Adjust the heuristics for handling of incomplete path operators (issue 14917)

This limits the heuristics for handling of incomplete path operators, see PR 9838, to only apply to *sequences* of such operators. In practice a couple of invalid path operators are (hopefully) unlikely to completely break rendering, whereas a sequence of them will easily lead to fairly chaotic rendering artifacts.

src/core/evaluator.js

@@ -4765,6 +4765,7 @@ class EvaluatorPreprocessor {
     });
     this.stateManager = stateManager;
     this.nonProcessedArgs = [];
+    this._isPathOp = false;
     this._numInvalidPathOPS = 0;
   }
 
@@ -4810,6 +4811,13 @@ class EvaluatorPreprocessor {
         const numArgs = opSpec.numArgs;
         let argsLength = args !== null ? args.length : 0;
 
+        // If the *previous* command wasn't a path operator, reset the heuristic
+        // used with incomplete path operators below (fixes issue14917.pdf).
+        if (!this._isPathOp) {
+          this._numInvalidPathOPS = 0;
+        }
+        this._isPathOp = fn >= OPS.moveTo && fn <= OPS.endPath;
+
         if (!opSpec.variableArgs) {
           // Postscript commands can be nested, e.g. /F2 /GS2 gs 5.711 Tf
           if (argsLength !== numArgs) {
@@ -4837,8 +4845,7 @@ class EvaluatorPreprocessor {
             // used to error, rather than just warn, once a number of invalid
             // path operators have been encountered (fixes bug1443140.pdf).
             if (
-              fn >= OPS.moveTo &&
-              fn <= OPS.endPath && // Path operator
+              this._isPathOp &&
               ++this._numInvalidPathOPS >
                 EvaluatorPreprocessor.MAX_INVALID_PATH_OPS
             ) {

test/pdfs/issue14917.pdf.link

@@ -0,0 +1 @@
+https://web.archive.org/web/20220515091440/https://pdf.cdn.readpaper.com/spd/2963250244.pdf

test/test_manifest.json

@@ -3016,6 +3016,14 @@
        },
        "about": "Need to test *at least* three pages, since the `GlobalImageCache` is involved."
     },
+    {  "id": "issue14917",
+       "file": "pdfs/issue14917.pdf",
+       "md5": "12201b35853f78a501ac46b91608f8b6",
+       "rounds": 1,
+       "link": true,
+       "lastPage": 1,
+       "type": "eq"
+    },
     {  "id": "issue1127-text",
        "file": "pdfs/issue1127.pdf",
        "md5": "4fb2be5ffefeafda4ba977de2a1bb4d8",