Dragged zoom is active only when the left mouse click is in
zoom mode, i.e. when the the magnifying glass button is pressed in
the toggled buttons as in Figure . In zoom
mode, the cursor within the canvas will appear like a magnifying glass
with plus sign in the center as in Figure
.
It is called zoom-plus cursor. The dragged zoom operation is initialized
by pressing the left mouse button at the beginning of the zoom-in
region, a white line will then appear. As soon as dragging is detected,
another white line will appear to mark the current ending of the zoom-in
region. The region that is marked by pair of white lines is lightly
shaded as shown in Figure
. The
process can be cancelled anytime by hitting the ESC key during dragging.
Once the left mouse button is released, zooming will be carried out
and the Timeline window will then be updated as in Figure
.
The time display panel is updated with the latest time related information
of the zoom-in region. Notice that the zooming as well as scrolling
can be achieved by explicitly editing the text fields in the time
display panel.