TImageEnView.ShowButtons

Declaration

property ShowButtons: TIEVButtons;

Description

Display Previous and/or Next buttons on the sides of the control (white chevrons).
Hovering over the left/right of the image will show a hint. Clicking will call OnButtonClick or perform a standard function.
You can specify the button color and size using ButtonParams.



Note:
◼The hover/clickable button area is the full height of the control, but the width of the button and offset
◼Use OnButtonState to specify an enabled/disabled state
◼You can use OnButtonClick to handle the click. If OnButtonClick is not specified, a default action will occur depending on the button type
◼To show buttons only when hovering over the click area, enable ImageEnView1.ButtonParams.OnlyOnHover
◼Hover hints can be disabled using EnableInteractionHints
◼iebtZoomIn and iebtZoomOut do not display at the same time. If both are specified, current zoom will determine which is shown
◼Before loading a new image, the OnBeforeLoadImage event will fire
◼If a new image is loaded due to a button click, the OnImageLoaded event will fire
◼Buttons will show automatically for the PdfViewer if iepoAutoButtons is specified for Options (enabled by default)

Default: [] (No buttons)

Available Buttons

Keyboard Shortcuts

If KeyboardShortcuts is enabled, the following shortcuts are supported:

Demos

Examples

// EXAMPLE 1: Show either Zoom In or Zoom Out depending on which is most relevant
ImageEnView1.ShowButtons := [ iebtZoomIn, iebtZoomOut ];


// EXAMPLE 2: Attach a TImageEnView to a TImageEnFolderMView and allow navigation by buttons on the TImageEnView and spinning the mouse wheel
IEFolderMView1.AttachedImageEnView := ImageEnView1;
ImageEnView1.ShowButtons := [ iebtPrevious, iebtNext ];
ImageEnMView1.MouseWheelParams.Action := iemwNavigate;
ImageEnView1.MouseWheelParams.Action  := iemwNavigate;


// EXAMPLE 3: Using buttons to navigate images in a TImageEnMView

// Select event of our TImageEnMView
procedure TForm1.ImageEnMView1ImageSelect(Sender: TObject; idx: Integer);
begin
  ImageEnView1.LockUpdate();

    // Show either Zoom In or Zoom Out depending on which is most relevant
    ImageEnView1.ShowButtons := [ iebtZoomIn, iebtZoomOut ];

    // Allow navigation
    ImageEnView1.ShowButtons := ImageEnView1.ShowButtons + [ iebtPrevious, iebtNext ];

  // Load Image
  if ImageEnMView1.SelectedFilename <> '' then
    ImageEnView1.IO.LoadFromFile( ImageEnMView1.SelectedFilename )
  else
    ImageEnView1.Blank;
  ImageEnView1.Fit( False );

  ImageEnView1.UnlockUpdate();
end;

// OnButtonClick event of our TImageEnView
procedure TForm1.ImageEnView1ButtonClick(Sender: TObject; Button: TIEVButton;
    MouseButton: TMouseButton; Shift: TShiftState; var Handled: Boolean);
begin
  case Button of
    iebtPrevious : begin
                     if ssShift in Shift then
                       ImageEnMView1.Seek( ieioSeekFirst )
                     else
                       ImageEnMView1.Seek( ieioSeekPrior );
                     ImageEnMView1ImageSelect(nil, 0); // Update preview and buttons
                   end;
    iebtNext     : begin
                     if ssShift in Shift then
                       ImageEnMView1.Seek( ieioSeekLast )
                     else
                       ImageEnMView1.Seek( ieioSeekNext );
                     ImageEnMView1ImageSelect(nil, 0); // Update preview and buttons
                   end;
    iebtZoomIn   : begin
                     if ImageEnView1.Zoom < ImageEnView1.GetIdealZoom() then
                       ImageEnView1.Zoom := ImageEnView1.GetIdealZoom()
                     else
                     if ImageEnView1.Zoom < 100 then
                       ImageEnView1.Zoom := 100;
                   end;
    iebtZoomOut  : begin
                     if ImageEnView1.Zoom > ImageEnView1.GetIdealZoom() then
                       ImageEnView1.Zoom := ImageEnView1.GetIdealZoom()
                     else
                     if ImageEnView1.Zoom > 100 then
                       ImageEnView1.Zoom := 100;
                   end;
  end;
end;

// OnButtonState event of our TImageEnView
procedure TImageEnMView.ImageEnView1ButtonState(Sender: TObject; Button: TIEVButton;
                                                var Visible: Boolean;
                                                var Enabled: Boolean);
begin
  case Button of
    iebtPrevious : Enabled := ImageEnMView1.SelectedImage > 0;
    iebtNext     : Enabled := ImageEnMView1.SelectedImage < ImageEnMView1.ImageCount - 1;
  end;
end;


// EXAMPLE 3: Using buttons to navigate pages of a multi-frame image, such as TIFF or GIF

procedure TMainForm.btnLoadClick(Sender: TObject);
begin
  if OpenImageEnDialog1.Execute then
  begin
    ImageEnView1.IO.Params.ImageIndex := 0;
    ImageEnView1.IO.LoadFromFile( OpenImageEnDialog1.FileName );
    UpdateStatus();
  end;
end;

procedure TMainForm.UpdateStatus();
var
  havePrev, haveNext: Boolean;
begin
  ImageEnView1.ButtonParams.Color := clSilver;
  ImageEnView1.ButtonParams.Size  := 30;

  havePrev := ( ImageEnView1.IO.Params.Filename <> '' ) and ( ImageEnView1.IO.Params.ImageIndex > 0 );
  haveNext := ( ImageEnView1.IO.Params.Filename <> '' ) and ( ImageEnView1.IO.Params.ImageIndex < ImageEnView1.IO.Params.ImageCount - 1 );

  if havePrev and haveNext then
    ImageEnView1.ShowButtons := [ iebtPrevious, iebtNext ]
  else
  if havePrev then
    ImageEnView1.ShowButtons := [ iebtPrevious ]
  else
  if haveNext then
    ImageEnView1.ShowButtons := [ iebtNext ]
  else
    ImageEnView1.ShowButtons := [];
end;

procedure TMainForm.ImageEnView1ButtonClick(Sender: TObject; Button: TIEVButton;
    MouseButton: TMouseButton; Shift: TShiftState; var Handled: Boolean);
begin
  Handled := False; // Let ImageEnView handle the navigation and zooming
  UpdateStatus();
end;

See Also

◼ButtonParams
◼TIEButtonInteraction
◼AttachedImageEnView
◼MouseWheelParams

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