What s the difference between StaticResource and DynamicResource in WPF

Question

When using resources such as brushes  templates and styles in WPF  they can be specified either as StaticResources    lt Rectangle Fill   StaticResource MyBrush     gt    or as a DynamicResource   lt ItemsControl ItemTemplate   DynamicResource MyItemTemplate      gt    Most of the times  always    only one works and the other will throw exception during runtime  But I d like to know why    What is the main difference  Like memory or performance implications Are there rules in WPF like  brushes are always static  and  templates are always dynamic  etc     I assume the choice between Static vs Dynamic isn t as arbitrary as it seems    but I fail to see the pattern

User · Answer

Important benefit of the dynamic resources

if application startup takes extremely long time, you must use dynamic resources, because static resources are always loaded when the window or app is created, while dynamic resources are loaded when they’re first used.

However, you won’t see any benefit unless your resource is extremely large and complex.

User · Answer

A StaticResource will be resolved and assigned to the property during the loading of the XAML which occurs before the application is actually run  It will only be assigned once and any changes to resource dictionary ignored   A DynamicResource assigns an Expression object to the property during loading but does not actually lookup the resource until runtime when the Expression object is asked for the value  This defers looking up the resource until it is needed at runtime  A good example would be a forward reference to a resource defined later on in the XAML  Another example is a resource that will not even exist until runtime  It will update the target if the source resource dictionary is changed

User · Answer

StaticResource uses first value  DynamicResource uses last value  DynamicResource can be used for nested styling  StaticResource cannot    Suppose you have this nested Style dictionary  LightGreen is at the root level while Pink is nested inside a Grid    lt ResourceDictionary xmlns  http   schemas microsoft com winfx 2006 xaml presentation                      xmlns x  http   schemas microsoft com winfx 2006 xaml  gt       lt Style TargetType   x Type Grid   gt           lt Style Resources gt               lt Style TargetType   x Type Button   x Key  ConflictButton  gt                   lt Setter Property  Background  Value  Pink   gt               lt  Style gt           lt  Style Resources gt       lt  Style gt       lt Style TargetType   x Type Button   x Key  ConflictButton  gt           lt Setter Property  Background  Value  LightGreen   gt       lt  Style gt   lt  ResourceDictionary gt    In view    lt Window x Class  WpfStyleDemo ConflictingStyleWindow          xmlns  http   schemas microsoft com winfx 2006 xaml presentation          xmlns x  http   schemas microsoft com winfx 2006 xaml          Title  ConflictingStyleWindow  Height  100  Width  100  gt       lt Window Resources gt           lt ResourceDictionary gt               lt ResourceDictionary MergedDictionaries gt                   lt ResourceDictionary Source  Styles ConflictingStyle xaml    gt               lt  ResourceDictionary MergedDictionaries gt           lt  ResourceDictionary gt       lt  Window Resources gt       lt Grid gt           lt Button Style   DynamicResource ConflictButton   Content  Test   gt       lt  Grid gt   lt  Window gt    StaticResource will render the button as LightGreen  the first value it found in the style  DynamicResource will override the LightGreen button as Pink as it renders the Grid    StaticResource   DynamicResource  Keep in mind that VS Designer treats DynamicResource as StaticResource  It will get first value  In this case  VS Designer will render the button as LightGreen although it actually ends up as Pink   StaticResource will throw an error when the root-level style  LightGreen  is removed

User · Answer

Dynamic resources can only be used when  property being set is  on object which is derived from dependency object or freezable where as static resources can be used anywhere   You can abstract away entire control using static resources    Static resources are used under following circumstances    When reaction resource changes at runtime is not required  If you need a good performance with lots of resources  While referencing resources within the same dictionary    Dynamic resources    Value of property or style setter theme is not known until runtime    This include system  aplication  theme based settings This also includes forward references   Referencing large resources that may not load when page  windows  usercontrol loads  Referencing theme styles in a custom control

User · Answer

StaticResource will be resolved on object construction   DynamicResource will be evaluated and resolved every time control needs the resource

