From 7273795eb63962912ad45b84b8e05a1074f90335 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sat, 16 Mar 2019 12:09:14 +0100
Subject: [PATCH 1/2] Actually transfer eligible ImageMask data, rather than
 always copying it

By transfering `ArrayBuffer`s you can avoid having two copies of the same data, i.e. one copy on each of the worker/main-thread, for data that's used only *once* on the worker-thread.

Note how the code in [`PDFImage.createMask`](https://github.com/mozilla/pdf.js/blob/80135378cadd98b55a835446f0857e4bc30524e0/src/core/image.js#L284-L285) goes to great lengths to actually enable tranfering of the image data. However in [`PartialEvaluator.buildPaintImageXObject`](https://github.com/mozilla/pdf.js/blob/80135378cadd98b55a835446f0857e4bc30524e0/src/core/evaluator.js#L336) the `cached` property is always set to `true`, which disqualifies the image data from being transfered; see [`getTransfers`](https://github.com/mozilla/pdf.js/blob/80135378cadd98b55a835446f0857e4bc30524e0/src/core/operator_list.js#L552-L554).

For most ImageMask data this patch won't matter, since images found in the `/Resources -> /XObject` dictionary will always be indexed by name. However for *inline* images which contains ImageMask data, where only "small" images are cached (in both `parser.js` and `evaluator.js`), the current code will result in some unnecessary memory usage.
---
 src/core/evaluator.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/core/evaluator.js b/src/core/evaluator.js
index dd13aeb64..06951cdee 100644
--- a/src/core/evaluator.js
+++ b/src/core/evaluator.js
@@ -333,8 +333,9 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
           imageIsFromDecodeStream: image instanceof DecodeStream,
           inverseDecode: (!!decode && decode[0] > 0),
         });
-        imgData.cached = true;
+        imgData.cached = !!cacheKey;
         args = [imgData];
+
         operatorList.addOp(OPS.paintImageMaskXObject, args);
         if (cacheKey) {
           imageCache[cacheKey] = {

From 56eeeea1dca9b9a4ee4a43e74614e91e0a518695 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sat, 16 Mar 2019 12:15:22 +0100
Subject: [PATCH 2/2] Re-factor the `getTransfers` helper function into a
 "private" getter method on the `OperatorList`

This function is currently called with the `OperatorList` instance as its argument, hence I cannot think of any good reason for not just moving it into the `OperatorList` properly. (This will also help with other planned changes regarding the `ImageCache` functionality.)
---
 src/core/operator_list.js | 56 +++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 28 deletions(-)

diff --git a/src/core/operator_list.js b/src/core/operator_list.js
index 3128ff6fb..b5690843d 100644
--- a/src/core/operator_list.js
+++ b/src/core/operator_list.js
@@ -534,30 +534,6 @@ var OperatorList = (function OperatorListClosure() {
   var CHUNK_SIZE = 1000;
   var CHUNK_SIZE_ABOUT = CHUNK_SIZE - 5; // close to chunk size
 
-  function getTransfers(queue) {
-    var transfers = [];
-    var fnArray = queue.fnArray, argsArray = queue.argsArray;
-    for (var i = 0, ii = queue.length; i < ii; i++) {
-      switch (fnArray[i]) {
-        case OPS.paintInlineImageXObject:
-        case OPS.paintInlineImageXObjectGroup:
-        case OPS.paintImageMaskXObject:
-          var arg = argsArray[i][0]; // first param in imgData
-
-          if (typeof PDFJSDev === 'undefined' ||
-              PDFJSDev.test('!PRODUCTION || TESTING')) {
-            assert(arg.data instanceof Uint8ClampedArray,
-                   'OperatorList - getTransfers: Unsupported "arg.data" type.');
-          }
-          if (!arg.cached) {
-            transfers.push(arg.data.buffer);
-          }
-          break;
-      }
-    }
-    return transfers;
-  }
-
   function OperatorList(intent, messageHandler, pageIndex) {
     this.messageHandler = messageHandler;
     this.fnArray = [];
@@ -630,10 +606,33 @@ var OperatorList = (function OperatorListClosure() {
       };
     },
 
-    flush(lastChunk) {
+    get _transfers() {
+      const transfers = [];
+      const { fnArray, argsArray, length, } = this;
+      for (let i = 0; i < length; i++) {
+        switch (fnArray[i]) {
+          case OPS.paintInlineImageXObject:
+          case OPS.paintInlineImageXObjectGroup:
+          case OPS.paintImageMaskXObject:
+            const arg = argsArray[i][0]; // first param in imgData
+
+            if (typeof PDFJSDev === 'undefined' ||
+                PDFJSDev.test('!PRODUCTION || TESTING')) {
+              assert(arg.data instanceof Uint8ClampedArray,
+                     'OperatorList._transfers: Unsupported "arg.data" type.');
+            }
+            if (!arg.cached) {
+              transfers.push(arg.data.buffer);
+            }
+            break;
+        }
+      }
+      return transfers;
+    },
+
+    flush(lastChunk = false) {
       this.optimizer.flush();
-      var transfers = getTransfers(this);
-      var length = this.length;
+      const length = this.length;
       this._totalLength += length;
 
       this.messageHandler.send('RenderPageChunk', {
@@ -645,7 +644,8 @@ var OperatorList = (function OperatorListClosure() {
         },
         pageIndex: this.pageIndex,
         intent: this.intent,
-      }, transfers);
+      }, this._transfers);
+
       this.dependencies = Object.create(null);
       this.fnArray.length = 0;
       this.argsArray.length = 0;