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Relatively aggressive version of autoscroll-forever

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(imported from commit f84e7bbbb3eaec1a5c8df93dffe3771a6fdbcd5f)
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acrefoot
2013-12-05 16:45:38 -05:00
parent 59bbe33954
commit cff1714209
1 changed files with 40 additions and 12 deletions
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52
static/js/message_list_view.js
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@@ -63,6 +63,8 @@ MessageListView.prototype = {
var table_name = this.table_name;
var table = rows.get_table(table_name);
// we we record if last_message_was_selected before updating the table
var last_message_was_selected = rows.id(rows.last_visible()) === list.selected_id();
var messages_to_render = [];
var ids_where_next_is_same_sender = {};
var prev;
@@ -435,15 +437,43 @@ MessageListView.prototype = {
}
if (list === current_msg_list && messages_are_new) {
self._maybe_autoscroll(rendered_elems);
self._maybe_autoscroll(rendered_elems, last_message_was_selected);
}
},
_maybe_autoscroll: function MessageListView__maybe_autoscroll(rendered_elems) {
_maybe_autoscroll: function MessageListView__maybe_autoscroll(rendered_elems, last_message_was_selected) {
// If we are near the bottom of our feed (the bottom is visible) and can
// scroll up without moving the pointer out of the viewport, do so, by
// up to the amount taken up by the new message.
var new_messages_height = 0;
var distance_to_last_message_sent_by_me = 0;
var id_of_last_message_sent_by_us = -1;
// C++ iterators would have made this less painful
_.each(rendered_elems.toArray().reverse(), function (elem) {
// Sometimes there are non-DOM elements in rendered_elems; only
// try to get the heights of actual trs.
if ($(elem).is("tr")) {
new_messages_height += elem.offsetHeight;
// starting from the last message, ignore message heights that weren't sent by me.
if(id_of_last_message_sent_by_us > -1) {
distance_to_last_message_sent_by_me += elem.offsetHeight;
} else if (elem.className !== "bookend_tr" &&
this.get_message(rows.id($(elem))).sender_email === page_params.email)
{
distance_to_last_message_sent_by_me += elem.offsetHeight;
id_of_last_message_sent_by_us = rows.id($(elem));
}
}
}, this);
// autoscroll_forever: if we're on the last message, keep us on the last message
if (last_message_was_selected && page_params.autoscroll_forever) {
this.list.select_id(this.list.last().id, {from_rendering: true});
scroll_to_selected();
this.list.reselect_selected_id();
return;
}
var selected_row = this.selected_row();
var last_visible = rows.last_visible();
@@ -457,20 +487,18 @@ MessageListView.prototype = {
var info = viewport.message_viewport_info();
var available_space_for_scroll = selected_row_offset - info.visible_top;
// autoscroll_forever: if we've sent a message, move pointer at least that far.
if (page_params.autoscroll_forever && id_of_last_message_sent_by_us > -1 && (rows.last_visible().offset().top - this.list.selected_row().offset().top) < (viewport.height())) {
this.list.select_id(id_of_last_message_sent_by_us, {from_rendering: true});
scroll_to_selected();
return;
}
// Don't scroll if we can't move the pointer up.
if (available_space_for_scroll <= 0) {
return;
}
var new_messages_height = 0;
_.each(rendered_elems, function (elem) {
// Sometimes there are non-DOM elements in rendered_elems; only
// try to get the heights of actual trs.
if ($(elem).is("tr")) {
new_messages_height += $(elem).height();
}
});
if (new_messages_height <= 0) {
return;
}