GitHub Image Previewer

Previews various image formats, including JPG, PNG, GIF, BMP, TIFF, WebP, SVG, and ICO.

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name         GitHub Image Previewer
// @description  Previews various image formats, including JPG, PNG, GIF, BMP, TIFF, WebP, SVG, and ICO.
// @icon         https://github.githubassets.com/favicons/favicon-dark.svg
// @version      1.2
// @author       afkarxyz
// @namespace    https://github.com/afkarxyz/userscripts/
// @supportURL   https://github.com/afkarxyz/userscripts/issues
// @license      MIT
// @match        https://github.com/*
// @grant        none
// @run-at       document-end
// ==/UserScript==

(function() {
    'use strict';

    const GitHubImagePreviewer = {
        supportedImageFormats: /\.(jpe?g|png|gif|bmp|ico|tiff?|webp|svg)$/i,
        imagePreviewContainer: null,
        imagePreviewElement: null,
        imagePreviewTitle: null,
        imagePreviewMetadata: null,

        init() {
            this.createImagePreviewElements();
            this.attachImagePreviewListeners();
            this.disableGitHubTooltips();
        },

        createImagePreviewElements() {
            this.imagePreviewContainer = document.createElement('div');
            this.imagePreviewContainer.style.cssText = `
                position: fixed;
                z-index: 9999;
                background: white;
                border: 1px solid #d1d5da;
                border-radius: 3px;
                box-shadow: 0 1px 5px rgba(27,31,35,0.15);
                display: none;
                padding: 10px;
                max-width: 300px;
                max-height: 300px;
                color: #24292e;
            `;

            this.imagePreviewTitle = document.createElement('div');
            this.imagePreviewTitle.style.cssText = `
                font-weight: bold;
                margin-bottom: 5px;
                white-space: nowrap;
                overflow: hidden;
                text-overflow: ellipsis;
            `;

            this.imagePreviewElement = document.createElement('img');
            this.imagePreviewElement.style.cssText = `
                max-width: 100%;
                max-height: 200px;
                display: block;
                margin: 0 auto;
                background-image: linear-gradient(45deg, #f0f0f0 25%, transparent 25%),
                      linear-gradient(-45deg, #f0f0f0 25%, transparent 25%),
                      linear-gradient(45deg, transparent 75%, #f0f0f0 75%),
                      linear-gradient(-45deg, transparent 75%, #f0f0f0 75%);
                background-size: 20px 20px;
                background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
            `;

            this.imagePreviewMetadata = document.createElement('div');
            this.imagePreviewMetadata.style.cssText = `
                font-size: 12px;
                color: #586069;
                margin-top: 5px;
                text-align: center;
            `;

            this.imagePreviewContainer.appendChild(this.imagePreviewTitle);
            this.imagePreviewContainer.appendChild(this.imagePreviewElement);
            this.imagePreviewContainer.appendChild(this.imagePreviewMetadata);
            document.body.appendChild(this.imagePreviewContainer);
        },

        attachImagePreviewListeners() {
            document.addEventListener('mouseover', this.handleImageMouseOver.bind(this));
            document.addEventListener('mouseout', this.handleImageMouseOut.bind(this));
            document.addEventListener('mousemove', this.handleImageMouseMove.bind(this));
        },

        disableGitHubTooltips() {
            const style = document.createElement('style');
            style.textContent = `
                .tooltipped::before, .tooltipped::after {
                    display: none !important;
                }
            `;
            document.head.appendChild(style);
        },

        handleImageMouseOver(event) {
            const target = event.target.closest('a');
            if (target && this.supportedImageFormats.test(target.href)) {
                if (target.hasAttribute('title')) {
                    target.dataset.originalTitle = target.getAttribute('title');
                    target.removeAttribute('title');
                }
                this.showImagePreview(target);
            }
        },

        handleImageMouseOut() {
            this.hideImagePreview();
        },

        handleImageMouseMove(event) {
            if (this.imagePreviewContainer.style.display !== 'none') {
                const mouseX = event.clientX;
                const mouseY = event.clientY;
                const viewportWidth = window.innerWidth;
                const viewportHeight = window.innerHeight;
                const previewWidth = this.imagePreviewContainer.offsetWidth;
                const previewHeight = this.imagePreviewContainer.offsetHeight;
                
                let x = mouseX + 15;
                let y = mouseY + 15;
                
                if (x + previewWidth > viewportWidth) {
                    x = mouseX - previewWidth - 15;
                }
                
                if (y + previewHeight > viewportHeight) {
                    y = mouseY - previewHeight - 15;
                }
                
                this.imagePreviewContainer.style.left = `${x}px`;
                this.imagePreviewContainer.style.top = `${y}px`;
            }
        },

        showImagePreview(target) {
            const imageUrl = target.href.replace('/blob/', '/raw/');
            this.imagePreviewTitle.textContent = target.dataset.originalTitle || target.getAttribute('title') || target.textContent;
            this.imagePreviewElement.src = imageUrl;
            this.imagePreviewContainer.style.display = 'block';

            this.imagePreviewElement.onload = this.updateImageMetadata.bind(this);
        },

        hideImagePreview() {
            this.imagePreviewContainer.style.display = 'none';
        },

        updateImageMetadata() {
            const width = this.imagePreviewElement.naturalWidth;
            const height = this.imagePreviewElement.naturalHeight;
            this.imagePreviewMetadata.textContent = `${width} x ${height} px`;
        },
    };

    GitHubImagePreviewer.init();
})();