Zoom / Pan / Mouse Wheel


Graph Selection
Axis Ranges
Data Inspection
Mouse Wheel Operation


In order to avoid discussions about what is the right way  for zoom and pan operations, TChart offers two different modes which can be selected via the File >> Preferences menu:
Zoom and pan can be done with the buttons of the bottom button-row or with the mouse wheel.

The  "Y-Zoom mode" radio buttons in the File >> Preferences dialog select if Zoom/Pan actions affect only the graph for which the Y-axis is shown or all selected graphs.


TChart displays one data (Y) axis at the left of the graph area and a time (X) axis at the bottom of the graph area.
Internally TChart maintains one individual Y-axis each for each plotted curve.

If one curve is selected (see below) its individual Y-axis is shown..
If multiple curves are selected, the Y-axis of the last selected curve is shown.
If no curves are selected, the Y-axis of the first curve is shown.

Graph Selection

By left-clicking on a data label,  the corresponding graph is selected. The  graph is shown with thicker line-width and its individual Y-axis is shown.
A selected graph has a rectangle drawn around the coloured line in the legend (if the legend is shown). Previously selected graphs are deselected.

Left-klicking on a selected data label deselects the corresponding graph. If any other items are selected, the next graph's individual Y-axis is shown.

CTRL-left-clicking on an unselected data label selects the corresponding graph. The  the graph is shown with thicker line-width and its individual axis is shown. Previously selected graphs remain selected.

CTRL-left-clicking on a selected legend item shows this item's Y-axis. 

By CTRL-SHIFT-left-clicking on any data labels all graphs are selected.

By SHIFT-left-clicking on any data label all graphs are deselected.

If all curves are de-selected, the first graph's Y-axis is displayed.

Axis Ranges

TChart stores four set of ranges for each graph's individual Y-axis:
The original range can be recalled at any time with the menu Zoom >> Vertical >>  Vertical Reset (or CTRL-R short-cut key).
The saved range  can be recalled at any time with the menu Zoom >> Vertical >>  Recall (or R short-cut key).

With the menu function Zoom >> Vertical >>  Remember (or S short-cut key) the current ranges are transferred to the saved ranges.

Data Inspection

Curve data can be inspected independent of graph selection.
Right-clicking on the plot will pop up a dialog which shows the data for all graphs with the X-coordinates of the present mouse position.
As long as the dialog is open, mouse movement will update the data values.
The dialog can be closed by using the dialog's close button in the top-right corner.

In addition, if the right-side data label display is active the present mouse coordinates will be displayed with respect to the currently shown Y-axis.

Mouse Wheel Operation

In addition to the zoom / pan buttons the following operations with the mouse wheel are possible:
(Note: the mouse pointer must be located within the plot for mouse-wheel actions to have any effect).
The File >> Preferences dialog has a button "Map Mouse-Wheel Actions" which pops up a dialog for doing just that.
The actions
can be mapped to any of the functions
Note: The direction of mouse wheel operations is determined by the File >> Preferences selection  "Pan/Zoom".

Note: In order not to overload the plot engine, mouse wheel events are throttled to 5 Hz.