Phil, I didn't see your message before posting my follow-up message. Appreciate the feedback. Jeremy Walsh > > I am using textout() to write text to the canvas of a TChart which > > works fine, except that when a redraw occurs (e.g. when resizing > > the form) the text disappears. I have struck similar behaviour > > when writing to the canvas of a form, though I also have some test > > code from the Delphi 4 Developers Guide which appears basically > > the same and which works fine. > > > > Am I missing something e.g. a parameter setting somewhere? > > Technique perhaps?? You have set up your Onrepaint handler so it can restore the > canvas completely. This means knowing some sort of "state" about how your canvas > should look. I generally have my screen drawing in a routine called from > OnPaint. When I wont to add something to the canvas, I modify the mechanism > by which I store State and then invalidate the rectangle on canvas where it is to > appear. As to how you store "state" then that depends on application. Rude and > crude would be to have all drawing to a bitmap and have OnPaint copy the > invalidated part of screen from the bitmap. In a CAD/GIS type application, you > would query your drawing/database structure to get the objects to redraw. OnPaint > handlers generally need some mechanism to look at what part of screen is > invalid and then just needs to be redrawn. > > ---------------------------------------------------------- > Phil Scadden, Institute of Geological and Nuclear Sciences > PO Box 30368, Lower Hutt, New Zealand > Ph +64 4 5704821, fax +64 4 5704603 > --------------------------------------------------------------------------- > New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] > Website: http://www.delphi.org.nz > =========================================================== Jeremy Walsh National Institute of Water and Atmospheric Research PO Box 8602 Riccarton Christchurch New Zealand 64-3-3437877 Phone 64-3-3485548 Fax [EMAIL PROTECTED] email =========================================================== --------------------------------------------------------------------------- New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED] Website: http://www.delphi.org.nz
