monochrome with white forecolor and a black background.
  • SCREEN 12 can use 16 color attributes with a black background. 256K possible RGB color hues. Background colors can be used with QB64.
  • SCREEN 13 can use 256 color attributes with a black background. 256K possible RGB hues.
  • PALETTE swaps can be made in SCREEN 7 and 9 only. Those screens were DAC screen modes in QBasic.
  • _DEST can be used to set the destination page or image to color using QB64.
  • _DEFAULTCOLOR returns the current color being used on an image or screen page handle.

24/32-Bit colors using QB64

  • Pixel color intensities for red, green, blue and alpha range from 0 to 255 when used with _RGB, _RGBA, _RGB32 and RGBA32.
  • Combined RGB function values returned are LONG values. Blue intensity values may be cut off using SINGLE variables.
  • _ALPHA transparency values can range from 0 as transparent up to 255 which is fully opaque.
  • _CLEARCOLOR can also be used to set a color as transparent.
  • Colors can be mixed by using _BLEND (default) in 32-bit screen modes. _DONTBLEND disables blending.
  • NOTE: Default 32-bit backgrounds are clear black or _RGBA(0, 0, 0, 0). Use CLS to make the black opaque.

RGB Palette Intensities

RGB intensity values can be converted to hexadecimal values to create the LONG _PALETTECOLOR value in non-32-bit screens:


SCREEN 12
alpha$ = "FF" 'solid alpha colors only
OUT &H3C8, 0: OUT &H3C9, 0: OUT &H3C9, 0: OUT &H3C9, 20 'set black background to dark blue
PRINT "Attribute = Hex value      Red          Green         Blue "
PRINT
COLOR 7 
FOR attribute = 0 TO 15
  OUT &H3C7, attribute 'set color attribute to read
  red$ = HEX$(INP(&H3C9) * 4) 'convert port setting to 32 bit values
  grn$ = HEX$(INP(&H3C9) * 4)
  blu$ = HEX$(INP(&H3C9) * 4)
  IF LEN(red$) = 1 THEN red$ = "0" + red$ '2 hex digits required
  IF LEN(grn$) = 1 THEN grn$ = "0" + grn$ 'for low or zero hex values
  IF LEN(blu$) = 1 THEN blu$ = "0" + blu$
  hex32$ = "&H" + alpha$ + red$ + grn$ + blu$
  _PALETTECOLOR attribute, VAL(hex32$) 'VAL converts hex string to a LONG 32 bit value
  IF attribute THEN COLOR attribute 'exclude black color print
  PRINT "COLOR" + STR$(attribute) + " = " + hex32$, red$, grn$, blu$ 'returns closest attribute
NEXT



Attribute  Hex value      Red        Green       Blue 

COLOR 0 = &HFF000050       00         00         50
COLOR 1 = &HFF0000A8       00         00         A8
COLOR 2 = &HFF00A800       00         A8         00
COLOR 3 = &HFF00A8A8       00         A8         A8
COLOR 4 = &HFFA80000       A8         00         00
COLOR 5 = &HFFA800A8       A8         00         A8
COLOR 6 = &HFFA85400       A8         54         00
COLOR 7 = &HFFA8A8A8       A8         A8         A8
COLOR 8 = &HFF545454       54         54         54
COLOR 9 = &HFF5454FC       54         54         FC
COLOR 10 = &HFF54FC54      54         FC         54
COLOR 11 = &HFF5454FC      54         FC         FC
COLOR 12 = &HFFFC5454      FC         54         54
COLOR 13 = &HFFFC54FC      FC         54         FC
COLOR 14 = &HFFFCFC54      FC         FC         54
COLOR 15 = &HFFFCFCFC      FC         FC         FC

Explanation: The RGB intensity values are multiplied by 4 to get the _RGB intensity values as HEX$ values. The individual 2 digit HEX$ intensity values can be added to "&HFF" to make up the 32-bit hexadecimal string value necessary for VAL to return to _PALETTECOLOR. The statement is only included in the example to show how that can be done with any 32-bit color value. Note: Black has a blue hex value of 50 due to the OUT background color setting which makes it dark blue.

