<!DOCTYPE html>
<html>
<head>
<title>Testing Widows and Orphans</title>
<style>
body.hide-containers .container {
    display: none;
}

.container {
    width: 600px;
    height: 200px;
    -webkit-columns: 3;
    -webkit-column-fill: auto;
    columns: 3;
    column-fill: auto;
    line-height: 20px; /* 10 lines per page */
    font-size: 16px;
    margin: 0 0 20px 0;
    padding: 0;
    overflow: hidden;
}

.block {
    margin: 0 0 15px 0;
    padding: 0;
}

.top {
    color: red;
}

.bottom {
    color: green;
}
</style>
<script>
var results;

function createTestContainer(id, description, blocks)
{
    var label = document.createElement("h3");
    label.textContent = id + " - " + description;
    document.body.appendChild(label);
    var element = document.createElement("div");
    element.className = "container";
    element.id = id;

    for (var i = 1; i <= blocks.length; i++) {
        var block = document.createElement("div");
        block.className = "block";
        var numLines = blocks[i-1];
        for (var j = 1; j <= numLines; j++) {
            var line = document.createElement("span");
            line.id = id + "-block-" + i + "-line-" + j;
            line.textContent = "Block " + i + " Line " + j;
            block.appendChild(line);
            block.appendChild(document.createElement("br"));
        }
        element.appendChild(block);
    }
    document.body.appendChild(element);
    return element;
}

function markTopLine(containerId, blockNumber, lineNumber)
{
    var element = document.getElementById(containerId + "-block-" + blockNumber + "-line-" + lineNumber);
    element.className = "top";
}

function markBottomLine(containerId, blockNumber, lineNumber)
{
    var element = document.getElementById(containerId + "-block-" + blockNumber + "-line-" + lineNumber);
    element.className = "bottom";
}

function logPass(msg) {
    log("PASS: " + msg);
}

function logFail(msg) {
    log("FAIL: " + msg);
}

function log(msg) {
    if (!results)
        results = document.createElement("div");

    var output = document.createElement("p");
    output.textContent = msg;
    results.appendChild(output);
}

function testIsFirstInColumn(containerId, blockNumber, lineNumber)
{
    // Get the upper bounds of the container and line.
    var topOfContainer = document.getElementById(containerId).getBoundingClientRect().top;
    var topOfLine = document.getElementById(containerId + "-block-" + blockNumber + "-line-" + lineNumber).getBoundingClientRect().top;

    if (Math.abs(topOfContainer - topOfLine) < 5) // Give 5 pixels to account for subpixel layout.
        logPass(containerId + " Block " + blockNumber + " Line " + lineNumber + " is correct.");
    else
        logFail(containerId + " Block " + blockNumber + " Line " + lineNumber + " wasn't at the top of the column.");
}

function runTest()
{
    var container;

    createTestContainer("test1", "Normal breaking", [5, 6, 5, 5]);

    markTopLine("test1", 1, 1);
    markBottomLine("test1", 2, 4);
    markTopLine("test1", 2, 5);
    markBottomLine("test1", 4, 1);
    markTopLine("test1", 4, 2);

    testIsFirstInColumn("test1", 1, 1);
    testIsFirstInColumn("test1", 2, 5);
    testIsFirstInColumn("test1", 4, 2);

    container = createTestContainer("test2", "Basic Orphan", [8, 6]);
    container.style.orphans = 2;

    markTopLine("test2", 1, 1);
    markBottomLine("test2", 1, 8); // Orphan break happens here.
    markTopLine("test2", 2, 1);

    testIsFirstInColumn("test2", 1, 1);
    testIsFirstInColumn("test2", 2, 1);

    container = createTestContainer("test3", "Basic Widow", [4, 6, 3]);
    container.style.widows = 2;

    markTopLine("test3", 1, 1);
    markBottomLine("test3", 2, 4); // Widow break happens here.
    markTopLine("test3", 2, 5);

    testIsFirstInColumn("test3", 1, 1);
    testIsFirstInColumn("test3", 2, 5);

    container = createTestContainer("test4", "Orphans causing Widows", [8, 6, 4, 4]);
    container.style.orphans = 2;
    container.style.widows = 2;

    markTopLine("test4", 1, 1);
    markBottomLine("test4", 1, 8); // Orphan break happens here.
    markTopLine("test4", 2, 1);
    markBottomLine("test4", 3, 2); // And that creates a widow forcing a break here.
    markTopLine("test4", 3, 3);

    testIsFirstInColumn("test4", 1, 1);
    testIsFirstInColumn("test4", 2, 1);
    testIsFirstInColumn("test4", 3, 3);

    container = createTestContainer("test5", "Widows blocked by Orphan rule", [7, 3, 4]);
    container.style.orphans = 2;
    container.style.widows = 2;

    markTopLine("test5", 1, 1);
    markBottomLine("test5", 2, 2); // This line should not move - protected by orphaning.
    markTopLine("test5", 2, 3); // This line won't be un-widowed - blocked by orphaning.

    testIsFirstInColumn("test5", 1, 1);
    testIsFirstInColumn("test5", 2, 3);

    container = createTestContainer("test6", "Ridiculous values", [7, 7, 7, 7]);
    container.style.orphans = 100;
    container.style.widows = 100;

    markTopLine("test6", 1, 1);
    markBottomLine("test6", 1, 7); // Orphan break happens here.
    markTopLine("test6", 2, 1); // Adopted.
    markBottomLine("test6", 2, 7); // Orphan break.
    markTopLine("test6", 3, 1); // Adopted.

    testIsFirstInColumn("test6", 1, 1);
    testIsFirstInColumn("test6", 2, 1);
    testIsFirstInColumn("test6", 3, 1);

    if (results)
        document.body.appendChild(results);

    if (window.testRunner) {
        // Hide all the containers and leave just the test results for text output.
        document.body.className = "hide-containers";
        testRunner.notifyDone();
    }
}

if (window.testRunner) {
    testRunner.dumpAsText();
    testRunner.waitUntilDone();
}

window.addEventListener("load", runTest, false);
</script>
</head>
<body>
    <p>
        Testing widows and orphans. Any green lines
        should be at the bottom of pages/columns, and any red lines
        should be at the top of pages/columns.
    </p>
</body>
</html>