Stackedit/public/res/extensions/scrollSync.js
2014-06-12 21:15:08 +01:00

271 lines
7.8 KiB
JavaScript

define([
"jquery",
"underscore",
"classes/Extension",
"text!html/scrollSyncSettingsBlock.html"
], function($, _, Extension, scrollSyncSettingsBlockHTML) {
var scrollSync = new Extension("scrollSync", "Scroll Sync", true, true);
scrollSync.settingsBlock = scrollSyncSettingsBlockHTML;
var sectionList;
scrollSync.onSectionsCreated = function(sectionListParam) {
sectionList = sectionListParam;
};
var editorElt;
var previewElt;
var mdSectionList = [];
var htmlSectionList = [];
var lastEditorScrollTop;
var lastPreviewScrollTop;
var buildSections = _.debounce(function() {
mdSectionList = [];
var mdSectionOffset;
var scrollHeight;
_.each(editorElt.querySelectorAll(".wmd-input-section"), function(delimiterElt) {
if(mdSectionOffset === undefined) {
// Force start to 0 for the first section
mdSectionOffset = 0;
return;
}
delimiterElt = delimiterElt.firstChild;
// Consider div scroll position
var newSectionOffset = delimiterElt.offsetTop;
mdSectionList.push({
startOffset: mdSectionOffset,
endOffset: newSectionOffset,
height: newSectionOffset - mdSectionOffset
});
mdSectionOffset = newSectionOffset;
});
// Last section
scrollHeight = editorElt.scrollHeight;
mdSectionList.push({
startOffset: mdSectionOffset,
endOffset: scrollHeight,
height: scrollHeight - mdSectionOffset
});
// Find corresponding sections in the preview
htmlSectionList = [];
var htmlSectionOffset;
_.each(previewElt.querySelectorAll(".wmd-preview-section"), function(delimiterElt) {
if(htmlSectionOffset === undefined) {
// Force start to 0 for the first section
htmlSectionOffset = 0;
return;
}
// Consider div scroll position
var newSectionOffset = delimiterElt.offsetTop;
htmlSectionList.push({
startOffset: htmlSectionOffset,
endOffset: newSectionOffset,
height: newSectionOffset - htmlSectionOffset
});
htmlSectionOffset = newSectionOffset;
});
// Last section
scrollHeight = previewElt.scrollHeight;
htmlSectionList.push({
startOffset: htmlSectionOffset,
endOffset: scrollHeight,
height: scrollHeight - htmlSectionOffset
});
// apply Scroll Link (-10 to have a gap > 9px)
lastEditorScrollTop = -10;
lastPreviewScrollTop = -10;
doScrollSync();
}, 500);
var isPreviewVisible = true;
var isScrollEditor = false;
var isScrollPreview = false;
var isEditorMoving = false;
var isPreviewMoving = false;
function getDestScrollTop(srcScrollTop, srcSectionList, destSectionList) {
// Find the section corresponding to the offset
var sectionIndex;
var srcSection = _.find(srcSectionList, function(section, index) {
sectionIndex = index;
return srcScrollTop < section.endOffset;
});
if(srcSection === undefined) {
// Something very bad happened
return;
}
var posInSection = (srcScrollTop - srcSection.startOffset) / (srcSection.height || 1);
var destSection = destSectionList[sectionIndex];
return destSection.startOffset + destSection.height * posInSection;
}
var timeoutId;
var currentEndCb;
function animate(elt, startValue, endValue, stepCb, endCb) {
if(currentEndCb) {
clearTimeout(timeoutId);
currentEndCb();
}
currentEndCb = endCb;
var diff = endValue - startValue;
var startTime = Date.now();
function tick() {
var currentTime = Date.now();
var progress = (currentTime - startTime) / 200;
if(progress < 1) {
var scrollTop = startValue + diff * Math.cos((1 - progress) * Math.PI / 2);
elt.scrollTop = scrollTop;
stepCb(scrollTop);
timeoutId = setTimeout(tick, 1);
}
else {
currentEndCb = undefined;
elt.scrollTop = endValue;
setTimeout(endCb, 100);
}
}
tick();
}
var doScrollSync = _.throttle(function() {
if(!isPreviewVisible || mdSectionList.length === 0 || mdSectionList.length !== htmlSectionList.length) {
return;
}
