Keep Zoom on Custom axes

[Tenaris]

Hi, I am using webchart, I have some custom Y axes, when I zoom in on the chart I make the follow in my CheckZoom function:

Code: Select all

...

for (int c = 0; c < this.CurvesWebChart.Chart.Axes.Custom.Count; c++)
{
     Axis axis = this.CurvesWebChart.Chart.Axes.Custom[c];
     double y1 = axis.CalcPosPoint(this.CurvesWebChart.Chart.Zoom.y1);
     double y0 = axis.CalcPosPoint(this.CurvesWebChart.Chart.Zoom.y0);
     axis.SetMinMax(y1, y0);
}

...

When I press a button and the page raise a postback, in my CheckZoom function I always get "0" in y1 and y0.

How can I keep the zoom when I press a button?

Thank you in advance.

[Sandra]

Hello Ternaris,

I recommend you that take a look in TeeChart ASP.net Demo concretely in Interacting with Charts\Zooming\Zoming on WebForm. If you have any problems, please let me know.

Thanks,

[Tenaris]

Hello Sandra,

I saw your Demo but It doesn't use custom axes. I use custom axes with automatic size, Do you have an example with custom axes?

Thank you.

[Sandra]

Hello Ternaris,

You need know that if you work with WebChart and you want do zoom you have to use ZoomTool, so you always need utilize properties of ZoomTool. I have made a simple example that use custom axis and ZoomTool and save the states of zoom to doesn't lose these and I think you can do something as next:

Code: Select all

bool zoomed;
    Steema.TeeChart.Styles.FastLine series1, series2, series3;
    Steema.TeeChart.Axis bottomAxis1, bottomAxis2, bottomAxis3;
    Steema.TeeChart.Tools.ZoomTool tool1;
    System.IO.MemoryStream tmpChart;
    protected void Page_Load(object sender, System.EventArgs e)
    {
        Steema.TeeChart.Chart ch1 = WebChart1.Chart;
        tmpChart = new System.IO.MemoryStream();
        if (Session["ch1"] == null)
        {
            ch1 = WebChart1.Chart;
            ch1.AutoRepaint = false;
            ch1.Aspect.View3D = false;
            tool1 = new Steema.TeeChart.Tools.ZoomTool(WebChart1.Chart);
            tool1.ZoomPenColor = System.Drawing.Color.OliveDrab;
            ch1.Panel.Gradient.Visible = false;
            ch1.Walls.Visible = false;

            series1 = new FastLine(ch1);
            series2 = new FastLine(ch1);
            series3 = new FastLine(ch1);

            series1.FillSampleValues();
            series2.FillSampleValues();
            series3.FillSampleValues();

            Steema.TeeChart.Axis bottomAxis = ch1.Axes.Bottom;
            bottomAxis1 = bottomAxis.Clone() as Steema.TeeChart.Axis;
            bottomAxis1.StartPosition = 0;
            bottomAxis1.EndPosition = 25;
            bottomAxis2 = bottomAxis.Clone() as Steema.TeeChart.Axis;
            bottomAxis2.StartPosition = 30;
            bottomAxis2.EndPosition = 55;
            bottomAxis3 = bottomAxis.Clone() as Steema.TeeChart.Axis;
            bottomAxis3.StartPosition = 60;
            bottomAxis3.EndPosition = 85;

            //series1.CustomHorizAxis = bottomAxis1;
            ch1.Axes.Bottom.EndPosition = 25;

            series2.CustomHorizAxis = bottomAxis2;
            series3.CustomHorizAxis = bottomAxis3;
            ch1.Panel.MarginBottom = 10;
            ch1.Export.Template.IncludeData = true;
            ch1.Export.Template.Save(tmpChart);
            //save template to a Session variable
            Session.Add("ch1", tmpChart);
        }
        else
        {
            //retrieve the session stored Chart
            tmpChart = (System.IO.MemoryStream)Session["ch1"];
            //set the Stream position to 0 as the last read/write
            //will have moved the position to the end of the stream
            tmpChart.Position = 0;
            //import saved Chart
            WebChart1.Chart.Import.Template.Load(tmpChart);
            CheckZoom(WebChart1);
            WebChart1.Chart.Invalidate();
        }

    }
    private void CheckZoom(Steema.TeeChart.Web.WebChart WebChart1)
        {
            Steema.TeeChart.Chart ch1 = WebChart1.Chart;

