Steema Central

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procedure TForm1.Chart1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
Chart1.ZoomRect(Rect(x-10,y-10,x+10,y+10));
end;

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procedure FitinViewExecute();
var
  chartWidth   : Integer;
  chartHeight  : Integer;
  screenWidth  : Integer;
  screenHeight : Integer;
  zoomWidth    : Integer;
  zoomHeight   : Integer;
  graphCenter  : TPoint;

begin
  chartWidth := teeTree1.TotalBounds.Right - teeTree1.TotalBounds.Left;
  chartHeight := teeTree1.TotalBounds.Bottom - teeTree1.TotalBounds.Top;
  screenWidth := teeTree1.Width;
  screenHeight := teeTree1.Height;
  zoomWidth := (screenWidth * 100) div chartWidth;
  zoomHeight := (screenHeight * 100) div chartHeight;
  if zoomWidth < zoomHeight then
  begin
    tttGraphic.View3DOptions.Zoom := Value;
  end
  else
  begin
    tttGraphic.View3DOptions.Zoom := Value;
  end;
  
  graphCenter.X := (teeTree1.TotalBounds.left +
                    (teeTree1.TotalBounds.Right -
                     teeTree1.TotalBounds.Left div 2));
  graphCenter.Y := (teeTree1.TotalBounds.Top  +
                    (teeTree1.TotalBounds.Bottom -
                     teeTree1.TotalBounds.Top div 2));

  //center the chart but only center the vert.  The horiz should stay at the top
  self.CenterImage(True, False);
end;

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  //the position of the View3DOptions to line up the left most object depends on the zoom level
  //and the width/height of the viewing area (chart.width/hight). The difference between the offset
  //position is liniar to the zoom when width/height of the chart is constant.  The offset at 100%
  //zoom is allways constant at x = -11 y = 1.  When the chart width/height is adjusted
  //the liniar zoom change is affected by some function f(x) & f(y).
  //f(x) = -11 - ((teeTree1.Width-40) /200)
  //f(y) = 1 - ((teeTree1.Height-40) /200)
  //the following is the known equasion.
  //HorizOffset := (-11) - f(x) * (100 - zoom))
  //VertOffset  := (1) - f(y) * (100 - zoom))
  //test results
  //Screen Width   liniar offset adjustment per Zoom %
  //100            0.3
  //200            0.8
  //300            1.3
  //400            1.8
  //500            2.3
  //600            2.8
  //700            3.3
  //800            3.8
  //900            4.3
  //1000           4.8

  //example width = 500 zoom = 85% offset := ((500-40)/200) * (100 - 85)

Code: Select all

procedure CenterImage(horiz, vert : Boolean);
var
  screenDistToCnt : TPoint;
  picDistToCnt    : TPoint; //center of the picture with zoom adjustment
  zoomShifts      : TPoint; //VHoriz and Vert offset for the left and top of the graph

begin
  zoomShifts.x := trunc(-11 - ((teeTree1.Width-40)/200) * (100 - teeTree1.View3DOptions.Zoom));
  zoomShifts.y := trunc(1 -   ((teeTree1.Height-40)/200) * (100 - teeTree1.View3DOptions.Zoom));

  picDistToCnt.x := Trunc((((teeTree1.TotalBounds.right *
                             teeTree1.View3DOptions.Zoom) / 100) / 2) -
                          teeTree1.TotalBounds.Left);
  picDistToCnt.y := Trunc((((teeTree1.TotalBounds.bottom *
                             teeTree1.View3DOptions.Zoom) / 100) / 2) -
                          teeTree1.TotalBounds.Top);

  screenDistToCnt.X := teeTree1.Width div 2;
  screenDistToCnt.Y := teeTree1.Height div 2;

  if horiz then
  begin
    teeTree1.View3DOptions.HorizOffset := zoomShifts.x - (picDistToCnt.x - screenDistToCnt.X);
  end
  else
  begin
    //adjust the horiz and vert offset to be at the left of the image
    teeTree1.View3DOptions.HorizOffset := zoomShifts.x;
  end;

  if vert then
  begin
    teeTree1.View3DOptions.VertOffset  := zoomShifts.y - (picDistToCnt.y - screenDistToCnt.Y);
  end
  else
  begin
    //adjust the horiz and vert offset to be at the top of the image
    teeTree1.View3DOptions.VertOffset  := zoomShifts.y;
  end;
end;