talkatu/talkatu

Add the power of the turtles
default tip
3 hours ago, Gary Kramlich
42c7cfb1acd1
Add the power of the turtles

Testing Done:
Ran `ninja clean` followed by `ninja turtles` without issue.

Reviewed at https://reviews.imfreedom.org/r/2389/
/*
* Talkatu - GTK widgets for chat applications
* Copyright (C) 2017-2020 Gary Kramlich <grim@reaperworld.com>
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this library; if not, see <https://www.gnu.org/licenses/>.
*/
#include <gtk/gtk.h>
#include <talkatu/talkatuautoscroller.h>
/**
* TalkatuAutoScroller:
*
* This is a simple subclass of [class@Gtk.Adjustment] that has helpers for
* keyboard navigation as well as the ability to automatically scroll to the
* max when new items are added if the widget was already scrolled all the
* way to the bottom.
*/
struct _TalkatuAutoScroller {
GtkAdjustment parent;
gboolean auto_scroll;
};
G_DEFINE_TYPE(TalkatuAutoScroller, talkatu_auto_scroller, GTK_TYPE_ADJUSTMENT)
/******************************************************************************
* Callbacks
*****************************************************************************/
static gboolean
talkatu_auto_scroller_scroll(gpointer data) {
GtkAdjustment *adjustment = data;
gdouble upper, pagesize;
upper = gtk_adjustment_get_upper(adjustment);
pagesize = gtk_adjustment_get_page_size(adjustment);
gtk_adjustment_set_value(adjustment, upper - pagesize);
return G_SOURCE_REMOVE;
}
static void
talkatu_auto_scroller_changed(GtkAdjustment *adjustment) {
TalkatuAutoScroller *auto_scroller = TALKATU_AUTO_SCROLLER(adjustment);
if(auto_scroller->auto_scroll) {
/* If we set the value here, we interrupt the updates to the other
* values of the adjustment which breaks the adjustment.
*
* The specific behavior we've seen is that the upper property doesn't
* get updated when we call set value here. Which means you can't even
* scroll down anymore in a scrolled window because you're already at
* the upper bound. However, if you scroll up, even if there's no where
* to scroll, it will update the adjustment's properties and you can
* then scroll down.
*
* By using a timeout to set the value during the next main loop
* iteration we avoid this problem.
*/
g_timeout_add(0, talkatu_auto_scroller_scroll, adjustment);
}
}
static void
talkatu_auto_scroller_value_changed(GtkAdjustment *adjustment) {
TalkatuAutoScroller *auto_scroller = TALKATU_AUTO_SCROLLER(adjustment);
gdouble current, upper, pagesize;
current = gtk_adjustment_get_value(adjustment);
upper = gtk_adjustment_get_upper(adjustment);
pagesize = gtk_adjustment_get_page_size(adjustment);
auto_scroller->auto_scroll = (current + pagesize >= upper);
}
/******************************************************************************
* GObject Implementation
*****************************************************************************/
static void
talkatu_auto_scroller_init(TalkatuAutoScroller *auto_scroller) {
auto_scroller->auto_scroll = TRUE;
}
static void
talkatu_auto_scroller_class_init(TalkatuAutoScrollerClass *klass) {
GtkAdjustmentClass *adjustment_class = GTK_ADJUSTMENT_CLASS(klass);
adjustment_class->changed = talkatu_auto_scroller_changed;
adjustment_class->value_changed = talkatu_auto_scroller_value_changed;
}
/******************************************************************************
* Public API
*****************************************************************************/
/**
* talkatu_auto_scroller_new:
*
* Creates a new #TalkatuAutoScroller.
*
* Returns: (transfer full): The new #TalkatuAutoScroller instance.
*/
GtkAdjustment *
talkatu_auto_scroller_new(void) {
return g_object_new(TALKATU_TYPE_AUTO_SCROLLER, NULL);
}
/**
* talkatu_auto_scroller_decrement:
* @auto_scroller: The #TalkatuAutoScroller instance.
*
* Decrements the value of @auto_scroller by a page increment.
*/
void
talkatu_auto_scroller_decrement(TalkatuAutoScroller *auto_scroller) {
gdouble value = 0.0;
g_return_if_fail(TALKATU_IS_AUTO_SCROLLER(auto_scroller));
value = gtk_adjustment_get_value(GTK_ADJUSTMENT(auto_scroller));
value -= gtk_adjustment_get_page_increment(GTK_ADJUSTMENT(auto_scroller));
gtk_adjustment_set_value(GTK_ADJUSTMENT(auto_scroller), value);
}
/**
* talkatu_auto_scroller_increment:
* @auto_scroller: The #TalkatuAutoScroller instance.
*
* Increments the value of @auto_scroller by a page increment.
*/
void
talkatu_auto_scroller_increment(TalkatuAutoScroller *auto_scroller) {
gdouble value = 0.0;
g_return_if_fail(TALKATU_IS_AUTO_SCROLLER(auto_scroller));
value = gtk_adjustment_get_value(GTK_ADJUSTMENT(auto_scroller));
value += gtk_adjustment_get_page_increment(GTK_ADJUSTMENT(auto_scroller));
gtk_adjustment_set_value(GTK_ADJUSTMENT(auto_scroller), value);
}