fix: reduce split-page hairline artifacts in canvas rendering

LICENSE

@@ -1,21 +1,19 @@
-MIT License
+All rights reserved.
 
 Copyright (c) 2026 Mummert
 
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
+This source code is publicly visible for informational and deployment purposes only.
 
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
+Permission is NOT granted to:
+- use this code for any commercial or non-commercial purpose
+- copy, modify, merge, publish, distribute, sublicense, or sell copies of the Software
+- use this code in any other project
 
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
+Any use of this code without explicit written permission from the author is strictly prohibited.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

README.md

@@ -33,6 +33,7 @@ Felder:
 
 - Das Inhaltselement rendert PDF-Seiten als `<canvas>` innerhalb von `.c-flipbook__page`.
 - Die benoetigten Open-Source-Dateien sind lokal im Bundle enthalten.
+- Fuer Shared-Hosting ohne konfigurierbare MIME-Types werden PDF.js-Module als `.js` ausgeliefert (statt `.mjs`).
 - Siehe `THIRD_PARTY_LICENSES.md` fuer Abhaengigkeiten.
 
 ## Release

THIRD_PARTY_LICENSES.md

@@ -6,7 +6,7 @@ This bundle contains the following third-party open source libraries in `public/
 
 - Project: https://github.com/mozilla/pdf.js
 - Package: `pdfjs-dist`
-- Version: `4.9.155`
+- Version: `5.6.205`
 - License: Apache-2.0
 
 ## flipbook-js

composer.json

@@ -2,7 +2,7 @@
   "name": "mummert/flipbook-bundle",
   "description": "PDF flipbook content element for Contao 5.7 using pdfjs-dist and flipbook-js.",
   "type": "contao-bundle",
-  "license": "MIT",
+  "license": "proprietary",
   "keywords": [
     "contao",
     "contao-bundle",

contao/dca/tl_content.php

@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-$GLOBALS['TL_DCA']['tl_content']['palettes']['blatterbares_pdf'] = '{type_legend},type,headline;{flipbook_legend},flipbookPdfSrc,flipbookInitialPages,flipbookStartMode,flipbookShowNavigation,flipbookPlaySound;{template_legend:hide},customTpl;{protected_legend:hide},protected;{expert_legend:hide},cssID;{invisible_legend:hide},invisible,start,stop';
+$GLOBALS['TL_DCA']['tl_content']['palettes']['blatterbares_pdf'] = '{type_legend},type,headline;{flipbook_legend},flipbookPdfSrc,flipbookInitialPages,flipbookStartMode,flipbookSplitSpreads,flipbookShowNavigation,flipbookPlaySound;{template_legend:hide},customTpl;{protected_legend:hide},protected;{expert_legend:hide},cssID;{invisible_legend:hide},invisible,start,stop';
 
 $GLOBALS['TL_DCA']['tl_content']['fields']['flipbookPdfSrc'] = [
     'label' => &$GLOBALS['TL_LANG']['tl_content']['flipbookPdfSrc'],
@@ -32,6 +32,14 @@ $GLOBALS['TL_DCA']['tl_content']['fields']['flipbookStartMode'] = [
     'sql' => ['type' => 'string', 'length' => 16, 'default' => 'center'],
 ];
 
+$GLOBALS['TL_DCA']['tl_content']['fields']['flipbookSplitSpreads'] = [
+    'label' => &$GLOBALS['TL_LANG']['tl_content']['flipbookSplitSpreads'],
+    'exclude' => true,
+    'inputType' => 'checkbox',
+    'eval' => ['tl_class' => 'w50 m12'],
+    'sql' => ['type' => 'string', 'length' => 1, 'fixed' => true, 'default' => '0'],
+];
+
 $GLOBALS['TL_DCA']['tl_content']['fields']['flipbookShowNavigation'] = [
     'label' => &$GLOBALS['TL_LANG']['tl_content']['flipbookShowNavigation'],
     'exclude' => true,

contao/languages/de/tl_content.php

@@ -15,5 +15,6 @@ $GLOBALS['TL_LANG']['tl_content']['flipbookStartModeOptions'] = [
     'center' => 'Zentriert starten',
     'spread' => 'als Doppelseite starten',
 ];
+$GLOBALS['TL_LANG']['tl_content']['flipbookSplitSpreads'] = ['Doppelseiten aufteilen', 'Teilt breite PDF-Seiten ab Seite 2 automatisch in linke und rechte Einzelseite.'];
 $GLOBALS['TL_LANG']['tl_content']['flipbookShowNavigation'] = ['Navigation anzeigen', 'Zeigt Vor-/Zurueck-Buttons unter dem Flipbook an.'];
 $GLOBALS['TL_LANG']['tl_content']['flipbookPlaySound'] = ['Blättersound abspielen', 'Spielt beim Blättern einen Sound ab.'];