            System.Collections.ArrayList zoomedState = (System.Collections.ArrayList)Session[WebChart1.ID +  "Zoomed"];
            zoomedState = ((Steema.TeeChart.Tools.ZoomTool)WebChart1.Chart.Tools[0]).SetCurrentZoom(Request,
                zoomedState);
            if (zoomedState == null)
            {
                Session.Remove(WebChart1.ID  +"Zoomed");
                zoomed = false;
                for (int i = 0; i < WebChart1.Chart.Series.Count; i++ )
                {
                    if (ch1[i].GetVertAxis.IsCustom())
                    {
                        ch1[i].CustomHorizAxis.Automatic = true;
                    }
                }
            }

            else
            {
                Session.Add(WebChart1.ID  + "Zoomed", zoomedState);
                zoomed = true;

                for (int i = 0; i < ch1.Series.Count; i++ )
                {
                    Steema.TeeChart.Axis axis = ch1[i].GetHorizAxis;
                    if (axis.IsCustom())
                    {
                                             
                        axis.SetMinMax(ch1.Axes.Bottom.Minimum, ch1.Axes.Bottom.Maximum);
                    }
                }

            }
        }
    protected void Button1_Click(object sender, EventArgs e)
    {
        WebChart1.AutoPostback=true;
    }

Could you tell if previous code help you to find a good solution?

Thanks,

[Tenaris]

Hello Sandra, Thank you for your example, It works great.

I have the problem that each Y custom axis has different scale, and I can not use the Minimum and Maximum value of a specific axis as you do in your example...

Code: Select all

...
axis.SetMinMax(ch1.Axes.Bottom.Minimum, ch1.Axes.Bottom.Maximum);
...

Another problem is that I use a button to add or remove series from the chart (and maybe add or remove axes), here is when I have problems to keep the zoom because when I call CheckZoom() in button_Click() I always get "0" in y1 and y0, However, if I call CheckZoom() in chart_AfterDraw() I get the correct values for y1 and y0, but the y-axes don't rescale.

This is part of my CheckZoom():

Code: Select all

...
for (int c = 0; c < this.CurvesWebChart.Chart.Axes.Custom.Count; c++)
{
     Axis axis = this.CurvesWebChart.Chart.Axes.Custom[c];
     double y1 = 0;
     double y0 = 0;

     if (applyNewZoom)//user makes zoom
     {//this works great...
          y1 = axis.CalcPosPoint(this.CurvesWebChart.Chart.Zoom.y1);
          y0 = axis.CalcPosPoint(this.CurvesWebChart.Chart.Zoom.y0);

          //save last zoomY1 and zoomY0
          this.lastZoomY1 = this.CurvesWebChart.Chart.Zoom.y1;
          this.lastZoomY0 = this.CurvesWebChart.Chart.Zoom.y0;
     }
     else//user pressed button to add/remove series, keep zoom using lastZoomY1 and lastZoomY0 because this.CurvesWebChart.Chart.Zoom.y1 and this.CurvesWebChart.Chart.Zoom.y0 are "0" at this momment
     {//here I get correct values only when CheckZoom() is called from chart_AfterDraw(), but axes don't rescale on chart...
          y1 = axis.CalcPosPoint(this.lastZoomY1);
          y0 = axis.CalcPosPoint(this.lastZoomY0);
     }

     axis.SetMinMax(y1, y0);
}
...

Am I doing something wrong?
How can I keep the zoom in this case?

Thank you.

[Sandra]

Hello Ternaris,

I have the problem that each Y custom axis has different scale, and I can not use the Minimum and Maximum value of a specific axis as you do in your example...

You can try to use SetMinMax() for each custom axis as different scale, changing next line:

Code: Select all

...
axis.SetMinMax(ch1.Axes.Bottom.Minimum, ch1.Axes.Bottom.Maximum);
...

To below lines:

Code: Select all

...
  axis.SetMinMax(ch1[i].CustomHorizAxis.Minimum, ch1[i].CustomHorizAxis.Maximum+10);
...

Another problem is that I use a button to add or remove series from the chart (and maybe add or remove axes), here is when I have problems to keep the zoom because when I call CheckZoom() in button_Click() I always get "0" in y1 and y0, However, if I call CheckZoom() in chart_AfterDraw() I get the correct values for y1 and y0, but the y-axes don't rescale.

This is part of my CheckZoom():
...
Am I doing something wrong?
How can I keep the zoom in this case?

I think can help you, use WebChart.Chart.Invalidate(); or System.Drawing.Bitmap bitmap = WebChart1.Chart.Bitmap((int)WebChart1.Width.Value,(int)WebChart1.Height.Value); to repaint chart. Please, could you confirm us if my recommendations solve your problems?

I hope will helps.

Thanks,

[Tenaris]

Hello Sandra, thank you for your recommendation.

I tried it in your example, but it doesn't work correctly, because x-axes don't rescale, only increase in 10.

I found a solution for me, I don't know if it is the best way. When I zoom in the chart I calculate the percentage of zoom represents in Y, and I save it. When I add another serie with another axis, I calculate y0 an y1 for this axis based on saved zoom percentage.

If you know a better solution, It would be great to know.

Thank you.