fix: make prev and next slides not focusable and aria-hidden

cypress/e2e/a11y.cy.ts

@@ -0,0 +1,79 @@
+describe('A11y tests', function() {
+	before(function() {
+		// Init user
+		cy.createRandomUser().then(user => {
+			// Upload test files
+			cy.uploadFile(user, 'image1.jpg', 'image/jpeg')
+			cy.uploadFile(user, 'image2.jpg', 'image/jpeg')
+			cy.uploadFile(user, 'video1.mp4', 'video/mp4')
+
+			// Visit nextcloud
+			cy.login(user)
+			cy.visit('/apps/files')
+		})
+	})
+
+	after(function() {
+		cy.logout()
+	})
+
+	it('See files in the list', function() {
+		cy.getFile('image1.jpg', { timeout: 10000 })
+			.should('contain', 'image1 .jpg')
+		cy.getFile('image2.jpg', { timeout: 10000 })
+			.should('contain', 'image2 .jpg')
+		cy.getFile('video1.mp4', { timeout: 10000 })
+			.should('contain', 'video1 .mp4')
+	})
+
+	it('Open the viewer on file click', function() {
+		cy.openFile('image2.jpg')
+		cy.get('body > .viewer').should('be.visible')
+	})
+
+	it('Does not see a loading animation', function() {
+		cy.get('body > .viewer', { timeout: 10000 })
+			.should('be.visible')
+			.and('have.class', 'modal-mask')
+			.and('not.have.class', 'icon-loading')
+	})
+
+	it('See the title on the viewer header', function() {
+		cy.get('body > .viewer .modal-name').should('contain', 'image2.jpg')
+	})
+
+	it('Should have rendered the previous video and the next image', function() {
+		// There are buttons to navigate to the previous and next image
+		cy.get('body > .viewer button.prev').should('be.visible')
+		cy.get('body > .viewer button.next').should('be.visible')
+		// The previous and the next image
+		cy.get('body > .viewer .modal-container img').should('have.length', 2)
+		// The next video
+		cy.get('body > .viewer .modal-container video').should('have.length', 1)
+	})
+
+	it('Should make the previous and the next slides hidden for assistive technologies', function() {
+		// Cypress doesn't respect aria-hidden in should.be.visible
+		cy.get('body > .viewer .modal-container .viewer__file:not(.viewer__file--active) video')
+			.parents('[aria-hidden="true"]')
+			.should('exist')
+		cy.get('body > .viewer .modal-container .viewer__file:not(.viewer__file--active) video')
+			.parents('[inert]')
+			.should('exist')
+		cy.get('body > .viewer .modal-container img.viewer__file:not(.viewer__file--active)')
+			.parents('[aria-hidden="true"]')
+			.should('exist')
+		cy.get('body > .viewer .modal-container img.viewer__file:not(.viewer__file--active)')
+			.parents('[inert]')
+			.should('exist')
+	})
+
+	it('Should make vido controls on the next slide not focusable', function() {
+		cy.get('body > .viewer .modal-container .viewer__file:not(.viewer__file--active):has(video) button')
+			.first()
+			.focus()
+		cy.get('body > .viewer .modal-container .viewer__file:not(.viewer__file--active):has(video) button')
+			.first()
+			.should('not.have.focus')
+	})
+})

src/views/Viewer.vue

@@ -113,65 +113,75 @@
 
 		<div class="viewer__content" :class="contentClass" @click.self.exact="close">
 			<!-- COMPARE FILE -->
-			<component :is="comparisonFile.modal"
-				v-if="comparisonFile && !comparisonFile.failed && showComparison"
-				:key="comparisonFile | uniqueKey"
-				ref="comparison-content"
-				v-bind="comparisonFile"
-				:active="true"
-				:can-swipe="false"
-				:can-zoom="false"
-				:editing="false"
-				:is-full-screen="isFullscreen"
-				:is-sidebar-shown="isSidebarShown"
-				:loaded.sync="comparisonFile.loaded"
-				class="viewer__file viewer__file--active"
-				@error="comparisonFailed" />
+			<div v-if="comparisonFile && !comparisonFile.failed && showComparison" class="viewer__file-wrapper">
+				<component :is="comparisonFile.modal"
+					:key="comparisonFile | uniqueKey"
+					ref="comparison-content"
+					v-bind="comparisonFile"
+					:active="true"
+					:can-swipe="false"
+					:can-zoom="false"
+					:editing="false"
+					:is-full-screen="isFullscreen"
+					:is-sidebar-shown="isSidebarShown"
+					:loaded.sync="comparisonFile.loaded"
+					class="viewer__file viewer__file--active"
+					@error="comparisonFailed" />
+			</div>
 
