Calendar Gantt

by Rolf Friedrich

HTML

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Kalender mit Events</title>
  <link rel="stylesheet" href="style.css">
</head>
<body>
  <div class="calendar">
    <!-- Hintergrund-Grid -->
    <div class="background-grid">
      <!-- 31 Tage für den Hintergrund -->
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
      <div></div>
    </div>

    <!-- Event-Container -->
        <!-- Event-Container -->
    <div class="event-container">
 <!-- Mehrtägiges Event -->
  <div
    class="event event-overlap"
    style="grid-column: 5 / span 5; grid-row: 1;"
    data-start="5"
    data-end="9"
    data-id="5_9"
    draggable="true"
  >
    <div class="event__title">Mehrtägiges Event</div>
    <div class="event__time">Beginn: 8:00 Uhr</div>
    <div class="event__description">Dies ist ein Büroevent für die Abteilung IT</div>
  </div>

  <!-- Einzeltermin -->
  <div
    class="event event-single"
    style="grid-column: 10 / span 1; grid-row: 1;"
    data-start="10"
    data-end="10"
    data-id="10_10"
    draggable="true"
  >
    <div class="event__title">Einzeltermin</div>
    <div class="event__time">10:00 - 10:30 Uhr</div>
    <div class="event__description">Kurzmeeting mit der Geschäftsleitung</div>
  </div>
      
    </div>
   

    <!-- Tage -->
    <!-- 31 Tage für den Kalender -->
    <div class="day" data-day="1">1</div>
    <div class="day" data-day="2">2</div>
    <div class="day"...

CSS

/* Verhindert Textmarkierung */
body {
  user-select: none;
}

/* Dragging-Effekt */
.dragging {
  opacity: 0.7; /* Leicht transparent */
  cursor: grabbing;
  position: absolute; /* Schwebt über dem Grid */
  z-index: 10; /* Höher als andere Elemente */
}

/* Kalender-Container mit Scrollbar */
.calendar-container {
  overflow-x: auto; /* Horizontal scrollbar */
  overflow-y: hidden; /* Kein vertikales Scrollen */
  width: 100%; /* Passt sich an den Bildschirm an */
}

/* Gesamtes Kalender-Grid */
.calendar {
  display: grid;
  grid-template-columns: repeat(31, minmax(3rem, 1fr)); /* 31 Tage in einer Reihe */
  grid-auto-rows: minmax(3rem, auto); /* Mindesthöhe pro Zeile */
  gap: 0; /* Abstand zwischen den Zellen */
  position: relative;
  width: max-content; /* Passt sich der Breite an */
}

/* Einzelne Tage */
.day {
  background: #f0f0f0;
  border-left: 1px solid #ccc;
  border-top: 1px solid #ccc;
  border-bottom: 1px solid #ccc;
  text-align: center;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  min-width: 3rem;
  min-height: 3rem; /* Mindesthöhe */
  z-index: 2;
  pointer-events: auto; /* Aktiviert Mausereignisse */
}

/* Hintergrund-Grid */
.background-grid {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: grid;
  grid-template-columns: repeat(31, minmax(3rem, 1fr)); /* 31 Tage */
  grid-auto-rows: minmax(3rem, auto);
  gap: 0;
  z-index: 0;
  pointer-events: none; /* Hintergrund ignoriert Mausereignisse */
}

.background-grid div {
  background: #f9f9f9;
  border: 1px dashed #ddd;
}

/* Container für Events */
.event-container {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: grid;

  grid-template-columns: repeat(31, minmax(3rem, 1fr)); /* 31 Tage */
  grid-auto-rows: 3rem; /* Dynamische Zeilenhöhe */
  gap: 0;
  z-index: 3;
  pointer-events: none; /* Events-Container ignoriert Mausereignisse */
}

/* Mehrtägige...

JavaScript

document.addEventListener('DOMContentLoaded', () => {
  const calendar = document.querySelector('.calendar');
  const eventContainer = document.querySelector('.event-container');
  const days = [...calendar.querySelectorAll('.day')];
  let isSelecting = false;
  let startDay = null;
  let endDay = null;
  let draggedEvent = null;
  let offsetX = 0;
  let originalStart = 0;
  let originalEnd = 0;
  let totalDays = days.length;

  /**
   * Passt die Höhe der gesamten Kalenderzeile und der Tage an die maximale Anzahl von Terminen an.
   */
  function adjustRowHeight() {
    const maxRows = [...eventContainer.children].reduce((max, event) => {
      const row = parseInt(event.style.gridRow) || 1;
      return Math.max(max, row);
    }, 1);

    calendar.style.gridAutoRows = `${maxRows * 3}rem`;
    days.forEach(day => {
      day.style.minHeight = `${maxRows * 3}rem`;
    });
  }

  /**
   * Initialisiert Drag-and-Drop für alle Events.
   */
  function initializeEvents() {
    const events = document.querySelectorAll('.event');

    events.forEach(event => {
        event.setAttribute('draggable', 'true');

        if (!event.dataset.start || !event.dataset.end) {
            const gridColumn = event.style.gridColumn.split('/');
            event.dataset.start = parseInt(gridColumn[0]) || 1;
            event.dataset.end = (parseInt(gridColumn[1]) || 1) + parseInt(gridColumn[0]) - 1;
        }

        event.addEventListener('dragstart', (e) => {
            draggedEvent = e.target;
            const rect = draggedEvent.getBoundingClientRect();

            offsetX = e.clientX - rect.left;
            originalStart = parseInt(draggedEvent.dataset.start, 10);
            originalEnd = parseInt(draggedEvent.dataset.end, 10);

            e.dataTransfer.setDragImage(new Image(), 0, 0);
            draggedEvent.classList.add('dragging');
        });

        event.addEventListener('dragend', () => {
            if (draggedEvent) {
               ...