[layouts] Hack around inconsistent subclassing of layout items by sip

Sometimes, calling some layout methods, results in sip being inable to downcast the items to their correct type, resulting only in a QgsLayoutItem object. This works around the problem, albeit in an incredibly hacky way.
tmathmeyer · Oct 19, 2018 · f00e43d · f00e43d
1 parent 0a66257
commit f00e43d
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diff --git a/python/core/auto_generated/layout/qgslayoutitem.sip.in b/python/core/auto_generated/layout/qgslayoutitem.sip.in
@@ -62,7 +62,6 @@ scaled by 50% in order to have a constant visible size.
     QgsLayoutItemRenderContext( const QgsLayoutItemRenderContext &rh );
 };
 
-
 class QgsLayoutItem : QgsLayoutObject, QGraphicsRectItem, QgsLayoutUndoObjectInterface
 {
 %Docstring
@@ -86,6 +85,12 @@ Base class for graphical items within a :py:class:`QgsLayout`.
 #include "qgslayoutitempage.h"
 %End
 %ConvertToSubClassCode
+
+    // FREAKKKKIIN IMPORTANT!!!!!!!!!!!
+    // IF YOU PUT SOMETHING HERE, PUT IT IN QgsLayoutObject CASTING *****ALSO******
+    // (it's not enough for it to be in only one of the places, as sip inconsistently
+    // decides which casting code to perform here)
+
     // the conversions have to be static, because they're using multiple inheritance
     // (seen in PyQt4 .sip files for some QGraphicsItem classes)
     switch ( sipCpp->type() )
@@ -135,8 +140,11 @@ Base class for graphical items within a :py:class:`QgsLayout`.
         sipType = sipType_QgsLayoutFrame;
         *sipCppRet = static_cast<QgsLayoutFrame *>( sipCpp );
         break;
+
+      // did you read that comment above? NO? Go read it now. You're about to break stuff.
+
       default:
-        sipType = 0;
+        sipType = NULL;
     }
 %End
   public:

diff --git a/python/core/auto_generated/layout/qgslayoutobject.sip.in b/python/core/auto_generated/layout/qgslayoutobject.sip.in
@@ -19,6 +19,85 @@ A base class for objects which belong to a layout.
 
 %TypeHeaderCode
 #include "qgslayoutobject.h"
+#include <qgslayoutitem.h>
+#include "qgslayoutitemgroup.h"
+#include "qgslayoutitemmap.h"
+#include "qgslayoutitempicture.h"
+#include "qgslayoutitemlabel.h"
+#include "qgslayoutitemlegend.h"
+#include "qgslayoutitempolygon.h"
+#include "qgslayoutitempolyline.h"
+#include "qgslayoutitemscalebar.h"
+#include "qgslayoutframe.h"
+#include "qgslayoutitemshape.h"
+#include "qgslayoutitempage.h"
+%End
+%ConvertToSubClassCode
+    if ( QgsLayoutItem *item = qobject_cast< QgsLayoutItem * >( sipCpp ) )
+    {
+      // the conversions have to be static, because they're using multiple inheritance
+      // (seen in PyQt4 .sip files for some QGraphicsItem classes)
+      switch ( item->type() )
+      {
+        // FREAKKKKIIN IMPORTANT!
+        // IF YOU PUT SOMETHING HERE, PUT IT IN QgsLayoutItem CASTING **ALSO**
+        // (it's not enough for it to be in only one of the places, as sip inconsistently
+        // decides which casting code to perform here)
+
+        // really, these *should* use the constants from QgsLayoutItemRegistry, but sip doesn't like that!
+        case QGraphicsItem::UserType + 101:
+          sipType = sipType_QgsLayoutItemGroup;
+          *sipCppRet = static_cast<QgsLayoutItemGroup *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 102:
+          sipType = sipType_QgsLayoutItemPage;
+          *sipCppRet = static_cast<QgsLayoutItemPage *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 103:
+          sipType = sipType_QgsLayoutItemMap;
+          *sipCppRet = static_cast<QgsLayoutItemMap *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 104:
+          sipType = sipType_QgsLayoutItemPicture;
+          *sipCppRet = static_cast<QgsLayoutItemPicture *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 105:
+          sipType = sipType_QgsLayoutItemLabel;
+          *sipCppRet = static_cast<QgsLayoutItemLabel *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 106:
+          sipType = sipType_QgsLayoutItemLegend;
+          *sipCppRet = static_cast<QgsLayoutItemLegend *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 107:
+          sipType = sipType_QgsLayoutItemShape;
+          *sipCppRet = static_cast<QgsLayoutItemShape *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 108:
+          sipType = sipType_QgsLayoutItemPolygon;
+          *sipCppRet = static_cast<QgsLayoutItemPolygon *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 109:
+          sipType = sipType_QgsLayoutItemPolyline;
+          *sipCppRet = static_cast<QgsLayoutItemPolyline *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 110:
+          sipType = sipType_QgsLayoutItemScaleBar;
+          *sipCppRet = static_cast<QgsLayoutItemScaleBar *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 111:
+          sipType = sipType_QgsLayoutFrame;
+          *sipCppRet = static_cast<QgsLayoutFrame *>( sipCpp );
+          break;
+
+        // did you read that comment above? NO? Go read it now. You're about to break stuff.
+
+        default:
+          sipType = sipType_QgsLayoutItem;
+      }
+    }
+    else
+      sipType = NULL;
 %End
   public:
 

