VisualStyleElement Klas

Definitie

public ref class VisualStyleElement

public class VisualStyleElement

type VisualStyleElement = class

Public Class VisualStyleElement

Overname

Object

VisualStyleElement

Voorbeelden

Het volgende codevoorbeeld is een volledige toepassing die een gebruikersinterface biedt voor het bladeren en tekenen van alle VisualStyleElement-objecten die worden weergegeven door de naamruimte System.Windows.Forms.VisualStyles. Als u een element wilt weergeven, gebruikt u het ListView besturingselement aan de linkerkant van het venster om naar het knooppunt te navigeren dat de status aangeeft van het element dat u wilt tekenen en klikt u vervolgens op het knooppunt. In dit voorbeeld wordt het geselecteerde element alleen getekend als het element is gedefinieerd door de huidige visuele stijl.

#using <System.Drawing.dll>
#using <System.Windows.Forms.dll>
#using <System.dll>

using namespace System;
using namespace System::Text;
using namespace System::Drawing;
using namespace System::Collections::Generic;
using namespace System::Reflection;
using namespace System::Windows::Forms;
using namespace System::Windows::Forms::VisualStyles;

namespace VisualStyleElementViewer
{
    public ref class ElementViewer : public UserControl
    {
    private:
        VisualStyleElement^ element;
        VisualStyleRenderer^ renderer;
        Dictionary<String^, VisualStyleElement^>^ elementDictionary;
        Rectangle descriptionRect;
        Rectangle displayRect;
        Rectangle displayRectFull;
        System::Drawing::Size currentTrueSize;
        StringBuilder^ elementDescription;
        Label^ infoLabel;
        TreeView^ treeView;
        DomainUpDown^ domainUpDown;
        bool drawElement;

    public:
        ElementViewer():UserControl()
        {
            elementDictionary = 
                gcnew Dictionary<String^, VisualStyleElement^>();
            currentTrueSize = System::Drawing::Size();
            elementDescription = gcnew StringBuilder();
            infoLabel = gcnew Label();
            treeView = gcnew TreeView();
            domainUpDown = gcnew DomainUpDown();

            this->Location = Point(10, 10);
            this->Size = System::Drawing::Size(650, 500);
            this->Text = "VisualStyleElement Viewer";
            this->Font = SystemFonts::IconTitleFont;
            this->BackColor = Color::White;
            this->BorderStyle = System::Windows::Forms::BorderStyle::Fixed3D;
            this->AutoSize = true;
            this->Load += gcnew EventHandler(this, 
                &ElementViewer::ElementViewer_Load);
        }

    private:
        void ElementViewer_Load(Object^ sender, EventArgs^ e)
        {
            // Make sure the visual styles are enabled before
            // going any further.
            if (!Application::RenderWithVisualStyles)
            {
                return;
            }

            infoLabel->Location = Point(320, 10);
            infoLabel->Size = System::Drawing::Size(300, 60);
            infoLabel->Text = "Expand the element class nodes " +
                "in the tree view to access visual style elements. " +
                "Click an element name to draw the element below. To " +
                "change the size of a resizable element, use the " +
                "spin control.";

            domainUpDown->Location = Point(320, 80);
            domainUpDown->Size = System::Drawing::Size(70, 30);
            domainUpDown->ReadOnly = true;
            domainUpDown->Items->Add(elementSizes::Large);
            domainUpDown->Items->Add(elementSizes::Medium);
            domainUpDown->Items->Add(elementSizes::TrueSize);
            domainUpDown->SelectedIndex = 2;
            domainUpDown->SelectedItemChanged +=
                gcnew EventHandler(this, 
                    &ElementViewer::DomainUpDown_SelectedItemChanged);
            domainUpDown->DownButton();

            descriptionRect = Rectangle(320, 120, 250, 50);
            displayRect = Rectangle(320, 160, 0, 0);
            displayRectFull = Rectangle(320, 160, 300, 200);

            // Initialize the element and renderer to known good values.
            element = VisualStyleElement::Button::PushButton::Normal;
            renderer = gcnew VisualStyleRenderer(element);

            SetupElementCollection();
            SetupTreeView();

            this->Controls->AddRange(gcnew array<Control^>{treeView,
                domainUpDown, infoLabel });
        }

        // Use reflection to build a Dictionary of all
        // VisualStyleElement objects exposed in the
        // System.Windows.Forms.VisualStyles namespace.
    private:
        void SetupElementCollection()
        {
            StringBuilder^ elementName = gcnew StringBuilder();
            VisualStyleElement^ currentElement;
            int plusSignIndex = 0;

