Modal Form doesn't close.
Eshwar
read a primer on how to use modal forms, understood it well to write
my code. I can open the form, but when i click the title bar exit
button it doesn't close. I want the modal form, which is Form2 to exit
and Form1 the mainform to remain.
Then i used a button to exit, wrote like Application.Terminate; or
Form2.Close or Form2.hide, Form2.Destroy, it throws an exception :(
I attach the Form1 procedure, from which i call the modal form, Form2,
below:
procedure TForm1.sLabel3Click(Sender: TObject);
var
f:Tform2;
begin
f := Tform2.Create(nil);
try
f.ShowModal;
finally
f.Release;
end;
end;
Its a label, clicking that opens the Form2
Here is the full code of Form2, its a code to get cpu usage per core
in a progress bar. Its in Delphi 7
===============================================================================
unit Unit2;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls,
Forms,
Dialogs, StdCtrls, JwaWindows, ExtCtrls, ComCtrls, Gauges;
type
TForm2 = class(TForm)
Timer33: TTimer;
StopBtn: TButton;
procedure FormCreate(Sender: TObject);
procedure Timer33Timer(Sender: TObject);
procedure StopBtnClick(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
TCounter = record
Path : string;
Handle : cardinal;
mLabel : TLabel;
mGauge : TGauge;
end;
var
Form2: TForm2;
Counters : array of TCounter;
Query : Cardinal = 0;
implementation
{$R *.dfm}
procedure TForm2.FormCreate(Sender: TObject);
var
dwSize, h : cardinal;
cnt, i : Integer;
pPaths:PAnsiChar;
pIterator:PAnsiChar;
InstanceId, CounterPath : string;
status : PDH_STATUS;
begin
//Create a performance query
if PdhOpenQuery(nil, 0, Query) = ERROR_SUCCESS then begin
//Get all valid processor/core usage counter paths by expanding
//a wildcard path. To do this, we must first call
PdhExpandWildCardPath
//with buffer size set to zero to get the actual required buffer
size.
dwSize := 0;
pPaths := nil;
status := PdhExpandWildCardPath(
nil, //search the local
computer
'\Processor(*/*#*)\% Processor Time', //we want CPU usage
counters for all CPUs/cores
pPaths, //user-allocated buffer;
currently null
dwSize, //buffer size
0) ; //no flags
if status = PDH_MORE_DATA then begin
dwSize := dwSize + 1; //+1 byte required in XP and below.
pPaths := GetMemory(dwSize); //Allocate an output buffer.
//Really get the counter paths.
status := PdhExpandWildCardPath(
nil,
'\Processor(*/*#*)\% Processor Time',
pPaths,
dwSize,
0) ;
if status = ERROR_SUCCESS then begin
cnt := 0;
SetLength(Counters, 32);
//PdhExpandWildCardPath returns the counter list (pPaths) as
an array
//of null-terminated strings where the last item is a zero-
length
//string (i.e. just #0). We'll now iterate over this list with
some
//simple pointer math.
pIterator := pPaths;
while (strlen(pIterator)>0) do begin
CounterPath := pIterator;
pIterator := pIterator + Length(pIterator) + 1;
//Find the counter instance ID (the part in parentheses)
i := Pos('(', CounterPath);
InstanceId := Copy(CounterPath, i+1, Pos(')', CounterPath)-
i-1);
//Skip the counter if it indicates the overall CPU usage,
//we only want the per-core values.
if InstanceId = '_Total' then continue;
//Add the counter to the query
status := PdhAddCounter(Query, PAnsiChar(CounterPath), 0,
h);
if status = ERROR_SUCCESS then begin
//Expand the internal counter array if necessary
if cnt > Length(Counters)-1 then
SetLength(Counters, Length(Counters)+16);
//Save the counter data to the array
with Counters[cnt] do begin
Path := CounterPath;
Handle := h;
//Create a label for this core/CPU
mLabel := TLabel.Create(Self);
mLabel.Parent := Self;
mLabel.Caption := 'Core '+InstanceId;
mLabel.Top := (mLabel.Height + 8) * cnt + 10;
mLabel.Left := 10;
mLabel.AutoSize := false;
mLabel.Width := 80;
//Create a "progress bar" to show the core/CPU usage
mGauge := TGauge.Create(Self);
mGauge.Parent := Self;
mGauge.Top := mLabel.Top;
mGauge.Left := mLabel.Width + 20;
mGauge.Height := mLabel.Height+2;
mGauge.Width := Self.ClientWidth - mGauge.Left - 10;
mGauge.ForeColor := $0031D329;
mGauge.Anchors := [akRight, akLeft, akTop];
end;
inc(cnt);
end;
end;//while
//Truncate the array to the actual number of discovered cores
SetLength(Counters, cnt);
//Collect the first data sample
PdhCollectQueryData(Query);
end;
end;
end;
//Did we get any valid counters?
if Length(Counters) = 0 then begin
//Nope. Show an unhelpful error message...
MessageBox(Handle, 'Initialization was unsuccessful. The
application will now exit.',
'Error', MB_OK or MB_ICONEXCLAMATION);
//...and quit.
Application.Terminate;
end else begin
//Everything went well.
//Resize the form to make sure all progress bars are visible.
Self.ClientHeight :=
Counters[Length(Counters)-1].mLabel.Top +
Counters[Length(Counters)-1].mLabel.Height +
Counters[0].mLabel.Top + 20;
StopBtn.Top := Self.ClientHeight - 25;
end;
end;
procedure TForm2.Timer33Timer(Sender: TObject);
var
i:integer;
counterType: PDword;
pValue:_PDH_FMT_COUNTERVALUE;
status : cardinal;
begin
if Query = 0 then exit;
//Collect a data sample.
PdhCollectQueryData(Query);
//Iterate over all counters and update progress bars.
for i := 0 to Length(Counters) - 1 do begin
counterType := nil;
//Get the current core/CPU usage
status := PdhGetFormattedCounterValue(
Counters[i].Handle, //Counter handle as returned by
PdhAddCounter.
PDH_FMT_DOUBLE, //Get the counter value as a double-
precision float.
CounterType, //Counter type; unused.
pValue); //Output buffer for the counter value.
//Update the progress bar.
if status = ERROR_SUCCESS then
Counters[i].mGauge.Progress := Round(pValue.doubleValue);
end;
end;
procedure TForm2.StopBtnClick(Sender: TObject);
begin
//Close the query when quitting.
if Query <> 0 then PdhCloseQuery(Query);
ModalResult:=mrAbort;
Form2.Close;
end;
end.
==================================================================
it uses JwaWindows, a Jedi windows API component which is free
available at : http://jedi-apilib.sourceforge.net/
Any ideas how to close the Form2?
Thanks
Esh