1Gtk2::ImageView::Tool::USseelrecCtoonrt(r3i)buted Perl DGotcku2m:e:nItmaatgieoVniew::Tool::Selector(3)
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6 Gtk2::ImageView::Tool::Selector - Image tool for selecting rectangular
7 regions
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10 Glib::Object
11 +----Gtk2::ImageView::Tool::Selector
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14 Gtk2::ImageView::Tool
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17 Gtk2::ImageView::Tool::Selector is a tool for selecting areas of an
18 image. It is useful for cropping an image, for example. The tool is an
19 implementor of the Gtk2::ImageView::Tool inteface which means that it
20 can be plugged into a Gtk2::ImageView by using the
21 Gtk2::ImageView::Tool::set_tool() method.
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23 Gtk2::ImageView::Tool::Selector changes the default display of the
24 Gtk2::ImageView. It darkens down the unselected region of the image
25 which provides a nice effect and makes it clearer what part of the
26 image that is currently selected. Unfortunately, this effect is
27 somewhat incompatible with how Gtk2::ImageView::Nav behaves because
28 that widget will show the image without darkening it.
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30 The tool also changes the default behaviour of the mouse. When a
31 Gtk2::ImageView::Tool::Selector is set on a Gtk2::ImageView, mouse
32 presses do not "grab" the image and you cannot scroll by dragging.
33 Instead mouse presses and dragging is used to resize and move the
34 selection rectangle. When the mouse drags the selection rectangle to
35 the border of the widget, the view autoscrolls which is a convenient
36 way for a user to position the selection.
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38 Please note that Gtk2::ImageView::Tool::Selector draws the image in two
39 layers. One darkened and the selection rectangle in normal luminosity.
40 Because it uses two draw operations instead one one like
41 Gtk2::ImageView::Tool::Dragger does, it is significantly slower than
42 that tool. Therefore, it makes sense for a user of this library to set
43 the interpolation to GDK_INTERP_NEAREST when using this tool to ensure
44 that performance is acceptable to the users of the program.
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46 Zoom bug
47 There is a small bug in Gtk2::ImageView::Tool::Selector that becomes
48 apparent when the zoom factor is greater than about 30. The edge of the
49 selection rectangle may in that case intersect a pixel.
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51 The bug is caused by bug 389832 in gdk-pixbuf. There is no way to solve
52 this bug on Gtk2::ImageView's level (but if someone knows how, I'd
53 really like to know).
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56 tool = Gtk2::ImageView::Tool::Selector->new ($view)
57 • $view (Gtk2::ImageView)
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59 Returns a new selector tool for the specified view with the following
60 default values:
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62 selection : (0, 0) - [0, 0]
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64 rectangle = $selector->get_selection
65 Returns a Gtk2::Gdk::Rectangle with the current selection. If either
66 the width or the height of the selection is zero, then nothing is
67 selected and undef is returned. See "selection-changed" for an example.
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69 $selector->set_selection ($rect)
70 • $rect (Gtk2::Gdk::Rectangle)
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72 Sets the selection rectangle for the tool. Setting this attribute will
73 cause the widget to immidiately repaint itself if its view is realized.
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75 This method does nothing under the following circumstances:
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77 If the views pixbuf is undef.
78 If rect is wider or taller than the size of the pixbuf
79 If rect equals the current selection rectangle.
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81 If the selection falls outside the pixbufs area, its position is moved
82 so that it is within the pixbuf.
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84 Calling this method causes the ::selection-changed signal to be
85 emitted.
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87 The default selection is (0,0) - [0,0].
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89 selector : a Gtk2::ImageView::Tool::Selector
90 rect : Selection rectangle in image space coordinates.
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93 'view' (Gtk2::ImageView : default undef : writable / construct-only)
94 Image View to navigate
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97 selection-changed (Gtk2::ImageView::Tool::Selector)
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100 Gtk2::ImageView, Glib::Object
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103 Copyright (C) 2007 by Jeffrey Ratcliffe.
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105 This software is licensed under the GPL-3; see Gtk2::ImageView for a
106 full notice.
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110perl v5.34.0 2021-07-22Gtk2::ImageView::Tool::Selector(3)