TcxCustomEditProperties.BeginUpdate Method

Postpones all editor redraw operations that reflect any editor setting change until an EndUpdate procedure call.

Declaration

procedure BeginUpdate;

Remarks

Every time you change an editor setting, the editor redraws its content to reflect the change. Enclose multiple editor setting changes between BeginUpdate and EndUpdate procedure calls to avoid UI flickering due to excessive redraw operations and improve performance.

BeginUpdate/EndUpdate Calls and Batch Changes

A BeginUpdate procedure call disables notifications and postpones all changes until an EndUpdate call. A subsequent EndUpdate call does the following:

• Re-enables change notifications and corresponding redraw operations
• Applies all changes made after a BeginUpdate call
• Sends corresponding notifications in a batch and raises the OnPropertiesChanged event
• Redraws the editor

Note

Ensure that every BeginUpdate procedure call is followed by an EndUpdate procedure call, even if an exception occurs. Otherwise, the editor remains frozen and unresponsive.

Code Example

The code example below demonstrates OnButtonClick and OnCreate event handlers.

The application form’s OnCreate event handler creates two additional embedded buttons in a TcxButtonEdit control and configures the appearance and behavior of all embedded buttons. The OnButtonClick event handler associates all created buttons with the editor’s functionality.

Note

This example uses a TcxImageList component with three SVG icons as a source of glyphs for the created buttons.

Delphi

procedure TMyForm.cxButtonEdit1PropertiesButtonClick(Sender: TObject;
  AButtonIndex: Integer);
var
  AEditor: TcxButtonEdit;
begin
  AEditor := Sender as TcxButtonEdit;
  if AButtonIndex = 0 then  // The first button clears the editor
    AEditor.Clear
  else if AButtonIndex = 1 then  // The second button selects content
    AEditor.SelectAll
  else if AButtonIndex = 2 then  // The third button hides or reveals content
  begin
    if AEditor.Properties.EchoMode = eemNormal then
      AEditor.Properties.EchoMode := eemPassword
    else
      AEditor.Properties.EchoMode := eemNormal;
  end;
end;

procedure TMyForm.FormCreate(Sender: TObject);
var
  AProperties: TcxButtonEditProperties;
  I: Integer;
begin
  cxButtonEdit1.ShowHint := True;  // Enables hints for the editor
  AProperties := cxButtonEdit1.Properties;
  AProperties.BeginUpdate;  // Initiates the following batch change
  try
    AProperties.Images := cxImageList1;  // Assigns the source of button glyphs
    // Create two additional buttons
    AProperties.Buttons.Add;
    AProperties.Buttons.Add;
    // Specify common button settings
    for I := 0 to AProperties.Buttons.Count - 1 do
    begin
      AProperties.Buttons.Items[I].Kind := bkGlyph;  // Changes the button content type to "glyph"
      AProperties.Buttons.Items[I].ImageIndex := I;  // Specifies image indexes in the source list
      AProperties.Buttons.Items[I].HotTrackMode := TcxEditButtonHotTrackMode.Editor;
    end;
    // Specify unique button settings
    AProperties.Buttons.Items[0].Hint := 'Clear';
    AProperties.Buttons.Items[1].Hint := 'Select All';
    AProperties.Buttons.Items[2].Hint := 'Hide/Reveal';
    AProperties.Buttons.Items[2].LeftAlignment := True;
    AProperties.Buttons.Items[2].Transparent := True;
  finally
    AProperties.EndUpdate;  // Calls EndUpdate regardless of the batch operation's success
  end;
end;

C++

void __fastcall TMyForm::cxButtonEdit1PropertiesButtonClick(TObject *Sender,
   int AButtonIndex)
{
  TcxButtonEdit *AEditor = dynamic_cast<TcxButtonEdit*>(Sender);
  // ...
  if(AButtonIndex == 0)  // The first button clears the editor
    AEditor->Clear();
  else if(AButtonIndex == 1)  // The second button selects content
    AEditor->SelectAll();
  else if(AButtonIndex == 2)  // The third button hides or reveals content
  {
    if(AEditor->Properties->EchoMode == eemNormal)
      AEditor->Properties->EchoMode = eemPassword;
    else
      AEditor->Properties->EchoMode = eemNormal;
  }
}

void __fastcall TMyForm::FormCreate(TObject *Sender)
{
  TcxButtonEditProperties *AProperties = cxButtonEdit1->Properties;
  cxButtonEdit1->ShowHint = true;  // Enables hints for the editor
  AProperties->BeginUpdate();  // Initiates the following batch change
  try
  {
    AProperties->Images = cxImageList1;  // Assigns the source of button glyphs
    // Create two additional buttons
    AProperties->Buttons->Add();
    AProperties->Buttons->Add();
    // Specify common button settings
    for(int i = 0; i < AProperties->Buttons->Count; i++)
    {
      AProperties->Buttons->Items[i]->Kind = bkGlyph;  // Changes the button content type to "glyph"
      AProperties->Buttons->Items[i]->ImageIndex = i;  // Specifies image indexes in the source list
      AProperties->Buttons->Items[i]->HotTrackMode = TcxEditButtonHotTrackMode::Editor;
    }
    // Specify unique button settings
    AProperties->Buttons->Items[0]->Hint = "Clear";
    AProperties->Buttons->Items[1]->Hint = "Select All";
    AProperties->Buttons->Items[2]->Hint = "Hide/Reveal";
    AProperties->Buttons->Items[2]->LeftAlignment = true;
    AProperties->Buttons->Items[2]->Transparent = true;
  }
  __finally
  {
    AProperties->EndUpdate();  // Calls EndUpdate regardless of the batch operation's success
  }
}