contao/languages/en/tl_content.php

@@ -15,5 +15,6 @@ $GLOBALS['TL_LANG']['tl_content']['flipbookStartModeOptions'] = [
     'center' => 'Start centered',
     'spread' => 'Start with double-page spread',
 ];
+$GLOBALS['TL_LANG']['tl_content']['flipbookSplitSpreads'] = ['Split double-page spreads', 'Automatically splits wide PDF pages from page 2 onwards into left and right single pages.'];
 $GLOBALS['TL_LANG']['tl_content']['flipbookShowNavigation'] = ['Show navigation', 'Displays previous/next buttons below the flipbook.'];
 $GLOBALS['TL_LANG']['tl_content']['flipbookPlaySound'] = ['Play page-turn sound', 'Plays a sound effect while turning pages.'];

contao/templates/content_element/blatterbares_pdf.html.twig

@@ -1,23 +1,24 @@
 {% set hasPdf = pdfUrl|default('') is not empty %}
 
 <div
-    class="ce-blatterbares-pdf mod-pdf-flipbook"
+    class="ce-blatterbares-pdf mod-pdf-flipbook is-loading"
     data-pdf-flipbook-element="1"
     data-pdf-url="{{ pdfUrl|default('')|e('html_attr') }}"
     data-initial-pages="{{ initialRenderPages|default(4)|e('html_attr') }}"
     data-start-mode="{{ startMode|default('center')|e('html_attr') }}"
+    data-split-spreads="{{ splitSpreads ? '1' : '0' }}"
     data-show-navigation="{{ showNavigation ? '1' : '0' }}"
     data-play-turn-sound="{{ ((playTurnSound is defined) ? playTurnSound : true) ? '1' : '0' }}"
     tabindex="0"
 >
     <div class="mod-pdf-flipbook__status" data-flipbook-loader="1" aria-live="polite">PDF wird geladen ...</div>
 
-    <div class="mod-pdf-flipbook__stage" data-flipbook-stage="1">
+    <div class="mod-pdf-flipbook__stage" data-flipbook-stage="1" style="visibility:hidden;opacity:0">
         <div id="flipbook-{{ data.id|default(random()) }}" class="c-flipbook" data-flipbook-book="1"></div>
     </div>
 
     {% if showNavigation %}
-        <div class="mod-pdf-flipbook__controls" aria-label="Flipbook Navigation">
+        <div class="mod-pdf-flipbook__controls" data-flipbook-controls="1" aria-label="Flipbook Navigation" style="visibility:hidden;opacity:0">
             <button type="button" data-flipbook-prev="1">Zurück</button>
             <button type="button" data-flipbook-next="1">Weiter</button>
         </div>
@@ -28,6 +29,6 @@
     {% endif %}
 </div>
 
-<link rel="stylesheet" href="/bundles/flipbook/assets/vendor/flipbook.min.css?v=20260414f">
-<link rel="stylesheet" href="/bundles/flipbook/assets/flipbook-module.css?v=20260414f">
-<script type="module" src="/bundles/flipbook/assets/flipbook-module.js?v=20260414f"></script>
+<link rel="stylesheet" href="/bundles/flipbook/assets/vendor/flipbook.min.css?v=20260414j">
+<link rel="stylesheet" href="/bundles/flipbook/assets/flipbook-module.css?v=20260414j">
+<script type="module" src="/bundles/flipbook/assets/flipbook-module.js?v=20260414j"></script>

public/assets/flipbook-module.css

@@ -13,11 +13,24 @@
 }
 
 .mod-pdf-flipbook__status {
+    display: inline-flex;
+    align-items: center;
+    gap: 0.55rem;
     margin-bottom: 0.8rem;
     font-size: 0.92rem;
     color: var(--flipbook-text);
 }
 
+.mod-pdf-flipbook__status::before {
+    content: '';
+    width: 0.9rem;
+    height: 0.9rem;
+    border: 2px solid rgba(48, 45, 41, 0.25);
+    border-top-color: rgba(48, 45, 41, 0.85);
+    border-radius: 50%;
+    animation: mod-pdf-flipbook-spin 0.75s linear infinite;
+}
+
 .mod-pdf-flipbook__status.is-hidden {
     display: none;
 }
@@ -26,18 +39,29 @@
     color: #9f1f1f;
 }
 
