From 2dd0985ea9e815e9b38f8a4e0ffe3edb45fe86a0 Mon Sep 17 00:00:00 2001
From: Yuri Karamian <yuri@arkhost.com>
Date: Mon, 3 Aug 2026 16:56:38 +0200
Subject: [PATCH] Add Android image pinch zoom (Closes #115)

---
 src/lib/components/Editor.svelte      |  39 ++-
 src/lib/components/ImageViewer.svelte | 385 ++++++++++++++++++++++++++
 2 files changed, 417 insertions(+), 7 deletions(-)
 create mode 100644 src/lib/components/ImageViewer.svelte

diff --git a/src/lib/components/Editor.svelte b/src/lib/components/Editor.svelte
index 8c3e742..49b5cc0 100644
--- a/src/lib/components/Editor.svelte
+++ b/src/lib/components/Editor.svelte
@@ -55,6 +55,7 @@
 	import { relativePath } from '$lib/utils/paths';
 	import GraphView from './GraphView.svelte';
 	import TagSuggestInput from './TagSuggestInput.svelte';
+	import ImageViewer from './ImageViewer.svelte';
 	import { isMobile, isAndroid } from '$lib/platform';
 	import ResizeHandle from './ResizeHandle.svelte';
 
@@ -471,7 +472,8 @@
 	let tableContextMenu = $state<{ x: number; y: number; hasStyling: boolean } | null>(null);
 	let tablePickerOpen = $state(false);
 	let tablePickerHover = $state({ rows: 0, cols: 0 });
-	let imageToolbar = $state<{ pos: number; x: number; y: number; size: string; src: string } | null>(null);
+	let imageToolbar = $state<{ pos: number; x: number; y: number; size: string; src: string; alt: string } | null>(null);
+	let imageViewer = $state<{ src: string; alt: string } | null>(null);
 	let copyToast = $state<'copying' | 'done' | null>(null);
 
 	$effect(() => {
@@ -4828,11 +4830,12 @@
 			const node = editor.state.doc.nodeAt(pos);
 			const currentSize = node?.attrs.size || 'full';
 			const imgSrc = node?.attrs.src || (target as HTMLImageElement).src || '';
-			const toolbarW = isMobile ? 130 : 250;
-			const toolbarH = 38;
-			const x = Math.min(event.clientX, window.innerWidth - toolbarW - 8);
-			const y = Math.min(event.clientY, window.innerHeight - toolbarH - 8);
-			imageToolbar = { pos, x, y, size: currentSize, src: imgSrc };
+			const imgAlt = node?.attrs.alt || (target as HTMLImageElement).alt || '';
+			const toolbarW = isAndroid ? 188 : isMobile ? 130 : 250;
+			const toolbarH = isAndroid ? 48 : 38;
+			const x = Math.max(8, Math.min(event.clientX, window.innerWidth - toolbarW - 8));
+			const y = Math.max(8, Math.min(event.clientY, window.innerHeight - toolbarH - 8));
+			imageToolbar = { pos, x, y, size: currentSize, src: imgSrc, alt: imgAlt };
 			// Move cursor after the image to clear ProseMirror's node selection highlight
 			const afterPos = pos + (node?.nodeSize || 1);
 			editor.chain().setTextSelection(afterPos).run();
@@ -4842,6 +4845,12 @@
 		imageToolbar = null;
 	}
 
+	function openImageViewer() {
+		if (!imageToolbar) return;
+		imageViewer = { src: imageToolbar.src, alt: imageToolbar.alt };
+		imageToolbar = null;
+	}
+
 	function setImageSize(size: string) {
 		if (!editor || !imageToolbar) return;
 		const { pos } = imageToolbar;
@@ -7345,10 +7354,16 @@
 	<!-- svelte-ignore a11y_no_static_element_interactions -->
 	<div class="img-toolbar-overlay" onclick={() => (imageToolbar = null)}>
 		<!-- svelte-ignore a11y_no_static_element_interactions -->
-		<div class="img-toolbar" style="left: {imageToolbar.x}px; top: {imageToolbar.y}px" onclick={(e) => e.stopPropagation()}>
