|3.2 The current selection|
Whenever you call an Ipe function, you have to specify which objects the function should operate on. This is done by selecting objects. The selected objects (the selection) consists of two parts: the primary selection consists of exactly one object (of course, this object could be a group). All additional selected objects form the secondary selection. Some functions (like the context menu) operate only on the primary selection, while others treat primary and secondary selections differently (the align functions, for instance, align the secondary selections with respect to the primary selection.)
The selection is shown by outlining the selected object in color. Note that the primary selection is shown with a slightly different look.
The primary and secondary selections can be set in selection mode. Clicking the left mouse button close to an object makes that object the primary selection and deselects all other objects. If you keep the Shift key pressed while clicking with the left mouse key, the object closest to the mouse will be added to or deleted from the current selection. You can also drag a rectangle with the mouse—when you release the mouse button, all objects inside the rectangle will be selected. With the Shift key, the selection status of all objects inside the rectangle will be switched.
To make it easier to select objects that are below or close to other
objects, it is convenient to understand exactly how selecting objects
works. In fact, when you press the mouse button, a list of all
objects is computed that are sufficiently close to the mouse position
(the exact distance is set as the
prefs.lua). This list is then sorted by increasing distance
from the mouse and by increasing depth in the drawing. If Shift
was not pressed, the current selection is now cleared. Then the first
object in the list is presented. Now, while still keeping the mouse
button pressed, you can use the Space key to step through the
list of objects near the mouse in order of increasing depth and
distance. When you release the right mouse button, the object is
selected (or deselected).
When measuring the distance from the mouse position to objects, Ipe considers the boundary of objects only. So to select a filled object, don't just click somewhere in its interior, but close to its boundary.
Another way to select objects is using the Select all function from the Edit menu. It selects all objects on the page. Similarly, the Select all in layer function in the Layer menu selects all objects in the active layer.