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Code Issues Releases Wiki Activity

Simplify page scrolling behaviour

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Fixes #2180
This commit is contained in:
Jermolene
2018-01-30 11:29:07 +00:00
parent 7534a97518
commit 1c8170463c
1 changed files with 24 additions and 37 deletions
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61
core/modules/utils/dom/scroller.js
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@@ -54,51 +54,35 @@ PageScroller.prototype.handleEvent = function(event) {
Handle a scroll event hitting the page document
*/
PageScroller.prototype.scrollIntoView = function(element) {
var duration = $tw.utils.getAnimationDuration();
var self = this,
duration = $tw.utils.getAnimationDuration();
// Now get ready to scroll the body
this.cancelScroll();
this.startTime = Date.now();
var scrollPosition = $tw.utils.getScrollPosition();
// Get the client bounds of the element and adjust by the scroll position
var clientBounds = element.getBoundingClientRect(),
bounds = {
left: clientBounds.left + scrollPosition.x,
top: clientBounds.top + scrollPosition.y,
width: clientBounds.width,
height: clientBounds.height
};
// We'll consider the horizontal and vertical scroll directions separately via this function
// targetPos/targetSize - position and size of the target element
// currentPos/currentSize - position and size of the current scroll viewport
// returns: new position of the scroll viewport
var getEndPos = function(targetPos,targetSize,currentPos,currentSize) {
var newPos = currentPos;
// If the target is above/left of the current view, then scroll to it's top/left
if(targetPos <= currentPos) {
newPos = targetPos;
// If the target is smaller than the window and the scroll position is too far up, then scroll till the target is at the bottom of the window
} else if(targetSize < currentSize && currentPos < (targetPos + targetSize - currentSize)) {
newPos = targetPos + targetSize - currentSize;
// If the target is big, then just scroll to the top
} else if(currentPos < targetPos) {
newPos = targetPos;
// Otherwise, stay where we are
} else {
newPos = currentPos;
}
var getBounds = function() {
var clientBounds = element.getBoundingClientRect(),
scrollPosition = $tw.utils.getScrollPosition();
return {
left: clientBounds.left + scrollPosition.x,
top: clientBounds.top + scrollPosition.y,
width: clientBounds.width,
height: clientBounds.height
};
},
// We'll consider the horizontal and vertical scroll directions separately via this function
// targetPos/targetSize - position and size of the target element
// currentPos/currentSize - position and size of the current scroll viewport
// returns: new position of the scroll viewport
getEndPos = function(targetPos,targetSize,currentPos,currentSize) {
var newPos = targetPos;
// If we are scrolling within 50 pixels of the top/left then snap to zero
if(newPos < 50) {
newPos = 0;
}
return newPos;
},
endX = getEndPos(bounds.left,bounds.width,scrollPosition.x,window.innerWidth),
endY = getEndPos(bounds.top,bounds.height,scrollPosition.y,window.innerHeight);
// Only scroll if the position has changed
if(endX !== scrollPosition.x || endY !== scrollPosition.y) {
var self = this,
drawFrame;
drawFrame = function () {
drawFrame = function drawFrame() {
var t;
if(duration <= 0) {
t = 1;
@@ -110,13 +94,16 @@ PageScroller.prototype.scrollIntoView = function(element) {
t = 1;
}
t = $tw.utils.slowInSlowOut(t);
var scrollPosition = $tw.utils.getScrollPosition(),
bounds = getBounds(),
endX = getEndPos(bounds.left,bounds.width,scrollPosition.x,window.innerWidth),
endY = getEndPos(bounds.top,bounds.height,scrollPosition.y,window.innerHeight);
window.scrollTo(scrollPosition.x + (endX - scrollPosition.x) * t,scrollPosition.y + (endY - scrollPosition.y) * t);
if(t < 1) {
self.idRequestFrame = self.requestAnimationFrame.call(window,drawFrame);
}
};
drawFrame();
}
drawFrame();
};
exports.PageScroller = PageScroller;