annotate mercurial/templates/static/followlines.js @ 31848:7160bdd56b84

hgweb: add a floating tooltip to invite on followlines action

In followlines.js, we create a <div id="followlines-tooltip"> element to draw
attention of users on "followlines" feature. The element shows up on hover of
source lines after one second and follows the cursor. After first click (start
line selection), the text changes and indicates that next click will terminate
selection.

// followlines.js - JavaScript utilities for followlines UI
//
// Copyright 2017 Logilab SA <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

//** Install event listeners for line block selection and followlines action */
document.addEventListener('DOMContentLoaded', function() {
    var sourcelines = document.getElementsByClassName('sourcelines')[0];
    if (typeof sourcelines === 'undefined') {
        return;
    }
    // URL to complement with "linerange" query parameter
    var targetUri = sourcelines.dataset.logurl;
    if (typeof targetUri === 'undefined') {
        return;
    }

    // tooltip to invite on lines selection
    var tooltip = document.createElement('div');
    tooltip.id = 'followlines-tooltip';
    tooltip.classList.add('hidden');
    var initTooltipText = 'click to start following lines history from here';
    tooltip.textContent = initTooltipText;
    sourcelines.appendChild(tooltip);

    var tooltipTimeoutID;
    //* move the "tooltip" with cursor (top-right) and show it after 1s */
    function moveAndShowTooltip(e) {
        if (typeof tooltipTimeoutID !== 'undefined') {
            // avoid accumulation of timeout callbacks (blinking)
            window.clearTimeout(tooltipTimeoutID);
        }
        tooltip.classList.add('hidden');
        var x = (e.clientX + 10) + 'px',
            y = (e.clientY - 20) + 'px';
        tooltip.style.top = y;
        tooltip.style.left = x;
        tooltipTimeoutID = window.setTimeout(function() {
            tooltip.classList.remove('hidden');
        }, 1000);
    }

    // on mousemove, show tooltip close to cursor position
    sourcelines.addEventListener('mousemove', moveAndShowTooltip);

    // retrieve all direct <span> children of <pre class="sourcelines">
    var spans = Array.prototype.filter.call(
        sourcelines.children,
        function(x) { return x.tagName === 'SPAN' });

    // add a "followlines-select" class to change cursor type in CSS
    for (var i = 0; i < spans.length; i++) {
        spans[i].classList.add('followlines-select');
    }

    var lineSelectedCSSClass = 'followlines-selected';

    //** add CSS class on <span> element in `from`-`to` line range */
    function addSelectedCSSClass(from, to) {
        for (var i = from; i <= to; i++) {
            spans[i].classList.add(lineSelectedCSSClass);
        }
    }

    //** remove CSS class from previously selected lines */
    function removeSelectedCSSClass() {
        var elements = sourcelines.getElementsByClassName(
            lineSelectedCSSClass);
        while (elements.length) {
            elements[0].classList.remove(lineSelectedCSSClass);
        }
    }

    // ** return the <span> element parent of `element` */
    function findParentSpan(element) {
        var parent = element.parentElement;
        if (parent === null) {
            return null;
        }
        if (element.tagName == 'SPAN' && parent.isSameNode(sourcelines)) {
            return element;
        }
        return findParentSpan(parent);
    }

    //** event handler for "click" on the first line of a block */
    function lineSelectStart(e) {
        var startElement = findParentSpan(e.target);
        if (startElement === null) {
            // not a <span> (maybe <a>): abort, keeping event listener
            // registered for other click with <span> target
            return;
        }

        // update tooltip text
        tooltip.textContent = 'click again to terminate line block selection here';

        var startId = parseInt(startElement.id.slice(1));
        startElement.classList.add(lineSelectedCSSClass); // CSS

        // remove this event listener
        sourcelines.removeEventListener('click', lineSelectStart);

        //** event handler for "click" on the last line of the block */
        function lineSelectEnd(e) {
            var endElement = findParentSpan(e.target);
            if (endElement === null) {
                // not a <span> (maybe <a>): abort, keeping event listener
                // registered for other click with <span> target
                return;
            }

            // remove this event listener
            sourcelines.removeEventListener('click', lineSelectEnd);

            // hide tooltip and disable motion tracking
            tooltip.classList.add('hidden');
            sourcelines.removeEventListener('mousemove', moveAndShowTooltip);
            window.clearTimeout(tooltipTimeoutID);

            //* restore initial "tooltip" state */
            function restoreTooltip() {
                tooltip.textContent = initTooltipText;
                sourcelines.addEventListener('mousemove', moveAndShowTooltip);
            }

            // compute line range (startId, endId)
            var endId = parseInt(endElement.id.slice(1));
            if (endId == startId) {
                // clicked twice the same line, cancel and reset initial state
                // (CSS, event listener for selection start, tooltip)
                removeSelectedCSSClass();
                sourcelines.addEventListener('click', lineSelectStart);
                restoreTooltip();
                return;
            }
            var inviteElement = endElement;
            if (endId < startId) {
                var tmp = endId;
                endId = startId;
                startId = tmp;
                inviteElement = startElement;
            }

            addSelectedCSSClass(startId - 1, endId -1);  // CSS

            // append the <div id="followlines"> element to last line of the
            // selection block
            var divAndButton = followlinesBox(targetUri, startId, endId);
            var div = divAndButton[0],
                button = divAndButton[1];
            inviteElement.appendChild(div);

            //** event handler for cancelling selection */
            function cancel() {
                // remove invite box
                div.parentNode.removeChild(div);
                // restore initial event listeners
                sourcelines.addEventListener('click', lineSelectStart);
                sourcelines.removeEventListener('click', cancel);
                // remove styles on selected lines
                removeSelectedCSSClass();
                // restore tooltip element
                restoreTooltip();
            }

            // bind cancel event to click on <button>
            button.addEventListener('click', cancel);
            // as well as on an click on any source line
            sourcelines.addEventListener('click', cancel);
        }

        sourcelines.addEventListener('click', lineSelectEnd);

    }

    sourcelines.addEventListener('click', lineSelectStart);

    //** return a <div id="followlines"> and inner cancel <button> elements */
    function followlinesBox(targetUri, fromline, toline) {
        // <div id="followlines">
        var div = document.createElement('div');
        div.id = 'followlines';

        //   <div class="followlines-cancel">
        var buttonDiv = document.createElement('div');
        buttonDiv.classList.add('followlines-cancel');

        //     <button>x</button>
        var button = document.createElement('button');
        button.textContent = 'x';
        buttonDiv.appendChild(button);
        div.appendChild(buttonDiv);

        //   <div class="followlines-link">
        var aDiv = document.createElement('div');
        aDiv.classList.add('followlines-link');

        //     <a href="/log/<rev>/<file>?patch=&linerange=...">
        var a = document.createElement('a');
        var url = targetUri + '?patch=&linerange=' + fromline + ':' + toline;
        a.setAttribute('href', url);
        a.textContent = 'follow lines ' + fromline + ':' + toline;
        aDiv.appendChild(a);
        div.appendChild(aDiv);

        return [div, button];
    }

}, false);