            // Get array of first-level nested types within
            // VisualStyleElement; these are the element classes.
            array<Type^>^ elementClasses =
                VisualStyleElement::typeid->GetNestedTypes();

            for each (Type^ elementClass in elementClasses)
            {
                // Get an array of second-level nested types within
                // VisualStyleElement; these are the element parts.
                array<Type^>^ elementParts = elementClass->GetNestedTypes();

                // Get the index of the first '+' character in
                // the full element class name.
                plusSignIndex = elementClass->FullName->IndexOf('+');

                for each (Type^ elementPart in elementParts)
                {
                    // Get an array of static property details
                    // for  the current type. Each of these types have
                    // properties that return VisualStyleElement objects.
                    array<PropertyInfo^>^ elementProperties =
                        elementPart->GetProperties(BindingFlags::Static |
                        BindingFlags::Public);

                    // For each property, insert the unique full element
                    // name and the element into the collection.
                    for each(PropertyInfo^ elementProperty in
                        elementProperties)
                    {
                        // Get the element.
                        currentElement =
                            (VisualStyleElement^)elementProperty->
                            GetValue(nullptr, BindingFlags::Static, nullptr,
                            nullptr, nullptr);

                        // Append the full element name.
                        elementName->Append(elementClass->FullName,
                            plusSignIndex + 1,
                            elementClass->FullName->Length -
                            plusSignIndex - 1);
                        elementName->Append("." +
                            elementPart->Name + "." +
                            elementProperty->Name);

                        // Add the element and element name to
                        // the Dictionary.
                        elementDictionary->Add(elementName->ToString(),
                            currentElement);

                        // Clear the element name for the
                        // next iteration.
                        elementName->Remove(0, elementName->Length);
                    }
                }
            }
        }

        // Initialize the tree view with the element names.
    private:
        void SetupTreeView()
        {
            treeView->Location = Point(10, 10);
            treeView->Size = System::Drawing::Size(300, 450);
            //    treeView->BorderStyle = BorderStyle.FixedSingle;
            treeView->BackColor = Color::WhiteSmoke;
            treeView->SelectedNode = nullptr;
            treeView->AfterSelect +=
                gcnew TreeViewEventHandler(this, 
                &ElementViewer::TreeView_AfterSelect);

            treeView->BeginUpdate();

            // An index into the top-level tree nodes.
            int nodeIndex = 0;

            // An index into the first '.' character in an element name.
            int firstDotIndex = 0;

            // Initialize the element class name to compare
            // with the class name of the first element
            // in the Dictionary, and set this name to the first
            // top-level node.
            StringBuilder^ compareClassName =
                gcnew StringBuilder("Button");
            treeView->Nodes->Add(
                gcnew TreeNode(compareClassName->ToString()));

            // The current element class name.
            StringBuilder^ currentClassName = gcnew StringBuilder();

            // The text for each second-level node.
            StringBuilder^ nodeText = gcnew StringBuilder();

            for each(KeyValuePair<String^, VisualStyleElement^>^ entry 
                in elementDictionary)
            {
                // Isolate the class name of the current element.
                firstDotIndex = entry->Key->IndexOf('.');
                currentClassName->Append(entry->Key, 0, firstDotIndex);

                // Determine whether we need to increment to the next
                // element class.
                if (currentClassName->ToString() !=
                    compareClassName->ToString())
                {
                    // Increment the index to the next top-level node
                    // in the tree view.
                    nodeIndex++;

                    // Get the new class name to compare with.
                    compareClassName->Remove(0, compareClassName->Length);
                    compareClassName->Append(entry->Key);
                    compareClassName->Remove(firstDotIndex,
                        compareClassName->Length - firstDotIndex);

                    // Add a new top-level node to the tree view.
                    treeView->Nodes->Add(
                        gcnew TreeNode(compareClassName->ToString()));
                }

                // Get the text for the new second-level node.
                nodeText->Append(entry->Key, firstDotIndex + 1,
                    entry->Key->Length - firstDotIndex - 1);

                // Create and insert the new second-level node.
                TreeNode^ newNode = gcnew TreeNode(nodeText->ToString());
                newNode->Name = entry->Key;
                treeView->Nodes[nodeIndex]->Nodes->Add(newNode);

                currentClassName->Remove(0, currentClassName->Length);
                nodeText->Remove(0, nodeText->Length);
            }
            treeView->EndUpdate();
        }

    protected:
        virtual void OnPaint(PaintEventArgs^ e) override
        {
            __super::OnPaint(e);

