Clarify and simplfiy unpagination logic

This commit is contained in:
Luke Barnard 2017-04-04 13:28:26 +01:00
parent 94fe9999db
commit 5737994957
2 changed files with 20 additions and 24 deletions

View file

@ -333,34 +333,28 @@ module.exports = React.createClass({
if (excessHeight <= 0) {
return;
}
var itemlist = this.refs.itemlist;
var tiles = itemlist.children;
const tiles = this.refs.itemlist.children;
// The scroll token of the first/last tile to be unpaginated
let markerScrollToken = null;
// Subtract clientHeights to simulate the events being unpaginated whilst counting
// the events to be unpaginated.
if (backwards) {
// Iterate forwards from start of tiles, subtracting event tile height
let i = 0;
while (i < tiles.length && excessHeight > tiles[i].clientHeight) {
// Subtract heights of tiles to simulate the tiles being unpaginated until the
// excess height is less than the height of the next tile to subtract. This
// prevents excessHeight becoming negative, which could lead to future
// pagination.
//
// If backwards is true, we unpaginate (remove) tiles from the back (top).
let i = backwards ? 0 : tiles.length - 1;
while (
(backwards ? i < tiles.length : i > 0) && excessHeight > tiles[i].clientHeight
) {
// Subtract height of tile as if it were unpaginated
excessHeight -= tiles[i].clientHeight;
// The tile may not have a scroll token, so guard it
if (tiles[i].dataset.scrollToken) {
markerScrollToken = tiles[i].dataset.scrollToken;
}
i++;
}
} else {
// Iterate backwards from end of tiles, subtracting event tile height
let i = tiles.length - 1;
while (i > 0 && excessHeight > tiles[i].clientHeight) {
excessHeight -= tiles[i].clientHeight;
if (tiles[i].dataset.scrollToken) {
markerScrollToken = tiles[i].dataset.scrollToken;
}
i--;
}
i += backwards ? 1 : -1;
}
if (markerScrollToken) {

View file

@ -251,10 +251,12 @@ var TimelinePanel = React.createClass({
},
onMessageListUnfillRequest: function(backwards, scrollToken) {
// If backwards, unpaginate from the back
let dir = backwards ? EventTimeline.BACKWARDS : EventTimeline.FORWARDS;
debuglog("TimelinePanel: unpaginating events in direction", dir);
// All tiles are inserted by MessagePanel to have a scrollToken === eventId
// All tiles are inserted by MessagePanel to have a scrollToken === eventId, and
// this particular event should be the first or last to be unpaginated.
let eventId = scrollToken;
let marker = this.state.events.findIndex(