diff --git a/src/core/layout/qgslayoutitem.h b/src/core/layout/qgslayoutitem.h
@@ -102,7 +102,6 @@ class CORE_EXPORT QgsLayoutItemRenderContext
     double mViewScaleFactor = 1.0;
 };
 
-
 /**
  * \ingroup core
  * \class QgsLayoutItem
@@ -125,9 +124,14 @@ class CORE_EXPORT QgsLayoutItem : public QgsLayoutObject, public QGraphicsRectIt
 #include "qgslayoutitempage.h"
 #endif
 
-
 #ifdef SIP_RUN
     SIP_CONVERT_TO_SUBCLASS_CODE
+
+    // FREAKKKKIIN IMPORTANT!!!!!!!!!!!
+    // IF YOU PUT SOMETHING HERE, PUT IT IN QgsLayoutObject CASTING *****ALSO******
+    // (it's not enough for it to be in only one of the places, as sip inconsistently
+    // decides which casting code to perform here)
+
     // the conversions have to be static, because they're using multiple inheritance
     // (seen in PyQt4 .sip files for some QGraphicsItem classes)
     switch ( sipCpp->type() )
@@ -177,8 +181,11 @@ class CORE_EXPORT QgsLayoutItem : public QgsLayoutObject, public QGraphicsRectIt
         sipType = sipType_QgsLayoutFrame;
         *sipCppRet = static_cast<QgsLayoutFrame *>( sipCpp );
         break;
+
+      // did you read that comment above? NO? Go read it now. You're about to break stuff.
+
       default:
-        sipType = 0;
+        sipType = NULL;
     }
     SIP_END
 #endif