var editorScrollTop = editorElt.scrollTop;
editorScrollTop < 0 && (editorScrollTop = 0);
var previewScrollTop = previewElt.scrollTop;
var destScrollTop;
// Perform the animation if diff > 9px
if(isScrollEditor === true) {
if(Math.abs(editorScrollTop - lastEditorScrollTop) <= 9) {
return;
}
isScrollEditor = false;
// Animate the preview
lastEditorScrollTop = editorScrollTop;
destScrollTop = getDestScrollTop(editorScrollTop, mdSectionList, htmlSectionList);
destScrollTop = _.min([
destScrollTop,
previewElt.scrollHeight - previewElt.offsetHeight
]);
if(Math.abs(destScrollTop - previewScrollTop) <= 9) {
// Skip the animation if diff is <= 9
lastPreviewScrollTop = previewScrollTop;
return;
}
animate(previewElt, previewScrollTop, destScrollTop, function(currentScrollTop) {
isPreviewMoving = true;
lastPreviewScrollTop = currentScrollTop;
}, function() {
isPreviewMoving = false;
});
}
else if(isScrollPreview === true) {
if(Math.abs(previewScrollTop - lastPreviewScrollTop) <= 9) {
return;
}
isScrollPreview = false;
// Animate the editor
lastPreviewScrollTop = previewScrollTop;
destScrollTop = getDestScrollTop(previewScrollTop, htmlSectionList, mdSectionList);
destScrollTop = _.min([
destScrollTop,
editorElt.scrollHeight - editorElt.offsetHeight
]);
if(Math.abs(destScrollTop - editorScrollTop) <= 9) {
// Skip the animation if diff is <= 9
lastEditorScrollTop = editorScrollTop;
return;
}
animate(editorElt, editorScrollTop, destScrollTop, function(currentScrollTop) {
isEditorMoving = true;
lastEditorScrollTop = currentScrollTop;
}, function() {
isEditorMoving = false;
});
}
}, 100);
scrollSync.onLayoutResize = function() {
isScrollEditor = true;
buildSections();
};
scrollSync.onFileClosed = function() {
mdSectionList = [];
};
var scrollAdjust = false;
scrollSync.onReady = function() {
previewElt = document.querySelector(".preview-container");
editorElt = document.querySelector("#wmd-input");
$(previewElt).scroll(function() {
if(isPreviewMoving === false && scrollAdjust === false) {
isScrollPreview = true;
isScrollEditor = false;
doScrollSync();
}
scrollAdjust = false;
});
$(editorElt).scroll(function() {
if(isEditorMoving === false) {
isScrollEditor = true;
isScrollPreview = false;
doScrollSync();
}
});
$(".preview-panel").on('hide.layout.toggle', function() {
isPreviewVisible = false;
}).on('shown.layout.toggle', function() {
isPreviewVisible = true;
});
// Reimplement anchor scrolling to work without preview
$('.extension-preview-buttons .table-of-contents').on('click', 'a', function(evt) {
evt.preventDefault();
var id = this.hash;
var anchorElt = previewElt.querySelector(id);
if(!anchorElt) {
return;
}
var previewScrollTop = anchorElt.getBoundingClientRect().top - previewElt.getBoundingClientRect().top + previewElt.scrollTop;
previewElt.scrollTop = previewScrollTop;
var editorScrollTop = getDestScrollTop(previewScrollTop, htmlSectionList, mdSectionList);
editorElt.scrollTop = editorScrollTop;
});
};
var previewContentsElt;
var previousHeight;
scrollSync.onPagedownConfigure = function(editor) {
previewContentsElt = document.getElementById("preview-contents");
editor.getConverter().hooks.chain("postConversion", function(text) {
// To avoid losing scrolling position before elements are fully loaded
previousHeight = previewContentsElt.offsetHeight;
previewContentsElt.style.height = previousHeight + 'px';
return text;
});
};
scrollSync.onPreviewFinished = function() {
// Now set the correct height
previewContentsElt.style.removeProperty('height');
var newHeight = previewContentsElt.offsetHeight;
isScrollEditor = true;
if(newHeight < previousHeight) {
// We expect a scroll adjustment
scrollAdjust = true;
}
buildSections();
};
return scrollSync;
});