From 8c1994e0df8d58b1fe1d09ebb102bb01fddacaf5 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Fri, 23 Jul 2021 11:37:38 +0200
Subject: [PATCH] [api-minor] XFA - Remove the `xfaLayer` from the DOM when
 resetting pages (bug 1721977, PR 13427 follow-up)

Originally the `xfaLayer` wasn't implemented in such a way that it supported being removed from the DOM when pages were evicted from the cache, however this limitation was lifted in PR 13427 and the `xfaLayer` should thus be handled similar to e.g. the `annotationLayer`.

In addition to removing the `xfaLayer` from the DOM, this patch *also* implements proper rendering/hiding-handling for it (mirroring the `annotationLayer`-code).

*Please note:* This patch is tagged API-minor just in case[1], since it changes the signatures of a couple of `PDFPageView`-methods to improve readability of the code.

---
[1] Although users are *hopefully* not directly accessing any of the affected methods, and are rather using e.g. `PDFViewer` in which case none of these changes will matter.
---
 web/pdf_page_view.js | 60 +++++++++++++++++++++++++++++++++-----------
 1 file changed, 46 insertions(+), 14 deletions(-)

diff --git a/web/pdf_page_view.js b/web/pdf_page_view.js
index a5d5a138507bfb..5f0d75c467469a 100644
--- a/web/pdf_page_view.js
+++ b/web/pdf_page_view.js
@@ -207,8 +207,12 @@ class PDFPageView {
     this.zoomLayer = null;
   }
 
-  reset(keepZoomLayer = false, keepAnnotations = false) {
-    this.cancelRendering(keepAnnotations);
+  reset({
+    keepZoomLayer = false,
+    keepAnnotationLayer = false,
+    keepXfaLayer = false,
+  } = {}) {
+    this.cancelRendering({ keepAnnotationLayer, keepXfaLayer });
     this.renderingState = RenderingStates.INITIAL;
 
     const div = this.div;
@@ -218,8 +222,8 @@ class PDFPageView {
     const childNodes = div.childNodes;
     const currentZoomLayerNode = (keepZoomLayer && this.zoomLayer) || null;
     const currentAnnotationNode =
-      (keepAnnotations && this.annotationLayer?.div) || null;
-    const currentXfaLayerNode = this.xfaLayer?.div || null;
+      (keepAnnotationLayer && this.annotationLayer?.div) || null;
+    const currentXfaLayerNode = (keepXfaLayer && this.xfaLayer?.div) || null;
     for (let i = childNodes.length - 1; i >= 0; i--) {
       const node = childNodes[i];
       if (
@@ -242,6 +246,15 @@ class PDFPageView {
       this.annotationLayer = null;
     }
 
+    if (currentXfaLayerNode) {
+      // Hide the XFA layer until all elements are resized
+      // so they are not displayed on the already resized page.
+      this.xfaLayer.hide();
+    } else if (this.xfaLayer) {
+      this.xfaLayer.cancel();
+      this.xfaLayer = null;
+    }
+
     if (!currentZoomLayerNode) {
       if (this.canvas) {
         this.paintedViewportMap.delete(this.canvas);
@@ -284,7 +297,11 @@ class PDFPageView {
     });
 
     if (this.svg) {
-      this.cssTransform(this.svg, true);
+      this.cssTransform({
+        target: this.svg,
+        redrawAnnotationLayer: true,
+        redrawXfaLayer: true,
+      });
 
       this.eventBus.dispatch("pagerendered", {
         source: this,
@@ -313,7 +330,11 @@ class PDFPageView {
         this.useOnlyCssZoom ||
         (this.hasRestrictedScaling && isScalingRestricted)
       ) {
-        this.cssTransform(this.canvas, true);
+        this.cssTransform({
+          target: this.canvas,
+          redrawAnnotationLayer: true,
+          redrawXfaLayer: true,
+        });
 
         this.eventBus.dispatch("pagerendered", {
           source: this,
@@ -330,16 +351,20 @@ class PDFPageView {
       }
     }
     if (this.zoomLayer) {
-      this.cssTransform(this.zoomLayer.firstChild);
+      this.cssTransform({ target: this.zoomLayer.firstChild });
     }
-    this.reset(/* keepZoomLayer = */ true, /* keepAnnotations = */ true);
+    this.reset({
+      keepZoomLayer: true,
+      keepAnnotationLayer: true,
+      keepXfaLayer: true,
+    });
   }
 
   /**
    * PLEASE NOTE: Most likely you want to use the `this.reset()` method,
    *              rather than calling this one directly.
    */
-  cancelRendering(keepAnnotations = false) {
+  cancelRendering({ keepAnnotationLayer = false, keepXfaLayer = false } = {}) {
     if (this.paintTask) {
       this.paintTask.cancel();
       this.paintTask = null;
@@ -350,17 +375,25 @@ class PDFPageView {
       this.textLayer.cancel();
       this.textLayer = null;
     }
-    if (!keepAnnotations && this.annotationLayer) {
+    if (!keepAnnotationLayer && this.annotationLayer) {
       this.annotationLayer.cancel();
       this.annotationLayer = null;
     }
+    if (!keepXfaLayer && this.xfaLayer) {
+      this.xfaLayer.cancel();
+      this.xfaLayer = null;
+    }
     if (this._onTextLayerRendered) {
       this.eventBus._off("textlayerrendered", this._onTextLayerRendered);
       this._onTextLayerRendered = null;
     }
   }
 
-  cssTransform(target, redrawAnnotations = false) {
+  cssTransform({
+    target,
+    redrawAnnotationLayer = false,
+    redrawXfaLayer = false,
+  }) {
     // Scale target (canvas or svg), its wrapper and page container.
     const width = this.viewport.width;
     const height = this.viewport.height;
@@ -429,11 +462,10 @@ class PDFPageView {
       textLayerDiv.style.transformOrigin = "0% 0%";
     }
 
-    if (redrawAnnotations && this.annotationLayer) {
+    if (redrawAnnotationLayer && this.annotationLayer) {
       this._renderAnnotationLayer();
     }
-
-    if (this.xfaLayer) {
+    if (redrawXfaLayer && this.xfaLayer) {
       this._renderXfaLayer();
     }
   }