+		<div class="img-toolbar" class:mobile-viewer-toolbar={isAndroid} style="left: {imageToolbar.x}px; top: {imageToolbar.y}px" onclick={(e) => e.stopPropagation()}>
 			<button class:active={imageToolbar.size === 'small'} onclick={() => setImageSize('small')} title="Small (33%)">S</button>
 			<button class:active={imageToolbar.size === 'medium'} onclick={() => setImageSize('medium')} title="Medium (50%)">M</button>
 			<button class:active={imageToolbar.size === 'full'} onclick={() => setImageSize('full')} title="Full width">L</button>
+			{#if isAndroid}
+				<span class="img-toolbar-sep"></span>
+				<button class="img-toolbar-view" onclick={openImageViewer} title="View and zoom image" aria-label="View and zoom image">
+					<svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M8 3H5a2 2 0 00-2 2v3M16 3h3a2 2 0 012 2v3M8 21H5a2 2 0 01-2-2v-3M16 21h3a2 2 0 002-2v-3"/></svg>
+				</button>
+			{/if}
 			{#if !isMobile && !imageToolbar.src.startsWith('imgproxy:') && !imageToolbar.src.startsWith('http://imgproxy.localhost')}
 				<span class="img-toolbar-sep"></span>
 				<button onclick={copyImageToClipboard} title="Copy image">
@@ -7362,6 +7377,10 @@
 	</div>
 {/if}
 
+{#if imageViewer}
+	<ImageViewer src={imageViewer.src} alt={imageViewer.alt} onclose={() => (imageViewer = null)} />
+{/if}
+
 {#if copyToast}
 	<div class="copy-toast" class:done={copyToast === 'done'}>
 		{#if copyToast === 'copying'}
@@ -10003,6 +10022,12 @@
 		display: block;
 	}
 
+	.img-toolbar.mobile-viewer-toolbar button {
+		min-width: 40px;
+		min-height: 40px;
+		padding: 8px 12px;
+	}
+
 	.copy-toast {
 		position: fixed;
 		bottom: 24px;
diff --git a/src/lib/components/ImageViewer.svelte b/src/lib/components/ImageViewer.svelte
new file mode 100644
index 0000000..3a903ea
--- /dev/null
+++ b/src/lib/components/ImageViewer.svelte
@@ -0,0 +1,385 @@
+<script lang="ts">
+	import { onMount } from 'svelte';
+
+	let { src, alt = '', onclose }: {
+		src: string;
+		alt?: string;
+		onclose: () => void;
+	} = $props();
+
+	const MIN_SCALE = 1;
+	const MAX_SCALE = 5;
+	const DOUBLE_TAP_MS = 300;
+	const TAP_MOVE_THRESHOLD = 6;
+
+	type Point = { x: number; y: number };
+	type ViewerGesture =
+		| { kind: 'pan'; start: Point; pan: Point }
+		| { kind: 'pinch'; distance: number; imagePoint: Point };
+
+	let canvasElement = $state<HTMLDivElement | null>(null);
+	let imageElement = $state<HTMLImageElement | null>(null);
+	let closeButton = $state<HTMLButtonElement | null>(null);
+	let scale = $state(1);
+	let panX = $state(0);
+	let panY = $state(0);
+	let interacting = $state(false);
+	let gesture: ViewerGesture | null = null;
+	let touchMoved = false;
+	let lastTapAt = 0;
+	let zoomPercent = $derived(Math.round(scale * 100));
+
+	function clamp(value: number, min: number, max: number): number {
+		return Math.min(max, Math.max(min, value));
+	}
+
+	function midpoint(first: Touch, second: Touch): Point {
+		return {
+			x: (first.clientX + second.clientX) / 2,
+			y: (first.clientY + second.clientY) / 2,
+		};
+	}
+
+	function touchDistance(first: Touch, second: Touch): number {
+		return Math.hypot(second.clientX - first.clientX, second.clientY - first.clientY);
+	}
+
