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Deleting and erasing lines [message #10484]

Thu, 11 December 1997 00:00

Andrew A. Baker
Messages: 2
Registered: December 1997

Junior Member

Hello,

I'm a fairly new user of pv-wave and I'm trying to do something which
I am sure will be very simple to more experienced pv-wave users.

I wish to draw a line on top of an image which follows the cursor as
the mouse is moved and continously updates the line on the screen
(after, of course, an initial point has been chosen). Drawing the
line is easy using PLOTS, but how do I erase it and leave the original
image intact? I don't wish to redraw the entire image, of course, for
speed reasons.

The best method that I know from other programming endeavours is to use
XOR (exclusive-OR), so that the colour drawn depends on the colour
already there and reversal (i.e. erasing the line) is then a trivial
process. I don't need a line of one colour only, so is there a way of
doing non-absolute colours? Or is there a better way?

Thanks in advance for any help.

Andy.

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Email: andy.baker@bristol.ac.uk H.H. Wills Physics Laboratory
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+44 (0)117 928 8747 (lab/messages) Bristol
Fax: +44 (0)117 925 5624 BS8 1TL
Web: http://teddy.phy.bris.ac.uk/~phaab/ UNITED KINGDOM
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[Message index]

		Deleting and erasing lines By: Andrew A. Baker on Thu, 11 December 1997 00:00
		Re: Deleting and erasing lines By: Andrew A. Baker on Fri, 12 December 1997 00:00
		Re: Deleting and erasing lines By: hegde on Thu, 11 December 1997 00:00

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