TImageEnView.OnLayerNotify

Declaration

property OnLayerNotify: TIELayerNotify;

Description

Occurs whenever layer actions occur, e.g selecting, moving or resizing. This event only fires on user actions (not programmatic changes).

OnLayerNotify and OnLayerNotifyEx are the same, except that OnLayerNotifyEx returns extra events where the layer index may be invalid (for layers that are not yet created or have already been removed). For example, with the ielBeginCreating event, the layer index will be -1.
With OnLayerNotify, the layer index is guaranteed to be valid because it skips any events for invalid layers. For events that are returned by OnLayerNotify, the layer index will be the same as OnLayerNotifyEx.
The following events do not occur with OnLayerNotify: ielBeginResizing, ielBeginRotating, ielBeginMoving, ielBeginCreating

Demo

Demos\LayerEditing\StampTextAndShapes\StampLayers.dpr

Examples

// Log all resizing of layers
procedure TfrmMain.IEView1LayerNotify(Sender: TObject; layer: integer; event: TIELayerEvent);
var
  ALayer: TIELayer;
  i: Integer;
  sChangedLayers: string;
begin
  if event = ielResized then
  begin
    sChangedLayers := '';
    for i := 0 to IEView1.LayersCount - 1 do
    begin
      ALayer := IEView1.Layers[ I ];
      if ( ALayer.Locked = False ) and ALayer.Selected then
        sChangedLayers := sChangedLayers + IntToStr( i ) +',';
    end;
    if sChangedLayers <> '' then
    begin
      SetLength( sChangedLayers, Length( sChangedLayers ) - 1 ); // Remove final comma
      memLog.Lines.Add( 'Layers Resized: ' + sChangedLayers );
    end;
  end;
end;

// Auto-size text only after rotation
procedure TMainForm.ImageEnView1LayerNotify(Sender: TObject; layer: Integer;
    event: TIELayerEvent);
begin
  if ( ImageEnView1.Layers[ layer ] is TIETextLayer ) and ( event is ielRotated ) then
  begin
    TIETextLayer( ImageEnView1.Layers[ layer ]).SizeToText();
    ImageEnView1.Update();
  end;
end;

// Automatically merge added layers to the background (e.g. "Select to draw" shapes onto image)
procedure Tfmain.ImageEnView1LayerNotify(Sender: TObject; layer: Integer; event: TIELayerEvent);
begin
  if AutoMergeLayers and ( layer >= 0 ) and ( layer < ImageEnView1.LayersCount ) then // Ensure it is a valid layer
  begin
    // For text layers with automatic text editing (loAutoTextEditing in LayerOptions) don't merge till we complete editing
    if (( ImageEnView1.Layers[layer].Kind = ielkText ) and ( event = ielEdited )) or
       (( ImageEnView1.Layers[layer].Kind <> ielkText ) and ( event = ielCreated )) then
      ImageEnView1.LayersMerge( 0, layer );
  end;
end;

// Prevent user from entering too much text
procedure Tfmain.ImageEnView1LayerNotify(Sender: TObject; layer: Integer; event: TIELayerEvent);
const
  Maximum_Text_Length = 10;
var
  editor: TIEEdit;
  pos: Integer;
  s: string;
begin
  if ( Maximum_Text_Length > 0 ) and ( event = ielTextEditorChange ) then
  begin
    if ImageEnView1.LayersTextEditor is TIEEdit then
    begin
      editor := TIEEdit( ImageEnView1.LayersTextEditor );
      if Length( editor.Text ) > Maximum_Text_Length then
      begin
        pos := editor.SelStart;
        s := editor.Text;
        SetLength( s, Maximum_Text_Length );
        editor.Text := s;
        editor.SelStart := pos;
      end;
    end;
  end;
end;

TImageEnView.OnLayerNotify