Panning and Zooming

For Windows and Mac users The graphical interface makes extensive use of all three mouse buttons where available. For mice with fewer buttons, the following are equivalent:
button 2 == any button with the SHIFT or ALT key held down
button 3 == any button with the CTRL or META key held down

Graphs

Most Catacomb graphs and diagrams allow zooming, panning and selecting regions with the mouse. A left click zooms in keeping the clicked point fixed. Clicks with the right button zoom out. Long clicks with the left button and clicks with the CTRL key held down also zoom out. Clicking to the left of or below the axes scale only that axis. Press-drag-release moves the data with the mouse. Pressing "f" with the mouse over the diagram re-centers the data in the window.

While you can probably work out a fair bit of how to manipulate the graphs by trial and error, all the details are below. They use left and right buttons separately, try click-drag-release with different starting points - on the data, to left or right of the axes, etc. You can also click on the data drag the mouse off, and draw loops. Dragging diagonally and then back across the starting point starts a box cursor to select a region.

There is a small menu in the top right corner of each graph. From here you can re-center the data, change the display style, and keep an image of the window in a new frame. The capital letters in the options indicate keyboard shortcuts which do the same. The mouse must be over the window when you press the key.

The scrollbars indicate the fraction of the useful display area currently visible, where useful is taken to mean the smallest box containing both the current view and all the data. So, for example, if the data is actually all to he left of the current range, the horizontal scrollbar will occupy the right half of its range, indicating that what you see is only the right part of a larger box which includes the data. The scrollbars can be dragged by the ends to change the scale of the graph, or by the center to pan the display. One consequence of the above definition of the "useful" area of the display is that if you drag the end of a scrollbar which is against the border, the bar will not shrink until the data begins to go out of the window.

Action	Operation	Notes
zoom in, keeping the point under the mouse fixed	short click	Avoid active points on the graph, or these will take precedence.
zoom out, keeping the point under the mouse fixed	long (> 150 ms) click or click with right button	Avoid active points on the graph, or these will take precedence.
pan	left mouse: click, drag, release	the axes are shifted so the point on the data where you clicked moves to where you released the mouse button.
continuous pan	right mouse: click, drag, release	as above, can be slow if a lot of data is plotted
select a region with a box cursor	diagonal drag, away, and then across the desired box (see below)	Any corner will do as a starting point, but you must drag diagonally away for ten pixels or so, and then back past the original point before the box appears (otherwise the motion will be taken as panning).
continuous zoom, in or out	click the fixed point, drag the mouse off the window, and then draw loops	clockwise loops zoom in; anti-clockwise loops zoom out

Most of these are modified depending on where you click the mouse:

Clicking on the graph re-scales both axes.
Clicking below the abscissa re-scale only the abscissa.
Clicking to the left of the ordinate re-scales only the ordinate.
Clicking above the graph (but still in its window) re-scale the background grid for the abscissa.
Clicking to the right of the graph re-scales the background grid for the ordinate.

To get a box cursor you click on one corner of the desired box, drag the mouse diagonally away from the opposite corner of the box you want and then back past your starting point to produce the cursor. For example, these mouse movements will initiate, and start to drag box cursors.

To start continuous zooming, you must drag the mouse out of the box. Drawing clockwise/anti-clockwise loops then zooms in/out. For example, the movements on the left will zoom in and/or out.

Sliders

Often the sliders will have appropriate ranges to start with. Then you just slide the knob back and forth. If necessary, however, you can change the upper and lower limits, change the precision of the value, switch between logarithmic and linear scales, or type a number from the keyboard. To gain more control, without changing the ranges, click on the knob, and drag the mouse up or down away from the slider: sliding left and right then gives a finer adjustment about the starting value.

To enter a value from the keyboard click on the slider and press the space-bar or return key. The slider should convert to text mode. When you have finished hit return or click ok for the value to take effect and the display to revert to a slider. When the number is shown as text on a white background it has not yet taken effect.

If you press the shift key with the mouse over a slider (you may need to click on the slider first), the display changes to three checkboxes and an "OK" button. The checkboxes indicate whether the display should include a zero button for setting the value to exactly zero, precision buttons for setting the number of significant figures, and if it should be logarithmic or linear.

If present the zero button appears on the left and overrides whatever value is set on the slider. The precision button appears on the right and shows the number of significant figures to round the value to. To reduce the number of figures click it with the left mouse button. Use the right mouse button to increase the number of figures.

To change the range of the slider, press and hold the mouse on the background away from the knob or arrows. Clicking in the left half changes the lower range and in the right half the upper range. The display will change to show the current limits. Moving the mouse left or right will change one of the limits. Alternatively, the little squares besides the arrows can be used to apply standard increments as described below.

All the possible slider operations are summarized in the table.

Action	Operation	Notes
set a coarse value within the current range	click and drag the knob with either button
key in a value	move mouse over the slider, hit return, type the number and hit return again.
set a fine value within the current range	set a value near the desired one, then release and start again. This time drag the mouse up or down away from the slider.	Left and right movements now give a fine adjustment of the value: the further above or below, the finer the adjustment.
set the number of significant figures in the value',	click on the figure on the right (if present) with left or right mouse buttons.	See below for how to set the slider to allow the precision to be changed
set the value to 0	click on the left button, marked zero (if present).
change the button display	put the mouse over the slider and press the space bar.	The three checkboxes on the left allow you to (un)select the display of the zero button and precision buttons and to switch between a logarithmic or linear range. To revert to the normal display, click the mouse in the number field and hit return.