From cfa2eb97fb9b38d62fd2cd8d54ab59bac503967f Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Sat, 12 Aug 2017 13:22:46 -0400
Subject: Add page rotation (fixes #132)

---
 libqpdf/QPDFObjectHandle.cc | 56 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

(limited to 'libqpdf')

diff --git a/libqpdf/QPDFObjectHandle.cc b/libqpdf/QPDFObjectHandle.cc
index e263a3ec..a8a7e5a7 100644
--- a/libqpdf/QPDFObjectHandle.cc
+++ b/libqpdf/QPDFObjectHandle.cc
@@ -673,6 +673,62 @@ QPDFObjectHandle::addPageContents(QPDFObjectHandle new_contents, bool first)
     this->replaceKey("/Contents", contents);
 }
 
+void
+QPDFObjectHandle::rotatePage(int angle, bool relative)
+{
+    assertPageObject();
+    if ((angle % 90) != 0)
+    {
+        throw std::runtime_error(
+            "QPDF::rotatePage called with an"
+            " angle that is not a multiple of 90");
+    }
+    int new_angle = angle;
+    if (relative)
+    {
+        int old_angle = 0;
+        bool found_rotate = false;
+        QPDFObjectHandle cur_obj = *this;
+        bool searched_parent = false;
+        std::set<QPDFObjGen> visited;
+        while (! found_rotate)
+        {
+            if (visited.count(cur_obj.getObjGen()))
+            {
+                // Don't get stuck in an infinite loop
+                break;
+            }
+            if (! visited.empty())
+            {
+                searched_parent = true;
+            }
+            visited.insert(cur_obj.getObjGen());
+            if (cur_obj.getKey("/Rotate").isInteger())
+            {
+                found_rotate = true;
+                old_angle = cur_obj.getKey("/Rotate").getIntValue();
+            }
+            else if (cur_obj.getKey("/Parent").isDictionary())
+            {
+                cur_obj = cur_obj.getKey("/Parent");
+            }
+            else
+            {
+                break;
+            }
+        }
+        QTC::TC("qpdf", "QPDFObjectHandle found old angle",
+                searched_parent ? 0 : 1);
+        if ((old_angle % 90) != 0)
+        {
+            old_angle = 0;
+        }
+        new_angle += old_angle;
+    }
+    new_angle = (new_angle + 360) % 360;
+    replaceKey("/Rotate", QPDFObjectHandle::newInteger(new_angle));
+}
+
 std::string
 QPDFObjectHandle::unparse()
 {
-- 
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