+.mod-pdf-flipbook__status.is-error::before {
+    display: none;
+}
+
 .mod-pdf-flipbook__stage {
     position: relative;
     width: 100%;
     margin: 0 auto;
     background: #e0e0e0;
     z-index: 1;
+    transition: opacity 1.3s ease 0.5s;
 }
 
 .mod-pdf-flipbook .c-flipbook {
     max-width: 100%;
 }
 
+.mod-pdf-flipbook .c-flipbook.is-booting,
+.mod-pdf-flipbook .c-flipbook.is-booting .c-flipbook__page,
+.mod-pdf-flipbook .c-flipbook.is-booting .c-flipbook__page::before {
+    transition: none !important;
+}
+
 .mod-pdf-flipbook .c-flipbook__page {
     background: #fefdf9;
     overflow: hidden;
@@ -73,6 +97,7 @@
     display: flex;
     gap: 0.6rem;
     margin-top: 0.9rem;
+    transition: opacity 1.3s ease 0.5s;
 }
 
 .mod-pdf-flipbook__error {
@@ -85,3 +110,9 @@
         justify-content: space-between;
     }
 }
+
+@keyframes mod-pdf-flipbook-spin {
+    to {
+        transform: rotate(360deg);
+    }
+}

public/assets/flipbook-module.js

@@ -1,10 +1,11 @@
 const MODULE_SELECTOR = '[data-pdf-flipbook-element="1"]';
-const PDF_MODULE_URL = '/bundles/flipbook/assets/vendor/pdf.min.mjs';
-const PDF_WORKER_URL = '/bundles/flipbook/assets/vendor/pdf.worker.min.mjs';
+const PDF_MODULE_URL = '/bundles/flipbook/assets/vendor/pdf.min.js';
+const PDF_WORKER_URL = '/bundles/flipbook/assets/vendor/pdf.worker.min.js';
 const FLIPBOOK_MODULE_URL = '/bundles/flipbook/assets/vendor/flipbook.esm.min.js';
 const TURN_SOUND_URL = '/bundles/flipbook/assets/audio/turn.mp3';
 const INIT_MARKER = 'pdfFlipbookInitialized';
 const BOOTSTRAP_MARKER = '__mummertPdfFlipbookBootstrapBound';
+const MIN_OUTPUT_SCALE = 2;
 
 let dependenciesPromise;
 let moduleCounter = 0;
@@ -36,9 +37,12 @@ class PdfFlipbookModule {
         this.root = root;
         this.dependencies = dependencies;
         this.pdfUrl = (root.dataset.pdfUrl || '').trim();
+        this.root.classList.add('is-loading');
+        this.root.classList.remove('is-ready');
         this.initialPages = Number.isFinite(parsedInitialPages)
             ? Math.min(4, Math.max(2, parsedInitialPages))
             : 4;
+        this.splitSpreads = root.dataset.splitSpreads === '1';
         this.showNavigation = root.dataset.showNavigation === '1';
         this.playTurnSoundEnabled = root.dataset.playTurnSound !== '0';
         this.startMode = (root.dataset.startMode === 'spread' || root.dataset.startMode === 'cover')
@@ -47,6 +51,7 @@ class PdfFlipbookModule {
         this.loader = root.querySelector('[data-flipbook-loader="1"]');
         this.stage = root.querySelector('[data-flipbook-stage="1"]');
         this.bookElement = root.querySelector('[data-flipbook-book="1"]');
+        this.controlsElement = root.querySelector('[data-flipbook-controls="1"]');
         this.nextButton = this.showNavigation ? root.querySelector('[data-flipbook-next="1"]') : null;
         this.prevButton = this.showNavigation ? root.querySelector('[data-flipbook-prev="1"]') : null;
 
@@ -64,7 +69,9 @@ class PdfFlipbookModule {
         this.pageWidth = 0;
         this.pageHeight = 0;
         this.pageGap = 2;
+        this.sourcePageCount = 0;
         this.totalPages = 0;
+        this.pageDescriptors = [];
 
         this.instanceId = `pdf-flipbook-${++moduleCounter}`;
     }
@@ -76,6 +83,7 @@ class PdfFlipbookModule {
 
         if (!this.pdfUrl) {
             this.setStatus('Keine PDF-Datei gefunden.', true);
+            this.root.classList.remove('is-loading');
 
             return;
         }
@@ -94,12 +102,49 @@ class PdfFlipbookModule {
             this.bindTouchSwipe();
             this.bindResize();
             this.queuePages(this.getLazyCandidates());
+            await this.showReadyState();
             this.setStatus('');
         } catch {
             this.setStatus('PDF konnte nicht geladen werden.', true);
+            this.root.classList.remove('is-loading');
         }
     }
 
