Hi,

See this Image:



I can zoom the diagram with ZoomIn and ZoomOut methods.

With ZoomIn I obtain this result (I can't see the selection anymore because the chart zooms on top left corner):



I want that Zoom "centers" on selected node, as shown in the following image:



Any hints?

It helped partially because the function zooms on the middle of the screen, while I need to zoom on a particular selected item (box, arrow or table)

However with your hints, I was able to write a function that does something similar but I've the problem that the object appears on top-left of the screen after Zooming.

This is the code (Delphi):

procedure btnNewZoomInClick;
var
    widthPixels, heightPixels: Single;
    H:HDC;
    centerBeforeZoomX,centerBeforeZoomY,
    centerAfterZoomX,centerAfterZoomY,
    FigureX, FigureY,
    LeftFig,RightFig,TopFig,BottomFig :Integer ;


begin
if fcx.ActiveItemType = aiNone then
  begin
    fcx.ZoomFactor := fcx.ZoomFactor +25;
  end
else
  begin
    H:= GetDC(0);
    widthPixels := GetDeviceCaps(H,HORZRES) ;
    heightPixels := GetDeviceCaps(H,VERTRES) ;

    fcx.ClientPtToDocPt(round(widthPixels/2),round(heightPixels/2),
		  centerBeforeZoomX, centerBeforeZoomY);

    fcx.ZoomFactor := fcx.ZoomFactor +25;

    if fcx.ActiveItemType = aiTable then
	fcx.ActiveTable.BoundingRect(LeftFig,TopFig,RightFig,BottomFig);

    if fcx.ActiveItemType = aiArrow then
	fcx.ActiveArrow.BoundingRect(LeftFig,TopFig,RightFig,BottomFig);

    if fcx.ActiveItemType = aiBox then
	fcx.ActiveBox.BoundingRect(LeftFig,TopFig,RightFig,BottomFig);

    fcx.ClientPtToDocPt(round(widthPixels/2),round(heightPixels/2),
		  centerAfterZoomX, centerAfterZoomY);

    //I get the "middle" of currently selected object...
    FigureX := (LeftFig+RightFig) div 2;
    FigureY := (TopFig+BottomFig) div 2;

    // old code:
    //    fcx.ScrollX := fcx.ScrollX + centerBeforeZoomX - centerAfterZoomX;
    //    fcx.ScrollY := fcx.ScrollY + centerBeforeZoomY - centerAfterZoomY;

    //I'm trying to scroll the chart: where am I wrong?
    fcx.ScrollX := FigureX - (centerBeforeZoomX- centerAfterZoomX );
    fcx.ScrollY := FigureY - (centerBeforeZoomY- centerAfterZoomY );

  end;

end;
 

this is what I get:

BEFORE Zooming:


AFTER Zooming:

(It's Wrong because selected box is not on the center of the screen)

Probably I'm wrong on the last two lines of the code, can you help me?

Thanks

Well, It works... but because I took the screen size instead of the document size, the box is not perfectly at the center of the screen.

Unfortunately it seems there aren't the ScaleX/ScaleY functions in Delphi and I didn't find an alternative method to get the document size.

Any hints?

Thank you in advance!

it seems that works just calling the following code:

widthPixels := fcx.Width;
heightPixels := fcx.Height;
 

more simple than I thought... I hope it continues to work well in other tests