Ray KonopkaRay Konopka

Developing Custom .NET Components

Developing Custom .NET Components

DevCon 2005 -- Course No: 3118DevCon 2005 -- Course No: 3118

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AgendaAgenda

.NET Component Model

Comparing the FCL to the VCL

Custom Events

Custom Painting

Component Related Attributes

Sample Control

.NET Component Model

Comparing the FCL to the VCL

Custom Events

Custom Painting

Component Related Attributes

Sample Control

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.NET Component Model.NET Component Model

Defined in the System.ComponentModel namespace

IncludesSystem.ComponentModel.Component

declarationCommon DelegatesComponent Related Attribute declarationsLicensing ClassesDesign-time Support Classes

Defined in the System.ComponentModel namespace

IncludesSystem.ComponentModel.Component

declarationCommon DelegatesComponent Related Attribute declarationsLicensing ClassesDesign-time Support Classes

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Component ClassComponent Class

System.ComponentModel.Component provides the base implementation of IComponent in the FCL

Defines the following propertiesDesignModeContainerSiteEvents

Descend from System.ComponentModel.Component to create a nonvisual component

System.ComponentModel.Component provides the base implementation of IComponent in the FCL

Defines the following propertiesDesignModeContainerSiteEvents

Descend from System.ComponentModel.Component to create a nonvisual component

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Two Control Classes in .NETTwo Control Classes in .NET

Most visual controls in .NET will descend from one of two classes:

System.Windows.Forms.ControlBase WinForms Control classMost similar to existing component models (e.g.

VCL)Rendering handled through Graphics class (i.e.

GDI+)

System.Web.UI.ControlBase ASP.NET Server Control classRenders markup text used by a client’s browser

or viewing device to display visual elements.

Most visual controls in .NET will descend from one of two classes:

System.Windows.Forms.ControlBase WinForms Control classMost similar to existing component models (e.g.

VCL)Rendering handled through Graphics class (i.e.

GDI+)

System.Web.UI.ControlBase ASP.NET Server Control classRenders markup text used by a client’s browser

or viewing device to display visual elements.

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System.Windows.Forms.Control

System.Windows.Forms.Control

Implements basic functionality for visualization

Defines the control’s bounds (i.e. its Position and Size)

Provides a window handle (Handle)

Provides access to keyboard events

Provides access to mouse events

Provides access to paint events

Supports ambient propertiesCursor, Font, BackColor, ForeColor,

RightToLeft.

Implements basic functionality for visualization

Defines the control’s bounds (i.e. its Position and Size)

Provides a window handle (Handle)

Provides access to keyboard events

Provides access to mouse events

Provides access to paint events

Supports ambient propertiesCursor, Font, BackColor, ForeColor,

RightToLeft.

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Comparing the FCL to the VCL

Comparing the FCL to the VCL

FCL is quite similar to the VCL, but there are significant differences

No equivalent to TGraphicControl

Actually, no TWinControl or TCustomControl classes either

System.Windows.Forms.Control is more like TCustomControl than TControl

Significantly fewer TCustomXxxx class called XxxxBase in FCL

FCL is quite similar to the VCL, but there are significant differences

No equivalent to TGraphicControl

Actually, no TWinControl or TCustomControl classes either

System.Windows.Forms.Control is more like TCustomControl than TControl

Significantly fewer TCustomXxxx class called XxxxBase in FCL

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Where is the Align property?

Where is the Align property?

Most of the functionality implemented in the VCL base classes is available in the base FCL classes

However, there are many property name changesAlign DockCaption TextColor BackColorFont.Color ForeColorPopupMenu ContextMenuModalResult DialogResultetc.

Tag is an Object

ParentXxxx properties replaced with ambient properties

Most of the functionality implemented in the VCL base classes is available in the base FCL classes

However, there are many property name changesAlign DockCaption TextColor BackColorFont.Color ForeColorPopupMenu ContextMenuModalResult DialogResultetc.

Tag is an Object

ParentXxxx properties replaced with ambient properties

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Control StylesControl Styles

TControl.ControlStyle replaced with GetStyle/SetStyle method pair

Some, but not all, styles have corresponding public propertiesResizeRedraw

TControl.ControlStyle replaced with GetStyle/SetStyle method pair

Some, but not all, styles have corresponding public propertiesResizeRedraw

SetStyle( ControlStyles.ResizeRedraw, True );SetStyle( ControlStyles.Opaque, True );

// Double BufferingSetStyle( ControlStyles.UserPaint, True );SetStyle( ControlStyles.AllPaintingInWmPaint, True );SetStyle( ControlStyles.DoubleBuffer, True );

SetStyle( ControlStyles.ResizeRedraw, True );SetStyle( ControlStyles.Opaque, True );

// Double BufferingSetStyle( ControlStyles.UserPaint, True );SetStyle( ControlStyles.AllPaintingInWmPaint, True );SetStyle( ControlStyles.DoubleBuffer, True );

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Component NotificationsComponent Notifications

Component notifications allow descendants to react to state changes implemented in an ancestor class

In the VCL, a component responds to notifications by handling special messagese.g. cm_EnabledChanged