+	function panLimits(nextScale: number): Point {
+		const canvasWidth = canvasElement?.clientWidth ?? window.innerWidth;
+		const canvasHeight = canvasElement?.clientHeight ?? window.innerHeight;
+		const imageWidth = imageElement?.clientWidth ?? 0;
+		const imageHeight = imageElement?.clientHeight ?? 0;
+		return {
+			x: Math.max(0, (imageWidth * nextScale - canvasWidth) / 2),
+			y: Math.max(0, (imageHeight * nextScale - canvasHeight) / 2),
+		};
+	}
+
+	function applyTransform(nextScale: number, nextPanX: number, nextPanY: number) {
+		const clampedScale = clamp(nextScale, MIN_SCALE, MAX_SCALE);
+		const limits = panLimits(clampedScale);
+		scale = clampedScale;
+		panX = clamp(nextPanX, -limits.x, limits.x);
+		panY = clamp(nextPanY, -limits.y, limits.y);
+	}
+
+	function resetViewer() {
+		interacting = false;
+		gesture = null;
+		applyTransform(MIN_SCALE, 0, 0);
+	}
+
+	function zoomAt(point: Point, nextScale: number) {
+		const canvasRect = canvasElement?.getBoundingClientRect();
+		const centerX = canvasRect ? canvasRect.left + canvasRect.width / 2 : window.innerWidth / 2;
+		const centerY = canvasRect ? canvasRect.top + canvasRect.height / 2 : window.innerHeight / 2;
+		const imageX = (point.x - centerX - panX) / scale;
+		const imageY = (point.y - centerY - panY) / scale;
+		applyTransform(
+			nextScale,
+			point.x - centerX - imageX * nextScale,
+			point.y - centerY - imageY * nextScale,
+		);
+	}
+
+	function beginPan(touch: Touch) {
+		gesture = {
+			kind: 'pan',
+			start: { x: touch.clientX, y: touch.clientY },
+			pan: { x: panX, y: panY },
+		};
+	}
+
+	function beginPinch(first: Touch, second: Touch) {
+		const point = midpoint(first, second);
+		const canvasRect = canvasElement?.getBoundingClientRect();
+		const centerX = canvasRect ? canvasRect.left + canvasRect.width / 2 : window.innerWidth / 2;
+		const centerY = canvasRect ? canvasRect.top + canvasRect.height / 2 : window.innerHeight / 2;
+		gesture = {
+			kind: 'pinch',
+			distance: Math.max(1, touchDistance(first, second)),
+			imagePoint: {
+				x: (point.x - centerX - panX) / scale,
+				y: (point.y - centerY - panY) / scale,
+			},
+		};
+	}
+
+	function handleTouchStart(event: TouchEvent) {
+		event.preventDefault();
+		interacting = true;
+		if (event.touches.length >= 2) {
+			touchMoved = true;
+			beginPinch(event.touches[0], event.touches[1]);
+			return;
+		}
+		if (event.touches.length === 1) {
+			touchMoved = false;
+			beginPan(event.touches[0]);
+		}
+	}
+
+	function handleTouchMove(event: TouchEvent) {
+		event.preventDefault();
+		if (event.touches.length >= 2) {
+			if (gesture?.kind !== 'pinch') beginPinch(event.touches[0], event.touches[1]);
+			if (gesture?.kind !== 'pinch') return;
+			const point = midpoint(event.touches[0], event.touches[1]);
+			const canvasRect = canvasElement?.getBoundingClientRect();
+			const centerX = canvasRect ? canvasRect.left + canvasRect.width / 2 : window.innerWidth / 2;
+			const centerY = canvasRect ? canvasRect.top + canvasRect.height / 2 : window.innerHeight / 2;
+			const nextScale = clamp(
+				scale * (touchDistance(event.touches[0], event.touches[1]) / gesture.distance),
+				MIN_SCALE,
+				MAX_SCALE,
+			);
+			gesture.distance = Math.max(1, touchDistance(event.touches[0], event.touches[1]));