Reading and setting color port intensities using INP and OUT

  • Legacy code may use INP and OUT to read or set color port intensities. QB64 emulates VGA memory to maintain compatibility.
  • The same can be achieved using _PALETTECOLOR (recommended practice).

OUT &H3C7, attribute 'Set port to read RGB settings with:

color_intensity = INP(&H3C9) 'reads present intensity setting

OUT &H3C8, attribute 'Set port to write RGB settings with:

OUT &H3C9, color_intensity 'writes new intensity setting

  • After every 3 reads or writes, changes to next higher color attribute. Loops can be used to set more than one attribute's intensities.
  • Color port setting of red, green and blue intensities can be done in ascending order.
  • Color port attribute intensity values range from 0 to 63 (1/4 of the 32-bit values) in QBasic's legacy 4 and 8 bit screen modes.

Example(s)

Reading the default RGB color settings of color attribute 15.


OUT &H3C7, 15
red% = INP(&H3C9)
green% = INP(&H3C9)
blue% = INP(&H3C9)
PRINT red%, green%, blue% 



 63       63       63

Changing the color settings of attribute 0 (the background) to dark blue in SCREENs 12 or 13.


SCREEN 12
OUT &H3C8, 0          'set color port attribute to write
OUT &H3C9, 0          'red intensity
OUT &H3C9, 0          'green intensity
OUT &H3C9, 30         'blue intensity

OUT &H3C7, 0
PRINT INP(&H3C9); INP(&H3C9); INP(&H3C9)
END



 0  0  30

Printing in fullscreen SCREEN 0 mode with a color background under the text only.


SCREEN 0: _FULLSCREEN ' used for fullscreen instead of window
COLOR 30, 6: LOCATE 12, 4: PRINT "Hello!"

Result: Hello! is printed in flashing high intensity yellow with brown background behind text only when in QBasic _FULLSCREEN.

Using CLS after setting the background color in SCREEN 0 to make the color cover the entire screen.


SCREEN 0: _FULLSCREEN
COLOR , 7: CLS
COLOR 9: PRINT "Hello" 



Hello

Result: The blue word Hello is printed to a totally grey background in _FULLSCREEN.

Using a different foreground color for each letter:


SCREEN 0
COLOR 1: PRINT "H";
COLOR 3: PRINT "E";
COLOR 4: PRINT "L";
COLOR 5: PRINT "L";
COLOR 6: PRINT "O"
COLOR 9: PRINT "W";
COLOR 11: PRINT "O";
COLOR 12: PRINT "R";
COLOR 13: PRINT "L";
COLOR 14: PRINT "D" 



HELLO
WORLD

Doing the same as Example 5 but in only a few lines:


SCREEN 0
text$ = "HelloWorld"
FOR textpos = 1 TO LEN(text$)
  COLOR textpos
  IF textpos <> 5 THEN PRINT MID$(text$, textpos, 1);
  IF textpos = 5 THEN PRINT MID$(text$, textpos, 1)    'start print on next row
NEXT




Hello
World

*Explanation:*Semicolon(;) means that the next PRINT happens on the same line, we don't want that when it comes to position 5 so when it is at position 5 the next PRINT will move to the next line (when it isn't at position 5 we want it to continue printing the letter side-by-side on the same line though).

Since SCREEN 0 only uses background colors 0 to 7 by default, use _PALETTECOLOR to change color intensities of color 0.


_PALETTECOLOR 0, _RGB32(255, 255, 255) 'change color 0 intensity
_PALETTECOLOR 8, _RGB32(0, 0, 0) 'change color 8 intensity

COLOR 8: PRINT "Black on bright white!"



Black on bright white!

Explanation: Since QB64 does not have DAC SCREEN 0 limitations, changing color intensities for custom background colors is possible.

Changing light gray text in SCREEN 0 to a 32 bit custom color using a LONG HTML hexadecimal value:


COLOR 7
PRINT "Color 7 is gray"
K$ = INPUT$(1)
_PALETTECOLOR 7, &HFFDAA520 ' FF alpha makes the color translucent
PRINT "Color 7 is now Goldenrod in SCREEN 0!



Color 7 is gray
Color 7 is now Goldenrod in SCREEN 0!

Explanation: _RGB32 could be used to make custom 32 bit colors or HTML values could be used after &HFF for solid colors.

See Also