Lazarus
Programming => Graphics and Multimedia => Graphics => Topic started by: jbmckim on September 12, 2020, 09:48:38 pm
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I get using OnPrepareCanvas to change cell color. I do this successfully in a couple places.
What's confusing me is a slightly different requirement. I need to allow the user to remove an alarm state (stringgrid cell, red background) from a row by pushing a button. (Going cell by cell is fine. The UI requirement is a column but that can be done cell by cell.)
When this happens, there's no change to the cell value per se, just a change to the background. Therefore, OnPrepareCanvas doesn't fire. (The problem only occurs on reset as the initial alarm is thrown in response to a new value being added to the cell in question.)
Therefore, how do I change the background color without modifying cell value?
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Call StringGrid.Invalidate to enforce a redraw of the grid; as a consequence of this OnPrepareCanvas will be called for each cell before it is painted.
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Outstanding. Thanks.