explorations/tiling.html at main · gever/explorations · 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, user-scalable=no">
    <title>Image Cropper & Tile Rotator</title>
    <style>
        body {
            font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            height: 100vh;
            margin: 0;
            background-color: #f0f0f0;
            color: #333;
            overflow: hidden; /* Prevent scroll on mobile during drag */
        }
        h1 {
            margin-top: 0;
            color: #2c3e50;
        }
        #canvasContainer {
            text-align: center;
            background-color: #fff;
            padding: 20px;
            border-radius: 8px;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
        }
        #imageCanvas {
            border: 3px dashed #a0a0a0;
            background-color: #e0e0e0;
            touch-action: none; /* Crucial for preventing default touch behaviors like scrolling/zooming */
            display: block; /* Remove extra space below canvas */
            margin: 0 auto;
        }
        #cropButton {
            display: none; /* Hidden by default */
            margin-top: 20px;
            padding: 12px 25px;
            font-size: 17px;
            cursor: pointer;
            border: none;
            background-color: #28a745; /* Green */
            color: white;
            border-radius: 6px;
            box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
            transition: background-color 0.2s ease;
        }
        #cropButton:hover {
            background-color: #218838;
        }
        p {
            margin-bottom: 15px;
            color: #555;
        }
    </style>
</head>
<body>

    <div id="canvasContainer">
        <h1>Image Cropper & Tile Rotator</h1>
        <p id="instructionText">Drop an image onto the canvas below.</p>
        <canvas id="imageCanvas" width="600" height="600"></canvas>
        <button id="cropButton">Apply Crop</button>
    </div>

    <script>
        const canvas = document.getElementById('imageCanvas');
        const ctx = canvas.getContext('2d');
        const cropButton = document.getElementById('cropButton');
        const instructionText = document.getElementById('instructionText');

        const TILE_SIZE = 100; // Size of each tile in the tiling stage
        let originalImage = null; // The full, original dropped image
        let tiledImage = null; // The cropped, square image for tiling
        let rotations = []; // Stores rotation state for each tile

        // --- App State ---
        let appState = 'idle'; // 'idle', 'cropping', 'tiling'

        // --- Cropping State ---
        const HANDLE_SIZE = 20; // Size of the draggable corner handles
        let imageDrawArgs = { x: 0, y: 0, width: 0, height: 0 }; // How the original image is drawn on canvas
        let cropBox = { x: 50, y: 50, size: 200 }; // Current crop box position and size
        let draggingState = {
            active: false,
            target: null, // 'box', 'topLeft', 'topRight', 'bottomLeft', 'bottomRight'
            startX: 0, // Mouse/touch start X
            startY: 0, // Mouse/touch start Y
            initialBox: null // Crop box state at start of drag
        };

        const numCols = canvas.width / TILE_SIZE;
        const numRows = canvas.height / TILE_SIZE;

        /**
         * Get mouse or touch position relative to the canvas.
         * @param {Event} evt - MouseEvent or TouchEvent
         */
        function getCanvasPos(evt) {
            const rect = canvas.getBoundingClientRect();
            let clientX, clientY;

            if (evt.touches && evt.touches.length > 0) {
                clientX = evt.touches[0].clientX;
                clientY = evt.touches[0].clientY;
            } else {
                clientX = evt.clientX;
                clientY = evt.clientY;
            }

            return {
                x: clientX - rect.left,
                y: clientY - rect.top
            };
        }

        /**
         * Checks if a point is within a given rectangle.
         */
        function isPointInRect(px, py, rect) {
            return px >= rect.x && px <= rect.x + rect.w && py >= rect.y && py <= rect.y + rect.h;
        }

        /**
         * Determines which part of the crop UI (handle or box) is being dragged.
         */
        function getDragTarget(pos) {
            // Define handle hit areas
            const handles = {
                topLeft: { x: cropBox.x - HANDLE_SIZE / 2, y: cropBox.y - HANDLE_SIZE / 2, w: HANDLE_SIZE, h: HANDLE_SIZE },
                topRight: { x: cropBox.x + cropBox.size - HANDLE_SIZE / 2, y: cropBox.y - HANDLE_SIZE / 2, w: HANDLE_SIZE, h: HANDLE_SIZE },
                bottomLeft: { x: cropBox.x - HANDLE_SIZE / 2, y: cropBox.y + cropBox.size - HANDLE_SIZE / 2, w: HANDLE_SIZE, h: HANDLE_SIZE },
                bottomRight: { x: cropBox.x + cropBox.size - HANDLE_SIZE / 2, y: cropBox.y + cropBox.size - HANDLE_SIZE / 2, w: HANDLE_SIZE, h: HANDLE_SIZE }
            };
            for (const [name, rect] of Object.entries(handles)) {
                if (isPointInRect(pos.x, pos.y, rect)) return name;
            }
            // Check if the point is inside the crop box (for moving the entire box)
            if (isPointInRect(pos.x, pos.y, {x: cropBox.x, y: cropBox.y, w: cropBox.size, h: cropBox.size})) return 'box';
            return null;
        }

