Re: [Nplot-devel] Zooming with NPlot

[Dave C. <dav...@gm...>]

I, personally, could never get the mousewheel interaction to perform.
I implemented a double click Zoom though (C#). You'll need to have the form
capture all key presses to catch the Control key (used to return the chart
to normal view). And a bunch of this code is my custom stuff - but you
should get the picture.


        protected void Zoom(NPlot.Windows.PlotSurface2D ps, int zoomFactor,
int x, int y) {
            try {

                Point minPoint = new Point(0, 0);
                minPoint.X = x - zoomFactor;
                minPoint.Y = y - (int)(zoomFactor / 1.4);

                Point maxPoint = new Point(0, 0);
                maxPoint.X = x + zoomFactor;
                maxPoint.Y = y + (int)(zoomFactor / 1.4);

                ps.CacheAxes();
                ps.PhysicalXAxis1Cache.SetWorldLimitsFromPhysical(minPoint,
maxPoint);
                ps.PhysicalXAxis2Cache.SetWorldLimitsFromPhysical(minPoint,
maxPoint);
                ps.PhysicalYAxis1Cache.SetWorldLimitsFromPhysical(maxPoint,
minPoint);
                ps.PhysicalYAxis2Cache.SetWorldLimitsFromPhysical(maxPoint,
minPoint);
                ps.Invalidate();

            } catch { }
        }


        private void plotSurface_DoubleClick(object sender, EventArgs e) {

            if (controlKeyIsBeingPressed) {
                RedrawAll();
            } else {
                Zoom(plotSurface, 100, ((MouseEventArgs)e).X,
((MouseEventArgs)e).Y);
            }
        }

        private void frmTest_KeyDown(object sender, KeyEventArgs e) {
            if (e.KeyCode == Keys.ControlKey)
                controlKeyIsBeingPressed = true;
            else
                controlKeyIsBeingPressed = false;
        }


        protected void RedrawAll() {

            Charting.DrawChart(plotSurface, chartDataTable, this.Symbol);
            DrawTrendLine(plotSurface, chartDataTable, 21, Color.Red,
false);
            DrawTrendLine(plotSurface, chartDataTable, 63, Color.Blue,
false);
            DrawTrendLine(plotSurface, chartDataTable, 189, Color.Black,
false);
            DrawEMATrendLine(plotSurface, chartDataTable,
Convert.ToInt32(txtArraySize.Text), Color.DarkGoldenrod, false);
            DrawTradeLines(plotSurface, tradeQuotes);
            plotSurface.Invalidate();
        }




On Wed, Jan 14, 2009 at 8:56 AM, FXHat - <fxh...@gm...> wrote:

> Does anybody use the MouseWheelZoom interaction? Even when I try the demo
> application - ABC plot example, I can not zoom in on the graph using my
> mouse wheel. This plot does have MouseWheelZoom enabled according to the
> source code. Also, is there a way to zoom programatically; i.e. zoom in as
> a
> starting point for the plot so that the user can zoom out if necessary.
>
> Thanks.
>
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Dav...@gm...
Lake Oswego, OR
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