--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/mmuifw_plat/alf_widgetmodel_api/inc/alf/ialflayoutpreferences.h Wed Sep 01 12:23:18 2010 +0100
@@ -0,0 +1,157 @@
+/*
+* Copyright (c) 2007 Nokia Corporation and/or its subsidiary(-ies).
+* All rights reserved.
+* This component and the accompanying materials are made available
+* under the terms of "Eclipse Public License v1.0"
+* which accompanies this distribution, and is available
+* at the URL "http://www.eclipse.org/legal/epl-v10.html".
+*
+* Initial Contributors:
+* Nokia Corporation - initial contribution.
+*
+* Contributors:
+*
+* Description: The interface for inquiring the layout preferences of a laid-out object
+*
+*/
+
+
+#ifndef I_ALFLAYOUTPERENCES_H
+#define I_ALFLAYOUTPERENCES_H
+
+#include <alf/ialfinterfacebase.h>
+#include <alf/alftypes.h>
+#include <alf/alfmetric.h>
+#include <osn/osntypes.h>
+
+using namespace osncore;
+
+namespace Alf
+ {
+
+class IAlfLayoutManager;
+
+namespace alflayoutpreferences
+ {
+ static const IfId Ident=
+ {
+ 0,"alflayoutpreferences"
+ };
+ }
+
+/**
+ * The interface for finding the layout preferences for an Alf widget model
+ * presentation object.
+ *
+ * This interface is called by layout managers (implementors of @c IAlfLayoutManager)
+ * in order to find out information about their contained presentation objects.
+ *
+ * It is implemented by presentation objects in order to report to the layout manager
+ * what sizes objects prefer.
+ *
+ * The layout manager is responsible for finding out layout preferences for all the
+ * AlfElement instances in the next level down of containment - the "child" elements.
+ * It calls @c makeInterface<IAlfLayoutPreferences> on these elements.
+ * The layout manager uses its knowledge about how these child elements relate to
+ * each other geometrically to come up with a decision on how many child elements
+ * can be shown, where they are to be positioned, and how big they should be.
+ * @see IAlfLayoutManager
+ *
+ * @c AlfElements that represent contained sets of visuals - those that take up
+ * space within the visual containment - should implement @c IAlfLayoutPreferences,
+ * or defer its implementation to another presentation object which is capable
+ * of reporting layout preferences.
+ *
+ * The following units are allowed to be used in the returned parameter values:
+ * EAlfUnitPixel - pixels
+ * EAlfUnitDisplaySize - units relative to the display
+ * EAlfS60Unit - S60 layout specification units
+ *
+ * Other units do not make sense, since the metric is being passed
+ * to a different layout context. Furthermore, the reason for this API
+ * is for the implementing object to state its own, internal, preferences
+ * without recourse to its containment. This implies the use of the more
+ * absolute units.
+ *
+ * The units used for the returned @c TAlfXYMetric objects are chosen independently
+ * by the implementations of each API. They do not have to be return the same units.
+ *
+ * @lib alfwidgetmodel.lib
+ * @since S60 ?S60_version
+ * @status Draft
+ */
+class IAlfLayoutPreferences : public IAlfInterfaceBase
+ {
+public:
+ static inline const IfId& type()
+ {
+ return alflayoutpreferences::Ident;
+ }
+
+ /**
+ * Return the minimum desirable size of a presentation object.
+ *
+ * Minimum size should mean the size at which the visual would start to become
+ * unreadable in the case of text, or too difficult to see with sufficient
+ * clarity in the case of graphics.
+ *
+ * false is to be returned if the implementing presentation object does
+ * not care how small it is made.
+ *
+ * @param aMinSize The minimum size that the object would like to be laid out to
+ * @return false iff the object queried does not care about a minimum size
+ */
+ virtual bool getMinimumSize( TAlfXYMetric& aMinSize ) const = 0;
+
+ /**
+ * Return the maximum size desired by a presentation object.
+ *
+ * There may often be no preference as to maximum size. The implementation
+ * should then return false.
+ *
+ * @param aMaxSize The maximum size that the object would like to be laid out to
+ * @return false iff the object queried does not care about a maximum size
+ */
+ virtual bool getMaximumSize( TAlfXYMetric& aMaxSize ) const = 0;
+
+ /**
+ * Return the preferred size for a presentation object.
+ *
+ * The preferred size is the optimum size of the object in the absence
+ * of external factors.
+ *
+ * The value returned should greater than or equal in size to a value
+ * returned by getMinimumSize()
+ *
+ * The value returned should less than or equal in size to a value
+ * returned by getMaximumSize()
+ *
+ * @param aPreferredSize The size that the object would like to be laid out to
+ * @return false iff the object queried does not have a preferred size
+ */
+ virtual bool getPreferredSize( TAlfXYMetric& aPreferredSize ) const = 0;
+
+ /**
+ * Set the preferred size into a presentation object.
+ *
+ * The preferred size is being dictated by external code in this case.
+ * This new value should over-ride any internal preferred size.
+ *
+ * Calling this API has several side-effects. Subsequent calls to
+ * getPreferredSize should return @c true and return the new preferred
+ * size.
+ *
+ * Subsequent calls to getMinimumSize must return either @c false, or return
+ * @c true with a value less than or equal to the preferred size.
+ *
+ * Subsequent calls to getMaximumSize must return either @c false, or return
+ * @c true with a value greater than or equal to the preferred size.
+ *
+ * @param aPreferredSize The new preferred size for the laid-out object
+ */
+ virtual void setPreferredSize( const TAlfXYMetric& aPreferredSize ) = 0;
+
+ };
+
+ } // namespace Alf
+#endif // I_ALFLAYOUTPERENCES_H