        // --- Drawing Functions ---

        /**
         * Draws the cropping UI (image, overlay, crop box, handles).
         */
        function drawCropUI() {
            if (appState !== 'cropping' || !originalImage) return;

            ctx.clearRect(0, 0, canvas.width, canvas.height);

            // Draw the scaled source image (fit to canvas)
            ctx.drawImage(originalImage, imageDrawArgs.x, imageDrawArgs.y, imageDrawArgs.width, imageDrawArgs.height);

            // Draw the dark overlay outside the crop box
            ctx.fillStyle = 'rgba(0, 0, 0, 0.6)';
            ctx.fillRect(0, 0, canvas.width, canvas.height); // Full canvas overlay

            // "Cut out" the crop box from the overlay
            ctx.clearRect(cropBox.x, cropBox.y, cropBox.size, cropBox.size);

            // Redraw the original image content inside the crop box area
            // This creates the effect of the image being visible only inside the box
            // Calculate source coordinates on original image that map to current cropBox
            const scaleX = originalImage.width / imageDrawArgs.width;
            const scaleY = originalImage.height / imageDrawArgs.height;

            const sx = (cropBox.x - imageDrawArgs.x) * scaleX;
            const sy = (cropBox.y - imageDrawArgs.y) * scaleY;
            const sWidth = cropBox.size * scaleX;
            const sHeight = cropBox.size * scaleY;

            ctx.drawImage(originalImage, sx, sy, sWidth, sHeight, cropBox.x, cropBox.y, cropBox.size, cropBox.size);


            // Draw the crop box border
            ctx.strokeStyle = 'white';
            ctx.lineWidth = 2;
            ctx.strokeRect(cropBox.x, cropBox.y, cropBox.size, cropBox.size);

            // Draw handles
            ctx.fillStyle = 'white';
            ctx.strokeStyle = '#333';
            ctx.lineWidth = 1;

            // Top-left
            ctx.fillRect(cropBox.x - HANDLE_SIZE / 2, cropBox.y - HANDLE_SIZE / 2, HANDLE_SIZE, HANDLE_SIZE);
            ctx.strokeRect(cropBox.x - HANDLE_SIZE / 2, cropBox.y - HANDLE_SIZE / 2, HANDLE_SIZE, HANDLE_SIZE);
            // Top-right
            ctx.fillRect(cropBox.x + cropBox.size - HANDLE_SIZE / 2, cropBox.y - HANDLE_SIZE / 2, HANDLE_SIZE, HANDLE_SIZE);
            ctx.strokeRect(cropBox.x + cropBox.size - HANDLE_SIZE / 2, cropBox.y - HANDLE_SIZE / 2, HANDLE_SIZE, HANDLE_SIZE);
            // Bottom-left
            ctx.fillRect(cropBox.x - HANDLE_SIZE / 2, cropBox.y + cropBox.size - HANDLE_SIZE / 2, HANDLE_SIZE, HANDLE_SIZE);
            ctx.strokeRect(cropBox.x - HANDLE_SIZE / 2, cropBox.y + cropBox.size - HANDLE_SIZE / 2, HANDLE_SIZE, HANDLE_SIZE);
            // Bottom-right
            ctx.fillRect(cropBox.x + cropBox.size - HANDLE_SIZE / 2, cropBox.y + cropBox.size - HANDLE_SIZE / 2, HANDLE_SIZE, HANDLE_SIZE);
            ctx.strokeRect(cropBox.x + cropBox.size - HANDLE_SIZE / 2, cropBox.y + cropBox.size - HANDLE_SIZE / 2, HANDLE_SIZE, HANDLE_SIZE);
        }

        /**
         * Draws the tiled image grid with rotations.
         */
        function drawTiles() {
            if (!tiledImage) return;
            ctx.clearRect(0, 0, canvas.width, canvas.height); // Clear entire canvas for tiling
            for (let r = 0; r < numRows; r++) {
                for (let c = 0; c < numCols; c++) {
                    const x = c * TILE_SIZE;
                    const y = r * TILE_SIZE;
                    const angle = (rotations[r][c] || 0) * (Math.PI / 2); // Convert rotation step to radians
                    ctx.save();
                    ctx.translate(x + TILE_SIZE / 2, y + TILE_SIZE / 2); // Move origin to tile center
                    ctx.rotate(angle); // Rotate
                    ctx.drawImage(tiledImage, -TILE_SIZE / 2, -TILE_SIZE / 2, TILE_SIZE, TILE_SIZE); // Draw image centered
                    ctx.restore(); // Restore canvas state
                }
            }
        }

