BAM: SCROLL statement "super-test"

[bplus]

Hi Charlie, what you are doing in demo could easily be done by color shifting on a pallet.
The same could be done with text by position shifting start point of display for text.

Here is old demo in QB64:

Code: (Select All)

_Title "Color Cycle AKA Palette Shifting?" 'B+ 2019-04-13 trans from SdlBasic code

'color cycle test.sdlbas {B+=MGA 2016-06-04





Randomize Timer

'option qbasic

Const xmax = 400 '<==== drawing area width

Const ymax = 300 '<==== drawing area height

'setdisplay(xmax, ymax, 32, 1)

'setcaption("Color Cycle test.sdlbas")  '<===================== screen title

'autoback(-2)

Screen _NewImage(xmax, ymax, 32)



'dim common pal(16), cIndex=0

Dim Shared pal(16) As _Unsigned Long

Dim Shared cIndex As Integer



'QB colors approx

pal(0) = &HFF000000

pal(1) = &HFF000077

pal(2) = &HFFFF8866

pal(3) = &HFF008888

pal(4) = &HFF880000

pal(5) = &HFFFF8800

pal(6) = &HFF008800

pal(7) = &HFFBBBBBB

pal(8) = &HFF666666

pal(9) = &HFF0000FF

pal(10) = &HFF00FF00

pal(11) = &HFF00FFFF

pal(12) = &HFFFF0000

pal(13) = &HFFFF00FF

pal(14) = &HFFFFFF00

pal(15) = &HFFFFFFFF





While 1

    Cls

    For i = 0 To 15

        'simulate a Palette Shift by shifting the indexs to Palette calls

        Line (i * 20 + 40, 100)-Step(20, 100), pal((cIndex + i) Mod 16), BF

        cText xmax / 2, 50, 16, pal(15), "Index called:"

        cText i * 20 + 5 + 40, 70, 16, pal(15), Str$(i)

        cText xmax / 2, 220, 16, pal(15), "Shifted Index call:"

        cText i * 20 + 5 + 40, 240, 16, pal(15), Str$((cIndex + i) Mod 16)

    Next

    _Display

    _Limit 1

    'INPUT "Press enter for Palette shifting +1 "; wate$

    cIndex = (cIndex + 1) Mod 16 'color shift

Wend



Function ccycle (cNum)

    ccycle = pal((cIndex + cNum) Mod 16)

End Function



Sub cText (x, y, textHeight, K As _Unsigned Long, txt$)

    fg = _DefaultColor

    'screen snapshot

    cur& = _Dest

    I& = _NewImage(8 * Len(txt$), 16, 32)

    _Dest I&

    Color K, _RGBA32(0, 0, 0, 0)

    _PrintString (1, 1), txt$

    mult = textHeight / 16

    xlen = Len(txt$) * 8 * mult

    _PutImage (x - .5 * xlen + 1, y - .5 * textHeight + 1)-Step(xlen, textHeight), I&, cur&

    Color fg

    _FreeImage I&

End Sub

Of course this can be done without _PutImage by redrawing over same screen area each loop.

Maybe I am missing something?