 			<!-- PREVIOUS -->
-			<component :is="previousFile.modal"
-				v-if="previousFile && !previousFile.failed"
+			<div v-if="previousFile"
 				:key="previousFile | uniqueKey"
-				ref="previous-content"
-				v-bind="previousFile"
-				:file-list="fileList"
-				class="viewer__file--hidden viewer__file"
-				@error="previousFailed" />
-			<Error v-else-if="previousFile"
-				class="hidden-visually"
-				:name="previousFile.basename" />
+				class="viewer__file-wrapper viewer__file-wrapper--hidden"
+				aria-hidden="true"
+				inert>
+				<component :is="previousFile.modal"
+					v-if="!previousFile.failed"
+					ref="previous-content"
+					v-bind="previousFile"
+					:file-list="fileList"
+					class="viewer__file"
+					@error="previousFailed" />
+				<Error v-else
+					:name="previousFile.basename" />
+			</div>
 
 			<!-- CURRENT -->
-			<component :is="currentFile.modal"
-				v-if="!currentFile.failed"
-				:key="currentFile | uniqueKey"
-				ref="content"
-				v-bind="currentFile"
-				:active="true"
-				:can-swipe.sync="canSwipe"
-				:can-zoom="canZoom"
-				:editing.sync="editing"
-				:file-list="fileList"
-				:is-full-screen="isFullscreen"
-				:is-sidebar-shown="isSidebarShown"
-				:loaded.sync="currentFile.loaded"
-				class="viewer__file viewer__file--active"
-				@error="currentFailed" />
-			<Error v-else
-				:name="currentFile.basename" />
+			<div :key="currentFile | uniqueKey" class="viewer__file-wrapper">
+				<component :is="currentFile.modal"
+					v-if="!currentFile.failed"
+					ref="content"
+					v-bind="currentFile"
+					:active="true"
+					:can-swipe.sync="canSwipe"
+					:can-zoom="canZoom"
+					:editing.sync="editing"
+					:file-list="fileList"
+					:is-full-screen="isFullscreen"
+					:is-sidebar-shown="isSidebarShown"
+					:loaded.sync="currentFile.loaded"
+					class="viewer__file viewer__file--active"
+					@error="currentFailed" />
+				<Error v-else
+					:name="currentFile.basename" />
+			</div>
 
 			<!-- NEXT -->
-			<component :is="nextFile.modal"
-				v-if="nextFile && !nextFile.failed"
+			<div v-if="nextFile"
 				:key="nextFile | uniqueKey"
-				ref="next-content"
-				v-bind="nextFile"
-				:file-list="fileList"
-				class="viewer__file--hidden viewer__file"
-				@error="nextFailed" />
-			<Error v-else-if="nextFile"
-				class="hidden-visually"
-				:name="nextFile.basename" />
+				class="viewer__file-wrapper viewer__file-wrapper--hidden"
+				aria-hidden="true"
+				inert>
+				<component :is="nextFile.modal"
+					v-if="!nextFile.failed"
+					ref="next-content"
+					v-bind="nextFile"
+					:file-list="fileList"
+					class="viewer__file"
+					@error="nextFailed" />
+				<Error v-else
+					:name="nextFile.basename" />
+			</div>
 		</div>
 	</NcModal>
 </template>
@@ -1234,17 +1244,16 @@ export default {
 	}
 
 	&__content {
-		// center views
+		width: 100%;
+		height: 100%;
+	}
+
+	&__file-wrapper {
 		display: flex;
 		align-items: center;
 		justify-content: center;
 		width: 100%;
 		height: 100%;
-	}
-
-	&__file {
-		transition: height 100ms ease,
-			width 100ms ease;
 
 		// display on page but make it invisible
 		&--hidden {
@@ -1254,6 +1263,11 @@ export default {
 		}
 	}
 
+	&__file {
+		transition: height 100ms ease,
+			width 100ms ease;
+	}
+
 	&.theme--dark:deep(.button-vue--vue-tertiary) {
 		&:hover {
 			background-color: rgba(255, 255, 255, .08) !important;