        // --- Logic and Event Handlers ---

        /**
         * Initializes the rotation state for all tiles to 0.
         */
        function initializeRotations() {
            rotations = Array(numRows).fill(0).map(() => Array(numCols).fill(0));
        }

        /**
         * Sets up the cropping stage after an image is loaded.
         */
        function startCropping() {
            // Calculate how to fit the original image inside the canvas, maintaining aspect ratio
            const canvasAspect = canvas.width / canvas.height;
            const imageAspect = originalImage.width / originalImage.height;

            if (imageAspect > canvasAspect) { // Image is wider relative to canvas
                imageDrawArgs.width = canvas.width;
                imageDrawArgs.height = canvas.width / imageAspect;
                imageDrawArgs.x = 0;
                imageDrawArgs.y = (canvas.height - imageDrawArgs.height) / 2;
            } else { // Image is taller or has same aspect ratio
                imageDrawArgs.height = canvas.height;
                imageDrawArgs.width = canvas.height * imageAspect;
                imageDrawArgs.y = 0;
                imageDrawArgs.x = (canvas.width - imageDrawArgs.width) / 2;
            }

            // Initialize crop box to be a square in the center, fitting within imageDrawArgs
            const minImageDimension = Math.min(imageDrawArgs.width, imageDrawArgs.height);
            const initialCropSize = minImageDimension * 0.8; // Start with 80% of the smaller dimension

            cropBox.size = initialCropSize;
            cropBox.x = imageDrawArgs.x + (imageDrawArgs.width - initialCropSize) / 2;
            cropBox.y = imageDrawArgs.y + (imageDrawArgs.height - initialCropSize) / 2;

            appState = 'cropping';
            instructionText.textContent = "Drag the box or its corners to crop. Then click 'Apply Crop'.";
            cropButton.style.display = 'block';
            drawCropUI();
        }

        /**
         * Applies the current crop, creating a new square image for tiling.
         */
        function applyCrop() {
            if (!originalImage || appState !== 'cropping') return;

            // Calculate source coordinates and size on the ORIGINAL image
            // This translates the crop box position/size from the canvas drawing to the original image pixels
            const scaleX = originalImage.width / imageDrawArgs.width;
            const scaleY = originalImage.height / imageDrawArgs.height;

            const sx = (cropBox.x - imageDrawArgs.x) * scaleX;
            const sy = (cropBox.y - imageDrawArgs.y) * scaleY;
            const sSize = cropBox.size * scaleX; // Since it's a square, width and height are the same

            // Create a temporary canvas to draw the cropped portion
            const tempCanvas = document.createElement('canvas');
            tempCanvas.width = TILE_SIZE; // The final tiled image should be TILE_SIZE x TILE_SIZE
            tempCanvas.height = TILE_SIZE;
            const tempCtx = tempCanvas.getContext('2d');

            // Draw the cropped portion of the original image onto the temporary canvas
            tempCtx.drawImage(originalImage, sx, sy, sSize, sSize, 0, 0, TILE_SIZE, TILE_SIZE);

            // Create a new Image object from the temporary canvas's content
            tiledImage = new Image();
            tiledImage.onload = () => {
                appState = 'tiling';
                cropButton.style.display = 'none';
                instructionText.textContent = "Tap a tile to rotate it. Drop a new image to start over.";
                initializeRotations();
                drawTiles();
            };
            tiledImage.src = tempCanvas.toDataURL(); // Get data URL of the cropped image
        }

        /**
         * Handles dropping of image files onto the canvas.
         */
        function handleFileDrop(event) {
            event.preventDefault();
            event.stopPropagation();
            const file = event.dataTransfer.files[0];
            if (file && file.type.startsWith('image/')) {
                const reader = new FileReader();
                reader.onload = (e) => {
                    originalImage = new Image();
                    originalImage.onload = startCropping;
                    originalImage.src = e.target.result;
                };
                reader.readAsDataURL(file);
            } else {
                alert('Please drop a valid image file!');
            }
        }

        /**
         * Handles the start of a drag interaction (mouse down or touch start).
         */
        function handleInteractionStart(event) {
            if (appState !== 'cropping') return;
            event.preventDefault(); // Prevent default browser actions (like scrolling/zooming on touch)

            const pos = getCanvasPos(event);
            const target = getDragTarget(pos);

            if (target) {
                draggingState.active = true;
                draggingState.target = target;
                draggingState.startX = pos.x;
                draggingState.startY = pos.y;
                draggingState.initialBox = { ...cropBox }; // Store initial state for delta calculations
            }
        }

