Add several methods for working with form XObjects (fixes #436)

Make some more methods in QPDFPageObjectHelper work with form
XObjects, provide forEach methods to walk through nested form
XObjects, possibly recursively. This should make it easier to work
with form XObjects from user code.

1 files changed, 15 insertions, 0 deletions

diff --git a/libqpdf/QPDFObjectHandle.cc b/libqpdf/QPDFObjectHandle.cc
index 180ccfa3..add0b14d 100644
--- a/libqpdf/QPDFObjectHandle.cc
+++ b/libqpdf/QPDFObjectHandle.cc
@@ -2948,6 +2948,21 @@ QPDFObjectHandle::isFormXObject()
             ("/Form" == dict.getKey("/Subtype").getName()));
 }
 
+bool
+QPDFObjectHandle::isImage(bool exclude_imagemask)
+{
+    if (! this->isStream())
+    {
+        return false;
+    }
+    QPDFObjectHandle dict = this->getDict();
+    return (dict.hasKey("/Subtype") &&
+            (dict.getKey("/Subtype").getName() == "/Image") &&
+            ((! exclude_imagemask) ||
+             (! (dict.getKey("/ImageMask").isBool() &&
+                 dict.getKey("/ImageMask").getBoolValue()))));
+}
+
 void
 QPDFObjectHandle::assertPageObject()
 {