From f5752b97e9f1293696232f197bd8684f3e782d1e Mon Sep 17 00:00:00 2001
From: kolaente <hello@kolaente.de>
Date: Sat, 4 Apr 2026 21:25:54 +0200
Subject: [PATCH] feat: add inline PDF viewer for task attachments (#2541)

---
 frontend/src/components/misc/Icon.ts          |  2 ++
 .../components/tasks/partials/Attachments.vue | 31 +++++++++++++++++--
 .../components/tasks/partials/FilePreview.vue | 18 +++++++++--
 frontend/src/models/attachment.ts             | 11 ++++++-
 4 files changed, 55 insertions(+), 7 deletions(-)

diff --git a/frontend/src/components/misc/Icon.ts b/frontend/src/components/misc/Icon.ts
index 8a5cab738..56a803f9a 100644
--- a/frontend/src/components/misc/Icon.ts
+++ b/frontend/src/components/misc/Icon.ts
@@ -37,6 +37,7 @@ import {
 	faEyeSlash,
 	faFile,
 	faFileImage,
+	faFilePdf,
 	faFillDrip,
 	faFilter,
 	faForward,
@@ -111,6 +112,7 @@ library.add(faSquareCheck)
 library.add(faTable)
 library.add(faFile)
 library.add(faFileImage)
+library.add(faFilePdf)
 library.add(faCheckSquare)
 library.add(faStrikethrough)
 library.add(faCode)
diff --git a/frontend/src/components/tasks/partials/Attachments.vue b/frontend/src/components/tasks/partials/Attachments.vue
index b246adcd0..3f65bd0a8 100644
--- a/frontend/src/components/tasks/partials/Attachments.vue
+++ b/frontend/src/components/tasks/partials/Attachments.vue
@@ -95,7 +95,7 @@
 								<Icon icon="trash-alt" />
 							</BaseButton>
 							<BaseButton
-								v-if="editEnabled && canPreview(a)"
+								v-if="editEnabled && canPreviewImage(a)"
 								v-tooltip="task.coverImageAttachmentId === a.id
 									? $t('task.attachment.unsetAsCover')
 									: $t('task.attachment.setAsCover')"
@@ -168,6 +168,19 @@
 				alt=""
 			>
 		</Modal>
+
+		<!-- Attachment PDF modal -->
+		<Modal
+			:enabled="attachmentPdfBlobUrl !== null"
+			:wide="true"
+			@close="attachmentPdfBlobUrl = null"
+		>
+			<iframe
+				v-if="attachmentPdfBlobUrl"
+				:src="attachmentPdfBlobUrl"
+				class="pdf-preview-iframe"
+			/>
+		</Modal>
 	</div>
 </template>
 
@@ -180,7 +193,7 @@ import ProgressBar from '@/components/misc/ProgressBar.vue'
 import BaseButton from '@/components/base/BaseButton.vue'
 
 import AttachmentService from '@/services/attachment'
-import {canPreview} from '@/models/attachment'
+import {canPreviewImage, canPreviewPdf} from '@/models/attachment'
 import type {IAttachment} from '@/modelTypes/IAttachment'
 import type {ITask} from '@/modelTypes/ITask'
 
@@ -365,10 +378,13 @@ async function deleteAttachment() {
 }
 
 const attachmentImageBlobUrl = ref<string | null>(null)
+const attachmentPdfBlobUrl = ref<string | null>(null)
 
 async function viewOrDownload(attachment: IAttachment) {
-	if (canPreview(attachment)) {
+	if (canPreviewImage(attachment)) {
 		attachmentImageBlobUrl.value = await attachmentService.getBlobUrl(attachment)
+	} else if (canPreviewPdf(attachment)) {
+		attachmentPdfBlobUrl.value = await attachmentService.getBlobUrl(attachment)
 	} else {
 		downloadAttachment(attachment)
 	}
@@ -576,6 +592,15 @@ defineExpose({
 	block-size: 100%;
 }
 
+.pdf-preview-iframe {
+	inline-size: 100%;
+	max-inline-size: calc(100% - 4rem);
+	block-size: calc(100vh - var(--modal-content-spacing-tablet));
+	border: none;
+	margin: 0 auto;
+	display: block;
+}
+
 .is-task-cover {
 	background: var(--primary);
 	color: var(--white);
diff --git a/frontend/src/components/tasks/partials/FilePreview.vue b/frontend/src/components/tasks/partials/FilePreview.vue
index 2aa247baf..78f6a422f 100644
--- a/frontend/src/components/tasks/partials/FilePreview.vue
+++ b/frontend/src/components/tasks/partials/FilePreview.vue
@@ -6,6 +6,17 @@
 		alt="Attachment preview"
 	>
 
+	<!-- PDF icon -->
+	<div
+		v-else-if="isPdf"
+		class="icon-wrapper"
+	>
+		<Icon
+			size="6x"
+			icon="file-pdf"
+		/>
+	</div>
+
 	<!-- Fallback -->
 	<div
 		v-else
@@ -19,10 +30,10 @@
 </template>
 
 <script setup lang="ts">
-import {ref, shallowReactive, watchEffect} from 'vue'
+import {computed, ref, shallowReactive, watchEffect} from 'vue'
 import AttachmentService, {PREVIEW_SIZE} from '@/services/attachment'
 import type {IAttachment} from '@/modelTypes/IAttachment'
-import {canPreview} from '@/models/attachment'
+import {canPreviewImage, canPreviewPdf} from '@/models/attachment'
 
 const props = defineProps<{
 	modelValue?: IAttachment
@@ -30,9 +41,10 @@ const props = defineProps<{
 
 const attachmentService = shallowReactive(new AttachmentService())
 const blobUrl = ref<string | undefined>(undefined)
+const isPdf = computed(() => props.modelValue && canPreviewPdf(props.modelValue))
 
 watchEffect(async () => {
-	if (props.modelValue && canPreview(props.modelValue)) {
+	if (props.modelValue && canPreviewImage(props.modelValue)) {
 		blobUrl.value = await attachmentService.getBlobUrl(props.modelValue, PREVIEW_SIZE.MD)
 	}
 })
diff --git a/frontend/src/models/attachment.ts b/frontend/src/models/attachment.ts
index f06409e64..1953b303b 100644
--- a/frontend/src/models/attachment.ts
+++ b/frontend/src/models/attachment.ts
@@ -6,9 +6,18 @@ import type { IFile } from '@/modelTypes/IFile'
 import type { IAttachment } from '@/modelTypes/IAttachment'
 
 export const SUPPORTED_IMAGE_SUFFIX = ['.jpeg', '.jpg', '.png', '.bmp', '.gif']
+export const SUPPORTED_PDF_SUFFIX = ['.pdf']
+
+export function canPreviewImage(attachment: IAttachment): boolean {
+	return SUPPORTED_IMAGE_SUFFIX.some((suffix) => attachment.file.name.toLowerCase().endsWith(suffix))
+}
+
+export function canPreviewPdf(attachment: IAttachment): boolean {
+	return SUPPORTED_PDF_SUFFIX.some((suffix) => attachment.file.name.toLowerCase().endsWith(suffix))
+}
 
 export function canPreview(attachment: IAttachment): boolean {
-	return SUPPORTED_IMAGE_SUFFIX.some((suffix) => attachment.file.name.toLowerCase().endsWith(suffix))
+	return canPreviewImage(attachment) || canPreviewPdf(attachment)
 }
 
 export default class AttachmentModel extends AbstractModel<IAttachment> implements IAttachment {