UI: Enhance image gallery with zoom, pan, accessibility, and focus management
This commit is contained in:
Simon Cordt
@@ -27,6 +27,114 @@
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if (e.target === overlay) UI.closeGallery();
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});
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// Accessibility and focus management
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try {
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overlay.setAttribute("role", "dialog");
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overlay.setAttribute("aria-modal", "true");
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overlay.tabIndex = -1;
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} catch (err) { /* noop */ }
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// Zoom/Pan state and helpers
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UI.galleryZoom = { scale: 1, x: 0, y: 0, dragging: false, lastX: 0, lastY: 0 };
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UI.updateGalleryTransform = function updateGalleryTransform() {
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try {
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const z = UI.galleryZoom || { scale: 1, x: 0, y: 0, dragging: false };
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img.style.transform = `translate(${z.x}px, ${z.y}px) scale(${z.scale})`;
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img.style.cursor = z.scale > 1 ? (z.dragging ? "grabbing" : "grab") : "default";
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img.style.userSelect = "none";
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img.style.willChange = "transform";
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img.draggable = false;
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} catch (err) { /* noop */ }
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};
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UI.resetGalleryTransform = function resetGalleryTransform() {
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UI.galleryZoom = { scale: 1, x: 0, y: 0, dragging: false, lastX: 0, lastY: 0 };
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UI.updateGalleryTransform();
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};
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// Double-click to toggle zoom (2x default)
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img.addEventListener("dblclick", (e) => {
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try {
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e.preventDefault();
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const z = UI.galleryZoom || (UI.galleryZoom = { scale: 1, x: 0, y: 0, dragging: false, lastX: 0, lastY: 0 });
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if (z.scale === 1) {
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z.scale = 2;
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} else {
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z.scale = 1; z.x = 0; z.y = 0;
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}
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UI.updateGalleryTransform();
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} catch (err) { /* noop */ }
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});
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// Wheel for fine zoom (1x - 5x)
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const onWheel = (e) => {
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try {
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e.preventDefault();
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const z = UI.galleryZoom || (UI.galleryZoom = { scale: 1, x: 0, y: 0, dragging: false, lastX: 0, lastY: 0 });
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const step = e.deltaY > 0 ? -0.2 : 0.2;
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const next = Math.max(1, Math.min(5, Number(z.scale || 1) + step));
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z.scale = Number(next.toFixed(2));
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if (z.scale === 1) { z.x = 0; z.y = 0; }
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UI.updateGalleryTransform();
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} catch (err) { /* noop */ }
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};
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img.addEventListener("wheel", onWheel, { passive: false });
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// Drag to pan when zoomed
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img.addEventListener("mousedown", (e) => {
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try {
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if (!UI.galleryZoom || UI.galleryZoom.scale <= 1) return;
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e.preventDefault();
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UI.galleryZoom.dragging = true;
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UI.galleryZoom.lastX = e.clientX;
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UI.galleryZoom.lastY = e.clientY;
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UI.updateGalleryTransform();
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} catch (err) { /* noop */ }
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});
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const onMove = (e) => {
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try {
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const z = UI.galleryZoom;
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if (!z || !z.dragging) return;
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const dx = e.clientX - z.lastX;
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const dy = e.clientY - z.lastY;
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z.x += dx; z.y += dy; z.lastX = e.clientX; z.lastY = e.clientY;
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UI.updateGalleryTransform();
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} catch (err) { /* noop */ }
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};
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const onUp = () => {
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try {
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if (!UI.galleryZoom) return;
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UI.galleryZoom.dragging = false;
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UI.updateGalleryTransform();
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} catch (err) { /* noop */ }
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};
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window.addEventListener("mousemove", onMove);
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window.addEventListener("mouseup", onUp);
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// Focus trap within gallery controls
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UI.bindGalleryFocusTrap = function bindGalleryFocusTrap(enabled) {
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const trapHandler = (e) => {
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try {
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if (!UI.galleryOverlay || UI.galleryOverlay.style.display !== "flex") return;
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if (e.key !== "Tab") return;
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const focusables = [closeBtn, prev, next].filter(Boolean);
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if (!focusables.length) return;
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const current = document.activeElement;
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const idx = Math.max(0, focusables.indexOf(current));
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e.preventDefault();
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const dir = e.shiftKey ? -1 : 1;
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const nextIdx = (idx + dir + focusables.length) % focusables.length;
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focusables[nextIdx].focus();
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} catch (err) { /* noop */ }
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};
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if (enabled) {
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UI.galleryFocusTrapHandler = trapHandler;
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overlay.addEventListener("keydown", trapHandler);
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} else if (UI.galleryFocusTrapHandler) {
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overlay.removeEventListener("keydown", UI.galleryFocusTrapHandler);
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UI.galleryFocusTrapHandler = null;
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}
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};
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document.body.appendChild(overlay);
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UI.galleryOverlay = overlay;
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UI.galleryImg = img;
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@@ -42,11 +150,26 @@
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UI.galleryOverlay.style.display = "flex";
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UI.galleryShow(UI.galleryState.index);
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UI.bindGalleryKeys(true);
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UI.bindGalleryFocusTrap(true);
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try {
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UI._galleryPrevFocus = document.activeElement || null;
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// Focus the close button initially
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const btn = UI.galleryOverlay.querySelector(".pqueue-button");
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if (btn && typeof btn.focus === "function") btn.focus();
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else UI.galleryOverlay.focus();
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} catch (err) { /* noop */ }
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};
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UI.closeGallery = function closeGallery() {
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if (UI.galleryOverlay) UI.galleryOverlay.style.display = "none";
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UI.bindGalleryKeys(false);
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UI.bindGalleryFocusTrap(false);
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try { UI.resetGalleryTransform && UI.resetGalleryTransform(); } catch (err) { /* noop */ }
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try {
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if (UI._galleryPrevFocus && document.body.contains(UI._galleryPrevFocus)) {
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UI._galleryPrevFocus.focus();
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}
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} catch (err) { /* noop */ }
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};
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UI.galleryShow = function galleryShow(index) {
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@@ -56,6 +179,7 @@
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const desc = images[UI.galleryState.index];
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UI.galleryImg.src = UI.buildPreviewUrl(desc, UI.galleryState.pid).href;
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UI.galleryCounter.textContent = `${UI.galleryState.index + 1} / ${images.length}`;
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try { UI.resetGalleryTransform && UI.resetGalleryTransform(); } catch (err) { /* noop */ }
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};
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UI.bindGalleryKeys = function bindGalleryKeys(enabled) {
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