tools/image-resizer.html at main · mathspp/tools · GitHub

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<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Image Resizer</title>
    <link rel="stylesheet" href="styles.css">
    <style>
        body {
            max-width: 960px;
            margin: 0 auto;
            padding: 24px 20px 56px;
        }

        header {
            margin-bottom: 1.25rem;
        }

        main {
            display: grid;
            gap: 1.5rem;
        }

        .panel {
            padding: clamp(1.25rem, 3vw, 2rem);
        }

        .drop-zone {
            border: 2px dashed var(--color-border, #d0d7de);
            border-radius: 12px;
            padding: 32px 20px;
            text-align: center;
            cursor: pointer;
            transition: border-color 0.2s ease, background-color 0.2s ease;
        }

        .drop-zone input {
            display: none;
        }

        .drop-zone.dragover {
            border-color: var(--color-accent, #0070f3);
            background-color: rgba(0, 112, 243, 0.08);
        }

        .drop-zone p {
            margin: 0.35rem 0 0;
            color: var(--color-muted, #57606a);
        }

        .resize-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
            gap: 1rem;
        }

        .form-group {
            display: flex;
            flex-direction: column;
            gap: 0.35rem;
        }

        .preset-buttons {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem;
        }

        .preset-buttons button {
            flex: 1 1 auto;
        }

        .info-row {
            display: flex;
            flex-wrap: wrap;
            gap: 0.5rem 1.5rem;
            color: var(--color-muted, #57606a);
            font-size: 0.95rem;
        }

        .preview-wrapper {
            display: grid;
            gap: 1rem;
        }

        .preview-wrapper img {
            max-width: 100%;
            border-radius: 10px;
            background: #fff;
            box-shadow: 0 2px 10px rgba(15, 23, 42, 0.08);
        }

        .status-text {
            min-height: 1.25rem;
            color: var(--color-muted, #57606a);
        }

        .status-text.error {
            color: #b42318;
        }

        @media (max-width: 640px) {
            body {
                padding: 18px 16px 48px;
            }
        }
    </style>
</head>

<body>
    <header class="page-header">
        <a class="site-link" href="https://tools.mathspp.com/" aria-label="Back to tools.mathspp.com">← tools.mathspp.com</a>
        <h1>Image Resizer</h1>
        <p class="lead">Drop a PNG, JPEG, or WebP image and generate a resized copy using quick presets or exact dimensions.</p>
    </header>

    <main>
        <section class="surface panel">
            <div class="drop-zone" tabindex="0" role="button" aria-label="Upload image" id="drop-zone">
                <strong>Drop your image here</strong>
                <p>or click to choose a file</p>
                <input type="file" accept="image/*" id="image-input" aria-label="Upload image">
            </div>
            <p class="status-text" id="status-text">No image loaded yet.</p>
        </section>

        <section class="surface panel" aria-live="polite">
            <h2>Resize options</h2>
            <div class="info-row" id="original-info" hidden>
                <span id="file-name"></span>
                <span id="original-dimensions"></span>
                <span id="scale-info"></span>
            </div>

            <div class="resize-grid">
                <div class="form-group">
                    <label for="target-width">Width (px)</label>
                    <input type="number" id="target-width" min="1" inputmode="numeric" placeholder="e.g. 1024" disabled>
                </div>
                <div class="form-group">
                    <label for="target-height">Height (px)</label>
                    <input type="number" id="target-height" min="1" inputmode="numeric" placeholder="e.g. 768" disabled>
                </div>
                <div class="form-group">
                    <label>
                        <input type="checkbox" id="lock-aspect" checked disabled>
                        Lock aspect ratio
                    </label>
                    <div class="preset-buttons">
                        <button type="button" data-scale="0.5" disabled>0.5×</button>
                        <button type="button" data-scale="1" disabled>1×</button>
                        <button type="button" data-scale="2" disabled>2×</button>
                    </div>
                </div>
            </div>
        </section>

        <section class="surface panel">
            <h2>Result</h2>
            <div class="preview-wrapper">
                <p class="status-text" id="result-status">Upload an image to see the resized preview.</p>
                <img id="preview" alt="Resized preview" hidden>
                <div class="tool-actions">
                    <button type="button" id="download-btn" disabled>Download resized image</button>
                </div>
            </div>
        </section>
    </main>

    <script>
        (function () {
            const dropZone = document.getElementById('drop-zone');
            const fileInput = document.getElementById('image-input');
            const statusText = document.getElementById('status-text');
            const resultStatus = document.getElementById('result-status');
            const preview = document.getElementById('preview');
            const downloadBtn = document.getElementById('download-btn');
            const widthInput = document.getElementById('target-width');
            const heightInput = document.getElementById('target-height');
            const lockAspectCheckbox = document.getElementById('lock-aspect');
            const presetButtons = document.querySelectorAll('[data-scale]');
            const fileNameEl = document.getElementById('file-name');
            const originalDimensionsEl = document.getElementById('original-dimensions');
            const scaleInfoEl = document.getElementById('scale-info');
            const originalInfo = document.getElementById('original-info');

            let originalImage = null;
            let originalWidth = 0;
            let originalHeight = 0;
            let suppressUpdate = false;
            let lastDataURL = '';

