Scrolling line graph

Code which produces a scrollable line graph in a graphicbox.

The original version ran too fast on a modern PC so I have made a small modification so that the scrolling speed is determined by the timer.

[[code format="lb"]]
nomainwin
WindowHeight = 350
WindowWidth = 550

graphicbox #main.graphicbox, 15, 15, 510, 290
open "experiment" for window as #main
print #main.graphicbox, "down; fill white"
print #main.graphicbox, "place 20 20"
print #main.graphicbox, "\Graph control:"
print #main.graphicbox, "place 20 40"
print #main.graphicbox, "\<<<          >>>"
print #main, "trapclose [quit]"
print #main.graphicbox, "when leftButtonDown [shift]"
print #main.graphicbox, "when leftButtonUp [null]"
print #main.graphicbox, "flush"

hWnd = hwnd(#main.graphicbox)

CallDLL #user32, "GetDC", hWnd As long, hDC As long

CallDLL #gdi32,"CreateCompatibleDC", hDC As long, memDC As long

calldll #gdi32, "CreateCompatibleBitmap", _
hDC As Long, _
3000 As Long, _
150 As Long, _
hBuffer as Long

CallDLL #gdi32,"SelectObject",_
memDC As long,_
hBuffer As long,_
oldObject As long

CallDll #gdi32, "GetStockObject", _WHITE_PEN as long, hpen as long

CallDll #gdi32, "SelectObject",_
memDC as long,_
hpen as long, _
Hpobj as long

struct Ppos,xlast as long, ylast as long
CallDll #gdi32, "MoveToEx",_
memDC as long,_
0 as long,_
0 as long,_
Ppos as struct,_
setstart as boolean

for traces = 1 to 100
stepper = traces * 30
dataplot = 10 + int(rnd(1)*60)
CallDll #gdi32, "LineTo",_
memDC as long,_
stepper as long,_
dataplot as long,_
linedone as boolean
next traces

dwRop = hexdec("00CC0020")
takefrom = 1400

call bitblock hDC, 160, 100, 300, 150, memDC, takefrom, 0, dwRop, breturnvalue

#main.graphicbox, "getbmp KeepIt 160 100 300 150";
#main.graphicbox, "drawbmp KeepIt 160 100; flush";

[null]
timer 0
wait

[shift]
timer 10, [tick]
wait

[tick]
if (MouseY>26 and MouseY<43) then
  if (MouseX>17 and MouseX<45) then goto [mleft]
  if (MouseX>83 and MouseX<108) then goto [mright]
end if
wait

[mright]
if (takefrom < 2700) then
  takefrom = takefrom + 1
  call bitblock hDC, 160, 100, 300, 150, memDC, takefrom, 0, dwRop, breturnvalue
end if
wait

[mleft]
if (takefrom > 0) then
  takefrom = takefrom - 1
  call bitblock hDC, 160, 100, 300, 150, memDC, takefrom, 0, dwRop, breturnvalue
end if
wait

sub bitblock destDC, tox, toy, wide, high, fromDC, fromx, fromy, variety, breturnvalue
calldll #gdi32, "BitBlt", _
destDC As Long, _
tox As Long, _
toy As Long, _
wide As Long, _
high As Long, _
fromDC As Long, _
fromx As Long, _
fromy As Long, _
variety As Long, _
result as Long
end sub

[quit]
CallDLL #gdi32, "DeleteDC",_
memDC As long,_
DCdeleted As Boolean
CallDll #user32, "ReleaseDC",_
hWnd as long,_
hDC as long,_
DCreleased as long
close #main
end
[[code]]