In .NET, a component responds to notifications by overriding a methodOnEnabledChanged Event Dispatch Method

.NET even surfaces component notifications as public eventsEnabledChanged Event

Component notifications allow descendants to react to state changes implemented in an ancestor class

In the VCL, a component responds to notifications by handling special messagese.g. cm_EnabledChanged

In .NET, a component responds to notifications by overriding a methodOnEnabledChanged Event Dispatch Method

.NET even surfaces component notifications as public eventsEnabledChanged Event

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FCL and VCL EventsFCL and VCL Events

Unfortunately, the naming convention used for events in the FCL is opposite that used in the VCL

In the VCL…OnPaint is the eventPaint is the event dispatch method

In the FCL… OnPaint is the event dispatch methodPaint is the event

Unfortunately, the naming convention used for events in the FCL is opposite that used in the VCL

In the VCL…OnPaint is the eventPaint is the event dispatch method

In the FCL… OnPaint is the event dispatch methodPaint is the event

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FCL and VCL EventsFCL and VCL Events

Please Note:Unfortunately, it is common in .NET literature to

see statements like “…take a look at the OnPaint event handler…”

Problem is that base (ancestor) does not get called and thus the real event never gets raised

Please Note:Unfortunately, it is common in .NET literature to

see statements like “…take a look at the OnPaint event handler…”

Problem is that base (ancestor) does not get called and thus the real event never gets raised

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EventsEvents

Events allow customization through delegation

Events are properties

Implemented using Delegates

Events are optional

Events allow customization through delegation

Events are properties

Implemented using Delegates

Events are optional

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Creating a Custom EventCreating a Custom Event

Determine the action that triggers event

Define the event type (i.e. the Delegate)Specifies the parameters that will be sent to an

event handler

Declare the event propertySingleton Event (read/write)Multicast Event (add/remove)

Dispatch the event when it occurs.

Determine the action that triggers event

Define the event type (i.e. the Delegate)Specifies the parameters that will be sent to an

event handler

Declare the event propertySingleton Event (read/write)Multicast Event (add/remove)

Dispatch the event when it occurs.

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Determine Event TriggerDetermine Event Trigger

Events allow developers to “hook” into normal processing

ExampleGenerate a ValueChanged event when data

represented by the component changes

Events allow developers to “hook” into normal processing

ExampleGenerate a ValueChanged event when data

represented by the component changes

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DelegatesDelegates

The FCL utilizes Delegates to support events

A delegate is a class that encapsulates a linked-list of method pointers

With delegates an event can be sent to multiple subscribers

Specify the parameters that will be sent to event handlers.

The FCL utilizes Delegates to support events

A delegate is a class that encapsulates a linked-list of method pointers

With delegates an event can be sent to multiple subscribers

Specify the parameters that will be sent to event handlers.

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Define the DelegateDefine the Delegate

May be possible to use predefined delegatee.g. EventHandler

First parameter always “object sender”

Second parameter always EventArgs or descendant

If you require passing additional parameters, you’ll need to create a new EventArgs descendant

May be possible to use predefined delegatee.g. EventHandler

First parameter always “object sender”

Second parameter always EventArgs or descendant

If you require passing additional parameters, you’ll need to create a new EventArgs descendantValueChangingEventHandler =

procedure ( sender: System.Object; e: ValueChangingEventArgs ) of object;

ValueChangingEventHandler = procedure ( sender: System.Object; e: ValueChangingEventArgs ) of object;

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Case Sensitivity in Delphi?Case Sensitivity in Delphi?

Delphi is not case sensitive, but other .NET languages are (namely C#)

Event handler signature is exported in case sensitiveIn C#, parameters are lower case

As such, recommended to use

and not

Delphi is not case sensitive, but other .NET languages are (namely C#)

Event handler signature is exported in case sensitiveIn C#, parameters are lower case

As such, recommended to use

and notValueChangingEventHandler = procedure ( Sender: System.Object; E: ValueChangingEventArgs ) of object;

ValueChangingEventHandler = procedure ( Sender: System.Object; E: ValueChangingEventArgs ) of object;

ValueChangingEventHandler = procedure ( sender: System.Object; e: ValueChangingEventArgs ) of object;

ValueChangingEventHandler = procedure ( sender: System.Object; e: ValueChangingEventArgs ) of object;

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Declare the Event PropertyDeclare the Event Property

Unlike the VCL, by convention event names in the FCL do not start with “On”Unlike the VCL, by convention event names in the FCL do not start with “On”

// Multicast Eventproperty ValueChanged: EventHandler add FValueChanged remove FValueChanged;

// Singleton Eventproperty ValueChanging: ValueChangingEventHandler read FValueChanging write FValueChanging;

// Multicast Eventproperty ValueChanged: EventHandler add FValueChanged remove FValueChanged;

// Singleton Eventproperty ValueChanging: ValueChangingEventHandler read FValueChanging write FValueChanging;

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Raise the EventRaise the Event

Use an Event Dispatch Method

In FCL, event dispatch methods start with “On”

