- If possible the dynamic property definition (see class LayouterDynamicProperties) should be contained in the source file and not in the header file. Otherwise, the code size may get unnecessarily increased due to the inability of Gcc and Multi linker to get rid of duplicate template instantiation in the object files.
- Dynamic properties
- can be set (see SetSize and SetLayoutDirection)
- can be retrieved (see GetSize and GetLayoutDirection)
- can be checked if they are set (see IsSizeSet and IsLayoutDirectionSet)
- can be cleared (see ClearLayoutDirection)
- have default values: C++ default initialization for simple types (see LayoutDirection) or specific values for complex types (see Size)
- can have an optional change notification (see OnSizeChanged and OnLayoutDirectionChanged)
- A convenience interface should be provided to set, get, clear and check the dynamic property (see class Layouter). The dynamic property is only accessed via that interface.
- The DynamicPropertyHost (see class Layouter) has to provide the ParentProvider method for inherited dynamic properties.
- In the Layouter sample it is guaranteed by the Layouter convenience interface that only CanderaObject instances are supported. Hence, a static\_cast to CanderaObject is safe.
- Layouter.h ```
class Layouter : public CanderaObject
{
…
static void SetSize(CanderaObject& node, const Vector2& size);
static const Vector2& GetSize(const CanderaObject& node);
static bool IsSizeSet(const CanderaObject &node);
…
static void SetLayoutDirection(CanderaObject& node,
LayoutAlignment::LayoutDirection::Enum direction);
static
LayoutAlignment::LayoutDirection::Enum GetLayoutDirection(const CanderaObject& node);
static bool IsLayoutDirectionSet(const CanderaObject &node);
static void ClearLayoutDirection(CanderaObject& node);
…
static const
Candera::DynamicProperties::DynamicPropertyHost* ParentProvider(const
Candera::DynamicProperties::DynamicPropertyHost* host);
…
static const Vector2& SizeDefault();
…
static void OnSizeChanged(DynamicPropertyHost* obj, const DynamicProperties::ValueChangedArgs
& /*args*/) { InvalidateLayout(obj); }
…
static void OnLayoutDirectionChanged(DynamicPropertyHost* obj, const DynamicProperties::ValueChangedArgs& /*args*/) { InvalidateLayout(obj); }
…
};
```
- Layouter.cpp ```
class LayouterDynamicProperties
{
…
static void SetSize(CanderaObject& node, const Vector2& size)
{
static_cast(node.SetValue(CdaDynamicPropertyInstance(Size), size));
}
static const Vector2& GetSize(const CanderaObject& node)
{
return node.GetValue(CdaDynamicPropertyInstance(Size));
}
static bool IsSizeSet(const CanderaObject &node)
{
return node.IsValueSet(CdaDynamicPropertyInstance(Size));
}
…
static void SetLayoutDirection(CanderaObject& node, LayoutAlignment::LayoutDirection::Enum direction)
{
static_cast(node.SetValue(CdaDynamicPropertyInstance(LayoutDirection), direction));
}
static LayoutAlignment::LayoutDirection::Enum GetLayoutDirection(const CanderaObject& node)
{
return node.GetValue(CdaDynamicPropertyInstance(LayoutDirection));
}
static bool IsLayoutDirectionSet(const CanderaObject& node)
{
return node.IsValueSet(CdaDynamicPropertyInstance(LayoutDirection));
}
static void ClearLayoutDirection(CanderaObject& node)
{
static_cast(node.ClearValue(CdaDynamicPropertyInstance(LayoutDirection)));
}
…
CdaDynamicPropertiesDefinition(Candera::Layouter, CanderaObject);
…
CdaDynamicProperty(Size, Vector2);
CdaDynamicPropertyValueChangedCb(&Layouter::OnSizeChanged);
CdaDynamicPropertyDefaultValue(Layouter::SizeDefault());
…
CdaDynamicPropertyEnd();
…
CdaDynamicProperty(LayoutDirection, LayoutAlignment::LayoutDirection::Enum);
CdaDynamicPropertyValueChangedCb(&Layouter::OnLayoutDirectionChanged);
…
CdaDynamicPropertyEnd();
…
CdaDynamicPropertiesEnd();
};
…
void Layouter::SetSize(CanderaObject& node, const Vector2& size)
{
LayouterDynamicProperties::SetSize(node, size);
}
const Vector2& Layouter::GetSize(const CanderaObject& node)
{
return LayouterDynamicProperties::GetSize(node);
}
bool Layouter::IsSizeSet(const CanderaObject &node)
{
return LayouterDynamicProperties::IsSizeSet(node);
}
…
void Layouter::SetLayoutDirection(CanderaObject& node, LayoutAlignment::LayoutDirection::Enum direction)
{
LayouterDynamicProperties::SetLayoutDirection(node, direction);
}
LayoutAlignment::LayoutDirection::Enum Layouter::GetLayoutDirection(const CanderaObject& node)
{
return LayouterDynamicProperties::GetLayoutDirection(node);
}
bool Layouter::IsLayoutDirectionSet(const CanderaObject& node)
{
return LayouterDynamicProperties::IsLayoutDirectionSet(node);
}
void Layouter::ClearLayoutDirection(CanderaObject& node)
{
LayouterDynamicProperties::ClearLayoutDirection(node);
}
…
const Candera::DynamicProperties::DynamicPropertyHost* Layouter::ParentProvider(const Candera::DynamicProperties::DynamicPropertyHost* host) {
CANDERA_SUPPRESS_LINT_FOR_NEXT_EXPRESSION(1774, "Layouter interface only allows CanderaObject for dynamic properties")
const CanderaObject* object = static_cast(host);
#ifdef CANDERA_2D_ENABLED
const Node2D* node2D = Dynamic_Cast(object);
if (0 != node2D) {
return node2D->GetParent();
}
#endif
#ifdef CANDERA_3D_ENABLED
const Node* node = Dynamic_Cast(object);
if (0 != node) {
return node->GetParent();
}
#endif
return 0;
}
void Layouter::Layout(const AbstractNodePointer& node)
{
…
Vector2 nodeSize(Layouter::GetSize(*node.ToCanderaObject()));
…
}
```