From 76cd7ea67aee7edd1004a68a28e63a00a38239dd Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Tue, 6 Sep 2022 19:00:40 -0400
Subject: Clarify and improve QPDFPageObjectHelper::get*Box methods

Add copy_if_fallback and explain how it differs from copy_if_shared.
---
 libqpdf/QPDFPageObjectHelper.cc | 77 ++++++++++++++++++++++++++++++++---------
 1 file changed, 61 insertions(+), 16 deletions(-)

(limited to 'libqpdf/QPDFPageObjectHelper.cc')

diff --git a/libqpdf/QPDFPageObjectHelper.cc b/libqpdf/QPDFPageObjectHelper.cc
index 23a54231..1c810318 100644
--- a/libqpdf/QPDFPageObjectHelper.cc
+++ b/libqpdf/QPDFPageObjectHelper.cc
@@ -237,6 +237,16 @@ QPDFPageObjectHelper::QPDFPageObjectHelper(QPDFObjectHandle oh) :
 
 QPDFObjectHandle
 QPDFPageObjectHelper::getAttribute(std::string const& name, bool copy_if_shared)
+{
+    return getAttribute(name, copy_if_shared, nullptr, false);
+}
+
+QPDFObjectHandle
+QPDFPageObjectHelper::getAttribute(
+    std::string const& name,
+    bool copy_if_shared,
+    std::function<QPDFObjectHandle()> get_fallback,
+    bool copy_if_fallback)
 {
     QPDFObjectHandle result;
     QPDFObjectHandle dict;
@@ -272,36 +282,71 @@ QPDFPageObjectHelper::getAttribute(std::string const& name, bool copy_if_shared)
             "qpdf",
             "QPDFPageObjectHelper copy shared attribute",
             is_form_xobject ? 0 : 1);
-        result = result.shallowCopy();
-        dict.replaceKey(name, result);
+        result = dict.replaceKeyAndGetNew(name, result.shallowCopy());
+    }
+    if (result.isNull() && get_fallback) {
+        result = get_fallback();
+        if (copy_if_fallback && !result.isNull()) {
+            QTC::TC("qpdf", "QPDFPageObjectHelper copied fallback");
+            result = dict.replaceKeyAndGetNew(name, result.shallowCopy());
+        } else {
+            QTC::TC(
+                "qpdf", "QPDFPageObjectHelper used fallback without copying");
+        }
     }
     return result;
 }
 
 QPDFObjectHandle
-QPDFPageObjectHelper::getTrimBox(bool copy_if_shared)
+QPDFPageObjectHelper::getMediaBox(bool copy_if_shared)
 {
-    QPDFObjectHandle result = getAttribute("/TrimBox", copy_if_shared);
-    if (result.isNull()) {
-        result = getCropBox(copy_if_shared);
-    }
-    return result;
+    return getAttribute("/MediaBox", copy_if_shared);
 }
 
 QPDFObjectHandle
-QPDFPageObjectHelper::getCropBox(bool copy_if_shared)
+QPDFPageObjectHelper::getCropBox(bool copy_if_shared, bool copy_if_fallback)
 {
-    QPDFObjectHandle result = getAttribute("/CropBox", copy_if_shared);
-    if (result.isNull()) {
-        result = getMediaBox();
-    }
-    return result;
+    return getAttribute(
+        "/CropBox",
+        copy_if_shared,
+        [this, copy_if_shared]() { return this->getMediaBox(copy_if_shared); },
+        copy_if_fallback);
 }
 
 QPDFObjectHandle
-QPDFPageObjectHelper::getMediaBox(bool copy_if_shared)
+QPDFPageObjectHelper::getTrimBox(bool copy_if_shared, bool copy_if_fallback)
 {
-    return getAttribute("/MediaBox", copy_if_shared);
+    return getAttribute(
+        "/TrimBox",
+        copy_if_shared,
+        [this, copy_if_shared, copy_if_fallback]() {
+            return this->getCropBox(copy_if_shared, copy_if_fallback);
+        },
+        copy_if_fallback);
+}
+
+QPDFObjectHandle
+QPDFPageObjectHelper::getArtBox(bool copy_if_shared, bool copy_if_fallback)
+{
+    return getAttribute(
+        "/ArtBox",
+        copy_if_shared,
+        [this, copy_if_shared, copy_if_fallback]() {
+            return this->getCropBox(copy_if_shared, copy_if_fallback);
+        },
+        copy_if_fallback);
+}
+
+QPDFObjectHandle
+QPDFPageObjectHelper::getBleedBox(bool copy_if_shared, bool copy_if_fallback)
+{
+    return getAttribute(
+        "/BleedBox",
+        copy_if_shared,
+        [this, copy_if_shared, copy_if_fallback]() {
+            return this->getCropBox(copy_if_shared, copy_if_fallback);
+        },
+        copy_if_fallback);
 }
 
 void
-- 
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