PALETTECOLOR (function): Difference between revisions

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''Example:'' How _PALETTECOLOR works on 32 bit RGB compared to a 4 BPP(SCREEN 12) QBasic procedure.
''Example:'' How _PALETTECOLOR works on 32 bit RGB compared to a 4 BPP(SCREEN 12) QBasic procedure.
{{CodeStart}} '' ''
{{CodeStart}} '' ''
SCREEN 12                        'can use any Qbasic legacy screen mode
SCREEN 12                        'can use any QBasic legacy screen mode
DIM RGB(0 TO 47) AS INTEGER      'color intensity array
DIM RGB(0 TO 47) AS INTEGER      'color intensity array
FOR c& = 0 TO 15
FOR c& = 0 TO 15

Revision as of 10:34, 29 April 2022

The _PALETTECOLOR function is used to return the 32 bit attribute color setting of an image or screen page handle's palette.


Syntax

color32Value& = _PALETTECOLOR(attributeNumber%, imgHandle&)


Description

  • attributeNumber% is the color attribute value from 0 to 255 for 1, 4 or 8 bit images.
  • imgHandle& is the image handle being read for color data. Zero can be used to read the current screen mode palette.
  • Returns the 32 bit color value to be used by the 32 bit RGB functions.
  • For 32 bit images send the _PALETTECOLOR return value to _RED32, _GREEN32 and _BLUE32 functions to get the red, green, and blue intensity values.
  • Although 32 bit palette values are returned, the function cannot be used with 32 bit images or screen modes.


Examples

Example: How _PALETTECOLOR works on 32 bit RGB compared to a 4 BPP(SCREEN 12) QBasic procedure.

  
SCREEN 12                         'can use any QBasic legacy screen mode
DIM RGB(0 TO 47) AS INTEGER       'color intensity array
FOR c& = 0 TO 15
  'OUT &H3C7, c&                  'set color attribute to read
  value32& = _PALETTECOLOR(c&, 0) 'sets color value to read of an image page handle.
  'red% = INP(&H3C9)
  red% = _RED32(value32&)
  'green% = INP(&H3C9)
  green% = _GREEN32(value32&)
  'blue% = INP(&H3C9)
  blue% = _BLUE32(value32&)
  RGB(c& * 3) = red%: RGB((c& * 3) + 1) = green%: RGB((c& * 3) + 2) = blue%
NEXT
FOR i = 0 TO 47 STEP 3
  RGBval$ = LTRIM$(STR$(RGB(i))) + "," + STR$(RGB(i + 1)) + "," + STR$(RGB(i + 2)) + ")"
  PRINT "Color"; i / 3, "_RGB(" + RGBval$;
  PRINT
NEXT
END  
Explanation: To save a bitmap or other image you need the RGB color settings or the colors will look all wrong. You can store that information into a larger image array and GET the image AFTER the color settings. Just GET the image starting at Array(48).


See also



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