pdfviewer: when q start, and an operator is called, it should not be able to see operands before q.…

experimental/PdfViewer/SkPdfRenderer.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvas.h"
 #include "SkDevice.h"
 #include "SkForceLinking.h"
@@ skipping 1067 matching lines @@
     canvas->restore();
     PdfOp_Q(pdfContext, canvas, NULL);
     return kPartial_SkPdfResult;
 }
 
 SkPdfResult PdfOp_q(SkPdfContext* pdfContext, SkCanvas* canvas, PdfTokenLooper** looper) {
     // TODO(edisonn): create a new stack of parameters, so once we start a q,
     // it is not possible to see under the previous q?
     pdfContext->fStateStack.push(pdfContext->fGraphicsState);
     canvas->save();
+    pdfContext->fObjectStack.nest();
     return kOK_SkPdfResult;
 }
 
 SkPdfResult PdfOp_Q(SkPdfContext* pdfContext, SkCanvas* canvas, PdfTokenLooper** looper) {
-    pdfContext->fGraphicsState = pdfContext->fStateStack.top();
-    pdfContext->fStateStack.pop();
-    canvas->restore();
+    if (pdfContext->fStateStack.count() > 0) {
+        pdfContext->fGraphicsState = pdfContext->fStateStack.top();
+        pdfContext->fStateStack.pop();
+        canvas->restore();
+
+        if (pdfContext->fObjectStack.nests() <= 0) {
+            return kIgnoreError_SkPdfResult;
+        } else {
+            pdfContext->fObjectStack.unnest();
+        }
+    } else {
+        return kIgnoreError_SkPdfResult;
+    }
+
     return kOK_SkPdfResult;
 }
 
 static SkPdfResult PdfOp_cm(SkPdfContext* pdfContext, SkCanvas* canvas, PdfTokenLooper** looper) {
     EXPECT_OPERANDS(pdfContext, 6);
     POP_NUMBER(pdfContext, f);
     POP_NUMBER(pdfContext, e);
     POP_NUMBER(pdfContext, d);
     POP_NUMBER(pdfContext, c);
     POP_NUMBER(pdfContext, b);
@@ skipping 1663 matching lines @@
     pdfContext.fOriginalMatrix = SkMatrix::I();
     pdfContext.fGraphicsState.fResources = fPdfDoc->pageResources(page);
 
     gPdfContext = &pdfContext;
 
     // TODO(edisonn): get matrix stuff right.
     SkScalar z = SkIntToScalar(0);
     SkScalar w = dst.width();
     SkScalar h = dst.height();
 
+    if (SkScalarTruncToInt(w) <= 0 || SkScalarTruncToInt(h) <= 0) {
+        return true;
+    }
+
     SkScalar wp = fPdfDoc->MediaBox(page).width();
     SkScalar hp = fPdfDoc->MediaBox(page).height();
 
     SkPoint pdfSpace[4] = {SkPoint::Make(z, z), SkPoint::Make(wp, z), SkPoint::Make(wp, hp), SkPoint::Make(z, hp)};
 //                SkPoint skiaSpace[4] = {SkPoint::Make(z, h), SkPoint::Make(w, h), SkPoint::Make(w, z), SkPoint::Make(z, z)};
 
     // TODO(edisonn): add flag for this app to create sourunding buffer zone
     // TODO(edisonn): add flagg for no clipping.
     // Use larger image to make sure we do not draw anything outside of page
     // could be used in tests.
@@ skipping 102 matching lines @@
 
     rect = SkRect::MakeWH(width, height);
 
     setup_bitmap(output, (int)SkScalarToDouble(width), (int)SkScalarToDouble(height));
 
     SkAutoTUnref<SkDevice> device(SkNEW_ARGS(SkDevice, (*output)));
     SkCanvas canvas(device);
 
     return renderer.renderPage(page, &canvas, rect);
 }