diff --git a/src/core/layout/qgslayoutobject.h b/src/core/layout/qgslayoutobject.h
@@ -38,6 +38,91 @@ class QgsReadWriteContext;
  */
 class CORE_EXPORT QgsLayoutObject: public QObject, public QgsExpressionContextGenerator
 {
+#ifdef SIP_RUN
+#include <qgslayoutitem.h>
+#include "qgslayoutitemgroup.h"
+#include "qgslayoutitemmap.h"
+#include "qgslayoutitempicture.h"
+#include "qgslayoutitemlabel.h"
+#include "qgslayoutitemlegend.h"
+#include "qgslayoutitempolygon.h"
+#include "qgslayoutitempolyline.h"
+#include "qgslayoutitemscalebar.h"
+#include "qgslayoutframe.h"
+#include "qgslayoutitemshape.h"
+#include "qgslayoutitempage.h"
+#endif
+
+#ifdef SIP_RUN
+    SIP_CONVERT_TO_SUBCLASS_CODE
+    if ( QgsLayoutItem *item = qobject_cast< QgsLayoutItem * >( sipCpp ) )
+    {
+      // the conversions have to be static, because they're using multiple inheritance
+      // (seen in PyQt4 .sip files for some QGraphicsItem classes)
+      switch ( item->type() )
+      {
+        // FREAKKKKIIN IMPORTANT!
+        // IF YOU PUT SOMETHING HERE, PUT IT IN QgsLayoutItem CASTING **ALSO**
+        // (it's not enough for it to be in only one of the places, as sip inconsistently
+        // decides which casting code to perform here)
+
+        // really, these *should* use the constants from QgsLayoutItemRegistry, but sip doesn't like that!
+        case QGraphicsItem::UserType + 101:
+          sipType = sipType_QgsLayoutItemGroup;
+          *sipCppRet = static_cast<QgsLayoutItemGroup *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 102:
+          sipType = sipType_QgsLayoutItemPage;
+          *sipCppRet = static_cast<QgsLayoutItemPage *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 103:
+          sipType = sipType_QgsLayoutItemMap;
+          *sipCppRet = static_cast<QgsLayoutItemMap *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 104:
+          sipType = sipType_QgsLayoutItemPicture;
+          *sipCppRet = static_cast<QgsLayoutItemPicture *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 105:
+          sipType = sipType_QgsLayoutItemLabel;
+          *sipCppRet = static_cast<QgsLayoutItemLabel *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 106:
+          sipType = sipType_QgsLayoutItemLegend;
+          *sipCppRet = static_cast<QgsLayoutItemLegend *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 107:
+          sipType = sipType_QgsLayoutItemShape;
+          *sipCppRet = static_cast<QgsLayoutItemShape *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 108:
+          sipType = sipType_QgsLayoutItemPolygon;
+          *sipCppRet = static_cast<QgsLayoutItemPolygon *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 109:
+          sipType = sipType_QgsLayoutItemPolyline;
+          *sipCppRet = static_cast<QgsLayoutItemPolyline *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 110:
+          sipType = sipType_QgsLayoutItemScaleBar;
+          *sipCppRet = static_cast<QgsLayoutItemScaleBar *>( sipCpp );
+          break;
+        case QGraphicsItem::UserType + 111:
+          sipType = sipType_QgsLayoutFrame;
+          *sipCppRet = static_cast<QgsLayoutFrame *>( sipCpp );
+          break;
+
+        // did you read that comment above? NO? Go read it now. You're about to break stuff.
+
+        default:
+          sipType = sipType_QgsLayoutItem;
+      }
+    }
+    else
+      sipType = NULL;
+    SIP_END
+#endif
+
     Q_OBJECT
   public:
 

diff --git a/tests/src/python/test_qgslayoutitem.py b/tests/src/python/test_qgslayoutitem.py
@@ -13,6 +13,7 @@
 __revision__ = '$Format:%H$'
 import qgis  # NOQA
 
+import os
 from qgis.testing import start_app, unittest
 from qgis.core import (QgsProject,
                        QgsLayout,
@@ -24,12 +25,17 @@
                        QgsUnitTypes,
                        QgsLayoutPoint,
                        QgsLayoutSize,
+                       QgsLayoutItemLabel,
+                       QgsLayoutItem,
                        QgsApplication)
 from qgis.PyQt.QtCore import QRectF
 from qgis.PyQt.QtGui import QColor, QPainter
 from qgis.PyQt.QtTest import QSignalSpy
+from utilities import unitTestDataPath
 
 
+TEST_DATA_DIR = unitTestDataPath()
+
 start_app()
 
 
@@ -166,6 +172,33 @@ def testDisplayName(self):
         self.assertEqual(item.displayName(), 'a')
         self.assertEqual(item.id(), 'a')
 
+    def testCasting(self):
+        """
+        Test that sip correctly casts stuff
+        """
+        p = QgsProject()
+        p.read(os.path.join(TEST_DATA_DIR, 'layouts', 'layout_casting.qgs'))
+
+        layout = p.layoutManager().layouts()[0]
+
+        # check a method which often fails casting
+        map = layout.itemById('map')
+        self.assertIsInstance(map, QgsLayoutItemMap)
+        label = layout.itemById('label')
+        self.assertIsInstance(label, QgsLayoutItemLabel)
+
+        # another method -- sometimes this fails casting for different(?) reasons
+        # make sure we start from a new project so sip hasn't remembered item instances
+        p2 = QgsProject()
+        p2.read(os.path.join(TEST_DATA_DIR, 'layouts', 'layout_casting.qgs'))
+        layout = p2.layoutManager().layouts()[0]
+
+        items = layout.items()
+        map2 = [i for i in items if isinstance(i, QgsLayoutItem) and i.id() == 'map'][0]
+        self.assertIsInstance(map2, QgsLayoutItemMap)
+        label2 = [i for i in items if isinstance(i, QgsLayoutItem) and i.id() == 'label'][0]
+        self.assertIsInstance(label2, QgsLayoutItemLabel)
+
 
 if __name__ == '__main__':
     unittest.main()