        /**
         * Handles drag movement (mouse move or touch move).
         */
        function handleInteractionMove(event) {
            if (!draggingState.active || appState !== 'cropping') return;
            event.preventDefault(); // Prevent default browser actions

            const pos = getCanvasPos(event);
            const dx = pos.x - draggingState.startX;
            const dy = pos.y - draggingState.startY;

            let { x, y, size } = draggingState.initialBox; // Start from the initial box position

            const minAllowedSize = TILE_SIZE / 2; // Minimum crop box size
            const maxAllowedSize = Math.min(imageDrawArgs.width, imageDrawArgs.height);

            if (draggingState.target === 'box') {
                x += dx;
                y += dy;
            } else if (draggingState.target === 'topLeft') {
                const d = Math.min(dx, dy); // Maintain square aspect ratio
                x += d;
                y += d;
                size -= d;
            } else if (draggingState.target === 'topRight') {
                const d = Math.max(-dx, dy);
                y += d;
                size -= d;
                // Adjust x if size changes too much to keep right edge stable
                x = draggingState.initialBox.x + (draggingState.initialBox.size - size);
            } else if (draggingState.target === 'bottomLeft') {
                const d = Math.max(dx, -dy);
                x += d;
                size -= d;
                // Adjust y if size changes too much to keep bottom edge stable
                y = draggingState.initialBox.y + (draggingState.initialBox.size - size);
            } else if (draggingState.target === 'bottomRight') {
                const d = Math.min(dx, dy); // Maintain square aspect ratio
                size += d;
            }

            // --- Size and Position Constraints ---

            // Ensure crop box doesn't go below min size or above max allowed size
            size = Math.max(minAllowedSize, Math.min(size, maxAllowedSize));

            // Ensure crop box stays within the displayed image boundaries (imageDrawArgs)
            x = Math.max(imageDrawArgs.x, x);
            y = Math.max(imageDrawArgs.y, y);

            // Adjust x/y if resizing pushed it out of bounds
            if (x + size > imageDrawArgs.x + imageDrawArgs.width) {
                x = imageDrawArgs.x + imageDrawArgs.width - size;
            }
            if (y + size > imageDrawArgs.y + imageDrawArgs.height) {
                y = imageDrawArgs.y + imageDrawArgs.height - size;
            }

            // Ensure x/y don't go below imageDrawArgs.x/y after being adjusted by size (can happen with small sizes)
            x = Math.max(imageDrawArgs.x, x);
            y = Math.max(imageDrawArgs.y, y);


            cropBox = { x, y, size };
            drawCropUI();
        }

        /**
         * Handles the end of a drag interaction (mouse up or touch end).
         */
        function handleInteractionEnd() {
            draggingState.active = false;
        }

        /**
         * Handles clicks/taps on the canvas during the tiling stage to rotate tiles.
         */
        function handleCanvasClick(event) {
            // Only respond to clicks when in 'tiling' state
            if (appState !== 'tiling' || !tiledImage) return;

            const pos = getCanvasPos(event);
            const col = Math.floor(pos.x / TILE_SIZE);
            const row = Math.floor(pos.y / TILE_SIZE);

            if (row >= 0 && row < numRows && col >= 0 && col < numCols) {
                rotations[row][col] = (rotations[row][col] + 1) % 4; // Cycle 0, 1, 2, 3 (0, 90, 180, 270 degrees)
                drawTiles(); // Redraw with the updated tile rotation
            }
        }

        // --- Event Listeners ---

        // Prevent default dragover behavior to allow drop
        canvas.addEventListener('dragover', (e) => e.preventDefault());
        canvas.addEventListener('drop', handleFileDrop);

        // Mouse Events for Cropping
        canvas.addEventListener('mousedown', handleInteractionStart);
        canvas.addEventListener('mousemove', handleInteractionMove);
        window.addEventListener('mouseup', handleInteractionEnd); // Use window for mouseup in case drag goes off canvas

        // Touch Events for Cropping
        canvas.addEventListener('touchstart', handleInteractionStart, { passive: false });
        canvas.addEventListener('touchmove', handleInteractionMove, { passive: false });
        window.addEventListener('touchend', handleInteractionEnd); // Use window for touchend in case drag goes off canvas

        // Click Event for Tiling (separate to avoid conflict with drag for cropping)
        canvas.addEventListener('click', handleCanvasClick);

        // Button for applying crop
        cropButton.addEventListener('click', applyCrop);

    </script>
</body>
</html>