ffe4eaf00d
Cut down on boilerplate by using the (no longer that) new helper macros. We don't care about breaking ABI in private libraries, so use G_DECLARE_FINAL_TYPE even where the class struct used to be exposed in the header, except for types we inherit from ourselves (obviously) or where the class exposes any vfuncs (where changes could affect inheritance in extensions).
133 lines
5.9 KiB
C
133 lines
5.9 KiB
C
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
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/*
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* st-scrollable.c: Scrollable interface
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*
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* Copyright 2008 OpenedHand
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* Copyright 2009 Intel Corporation.
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* Copyright 2010 Red Hat, Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU Lesser General Public License,
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* version 2.1, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT ANY
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* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
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* more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "st-scrollable.h"
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G_DEFINE_INTERFACE (StScrollable, st_scrollable, G_TYPE_OBJECT)
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/**
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* SECTION:st-scrollable
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* @short_description: A #ClutterActor that can be scrolled
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*
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* The #StScrollable interface is exposed by actors that support scrolling.
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*
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* The interface contains methods for getting and setting the adjustments
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* for scrolling; these adjustments will be used to hook the scrolled
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* position up to scrollbars or other external controls. When a #StScrollable
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* is added to a parent container, the parent container is responsible
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* for setting the adjustments. The parent container then sets the adjustments
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* back to %NULL when the scrollable is removed.
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*
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* For #StScrollable supporting height-for-width size negotation, size
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* negotation works as follows:
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*
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* In response to get_preferred_width(), the scrollable should report
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* the minimum width at which horizontal scrolling is needed for the
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* preferred width, and natural width of the actor when not
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* horizontally scrolled as the natural width.
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*
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* The for_width passed into get_preferred_height() is the width at which
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* the scrollable will be allocated; this will be smaller than the minimum
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* width when scrolling horizontally, so the scrollable may want to adjust
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* it up to the minimum width before computing a preferred height. (Other
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* scrollables may want to fit as much content into the allocated area
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* as possible and only scroll what absolutely needs to scroll - consider,
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* for example, the line-wrapping behavior of a text editor where there
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* is a long line without any spaces.) As for width, get_preferred_height()
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* should return the minimum size at which no scrolling is needed for the
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* minimum height, and the natural size of the actor when not vertically scrolled
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* as the natural height.
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*
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* In allocate() the allocation box passed in will be actual allocated
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* size of the actor so will be smaller than the reported minimum
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* width and/or height when scrolling is present. Any scrollable actor
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* must support being allocated at any size down to 0x0 without
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* crashing, however if the actor has content around the scrolled area
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* and has an absolute minimum size that's bigger than 0x0 its
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* acceptable for it to misdraw between 0x0 and the absolute minimum
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* size. It's up to the application author to avoid letting the user
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* resize the scroll view small enough so that the scrolled area
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* vanishes.
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*
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* In response to allocate, in addition to normal handling, the
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* scrollable should also set the limits of the the horizontal and
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* vertical adjustments that were set on it earlier. The standard
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* settings are:
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*
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* lower: 0
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* page_size: allocated size (width or height)
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* upper: MAX (total size of the scrolled area,allocated_size)
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* step_increment: natural row/column height or a fixed fraction of the page size
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* page_increment: page_size - step_increment
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*/
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static void
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st_scrollable_default_init (StScrollableInterface *g_iface)
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{
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static gboolean initialized = FALSE;
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if (!initialized)
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{
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g_object_interface_install_property (g_iface,
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g_param_spec_object ("hadjustment",
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"StAdjustment",
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"Horizontal adjustment",
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ST_TYPE_ADJUSTMENT,
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G_PARAM_READWRITE));
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g_object_interface_install_property (g_iface,
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g_param_spec_object ("vadjustment",
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"StAdjustment",
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"Vertical adjustment",
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ST_TYPE_ADJUSTMENT,
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G_PARAM_READWRITE));
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initialized = TRUE;
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}
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}
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void
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st_scrollable_set_adjustments (StScrollable *scrollable,
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StAdjustment *hadjustment,
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StAdjustment *vadjustment)
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{
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ST_SCROLLABLE_GET_IFACE (scrollable)->set_adjustments (scrollable,
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hadjustment,
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vadjustment);
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}
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/**
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* st_scroll_bar_get_adjustments:
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* @hadjustment: (transfer none) (out) (optional) (nullable): location to store the horizontal adjustment, or %NULL
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* @vadjustment: (transfer none) (out) (optional) (nullable): location to store the vertical adjustment, or %NULL
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*
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* Gets the adjustment objects that store the offsets of the scrollable widget
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* into its possible scrolling area.
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*/
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void
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st_scrollable_get_adjustments (StScrollable *scrollable,
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StAdjustment **hadjustment,
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StAdjustment **vadjustment)
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{
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ST_SCROLLABLE_GET_IFACE (scrollable)->get_adjustments (scrollable,
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hadjustment,
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vadjustment);
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}
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