Gtk2::ImageView::Tool:UsereContributed Perl Gtk2::ImageView::Tool::Selector(3)NAMEGtk2::ImageView::Tool::Selector - Image tool for selecting rectangular
regions
HIERARCHY
Glib::Object
+----Gtk2::ImageView::Tool::Selector
INTERFACES
Gtk2::ImageView::Tool
DESCRIPTIONGtk2::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.
Zoom bug
There is a small bug in Gtk2::ImageView::Tool::Selector that becomes
apparent when the zoom factor is greater than about 30. The edge of the
selection rectangle may in that case intersect a pixel.
The bug is caused by bug 389832 in gdk-pixbuf. There is no way to solve
this bug on Gtk2::ImageView's level (but if someone knows how, I'd
really like to know).
METHODS
tool = Gtk2::ImageView::Tool::Selector->new ($view)
· $view (Gtk2::ImageView)
Returns a new selector tool for the specified view with the following
default values:
selection : (0, 0) - [0, 0]
rectangle = $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.
$selector->set_selection ($rect)
· $rect (Gtk2::Gdk::Rectangle)
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 views pixbuf is undef.
If rect is wider or taller than the size of the pixbuf
If rect equals the current selection rectangle.
If the selection falls outside the pixbufs area, its position is moved
so that it is within the pixbuf.
Calling this method causes the ::selection-changed signal to be
emitted.
The default selection is (0,0) - [0,0].
selector : a Gtk2::ImageView::Tool::Selector
rect : Selection rectangle in image space coordinates.
PROPERTIES
'view' (Gtk2::ImageView : writable / construct-only)
Image View to navigate
SIGNALS
selection-changed (Gtk2::ImageView::Tool::Selector)
SEE ALSO
Gtk2::ImageView, Glib::Object
COPYRIGHT
Copyright (C) 2007 by Jeffrey Ratcliffe.
This software is licensed under the GPL-3; see Gtk2::ImageView for a
full notice.
perl v5.10.02009-07-29Gtk2::ImageView::Tool::Selector(3)