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146 lines
4.4 KiB
Markdown
146 lines
4.4 KiB
Markdown
The **PRESET** graphic [SCREEN](SCREEN) statement turns a pixel at a coordinate to the background color or a designated color attribute.
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## Syntax
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> **PRESET** [STEP]**(***column%*, *row%***)**[, colorAttribute]
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## Parameter(s)
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* Can use [STEP](STEP) when relative graphics coordinates are required.
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* *column* and *row* coordinates can be literal ot variable [INTEGER](INTEGER) values which can be offscreen.
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* If the *colorAttribute* is omitted, PRESET will use the current [_DEST](_DEST) page's [_BACKGROUNDCOLOR](_BACKGROUNDCOLOR).
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## Usage
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* Color attributes are limited to those available in the [SCREEN](SCREEN) mode used. [PSET](PSET) can be used to adopt previously used colors.
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* Any color value other than 0 will be white in monochrome [SCREEN](SCREEN) modes 2 and 11 where the [COLOR](COLOR) statement cannot be used.
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* PRESET can invisibly locate other graphics objects like [CIRCLE](CIRCLE)s and add color to subsequent graphic objects and [DRAW](DRAW) when used.
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* The PRESET action can be used in a graphics [PUT (graphics statement)](PUT-(graphics-statement)) to produce a color inverted image on any background. See Example 2.
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* The graphic cursor is set to the center of the program window on program start for [STEP](STEP) relative coordinates.
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* **PRESET can be used in any graphic screen mode, but cannot be used in the default screen mode 0 as it is text only!**
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## Example(s)
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Using PRESET to locate a [DRAW](DRAW) statement that draws a box that is bright red.
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```vb
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SCREEN 12
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PRESET(100, 100)
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DRAW "C12 U20 R20 D20 L20"
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```
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> *Explanation:* The [DRAW](DRAW) string required a color designation as PRESET defaulted to the black background color.
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Displays the flags of countries that use simple horizontal or vertical color blocks with a highlighted arrow key menu.
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```vb
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DIM SHARED c$(21), x$(21), gg%(477)
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ARRAY
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SETUP
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SELECTION
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TERMINATE
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END
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SUB ARRAY
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c$(1) = "Armenia H040914"
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c$(2) = "Austria H041504"
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c$(3) = "Belgium V001404"
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c$(4) = "Bulgaria H150204"
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c$(5) = "Chad V011404"
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c$(6) = "C“te D'Ivoire V061502"
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c$(7) = "Estonia H090015"
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c$(8) = "France V011504"
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c$(9) = "Germany H000414"
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c$(10) = "Hungary H041502"
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c$(11) = "Ireland V021506"
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c$(12) = "Italy V021504"
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c$(13) = "Lithuania H140204"
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c$(14) = "Luxembourg H041509"
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c$(15) = "Mali V021404"
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c$(16) = "Netherlands H041501"
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c$(17) = "Nigeria V021502"
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c$(18) = "Romania V091404"
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c$(19) = "Russia H150104"
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c$(20) = "Sierra Leone H021509"
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c$(21) = "Yemen H041500"
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END SUB
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SUB DISPLAY.FLAG (calc%)
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f% = VAL(MID$(x$(calc%), 2, 2))
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s% = VAL(MID$(x$(calc%), 4, 2))
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t% = VAL(MID$(x$(calc%), 6, 2))
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IF LEFT$(x$(calc%), 1) = "V" THEN
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LINE (120, 225)-(253, 465), f%, BF
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LINE (254, 225)-(385, 465), s%, BF
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LINE (386, 225)-(519, 465), t%, BF
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END IF
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IF LEFT$(x$(calc%), 1) = "H" THEN
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LINE (120, 225)-(519, 305), f%, BF
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LINE (120, 306)-(519, 386), s%, BF
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LINE (120, 387)-(519, 465), t%, BF
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END IF
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END SUB
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SUB SELECTION 'menu selection using arrow keys
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x% = 2: y% = 4
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DO
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WHILE (x% <> prevx% OR y% <> prevy%) AND k$ <> CHR$(27)
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k$ = INKEY$
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x% = x% + (k$ = (CHR$(0) + "K") AND x% > 1) + ABS(k$ = (CHR$(0) + "M") AND x% < 3)
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y% = y% + (k$ = (CHR$(0) + "H") AND y% > 1) + ABS(k$ = (CHR$(0) + "P") AND y% < 7)
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calc% = (x% - 1) * 7 + y%: LOCATE 14, 18: PRINT c$(calc%); SPACE$(10)
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x1% = 140 + (x% - 1) * 128
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x2% = x1% + LEN(c$(calc%)) * 8 + 7
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y1% = 48 + y% * 16
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IF x1% <> prevx1% OR y1% <> prevy1% THEN
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IF g% THEN PUT(prevx1%, prevy1%), gg%(), PSET
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GET(x1%, y1%)-(x2%, y1% + 16), gg%(): g% = 1
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PUT(x1%, y1%), gg%(), PRESET
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prevx1% = x1%: prevx2% = x2%: prevy1% = y1%
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DISPLAY.FLAG calc%
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END IF
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WEND
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LOOP UNTIL k$ = CHR$(27)
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END SUB
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SUB SETUP
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SCREEN 12
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COLOR 6
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c% = 1
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FOR x% = 11 TO 50 STEP 16
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FOR y% = 1 TO 7
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x$(c%) = RIGHT$(c$(c%), 7)
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c$(c%) = RTRIM$(LEFT$(c$(c%), LEN(c$(c%)) - 7))
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LOCATE y% + 4, x% + 8: PRINT c$(c%)
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c% = c% + 1
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NEXT y%, x%
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COLOR 11: LOCATE 3, 20: PRINT "Use the Cursor Keys to Select a Country:"
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LINE (119, 224)-(520, 466), 7, B
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END SUB
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SUB TERMINATE
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FOR c% = 1 TO 219
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LINE (116 + c%, 29 + c%)-(523 - c%, 469 - c%), 0, B
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NEXT
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END SUB
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```
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> *Explanation:* Using the [PUT (graphics statement)](PUT-(graphics-statement)) PRESET action highlights the menu selection in graphic screen modes by returning a negative image.
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## See Also
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* [PUT (graphics statement)](PUT-(graphics-statement))
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* [GET (graphics statement)](GET-(graphics-statement))
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* [CIRCLE](CIRCLE), [LINE](LINE), [PSET](PSET)
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