+			applyTransform(
+				nextScale,
+				point.x - centerX - gesture.imagePoint.x * nextScale,
+				point.y - centerY - gesture.imagePoint.y * nextScale,
+			);
+			touchMoved = true;
+			return;
+		}
+		if (event.touches.length === 1 && gesture?.kind === 'pan') {
+			const dx = event.touches[0].clientX - gesture.start.x;
+			const dy = event.touches[0].clientY - gesture.start.y;
+			if (Math.hypot(dx, dy) > TAP_MOVE_THRESHOLD) touchMoved = true;
+			applyTransform(scale, gesture.pan.x + dx, gesture.pan.y + dy);
+		}
+	}
+
+	function handleTouchEnd(event: TouchEvent) {
+		event.preventDefault();
+		if (event.touches.length >= 2) {
+			beginPinch(event.touches[0], event.touches[1]);
+			return;
+		}
+		if (event.touches.length === 1) {
+			beginPan(event.touches[0]);
+			touchMoved = true;
+			return;
+		}
+
+		interacting = false;
+		gesture = null;
+		if (!touchMoved && event.changedTouches.length > 0) {
+			const now = performance.now();
+			const touch = event.changedTouches[0];
+			if (now - lastTapAt <= DOUBLE_TAP_MS) {
+				if (scale > MIN_SCALE + 0.01) resetViewer();
+				else zoomAt({ x: touch.clientX, y: touch.clientY }, 2);
+				lastTapAt = 0;
+			} else {
+				lastTapAt = now;
+			}
+		}
+	}
+
+	function handleTouchCancel(event: TouchEvent) {
+		event.preventDefault();
+		interacting = false;
+		gesture = null;
+		touchMoved = false;
+		applyTransform(scale, panX, panY);
+	}
+
+	function attachTouchGestures(node: HTMLElement) {
+		node.addEventListener('touchstart', handleTouchStart, { passive: false });
+		node.addEventListener('touchmove', handleTouchMove, { passive: false });
+		node.addEventListener('touchend', handleTouchEnd, { passive: false });
+		node.addEventListener('touchcancel', handleTouchCancel, { passive: false });
+		return {
+			destroy() {
+				node.removeEventListener('touchstart', handleTouchStart);
+				node.removeEventListener('touchmove', handleTouchMove);
+				node.removeEventListener('touchend', handleTouchEnd);
+				node.removeEventListener('touchcancel', handleTouchCancel);
+			},
+		};
+	}
+
+	onMount(() => {
+		closeButton?.focus();
+		const handleResize = () => applyTransform(scale, panX, panY);
+		window.addEventListener('resize', handleResize);
+		return () => window.removeEventListener('resize', handleResize);
+	});
+</script>
+
+<div
+	class="image-viewer"
+	role="dialog"
+	aria-modal="true"
+	aria-label={alt ? `Image viewer: ${alt}` : 'Image viewer'}
+	tabindex="-1"
+	onkeydown={(event) => {
+		if (event.key === 'Escape') {
+			event.preventDefault();
+			onclose();
+		}
+	}}
+>
+	<!-- svelte-ignore a11y_no_static_element_interactions -->
+	<div
+		class="image-viewer-canvas"
+		bind:this={canvasElement}
+		use:attachTouchGestures
+		onclick={(event) => {
+			if (event.target === event.currentTarget) onclose();
+		}}
+		onkeydown={(event) => {
+			if (event.target === event.currentTarget && (event.key === 'Enter' || event.key === ' ')) onclose();
+		}}
+	>
+		<img
+			bind:this={imageElement}
+			class:interacting
+			src={src}
+			alt={alt}
+			draggable="false"
+			style:transform={`translate3d(${panX}px, ${panY}px, 0) scale(${scale})`}
+			onload={resetViewer}
+		/>
+	</div>
+
+	<div class="image-viewer-controls">
+		<button
