[Lazarus] Drawing memo text in DBGrid - tried but stuck
Reinier Olislagers
reinierolislagers at gmail.com
Fri Sep 16 08:06:55 CEST 2011
Hi all,
I'm trying to draw text from DBF memo fields on a dbgrid instead of the
standard "(Memo)".
The memo fields contain text data that is probably not that long (about
a couple of thousand characters max), which I'd like to display in a
read-only dbgrid.
I've come up with some code that:
1. Still correctly displays an integer field
2. Does not seem to write anything in memo cells (cells are blank)
I suppose I have to manually refresh the grid contents somehow because
.DefaultDrawing is false? But why are the integer fields then displayed
correctly? So it must be something in my code below, I suppose.
Thanks for any hints.
The complete project can be found at
https://bitbucket.org/reiniero/db2securityscript/downloads (to run it,
please import the file db2secout.txt that can be found on that download
page as well)
The code I have now is:
procedure TForm1.ResultsGridDrawColumnCell(Sender: TObject; const Rect:
TRect;
DataCol: Integer; Column: TColumn; State: TGridDrawState);
// Draw memo text instead of (Memo)
// Note: grid DefaultDrawing property must be off to avoid duplicate drawing
// To get this, I basically copied the existing DefaultDrawColumnCell
procedure
// but tested for memo first. If no memo, pass on to default procedure.
// Maybe slower, more complicated, but it allows for changes in the
// core Lazarus DefaultDrawColumnCell procedure.
var
OverrideDraw: boolean; //determine if we're going to override drawing
S: string;
F: TField;
DataRow: Integer;
begin
OverrideDraw:=false;
try
F := Column.Field;
if F.DataType = ftMemo then
begin
OverRideDraw:=true;
end;
except
on E: exception do
begin
// We might have an inactive datalink or whatever,
// in that case, pass on our problems to the existing
// procedure.
//showMessage('Exception: ' + E.Classname + '/' + E.Message);
OverRideDraw:=false;
end;
end;
if OverRideDraw=false then
begin
// Call normal procedure to handle drawing for us.
ResultsGrid.DefaultDrawColumnCell(Rect,DataCol,Column,State);
end
else
begin
// Get to work displaying our memo contents
// Basically shamelessly ripped from
// DefaultDrawColumnCell
// maybe fix something for first/header row
if F<>nil then
begin
//DO display memo ;)
S := F.AsString; //DisplayText will only show (Memo)
end
else
begin
S := '';
end;
//Actual drawing, taken from Grids.DrawCellText coding:
ResultsGrid.Canvas.TextRect(Rect,Left,Top, S);
end;
end;
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