+    async showReadyState() {
+        await new Promise((resolve) => {
+            window.requestAnimationFrame(() => {
+                window.requestAnimationFrame(resolve);
+            });
+        });
+
+        if (this.bookElement) {
+            this.bookElement.classList.remove('is-booting');
+        }
+
+        this.root.classList.remove('is-loading');
+        this.root.classList.add('is-ready');
+
+        if (this.stage) {
+            this.stage.style.visibility = 'visible';
+        }
+
+        if (this.controlsElement) {
+            this.controlsElement.style.visibility = 'visible';
+        }
+
+        window.requestAnimationFrame(() => {
+            if (this.stage) {
+                this.stage.style.opacity = '1';
+            }
+
+            if (this.controlsElement) {
+                this.controlsElement.style.opacity = '1';
+            }
+
+            this.updateNavigationState();
+        });
+    }
+
     async loadPdf() {
         const loadingTask = this.dependencies.pdfjsLib.getDocument({
             url: this.pdfUrl,
@@ -108,19 +153,84 @@ class PdfFlipbookModule {
         });
 
         this.pdf = await loadingTask.promise;
-        this.totalPages = Number(this.pdf.numPages || 0);
+        this.sourcePageCount = Number(this.pdf.numPages || 0);
 
-        if (this.totalPages <= 0) {
+        if (this.sourcePageCount <= 0) {
             throw new Error('The selected PDF has no pages.');
         }
+
+        await this.buildPageDescriptors();
+        this.totalPages = this.pageDescriptors.length;
+    }
+
+    async buildPageDescriptors() {
+        const descriptors = [];
+
+        for (let sourcePageNumber = 1; sourcePageNumber <= this.sourcePageCount; sourcePageNumber += 1) {
+            const page = await this.pdf.getPage(sourcePageNumber);
+            const viewport = page.getViewport({ scale: 1 });
+
+            if (this.shouldSplitSpread(sourcePageNumber, viewport)) {
+                descriptors.push({
+                    sourcePageNumber,
+                    segment: 'left',
+                });
+                descriptors.push({
+                    sourcePageNumber,
+                    segment: 'right',
+                });
+            } else {
+                descriptors.push({
+                    sourcePageNumber,
+                    segment: 'full',
+                });
+            }
+        }
+
+        this.pageDescriptors = descriptors;
+    }
+
+    shouldSplitSpread(sourcePageNumber, viewport) {
+        if (!this.splitSpreads) {
+            return false;
+        }
+
+        if (sourcePageNumber <= 1) {
+            return false;
+        }
+
+        const width = Number(viewport.width || 0);
+        const height = Number(viewport.height || 0);
+
+        if (width <= 0 || height <= 0) {
+            return false;
+        }
+
+        return width >= (height * 1.2);
+    }
+
+    getDescriptor(pageNumber) {
+        if (!Number.isInteger(pageNumber) || pageNumber < 1) {
+            return null;
+        }
+
+        return this.pageDescriptors[pageNumber - 1] || null;
     }
 
     async resolveInitialAspectRatio() {
-        const firstPage = await this.pdf.getPage(1);
-        const viewport = firstPage.getViewport({ scale: 1 });
+        const firstDescriptor = this.getDescriptor(1);
 
-        if (viewport.width > 0 && viewport.height > 0) {
-            this.aspectRatio = viewport.height / viewport.width;
+        if (!firstDescriptor) {
+            return;
+        }
+
+        const firstPage = await this.pdf.getPage(firstDescriptor.sourcePageNumber);
+        const viewport = firstPage.getViewport({ scale: 1 });
+        const divisor = firstDescriptor.segment === 'full' ? 1 : 2;
+        const width = viewport.width / divisor;
+
+        if (width > 0 && viewport.height > 0) {
+            this.aspectRatio = viewport.height / width;
         }
     }
 
@@ -178,6 +288,8 @@ class PdfFlipbookModule {
     initializeFlipbook() {
         const startsWithDoubleSpread = this.startMode === 'spread';
 
