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Switch the MessageList from using a closed interval for its render window to a half-open interval 

(imported from commit 53cdbd603d8ab68fdbb338a852cb214a35a0403d)
This commit is contained in:
Zev Benjamin 2013-03-07 15:16:20 -05:00
parent 94a3e2c7a4
commit 740e48d427
1 changed files with 19 additions and 19 deletions
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38
zephyr/static/js/message_list.js
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@ -6,8 +6,9 @@ function MessageList(table_name, opts) {
this.table_name = table_name;
this._selected_id = -1;
this._message_groups = [];
this._min_rendered_idx = 0;
this._max_rendered_idx = -1;
// Half-open interval of the indices that define the current render window
this._render_win_start = 0;
this._render_win_end = 0;
if (this.table_name) {
this._clear_table();
@ -175,7 +176,7 @@ MessageList.prototype = {
var selected_idx = util.lower_bound(this._items, this._selected_id,
function (a, b) { return a.id < b; });
var new_min_idx;
var new_start;
// We rerender under the following conditions:
// * The selected message is within this._RENDER_THRESHOLD messages
@ -186,27 +187,26 @@ MessageList.prototype = {
// of the bottom of the currently rendered window and the
// bottom of the window does not abut the end of the
// message list
if (! (((selected_idx - this._min_rendered_idx < this._RENDER_THRESHOLD)
&& (this._min_rendered_idx !== 0)) ||
((this._max_rendered_idx - selected_idx < this._RENDER_THRESHOLD)
&& (this._max_rendered_idx !== this._items.length - 1))))
if (! (((selected_idx - this._render_win_start < this._RENDER_THRESHOLD)
&& (this._render_win_start !== 0)) ||
((this._render_win_end - selected_idx <= this._RENDER_THRESHOLD)
&& (this._render_win_end !== this._items.length))))
{
return false;
}
new_min_idx = Math.max(selected_idx - this._RENDER_WINDOW_SIZE / 2, 0);
if (new_min_idx === this._min_rendered_idx) {
new_start = Math.max(selected_idx - this._RENDER_WINDOW_SIZE / 2, 0);
if (new_start === this._render_win_start) {
return false;
}
this._min_rendered_idx = new_min_idx;
this._max_rendered_idx = Math.max(Math.min(this._min_rendered_idx + this._RENDER_WINDOW_SIZE - 1,
this._items.length - 1),
0);
this._render_win_start = new_start;
this._render_win_end = Math.min(this._render_win_start + this._RENDER_WINDOW_SIZE,
this._items.length);
this._clear_table();
this._render(this._items.slice(this._min_rendered_idx,
this._max_rendered_idx + 1),
this._render(this._items.slice(this._render_win_start,
this._render_win_end),
'bottom', true);
return true;
},
@ -364,11 +364,11 @@ MessageList.prototype = {
this._items = this._items.concat(messages);
this._add_to_hash(messages);
var cur_window_size = this._max_rendered_idx - this._min_rendered_idx + 1;
var cur_window_size = this._render_win_end - this._render_win_start;
if (cur_window_size < this._RENDER_WINDOW_SIZE) {
var slice_to_render = messages.slice(0, this._RENDER_WINDOW_SIZE - cur_window_size);
this._render(slice_to_render, 'bottom');
this._max_rendered_idx += slice_to_render.length;
this._render_win_end += slice_to_render.length;
}
},
@ -376,8 +376,8 @@ MessageList.prototype = {
this._items = messages.concat(this._items);
this._add_to_hash(messages);
this._min_rendered_idx += messages.length;
this._max_rendered_idx += messages.length;
this._render_win_start += messages.length;
this._render_win_end += messages.length;
},
all: function MessageList_all() {