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60 lines
2.9 KiB
Markdown
60 lines
2.9 KiB
Markdown
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[LONG](LONG) [HEX$](HEX$) values can be used to set a [_PALETTECOLOR](_PALETTECOLOR) instead of using [_RGB32](_RGB32) or [_RGBA32](_RGBA32) values.
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* Hexadecimal digits can be represented as any number or letter up to F: **0 1 2 3 4 5 6 7 8 9 A B C D E F**
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* [_BYTE](_BYTE) values up to 255 can represented by two hexadecimal digits such as 1C, 23, FA, etc.
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* The [HEX$](HEX$) value for bright white(attribute 15) is &HFFFFFFFF or:
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- [_ALPHA](_ALPHA) = FF (255), Red = FF (255), Green = FF (255), Blue = FF (255)
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* [_RGB](_RGB) will return an alpha value of 255 for fully opaque 32 bit colors only. Values range from &HFF000000 to &HFFFFFFFF.
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* [_RGB32](_RGB32) will return an alpha value of 255 for fully opaque colors only. Values range from &HFF000000 to &HFFFFFFFF.
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* [_RGBA](_RGBA) can set the transparency so hexadecimal values range from &H000000 (zero alpha) to &HFFFFFFFF (full alpha).
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* [_RGBA32](_RGBA32) can set the transparency so hexadecimal values range from &H000000 (zero alpha) to &HFFFFFFFF (full alpha).
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* So expanding on the principle above allows us to easily make up our own hex color values:
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- _PALETTECOLOR 1, **&HFFFF0000** 'COLOR 1 is full red
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- _PALETTECOLOR 2, **&HFFFF00FF** 'COLOR 2 is purple
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- _PALETTECOLOR 3, **&HFFFFFF00** 'COLOR 3 is brown
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> Where **FF** is the fully opaque [_ALPHA](_ALPHA) and the 3 hex color values can range from **00** to **FF** (0 to 255) each.
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## Example(s)
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Converting the color port RGB intensity palette values 0 to 63 to 32 bit hexadecimal [STRING](STRING) values.
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```vb
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SCREEN 12
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DIM hex32$(15)
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alpha$ = "FF" 'solid alpha colors only
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OUT &H3C8, 0: OUT &H3C9, 0: OUT &H3C9, 0: OUT &H3C9, 20 'set black background to dark blue
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FOR attribute = 0 TO 15
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OUT &H3C7, attribute 'set color attribute to read
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red$ = HEX$(INP(&H3C9) * 4) 'convert port setting to 32 bit values
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grn$ = HEX$(INP(&H3C9) * 4)
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blu$ = HEX$(INP(&H3C9) * 4)
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IF LEN(red$) = 1 THEN red$ = "0" + red$ 'necessary for low or zero color intensities
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IF LEN(grn$) = 1 THEN grn$ = "0" + grn$
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IF LEN(blu$) = 1 THEN blu$ = "0" + blu$
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hex32$(attribute) = "&H" + alpha$ + red$ + grn$ + blu$
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NEXT
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PRINT "COLOR 0 = " + hex32$(0)
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FOR i = 1 TO 15
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_PALETTECOLOR i, VAL(hex32$(i))
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COLOR i
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PRINT "COLOR" + STR$(i) + " = " + hex32$(i) 'returns closest attribute
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NEXT
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```
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<sub>Code by Ted Weissgerber</sub>
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> *Explanation:* [VAL](VAL) is used to convert the [HEX$](HEX$) [STRING](STRING) values to valid 32 bit color values for [_PALETTECOLOR](_PALETTECOLOR).
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> No VAL conversion is necessary if the [LONG](LONG) [&H](&H) hexadecimal values are entered into the program directly by the programmer.
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## See Also
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* [_PALETTECOLOR](_PALETTECOLOR)
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* [_RGB32](_RGB32), [_RGBA32](_RGBA32)
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* [_RGB](_RGB), [_RGBA](_RGBA) (when used in 32 bit only)
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* [COLOR](COLOR), [SCREEN](SCREEN), [POINT](POINT)
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* [HTML Color Table HEX Values and Names](https://en.wikipedia.org/wiki/Web_colors#Basic_colors)
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