Delphi Form Minimize and Restore using Timer - delphi

Question

I am a delphi learner. I am having one Delphi Progect with "MainForm", "MinimizeTimer" and "RestoreTimer". I have defined the following codes.
Minimize Timer :
if MainForm.AlphaBlendValue >= 225 then
begin
MinimizeTimer.Enabled := true;
MainForm.AlphaBlendValue := MainForm.AlphaBlendValue - 5;
end;
Restore Timer :
if MainForm.AlphaBlendValue >= 0 then
begin
RestoreTimer.Enabled := true;
MainForm.AlphaBlendValue := MainForm.AlphaBlendValue + 5;
end;
My requirement is that the MainForm will be first fadeout using "MinimizeTimer" and then will be minimized when "_" Button on Caption Bar is pressed. And also be fadein using "RestoreTimer" and then will be restored after clicking on taskbar. So I defined again the following codes:
private
{ Private declarations }
procedure WMSysCommand(var Msg: TWMSysCommand) ; message WM_SYSCOMMAND;
..
..
..
..
..
procedure TMainForm.WMSysCommand(var Msg: TWMSysCommand) ;
begin
if Msg.CmdType = SC_MINIMIZE then MinimizeTimer.Enabled := true;
DefaultHandler(Msg);
if Msg.CmdType = SC_RESTORE then RestoreTimer.Enabled := true;
DefaultHandler(Msg);
end;
But I am not getting the expected result. The MainForm is Minimized and Restored as in regular way. Please remember in my project I have one "FormCloseQuery" event also.
Please help me.

Answer 1

You are using the wrong logic for your requirements. Try this instead:
procedure TMainForm.MinimizeTimerTimer(Sender: TObject);
begin
if AlphaBlendValue > 0 then
begin
AlphaBlendValue := AlphaBlendValue - 5;
end
else
begin
MinimizeTimer.Enabled := False;
Perform(WM_SYSCOMMAND, SC_MINIMIZE, 0);
end;
end;
procedure TMainForm.RestoreTimerTimer(Sender: TObject);
begin
if AlphaBlendValue < 255 then
begin
AlphaBlendValue := AlphaBlendValue + 5;
end else begin
RestoreTimer.Enabled := False;
end;
end;
procedure TMainForm.WMSysCommand(var Msg: TWMSysCommand);
begin
case Msg.CmdType of
SC_MINIMIZE: begin
if AlphaBlendValue > 0 then
begin
MinimizeTimer.Enabled := True;
Exit;
end;
end;
SC_RESTORE: begin
if AlphaBlendValue < 255 then begin
RestoreTimer.Enabled := True;
end;
end;
end;
inherited;
end;