User · Answer

I was also confused about them  See this example below      lt Window x Class  WpfApplicationWPF CommandsWindow          xmlns  http   schemas microsoft com winfx 2006 xaml presentation          xmlns x  http   schemas microsoft com winfx 2006 xaml          Title  CommandsWindow  Height  300  Width  300  gt        lt StackPanel gt           lt Button Name  ButtonNew                   Click  ButtonNew Click                   Background   DynamicResource PinkBrush   gt NEW lt  Button gt           lt Image Name  ImageNew                  Source  pack   application     images winter jpg  gt  lt  Image gt       lt  StackPanel gt         lt Window Background gt           lt DynamicResource ResourceKey  PinkBrush  gt  lt  DynamicResource gt       lt  Window Background gt    lt  Window gt    Here I have used dynamic resource for button and window and have not declared it anywhere Upon runtime  the ResourceDictionary of the hierarchy will be checked Since I have not defined it  I guess the default will be used     If I add the code below to click event of Button  since they use DynamicResource  the background will be updated accordingly     private void ButtonNew Click object sender  RoutedEventArgs e        this Resources Add    PinkBrush                            new SolidColorBrush SystemColors DesktopColor                                If they had used StaticResource       The resource has to be declared in XAML   And that too  before  they are used      Hope I cleared some confusion

User · Answer

What is the main difference  Like memory or performance implications  The difference between static and dynamic resources comes when the underlying object changes  If your Brush defined in the Resources collection were accessed in code and set to a different object instance  Rectangle will not detect this change    Static Resources retrieved once by referencing element and used for the lifetime of the resources  Whereas  DynamicResources retrieve every time they are used   The downside of Dynamic resources is that they tend to decrease application performance   Are there rules in WPF like  brushes are always static  and  templates are always dynamic  etc    The best practice is to use Static Resources unless there is a specific reason like you want to change resource in the code behind dynamically  Another example of instance in which you would want t to use dynamic resoruces include when you use the SystemBrushes  SystenFonts and System Parameters

User · Answer

I was also confused about them  See this example below      lt Window x Class  WpfApplicationWPF CommandsWindow          xmlns  http   schemas microsoft com winfx 2006 xaml presentation          xmlns x  http   schemas microsoft com winfx 2006 xaml          Title  CommandsWindow  Height  300  Width  300  gt        lt StackPanel gt           lt Button Name  ButtonNew                   Click  ButtonNew Click                   Background   DynamicResource PinkBrush   gt NEW lt  Button gt           lt Image Name  ImageNew                  Source  pack   application     images winter jpg  gt  lt  Image gt       lt  StackPanel gt         lt Window Background gt           lt DynamicResource ResourceKey  PinkBrush  gt  lt  DynamicResource gt       lt  Window Background gt    lt  Window gt    Here I have used dynamic resource for button and window and have not declared it anywhere Upon runtime  the ResourceDictionary of the hierarchy will be checked Since I have not defined it  I guess the default will be used     If I add the code below to click event of Button  since they use DynamicResource  the background will be updated accordingly     private void ButtonNew Click object sender  RoutedEventArgs e        this Resources Add    PinkBrush                            new SolidColorBrush SystemColors DesktopColor                                If they had used StaticResource       The resource has to be declared in XAML   And that too  before  they are used      Hope I cleared some confusion

User · Answer

Found all answers useful  just wanted to add one more use case   In a composite WPF scenario  your user control can make use of resources defined in any other parent window control  that is going to host this user control  by referring to that resource as DynamicResource   As mentioned by others  Staticresource will be looked up at compile time  User controls can not refer to those resources which are defined in hosting parent control  Though  DynamicResource could be used in this case

User · Answer

Important benefit of the dynamic resources

if application startup takes extremely long time, you must use dynamic resources, because static resources are always loaded when the window or app is created, while dynamic resources are loaded when they’re first used.

However, you won’t see any benefit unless your resource is extremely large and complex.

User · Answer

StaticResource will be resolved on object construction   DynamicResource will be evaluated and resolved every time control needs the resource

User · Answer

A StaticResource will be resolved and assigned to the property during the loading of the XAML which occurs before the application is actually run  It will only be assigned once and any changes to resource dictionary ignored   A DynamicResource assigns an Expression object to the property during loading but does not actually lookup the resource until runtime when the Expression object is asked for the value  This defers looking up the resource until it is needed at runtime  A good example would be a forward reference to a resource defined later on in the XAML  Another example is a resource that will not even exist until runtime  It will update the target if the source resource dictionary is changed