+			type="button"
+			class="image-viewer-reset"
+			onclick={resetViewer}
+			disabled={scale === MIN_SCALE && panX === 0 && panY === 0}
+			aria-label={`Reset zoom, currently ${zoomPercent}%`}
+		>
+			<svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
+				<path d="M3 12a9 9 0 1 0 3-6.7" />
+				<path d="M3 4v6h6" />
+			</svg>
+			<span>{zoomPercent}%</span>
+		</button>
+		<button bind:this={closeButton} type="button" class="image-viewer-close" onclick={onclose} aria-label="Close image viewer">
+			<svg width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" aria-hidden="true">
+				<path d="M18 6 6 18M6 6l12 12" />
+			</svg>
+		</button>
+	</div>
+
+	<div class="image-viewer-hint" aria-hidden="true">Pinch to zoom · drag to move · double-tap to zoom or reset</div>
+	<span class="sr-only" aria-live="polite">Zoom {zoomPercent}%</span>
+</div>
+
+<style>
+	.image-viewer {
+		position: fixed;
+		inset: 0;
+		z-index: 10000;
+		background: #06080c;
+		color: #fff;
+		overflow: hidden;
+		overscroll-behavior: contain;
+	}
+
+	.image-viewer-canvas {
+		position: absolute;
+		inset: 0;
+		display: flex;
+		align-items: center;
+		justify-content: center;
+		touch-action: none;
+		user-select: none;
+		-webkit-user-select: none;
+	}
+
+	.image-viewer-canvas img {
+		display: block;
+		max-width: calc(100vw - 24px);
+		max-height: calc(100dvh - 24px);
+		object-fit: contain;
+		transform-origin: center center;
+		transition: transform 160ms ease-out;
+		will-change: transform;
+		-webkit-user-drag: none;
+		user-select: none;
+	}
+
+	.image-viewer-canvas img.interacting {
+		transition: none;
+	}
+
+	.image-viewer-controls {
+		position: absolute;
+		inset: max(12px, env(safe-area-inset-top)) max(12px, env(safe-area-inset-right)) auto max(12px, env(safe-area-inset-left));
+		display: flex;
+		align-items: center;
+		justify-content: space-between;
+		pointer-events: none;
+	}
+
+	.image-viewer-controls button {
+		min-height: 44px;
+		border: 1px solid rgba(255, 255, 255, 0.18);
+		background: rgba(20, 23, 30, 0.86);
+		color: #fff;
+		box-shadow: 0 8px 24px rgba(0, 0, 0, 0.3);
+		pointer-events: auto;
+	}
+
+	.image-viewer-reset {
+		display: flex;
+		align-items: center;
+		gap: 8px;
+		padding: 0 14px;
+		border-radius: 10px;
+		font: inherit;
+		font-size: 13px;
+		font-weight: 600;
+	}
+
+	.image-viewer-reset:disabled {
+		opacity: 0.45;
+	}
+
+	.image-viewer-close {
+		display: grid;
+		place-items: center;
+		width: 44px;
+		padding: 0;
+		border-radius: 50%;
+	}
+
+	.image-viewer-hint {
+		position: absolute;
+		left: 50%;
+		bottom: max(18px, calc(env(safe-area-inset-bottom) + 10px));
+		transform: translateX(-50%);
+		width: max-content;
+		max-width: calc(100vw - 32px);
+		padding: 8px 12px;
+		border-radius: 8px;
+		background: rgba(20, 23, 30, 0.82);
+		color: rgba(255, 255, 255, 0.72);
+		font-size: 12px;
+		line-height: 1.35;
+		text-align: center;
+		pointer-events: none;
+	}
+
+	.sr-only {
+		position: absolute;
+		width: 1px;
+		height: 1px;
+		padding: 0;
+		margin: -1px;
+		overflow: hidden;
+		clip: rect(0, 0, 0, 0);
+		white-space: nowrap;
+		border: 0;
+	}
+
+	@media (prefers-reduced-motion: reduce) {
+		.image-viewer-canvas img {
+			transition: none;
+		}
+	}
+</style>