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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/*
* st-scrollable.c: Scrollable interface
*
* Copyright 2008 OpenedHand
* Copyright 2009 Intel Corporation.
* Copyright 2010 Red Hat, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU Lesser General Public License,
* version 2.1, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
* more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "st-private.h"
#include "st-scrollable.h"
G_DEFINE_INTERFACE (StScrollable, st_scrollable, G_TYPE_OBJECT)
/**
* SECTION:st-scrollable
* @short_description: A #ClutterActor that can be scrolled
*
* The #StScrollable interface is exposed by actors that support scrolling.
*
* The interface contains methods for getting and setting the adjustments
* for scrolling; these adjustments will be used to hook the scrolled
* position up to scrollbars or other external controls. When a #StScrollable
* is added to a parent container, the parent container is responsible
* for setting the adjustments. The parent container then sets the adjustments
* back to %NULL when the scrollable is removed.
*
* For #StScrollable supporting height-for-width size negotiation, size
* negotiation works as follows:
*
* In response to get_preferred_width(), the scrollable should report
* the minimum width at which horizontal scrolling is needed for the
* preferred width, and natural width of the actor when not
* horizontally scrolled as the natural width.
*
* The for_width passed into get_preferred_height() is the width at which
* the scrollable will be allocated; this will be smaller than the minimum
* width when scrolling horizontally, so the scrollable may want to adjust
* it up to the minimum width before computing a preferred height. (Other
* scrollables may want to fit as much content into the allocated area
* as possible and only scroll what absolutely needs to scroll - consider,
* for example, the line-wrapping behavior of a text editor where there
* is a long line without any spaces.) As for width, get_preferred_height()
* should return the minimum size at which no scrolling is needed for the
* minimum height, and the natural size of the actor when not vertically scrolled
* as the natural height.
*
* In allocate() the allocation box passed in will be actual allocated
* size of the actor so will be smaller than the reported minimum
* width and/or height when scrolling is present. Any scrollable actor
* must support being allocated at any size down to 0x0 without
* crashing, however if the actor has content around the scrolled area
* and has an absolute minimum size that's bigger than 0x0 its
* acceptable for it to misdraw between 0x0 and the absolute minimum
* size. It's up to the application author to avoid letting the user
* resize the scroll view small enough so that the scrolled area
* vanishes.
*
* In response to allocate, in addition to normal handling, the
* scrollable should also set the limits of the the horizontal and
* vertical adjustments that were set on it earlier. The standard
* settings are:
*
* lower: 0
* page_size: allocated size (width or height)
* upper: MAX (total size of the scrolled area,allocated_size)
* step_increment: natural row/column height or a fixed fraction of the page size
* page_increment: page_size - step_increment
*/
static void
st_scrollable_default_init (StScrollableInterface *g_iface)
{
static gboolean initialized = FALSE;
if (!initialized)
{
/**
* StScrollable:hadjustment:
*
* The horizontal #StAdjustment used by the #StScrollable.
*
* Implementations should override this property to provide read-write
* access to the #StAdjustment.
*
* JavaScript code may override this as demonstrated below:
*
* |[<!-- language="JavaScript" -->
* var MyScrollable = GObject.registerClass({
* Properties: {
* 'hadjustment': GObject.ParamSpec.override(
* 'hadjustment',
* St.Scrollable
* )
* }
* }, class MyScrollable extends St.Scrollable {
*
* get hadjustment() {
* return this._hadjustment || null;
* }
*
* set hadjustment(adjustment) {
* if (this.hadjustment === adjustment)
* return;
*
* this._hadjustment = adjustment;
* this.notify('hadjustment');
* }
* });
* ]|
*/
g_object_interface_install_property (g_iface,
g_param_spec_object ("hadjustment",
"StAdjustment",
"Horizontal adjustment",
ST_TYPE_ADJUSTMENT,
ST_PARAM_READWRITE));
/**
* StScrollable:vadjustment:
*
* The vertical #StAdjustment used by the #StScrollable.
*
* Implementations should override this property to provide read-write
* access to the #StAdjustment.
*
* See #StScrollable:hadjustment for an example of how to override this
* property in JavaScript code.
*/
g_object_interface_install_property (g_iface,
g_param_spec_object ("vadjustment",
"StAdjustment",
"Vertical adjustment",
ST_TYPE_ADJUSTMENT,
ST_PARAM_READWRITE));
initialized = TRUE;
}
}
/**
* st_scrollable_set_adjustments:
* @scrollable: a #StScrollable
* @hadjustment: the horizontal #StAdjustment
* @vadjustment: the vertical #StAdjustment
*
* This method should be implemented by classes implementing the #StScrollable
* interface.
*
* JavaScript code should do this by overriding the `vfunc_set_adjustments()`
* method.
*/
void
st_scrollable_set_adjustments (StScrollable *scrollable,
StAdjustment *hadjustment,
StAdjustment *vadjustment)
{
ST_SCROLLABLE_GET_IFACE (scrollable)->set_adjustments (scrollable,
hadjustment,
vadjustment);
}
/**
* st_scroll_bar_get_adjustments:
* @hadjustment: (transfer none) (out) (optional): location to store the horizontal adjustment, or %NULL
* @vadjustment: (transfer none) (out) (optional): location to store the vertical adjustment, or %NULL
*
* Gets the adjustment objects that store the offsets of the scrollable widget
* into its possible scrolling area.
*
* This method should be implemented by classes implementing the #StScrollable
* interface.
*
* JavaScript code should do this by overriding the `vfunc_get_adjustments()`
* method.
*/
void
st_scrollable_get_adjustments (StScrollable *scrollable,
StAdjustment **hadjustment,
StAdjustment **vadjustment)
{
ST_SCROLLABLE_GET_IFACE (scrollable)->get_adjustments (scrollable,
hadjustment,
vadjustment);
}
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