In zoom operations for charts, it is common to restrict zooming to one direction only. For example, in a chart plotting temperature against time, zooming in from a yearly chart to a daily chart may mean the time axis (x-axis) is zoomed in by 36500%, while the temperature axis (y-axis) may be auto-scaled and not zoomed in at all. The user may be surprise if you also zoom in the y-axis by 36500%, in which case the chart may become hardly readable.
This method allows you to determine the zoom direction for mouse zoom actions (see ChartViewer.MouseUsage), specified using the following predefined constants:
| Constant | Value | Description |
|---|---|---|
| cvHorizontal | 0 | Zoom actions apply to horizontal direction only. |
| cvVertical | 1 | Zoom actions apply to vertical direction only. |
| cvHorizontalVertical | 2 | Zoom actions apply to both horizontal and vertical directions. |