User · Answer

What is the main difference  Like memory or performance implications  The difference between static and dynamic resources comes when the underlying object changes  If your Brush defined in the Resources collection were accessed in code and set to a different object instance  Rectangle will not detect this change    Static Resources retrieved once by referencing element and used for the lifetime of the resources  Whereas  DynamicResources retrieve every time they are used   The downside of Dynamic resources is that they tend to decrease application performance   Are there rules in WPF like  brushes are always static  and  templates are always dynamic  etc    The best practice is to use Static Resources unless there is a specific reason like you want to change resource in the code behind dynamically  Another example of instance in which you would want t to use dynamic resoruces include when you use the SystemBrushes  SystenFonts and System Parameters

User · Answer

StaticResource uses first value  DynamicResource uses last value  DynamicResource can be used for nested styling  StaticResource cannot    Suppose you have this nested Style dictionary  LightGreen is at the root level while Pink is nested inside a Grid    lt ResourceDictionary xmlns  http   schemas microsoft com winfx 2006 xaml presentation                      xmlns x  http   schemas microsoft com winfx 2006 xaml  gt       lt Style TargetType   x Type Grid   gt           lt Style Resources gt               lt Style TargetType   x Type Button   x Key  ConflictButton  gt                   lt Setter Property  Background  Value  Pink   gt               lt  Style gt           lt  Style Resources gt       lt  Style gt       lt Style TargetType   x Type Button   x Key  ConflictButton  gt           lt Setter Property  Background  Value  LightGreen   gt       lt  Style gt   lt  ResourceDictionary gt    In view    lt Window x Class  WpfStyleDemo ConflictingStyleWindow          xmlns  http   schemas microsoft com winfx 2006 xaml presentation          xmlns x  http   schemas microsoft com winfx 2006 xaml          Title  ConflictingStyleWindow  Height  100  Width  100  gt       lt Window Resources gt           lt ResourceDictionary gt               lt ResourceDictionary MergedDictionaries gt                   lt ResourceDictionary Source  Styles ConflictingStyle xaml    gt               lt  ResourceDictionary MergedDictionaries gt           lt  ResourceDictionary gt       lt  Window Resources gt       lt Grid gt           lt Button Style   DynamicResource ConflictButton   Content  Test   gt       lt  Grid gt   lt  Window gt    StaticResource will render the button as LightGreen  the first value it found in the style  DynamicResource will override the LightGreen button as Pink as it renders the Grid    StaticResource   DynamicResource  Keep in mind that VS Designer treats DynamicResource as StaticResource  It will get first value  In this case  VS Designer will render the button as LightGreen although it actually ends up as Pink   StaticResource will throw an error when the root-level style  LightGreen  is removed

User · Answer

Dynamic resources can only be used when  property being set is  on object which is derived from dependency object or freezable where as static resources can be used anywhere   You can abstract away entire control using static resources    Static resources are used under following circumstances    When reaction resource changes at runtime is not required  If you need a good performance with lots of resources  While referencing resources within the same dictionary    Dynamic resources    Value of property or style setter theme is not known until runtime    This include system  aplication  theme based settings This also includes forward references   Referencing large resources that may not load when page  windows  usercontrol loads  Referencing theme styles in a custom control

User · Answer

Found all answers useful  just wanted to add one more use case   In a composite WPF scenario  your user control can make use of resources defined in any other parent window control  that is going to host this user control  by referring to that resource as DynamicResource   As mentioned by others  Staticresource will be looked up at compile time  User controls can not refer to those resources which are defined in hosting parent control  Though  DynamicResource could be used in this case

User · Answer

A StaticResource will be resolved and assigned to the property during the loading of the XAML which occurs before the application is actually run  It will only be assigned once and any changes to resource dictionary ignored   A DynamicResource assigns an Expression object to the property during loading but does not actually lookup the resource until runtime when the Expression object is asked for the value  This defers looking up the resource until it is needed at runtime  A good example would be a forward reference to a resource defined later on in the XAML  Another example is a resource that will not even exist until runtime  It will update the target if the source resource dictionary is changed

User · Answer

A StaticResource will be resolved and assigned to the property during the loading of the XAML which occurs before the application is actually run  It will only be assigned once and any changes to resource dictionary ignored   A DynamicResource assigns an Expression object to the property during loading but does not actually lookup the resource until runtime when the Expression object is asked for the value  This defers looking up the resource until it is needed at runtime  A good example would be a forward reference to a resource defined later on in the XAML  Another example is a resource that will not even exist until runtime  It will update the target if the source resource dictionary is changed

[.net] What's the difference between StaticResource and DynamicResource in WPF?

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