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HTML 

              
                <!DOCTYPE html>
<html lang="el">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Brainstorming Gadget</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            margin: 0;
            padding: 0;
            overflow-x: hidden;
        }

        #canvas-container {
            display: flex;
            justify-content: center;
            align-items: center;
            margin: 20px auto;
            position: relative;
            width: 100%;
            height: 90vh; /* Μεγαλύτερος καμβάς που καταλαμβάνει σχεδόν όλο το ύψος της οθόνης */
        }

        #canvas {
            width: 95% !important;  /* Χρήση important για να υπερισχύσει οποιοδήποτε άλλο στυλ */
            max-width: 1600px !important;  /* Μεγαλύτερο πλάτος */
            height: 100% !important;
            border: 2px solid #ccc;
            background-color: #f9f9f9;
            position: relative;
            overflow: hidden;
        }

        #centralQuestion {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            font-size: 24px;
            font-weight: bold;
            text-align: center;
            width: 300px;
            border: 1px solid #ddd;
            padding: 10px;
            background-color: pink;
        }

        .note {
            position: absolute;
            min-width: 150px;
            min-height: 100px;
            padding: 10px;
            background-color: yellow;
            box-shadow: 0 0 5px rgba(0,0,0,0.3);
            border: 1px solid #ddd;
            color: black;
            overflow: hidden;
            resize: both;
            white-space: pre-wrap;
            cursor: move;
        }

        #controls {
            position: absolute;
            top: 10px;
            left: 50%;
            transform: translateX(-50%);
            display: flex;
            gap: 10px;
            z-index: 10;
        }

        #addNoteBtn, #resetBtn, #downloadBtn {
            padding: 10px 20px;
            font-size: 16px;
            cursor: pointer;
            background-color: white;
            border: 1px solid #ccc;
            border-radius: 5px;
        }
    </style>
</head>
<body>

<div id="canvas-container">
    <div id="canvas">
        <div id="centralQuestion" contentEditable="true">Κεντρικό Ερώτημα</div>
        <div id="controls">
            <button id="addNoteBtn">Προσθήκη Σημείωσης</button>
            <button id="resetBtn">Επαναφορά</button>
            <button id="downloadBtn">Λήψη Εικόνας για Εκτύπωση</button>
        </div>
    </div>
</div>

<script src="https://cdnjs.cloudflare.com/ajax/libs/html2canvas/1.4.1/html2canvas.min.js"></script>

<script>
    const colors = ["#ffeb3b", "#ff5722", "#8bc34a", "#03a9f4", "#e91e63"];
    let colorIndex = 0;

    function adjustCanvasSize() {
        const canvas = document.getElementById('canvas');
        canvas.style.width = '1600px';  // Εξαναγκασμός πλάτους
        canvas.style.height = '800px';  // Εξαναγκασμός ύψους
    }

    function addNoteToCanvas(canvas = document.getElementById('canvas')) {
        const note = document.createElement('div');
        note.className = 'note';
        note.contentEditable = true;
        note.style.backgroundColor = colors[colorIndex];
        note.style.top = Math.random() * (canvas.offsetHeight - 100) + 'px';
        note.style.left = Math.random() * (canvas.offsetWidth - 150) + 'px';
        note.dataset.id = Date.now(); // Unique ID
        canvas.appendChild(note);

        makeNoteMovable(note);

        colorIndex = (colorIndex + 1) % colors.length;
    }

    function makeNoteMovable(note) {
        note.addEventListener('mousedown', function(e) {
            const offsetX = e.clientX - note.offsetLeft;
            const offsetY = e.clientY - note.offsetTop;
            note.style.cursor = 'grabbing';

            function onMouseMove(e) {
                note.style.left = e.clientX - offsetX + 'px';
                note.style.top = e.clientY - offsetY + 'px';
            }

            document.addEventListener('mousemove', onMouseMove);

            document.addEventListener('mouseup', function() {
                document.removeEventListener('mousemove', onMouseMove);
                note.style.cursor = 'move';
                constrainNotePosition(note, canvas);
            }, { once: true });
        });
    }

    function constrainNotePosition(note, canvas) {
        const noteRect = note.getBoundingClientRect();
        const canvasRect = canvas.getBoundingClientRect();

        // Περιορισμός σημειώσεων εντός των ορίων του καμβά
        if (noteRect.right > canvasRect.right) {
            note.style.left = canvasRect.width - noteRect.width + 'px';
        }
        if (noteRect.bottom > canvasRect.bottom) {
            note.style.top = canvasRect.height - noteRect.height + 'px';
        }
        if (noteRect.left < canvasRect.left) {
            note.style.left = '0px';
        }
        if (noteRect.top < canvasRect.top) {
            note.style.top = '0px';
        }
    }

    document.getElementById('addNoteBtn').addEventListener('click', function() {
        addNoteToCanvas();
    });

    document.getElementById('resetBtn').addEventListener('click', function() {
        if (confirm('Είστε σίγουροι ότι θέλετε να διαγράψετε όλες τις σημειώσεις;')) {
            document.getElementById('canvas').innerHTML = '<div id="centralQuestion" contentEditable="true">Κεντρικό Ερώτημα</div>';
            colorIndex = 0; // Επαναφορά του δείκτη χρώματος
        }
    });

    document.getElementById('downloadBtn').addEventListener('click', function() {
        html2canvas(document.getElementById('canvas')).then(function(canvas) {
            const link = document.createElement('a');
            link.href = canvas.toDataURL('image/png');
            link.download = 'canvas_image.png';
            link.click();
        });
    });

    // Εξαναγκασμός μεγέθους του καμβά κατά την εκκίνηση
    window.onload = adjustCanvasSize;
</script>

</body>
</html>
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