TImageEnView.PrepareTransition

Declaration

procedure PrepareTransition();

Description

PrepareTransition must be called prior to running a transition effect.
It copies the currently displayed image to an internal buffer, which allows you to change current image (load, update, etc.) before starting the transition with RunTransition.

Demos

	Demos\Display\Transitions\Transitions.dpr
	Demos\Display\PanZoomEffects\PanZoomEffects.dpr

Note:
◼An easier way to use display transition is just to set TransitionEffect
◼PrepareTransition() is optional when showing a Pan-Zoom (iettPanZoom) transition

Examples

// Transition from Image1.jpg to Image2.jpg with "Random Points" transition
ImageEnView1.IO.LoadFromFile('D:\image1.jpg');         // Load initial image
ImageEnView1.PrepareTransition();                      // Prepare the transition
ImageEnView1.IO.LoadFromFile('D:\image2.jpg');         // Load the next image (but does not display it)
ImageEnView1.RunTransition(iettRandompoints, 500);     // Execute the transition

// Set properties for Word transition
ImageEnView1.TransitionParams.WordTransWord      := 'BLAM';
ImageEnView1.TransitionParams.WordTransFontName := 'Arial';
ImageEnView1.TransitionParams.WordTransFontStyle := [fsBold];

// Prepare ImageEnView1 for a transition (e.g. so loading the image will not immediately update the display)
ImageEnView1.PrepareTransition();

// Load the next image
ImageEnView1.IO.LoadFromFile( GetNextImage() );

// Run the transition
ImageEnView1.RunTransition( iettRandomBoxesWithWord, 1000 );

// Slide Transition from old.bmp to new.bmp ensuring that both are shown as the same height
procedure TForm1.btnCompareClick(Sender: TObject);
const
  Display_Zoom = 100;
  Center_Image = True;
var
  bh: Integer;
  iz: Double;
begin
  // Get original image as transition start
  ImageEnView1.IO.LoadFromFile( ExtractFilePath( Application.ExeName ) + 'old.bmp' );
  ImageEnView1.Zoom := Display_Zoom;
  if Center_Image then
    ImageEnView1.CenterImage()
  else
   ImageEnView1.SetViewXY( 0, 0 );

  bh := ImageEnView1.IEBitmap.Height;
  iz := ImageEnView1.Zoom;
  ImageEnView1.PrepareTransition();

  // Load second image as transition result (Zoom to match display size of old image)
  ImageEnView1.IO.LoadFromFile( ExtractFilePath( Application.ExeName ) + 'new.bmp' );
  ImageEnView1.Zoom := iz / ( ImageEnView1.IEBitmap.Height / bh );
  if Center_Image then
    ImageEnView1.CenterImage()
  else
   ImageEnView1.SetViewXY( 0, 0 );

  // Run the transition
  ImageEnView1.TransitionParams.AlternativeStyle := True; // Include transition line
  ImageEnView1.TransitionParams.WipeLineColor := clYellow;
  ImageEnView1.RunTransition( iettRightLeft, 3000 );       // Wipe Right to Left
end;

TImageEnView.PrepareTransition