Gtk2::ImageView::Tool::Selector is a tool for selecting areas of an image. It
is useful for cropping an image, for example. The tool is an implementor of the
Gtk2::ImageView::Tool inteface which means that it can be plugged into a
Gtk2::ImageView by using the Gtk2::ImageView::Tool::set_tool() method.
Gtk2::ImageView::Tool::Selector changes the default display of the
Gtk2::ImageView. It darkens down the unselected region of the image which
provides a nice effect and makes it clearer what part of the image that is
currently selected. Unfortunately, this effect is somewhat incompatible with
how Gtk2::ImageView::Nav behaves because that widget will show the image
without darkening it.
The tool also changes the default behaviour of the mouse. When a
Gtk2::ImageView::Tool::Selector is set on a Gtk2::ImageView, mouse presses do
not grab the image and you cannot scroll by dragging. Instead mouse presses
and dragging is used to resize and move the selection rectangle. When the mouse
drags the selection rectangle to the border of the widget, the view autoscrolls
which is a convenient way for a user to position the selection.
Please note that Gtk2::ImageView::Tool::Selector draws the image in two layers.
One darkened and the selection rectangle in normal luminosity. Because it uses
two draw operations instead one one like Gtk2::ImageView::Tool::Dragger does, it
is significantly slower than that tool. Therefore, it makes sense for a user of
this library to set the interpolation to GDK_INTERP_NEAREST when using this tool
to ensure that performance is acceptable to the users of the program.
Returns a new selector tool for the specified view with the following default
selection : (0, 0) - [0, 0]
rectangle = CW$selector->get_selection
Returns a Gtk2::Gdk::Rectangle with the current selection. If either the width
or the height of the selection is zero, then nothing is selected and undef is
returned. See selection-changed for an example.
Sets the selection rectangle for the tool. Setting this attribute will cause the widget to immidiately repaint itself if its view is realized.
This method does nothing under the following circumstances:
If the selection falls outside the pixbufs area, its position is moved so that it is within the pixbuf.
If the views pixbuf is undef.
If rect is wider or taller than the size of the pixbuf
If rect equals the current selection rectangle.
Calling this method causes the ::selection-changed signal to be emitted.
The default selection is (0,0) - [0,0].