RAD Studio VCL Reference
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Forces the control to update.
procedure Update; override;
virtual __fastcall Update();
Update repaints any part of the control surface that is out of date. Normally, updates occur automatically, but an Update call may be necessary before lengthy processing that might interfere with automatic updates. Calling Update unnecessarily can increase overhead and cause screen flicker.
Update only repaints areas of the control the have been determined to be out of date. To force immediate repainting of the entire control, call the Repaint method. To notify a control that it is out of date (without forcing an immediate repaint), call the Invalidate method.
C++ Examples:
/* This example shows progress of loading forms as an application starts up. The code example is placed in the project source (*_proj.cpp) file. To see project source, right click on the executable file in the Project Manager and select the View Source menu item. You will need to set up your project with the following steps before using the code example: o Add four additional forms to a default project. o Place a TProgressBar on Form5 o Take the Project|Options|Forms menu option and place Form5 on the available forms list. o Change the code of your project (*_proj.cpp) file to look like the example. */ #include <vcl\vcl.h> #include "Unit5.h" #pragma hdrstop //--------------------------------------------------------------------------- USEFORM("TAppCreateForm.cpp", Form1); USERES("Project1.res"); USEFORM("Unit2.cpp", Form2); USEFORM("Unit3.cpp", Form3); USEFORM("Unit4.cpp", Form4); USEFORM("Unit5.cpp", Form5); //--------------------------------------------------------------------------- WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int) { try { Application->Initialize(); SetApplicationMainFormOnTaskBar(Application, true); Application->CreateForm(__classid(TForm5), &Form5); Form5->ProgressBar1->Max = 100; Form5->Show(); // show a splash screen contain ProgressBar control Form5->Update(); // force display of Form5 Application->CreateForm(__classid(TForm1), &Form1); Form5->ProgressBar1->StepBy(25); Form5->Label1->Caption = "Form1 loaded successfully."; Form5->Update(); // force display of Form5 Sleep(3000); Application->CreateForm(__classid(TForm2), &Form2); Form5->ProgressBar1->StepBy(25); Form5->Label1->Caption = "Form2 loaded successfully."; Form5->Update(); // force display of Form5 Sleep(3000); Application->CreateForm(__classid(TForm3), &Form3); Form5->ProgressBar1->StepBy(25); Form5->Label1->Caption = "Form3 loaded successfully."; Form5->Update(); // force display of Form5 Sleep(3000); Application->CreateForm(__classid(TForm4), &Form4); Form5->ProgressBar1->StepBy(25); Form5->Label1->Caption = "Form4 loaded successfully."; Form5->Update(); // force display of Form5 Sleep(3000); // delete Form5; Application->Run(); } catch (Exception &exception) { Application->ShowException(&exception); } return 0; }
Delphi Examples:
{ This example shows progress of loading forms as an application starts up. The code example is placed in the project source (*.dpr) file. To see project source, right click on the executable file in the Project Manager and select the View Source menu item. You will need to set up your project with the following steps before using the codeexample: Add four additional forms to a default project. Place a TProgressBar on Form5 Take the Project|Options|Forms menu option and place Form5 on the available forms list. Change the code of your project (*.dpr) file to look like the example. } begin Application.Initialize; with TForm5.Create(nil) do try Application.MainFormOnTaskbar := True; ProgressBar1.Max := 100; Show; // show a splash screen contain ProgressBar control Update; // force display of Form5 Application.CreateForm(TForm1, Form1); ProgressBar1.StepBy(25); Label1.Caption := 'Form1 loaded successfully.'; Update; // force display of Form5 Sleep(3000); Application.CreateForm(TForm2, Form2); ProgressBar1.StepBy(25); Label1.Caption := 'Form2 loaded successfully.'; Update; // force display of Form5 Sleep(3000); Application.CreateForm(TForm3, Form3); ProgressBar1.StepBy(25); Label1.Caption := 'Form3 loaded successfully.'; Update; // force display of Form5 Sleep(3000); Application.CreateForm(TForm4, Form4); ProgressBar1.StepBy(25); Label1.Caption := 'Form4 loaded successfully.'; Update; // force display of Form5 Sleep(3000); finally Free; end; Application.Run;
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