            function setControlsEnabled(enabled) {
                widthInput.disabled = !enabled;
                heightInput.disabled = !enabled;
                lockAspectCheckbox.disabled = !enabled;
                presetButtons.forEach(btn => {
                    btn.disabled = !enabled;
                });
            }

            function updateScaleInfo(targetWidth, targetHeight) {
                if (!originalWidth || !originalHeight) {
                    scaleInfoEl.textContent = '';
                    return;
                }
                const widthScale = (targetWidth / originalWidth).toFixed(2);
                const heightScale = (targetHeight / originalHeight).toFixed(2);
                scaleInfoEl.textContent = `Scale: ${widthScale}× width, ${heightScale}× height`;
            }

            function updatePreview() {
                if (!originalImage) {
                    return;
                }
                const width = Number(widthInput.value);
                const height = Number(heightInput.value);

                if (!width || !height) {
                    resultStatus.textContent = 'Enter both width and height to resize the image.';
                    preview.hidden = true;
                    downloadBtn.disabled = true;
                    return;
                }

                const canvas = document.createElement('canvas');
                canvas.width = width;
                canvas.height = height;
                const ctx = canvas.getContext('2d');
                ctx.drawImage(originalImage, 0, 0, width, height);
                lastDataURL = canvas.toDataURL('image/png');
                preview.src = lastDataURL;
                preview.hidden = false;
                resultStatus.textContent = `Resized image: ${width} × ${height} pixels`;
                downloadBtn.disabled = false;
                updateScaleInfo(width, height);
            }

            function handleDimensionInput(changedInput) {
                if (!originalWidth || !originalHeight) return;
                if (suppressUpdate) return;
                const widthRatio = originalWidth / originalHeight;
                if (lockAspectCheckbox.checked) {
                    suppressUpdate = true;
                    if (changedInput === widthInput) {
                        const newWidth = Number(widthInput.value);
                        if (newWidth) {
                            heightInput.value = Math.max(1, Math.round(newWidth / widthRatio));
                        }
                    } else if (changedInput === heightInput) {
                        const newHeight = Number(heightInput.value);
                        if (newHeight) {
                            widthInput.value = Math.max(1, Math.round(newHeight * widthRatio));
                        }
                    }
                    suppressUpdate = false;
                }
                updatePreview();
            }

            function handleFiles(files) {
                const file = files && files[0];
                if (!file) return;
                if (!file.type.startsWith('image/')) {
                    statusText.textContent = 'Please choose an image file (PNG, JPEG, WebP, ...).';
                    statusText.classList.add('error');
                    return;
                }

                statusText.classList.remove('error');
                statusText.textContent = 'Loading image…';
                const reader = new FileReader();
                reader.onload = (event) => {
                    const img = new Image();
                    img.onload = () => {
                        originalImage = img;
                        originalWidth = img.naturalWidth;
                        originalHeight = img.naturalHeight;
                        widthInput.value = originalWidth;
                        heightInput.value = originalHeight;
                        originalInfo.hidden = false;
                        fileNameEl.textContent = `File: ${file.name}`;
                        originalDimensionsEl.textContent = `Original: ${originalWidth} × ${originalHeight}`;
                        setControlsEnabled(true);
                        statusText.textContent = 'Image loaded. Adjust the dimensions below to resize it.';
                        updatePreview();
                    };
                    img.onerror = () => {
                        statusText.textContent = 'Could not read this file as an image.';
                        statusText.classList.add('error');
                    };
                    img.src = event.target.result;
                };
                reader.readAsDataURL(file);
            }

            dropZone.addEventListener('click', () => fileInput.click());
            dropZone.addEventListener('keydown', (event) => {
                if (event.key === 'Enter' || event.key === ' ') {
                    event.preventDefault();
                    fileInput.click();
                }
            });

            dropZone.addEventListener('dragover', (event) => {
                event.preventDefault();
                dropZone.classList.add('dragover');
            });

            dropZone.addEventListener('dragleave', () => {
                dropZone.classList.remove('dragover');
            });

            dropZone.addEventListener('drop', (event) => {
                event.preventDefault();
                dropZone.classList.remove('dragover');
                handleFiles(event.dataTransfer.files);
            });

            fileInput.addEventListener('change', () => handleFiles(fileInput.files));

            widthInput.addEventListener('input', () => handleDimensionInput(widthInput));
            heightInput.addEventListener('input', () => handleDimensionInput(heightInput));
            lockAspectCheckbox.addEventListener('change', () => handleDimensionInput(widthInput));

            presetButtons.forEach(button => {
                button.addEventListener('click', () => {
                    if (!originalWidth || !originalHeight) return;
                    const scale = Number(button.dataset.scale);
                    widthInput.value = Math.max(1, Math.round(originalWidth * scale));
                    heightInput.value = Math.max(1, Math.round(originalHeight * scale));
                    updatePreview();
                });
            });

            downloadBtn.addEventListener('click', () => {
                if (!lastDataURL) return;
                const link = document.createElement('a');
                link.href = lastDataURL;
                link.download = 'resized-image.png';
                link.click();
            });
        })();
    </script>

    <footer class="page-footer">
        <p>Built with ❤️, 🤖, and 🐍, by <a href="https://mathspp.com/">Rodrigo Girão Serrão</a></p>
    </footer>
</body>

</html>