# HG changeset patch
# User Chris Cannam
# Date 1298036356 0
# Node ID 1ec306df738e767cffe386d82565463540fda551
# Parent  9162f14c5ab7f5580abc24d8a5ac220662451789# Parent  a98e76fa58f2f9142b0d38206da24b44e57add60
Merge

diff -r a98e76fa58f2 -r 1ec306df738e changesetitem.cpp
--- a/changesetitem.cpp	Thu Feb 17 12:10:09 2011 +0000
+++ b/changesetitem.cpp	Fri Feb 18 13:39:16 2011 +0000
@@ -16,6 +16,7 @@
 */
 
 #include "changesetitem.h"
+#include "changesetscene.h"
 #include "changesetdetailitem.h"
 #include "changeset.h"
 #include "textabbrev.h"
@@ -121,15 +122,51 @@
 
     menu->addSeparator();
 
-    if (m_changeset->parents().size() > 1) {
+    QStringList parents = m_changeset->parents();
 
-        foreach (QString parentId, m_changeset->parents()) {
-            QAction *diffParent =
-                menu->addAction(tr("Diff to parent %1")
-                                .arg(Changeset::hashOf(parentId)));
+    if (parents.size() > 1) {
+
+        QString leftId, rightId;
+        ChangesetScene *cs = dynamic_cast<ChangesetScene *>(scene());
+        bool havePositions = false;
+
+        if (cs && parents.size() == 2) {
+            ChangesetItem *i0 = cs->getItemById(parents[0]);
+            ChangesetItem *i1 = cs->getItemById(parents[1]);
+            if (i0 && i1) {
+                if (i0->x() < i1->x()) {
+                    leftId = parents[0];
+                    rightId = parents[1];
+                } else {
+                    leftId = parents[1];
+                    rightId = parents[0];
+                }
+                havePositions = true;
+            }
+        }
+
+        if (havePositions) {
+            
+            QAction *diffParent = menu->addAction(tr("Diff to left parent"));
             connect(diffParent, SIGNAL(triggered()),
                     this, SLOT(diffToParentActivated()));
-            m_parentDiffActions[diffParent] = parentId;
+            m_parentDiffActions[diffParent] = leftId;
+            
+            diffParent = menu->addAction(tr("Diff to right parent"));
+            connect(diffParent, SIGNAL(triggered()),
+                    this, SLOT(diffToParentActivated()));
+            m_parentDiffActions[diffParent] = rightId;
+
+        } else {
+
+            foreach (QString parentId, parents) {
+                QString text = tr("Diff to parent %1")
+                    .arg(Changeset::hashOf(parentId));
+                QAction *diffParent = menu->addAction(text);
+                connect(diffParent, SIGNAL(triggered()),
+                        this, SLOT(diffToParentActivated()));
+                m_parentDiffActions[diffParent] = parentId;
+            }
         }
 
     } else {
diff -r a98e76fa58f2 -r 1ec306df738e changesetscene.cpp
--- a/changesetscene.cpp	Thu Feb 17 12:10:09 2011 +0000
+++ b/changesetscene.cpp	Fri Feb 18 13:39:16 2011 +0000
@@ -108,3 +108,13 @@
     }
 }
 
+ChangesetItem *
+ChangesetScene::getItemById(QString id)
+{
+    foreach (QGraphicsItem *it, items()) {
+        ChangesetItem *csit = dynamic_cast<ChangesetItem *>(it);
+        if (csit && csit->getId() == id) return csit;
+    }
+}
+
+
diff -r a98e76fa58f2 -r 1ec306df738e changesetscene.h
--- a/changesetscene.h	Thu Feb 17 12:10:09 2011 +0000
+++ b/changesetscene.h	Fri Feb 18 13:39:16 2011 +0000
@@ -35,6 +35,8 @@
     void addUncommittedItem(UncommittedItem *item);
     void addDateItem(DateItem *item);
 
+    ChangesetItem *getItemById(QString id); // Slow: traversal required
+
 signals:
     void commit();
     void revert();
diff -r a98e76fa58f2 -r 1ec306df738e mainwindow.cpp
--- a/mainwindow.cpp	Thu Feb 17 12:10:09 2011 +0000
+++ b/mainwindow.cpp	Fri Feb 18 13:39:16 2011 +0000
@@ -590,7 +590,7 @@
 
     QStringList params;
 
-    // Diff given revision against working folder
+    // Diff given revision against parent revision
 
     params << "--config" << "extensions.extdiff=" << "extdiff";
     params << "--program" << diff;