+        this.bookElement.classList.add('is-booting');
+
         this.flipbook = new this.dependencies.FlipBook(this.bookElement, {
             nextButton: this.nextButton,
             previousButton: this.prevButton,
@@ -190,8 +302,42 @@ class PdfFlipbookModule {
             onPageTurn: () => {
                 this.playTurnSound();
                 this.queuePages(this.getLazyCandidates());
+                this.updateNavigationState();
             },
         });
+
+        window.requestAnimationFrame(() => {
+            this.updateNavigationState();
+        });
+    }
+
+    updateNavigationState() {
+        if (!this.showNavigation || !this.prevButton || !this.nextButton) {
+            return;
+        }
+
+        const activePages = Array.from(this.bookElement.querySelectorAll('.c-flipbook__page.is-active'))
+            .map((element) => Number(element.dataset.pageNumber || 0))
+            .filter((pageNumber) => Number.isInteger(pageNumber) && pageNumber > 0);
+
+        let disablePrev = false;
+        let disableNext = false;
+
+        if (activePages.length === 0) {
+            disablePrev = true;
+            disableNext = this.totalPages <= 1;
+        } else {
+            const minActivePage = Math.min(...activePages);
+            const maxActivePage = Math.max(...activePages);
+
+            disablePrev = minActivePage <= 1;
+            disableNext = maxActivePage >= this.totalPages;
+        }
+
+        this.prevButton.disabled = disablePrev;
+        this.nextButton.disabled = disableNext;
+        this.prevButton.setAttribute('aria-disabled', disablePrev ? 'true' : 'false');
+        this.nextButton.setAttribute('aria-disabled', disableNext ? 'true' : 'false');
     }
 
     createTurnSound() {
@@ -408,17 +554,21 @@ class PdfFlipbookModule {
         }
 
         const pageElement = this.pageElements.get(pageNumber);
+        const descriptor = this.getDescriptor(pageNumber);
 
-        if (!pageElement) {
+        if (!pageElement || !descriptor) {
             return;
         }
 
-        const page = await this.pdf.getPage(pageNumber);
+        const page = await this.pdf.getPage(descriptor.sourcePageNumber);
         const viewportAtScale1 = page.getViewport({ scale: 1 });
-        const scale = this.pageWidth / viewportAtScale1.width;
+        const renderWidth = descriptor.segment === 'full'
+            ? viewportAtScale1.width
+            : viewportAtScale1.width / 2;
+        const scale = this.pageWidth / renderWidth;
         const viewport = page.getViewport({ scale });
         const devicePixelRatio = window.devicePixelRatio || 1;
-        const outputScale = Math.max(1, devicePixelRatio);
+        const outputScale = Math.max(MIN_OUTPUT_SCALE, devicePixelRatio);
         const existingCanvas = pageElement.querySelector('canvas');
 
         if (existingCanvas) {
@@ -432,15 +582,30 @@ class PdfFlipbookModule {
             throw new Error('Could not create canvas 2D context.');
         }
 
-        canvas.width = Math.floor(viewport.width * outputScale);
+        const canvasCssWidth = descriptor.segment === 'full'
+            ? Math.floor(viewport.width)
+            : Math.floor(viewport.width / 2);
+
+        canvas.width = Math.floor(canvasCssWidth * outputScale);
         canvas.height = Math.floor(viewport.height * outputScale);
-        canvas.style.width = `${Math.floor(viewport.width)}px`;
+        canvas.style.width = `${canvasCssWidth}px`;
         canvas.style.height = `${Math.floor(viewport.height)}px`;
 
+        const baseTransform = outputScale === 1 ? null : [outputScale, 0, 0, outputScale, 0, 0];
+        let transform = baseTransform;
+
+        if (descriptor.segment !== 'full' && baseTransform) {
+            const segmentOffsetX = descriptor.segment === 'left'
+                ? 0
+                : -Math.floor((viewport.width * outputScale) / 2);
+
+            transform = [outputScale, 0, 0, outputScale, segmentOffsetX, 0];
+        }
+
         const renderTask = page.render({
             canvasContext: context,
             viewport,
-            transform: outputScale === 1 ? null : [outputScale, 0, 0, outputScale, 0, 0],
+            transform,
             intent: 'display',
         });
 

src/Controller/ContentElement/BlatterbaresPdfController.php

@@ -20,6 +20,7 @@ class BlatterbaresPdfController extends AbstractContentElementController
         $template->set('pdfUrl', $this->resolvePdfUrl($model));
         $template->set('showNavigation', '1' === (string) ($model->flipbookShowNavigation ?? '1'));
         $template->set('playTurnSound', '1' === (string) ($model->flipbookPlaySound ?? '1'));
+        $template->set('splitSpreads', '1' === (string) ($model->flipbookSplitSpreads ?? '0'));
         $template->set('initialRenderPages', $this->normalizeInitialRenderPages((string) ($model->flipbookInitialPages ?? '4')));
         $template->set('startMode', $this->normalizeStartMode((string) ($model->flipbookStartMode ?? 'center')));