Usually defined as strict protected and virtual

Calling the event (e.g. FValueChanged) causes all of the event handlers in the delegate’s list to be called

Use an Event Dispatch Method

In FCL, event dispatch methods start with “On”

Usually defined as strict protected and virtual

Calling the event (e.g. FValueChanged) causes all of the event handlers in the delegate’s list to be called

procedure RkSpinner.OnValueChanged( e: EventArgs );begin if Assigned( FValueChanged ) then FValueChanged( Self, e );end;

procedure RkSpinner.OnValueChanged( e: EventArgs );begin if Assigned( FValueChanged ) then FValueChanged( Self, e );end;

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Custom PaintingCustom Painting

Custom painting supported by Graphics class (GDI+)System.DrawingSystem.Drawing.Drawing2DSystem.Drawing.ImagingSystem.Drawing.Text

GDI+ FeaturesAlpha Blending & Anti-Aliased 2D DrawingGradient BrushesUniversal Transformations & FP coordinatesSupport for more Image formats

BMP, GIF, JPEG, PNG, TIFF, ICON, WMF, EMF.

Custom painting supported by Graphics class (GDI+)System.DrawingSystem.Drawing.Drawing2DSystem.Drawing.ImagingSystem.Drawing.Text

GDI+ FeaturesAlpha Blending & Anti-Aliased 2D DrawingGradient BrushesUniversal Transformations & FP coordinatesSupport for more Image formats

BMP, GIF, JPEG, PNG, TIFF, ICON, WMF, EMF.

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GDI+ Programming ModelGDI+ Programming Model

No more device contexts (DC) – Graphics Object

GDI+ is StatelessNo more selecting pens and brushes into a DCPens, Brushes, etc. are passed to each GDI+

drawing method

Graphic elements are no longer drawn with both Pen and BrushDraw methods use a Pen (eg. DrawRectangle)Fill methods use a Brush (eg. FillEllipse).

No more device contexts (DC) – Graphics Object

GDI+ is StatelessNo more selecting pens and brushes into a DCPens, Brushes, etc. are passed to each GDI+

drawing method

Graphic elements are no longer drawn with both Pen and BrushDraw methods use a Pen (eg. DrawRectangle)Fill methods use a Brush (eg. FillEllipse).

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GDI+ Programming ModelGDI+ Programming Model

Colors support Alpha ChannelsARGB format

0x880000FF semi-transparent blue

A = 0x00 fully transparentA = 0xFF fully opaque

Rectangles, Points, etc. are classesr.Inflate( 5, 5 ); // Instead of InflateRect( r, 5, 5

);

Rectangles are defined differently!Left, Top, Width, Height.

Colors support Alpha ChannelsARGB format

0x880000FF semi-transparent blue

A = 0x00 fully transparentA = 0xFF fully opaque

Rectangles, Points, etc. are classesr.Inflate( 5, 5 ); // Instead of InflateRect( r, 5, 5

);

Rectangles are defined differently!Left, Top, Width, Height.

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GDI+ Programming ModelGDI+ Programming Model

Obtaining a Graphics ObjectPassed to OnPaint methods in

PaintEventArgsRequest one using

Graphics.FromHwnd( Handle )If utilizing double-buffering, do not use

FromHwnd

Cleaning UpDispose all GDI+ objectsDispose Graphics object if requested via

FromHwnd

Obtaining a Graphics ObjectPassed to OnPaint methods in

PaintEventArgsRequest one using

Graphics.FromHwnd( Handle )If utilizing double-buffering, do not use

FromHwnd

Cleaning UpDispose all GDI+ objectsDispose Graphics object if requested via

FromHwnd

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AttributesAttributes

Attributes used to modify the behavior of properties, methods, eventsAttributes used to modify the behavior of properties, methods, events

[ Category( 'Appearance' ) ][ Description( 'The width of buttons, in pixels.' ) ][ DefaultValue( 18 ) ]property ButtonWidth: Integer read FButtonWidth write SetButtonWidth;

// No Category or Description, but DefaultValueproperty ButtonHeight: Integer read FButtonHeight write SetButtonHeight default 18;

[ Category( 'Appearance' ) ][ Description( 'The width of buttons, in pixels.' ) ][ DefaultValue( 18 ) ]property ButtonWidth: Integer read FButtonWidth write SetButtonWidth;

// No Category or Description, but DefaultValueproperty ButtonHeight: Integer read FButtonHeight write SetButtonHeight default 18;

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AttributesAttributes

Category

Description

Browsable

DefaultValue

DefaultProperty & DefaultEvent

Localizable

ToolboxBitmap

Category

Description

Browsable

DefaultValue

DefaultProperty & DefaultEvent

Localizable

ToolboxBitmap

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ExampleExample

RayKonopka.Delphi.Controls AssemblyRkSpinner Component

RayKonopka.Delphi.Controls AssemblyRkSpinner Component

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The Finish LineThe Finish Line

Contact Information

Evaluation Forms

Questions & Answers

Contact Information

Evaluation Forms

Questions & Answers

Ray Konopkarkonopka@raize.comhttp://www.raize.com

Ray Konopkarkonopka@raize.comhttp://www.raize.com