Difference between revisions of "Testing, if form exists"
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Use CloseACtion := caFree in the form onClose event. | Use CloseACtion := caFree in the form onClose event. | ||
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Revision as of 21:58, 18 November 2013
Sometimes a form may be launched from several places in a program. If it already exists, it only needs to be brought to the front. If not, it needs to be created.
One way to do this is to use a global boolean variable which is set to true or false as the form is created or destroyed.
Another way is to use a function as below.
These functions are copied from Wiki discussions.
How to list all data modules opened in an Application? [1]
function FindForm(const aClass:TClass):TForm;
var
I: Integer;
begin
for I := 0 to Screen.FormCount -1 do
if Screen.Forms[vCnt].ClassType = aClass then begin
Result := Screen.Forms[I];
Break;
end;
end;
Call it with:
if FindForm(TMyForm) <> nil then MyForm.Show
else
begin
MyForm := TMyForm.Create(Application);
MyForm.Show;
end;
Use CloseACtion := caFree in the form onClose event.