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Gtk2::ImageView::Tool:UsereContributed Perl Gtk2::ImageView::Tool::Selector(3)

NAME
       Gtk2::ImageView::Tool::Selector -  Image	tool for selecting rectangular
       regions

HIERARCHY
	 Glib::Object
	 +----Gtk2::ImageView::Tool::Selector

INTERFACES
	 Gtk2::ImageView::Tool

DESCRIPTION
       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.

   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)
       o   $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)
       o   $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 : default undef : 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 v5.32.0			  2020-08-30Gtk2::ImageView::Tool::Selector(3)

NAME | HIERARCHY | INTERFACES | DESCRIPTION | METHODS | PROPERTIES | SIGNALS | SEE ALSO | COPYRIGHT

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