            // Do nothing further if visual styles are disabled.
            if (!Application::RenderWithVisualStyles)
            {
                this->Text = "Visual styles are disabled.";
                TextRenderer::DrawText(e->Graphics, this->Text, this->Font,
                    this->Location, this->ForeColor);
                return;
            }

            // Draw the element description.
            TextRenderer::DrawText(e->Graphics, elementDescription->ToString(),
                this->Font, descriptionRect, this->ForeColor,
                TextFormatFlags::WordBreak);

            // Draw the element, if an element is selected.
            if (drawElement)
            {
                renderer->DrawBackground(e->Graphics, this->displayRect);
            }
        }

        // Set the element to draw.
    private:
        void TreeView_AfterSelect(Object^ sender, TreeViewEventArgs^ e)
        {
            // Clear the element description.
            elementDescription->Remove(0, elementDescription->Length);

            // If the user clicked a first-level node, disable drawing.
            if (e->Node->Nodes->Count > 0)
            {
                drawElement = false;
                elementDescription->Append("No element is selected");
                domainUpDown->Enabled = false;
            }

            // The user clicked an element node.
            else
            {
                // Add the element name to the description.
                elementDescription->Append(e->Node->Text);

                // Get the element that corresponds to the selected
                // node's name.
                String^ key = e->Node->Name;
                element = elementDictionary[key];

                // Disable resizing if the element is not defined.
                if (!VisualStyleRenderer::IsElementDefined(element))
                {
                    drawElement = false;
                    elementDescription->Append(" is not defined.");
                    domainUpDown->Enabled = false;
                }
                else
                {
                    // Set the element to the renderer.
                    drawElement = true;
                    renderer->SetParameters(element);
                    elementDescription->Append(" is defined.");

                    // Get the system-defined size of the element.
                    Graphics^ g = this->CreateGraphics();
                    currentTrueSize = renderer->GetPartSize(g,
                        ThemeSizeType::True);
                    delete g;
                    displayRect.Size = currentTrueSize;

                    domainUpDown->Enabled = true;
                    domainUpDown->SelectedIndex = 2;
                }
            }

            Invalidate();
        }

        // Resize the element display area.
    private:
        void DomainUpDown_SelectedItemChanged(Object^ sender,
            EventArgs^ e)
        {
            switch ((int)domainUpDown->SelectedItem)
            {
            case this->elementSizes::TrueSize:
                displayRect.Size = currentTrueSize;
                break;
            case this->elementSizes::Medium:
                displayRect.Size = 
                    System::Drawing::Size(displayRectFull.Width / 2, 
                        displayRectFull.Height / 2);
                break;
            case this->elementSizes::Large:
                displayRect.Size = displayRectFull.Size;
                break;
            }

            Invalidate();
        }

        // These values represent the options in the UpDown control.
    private:
        enum class elementSizes
        {
            TrueSize,
            Medium,
            Large
        };
    };
    public ref class ElementViewerForm : public Form
    {
    public:
        ElementViewerForm()
        {
            ElementViewer^ elementViewer = gcnew ElementViewer();
            this->Controls->Add(elementViewer);
            this->Text = elementViewer->Text;
            this->Size = System::Drawing::Size(700, 550);
        }
    };
}

using namespace VisualStyleElementViewer;

[STAThread]
int main()
{
    Application::EnableVisualStyles();
    Application::Run(gcnew ElementViewerForm());
}

using System;
using System.Text;
using System.Drawing;
using System.Collections.Generic;
using System.Reflection;
using System.Windows.Forms;
using System.Windows.Forms.VisualStyles;

namespace VisualStyleElementViewer
{
    class Form1 : Form
    {
        public Form1()
        {
            ElementViewer ElementViewer1 = new ElementViewer();
            this.Controls.Add(ElementViewer1);
            this.Text = ElementViewer1.Text;
            this.Size = new Size(700, 550);
        }

        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.Run(new Form1());
        }
    }

    public class ElementViewer : UserControl
    {
        private VisualStyleElement element;
        private VisualStyleRenderer renderer;
        private Dictionary<string, VisualStyleElement> elementDictionary =
            new Dictionary<string, VisualStyleElement>();

        private Rectangle descriptionRect;
        private Rectangle displayRect;
        private Rectangle displayRectFull;
        private Size currentTrueSize = new Size();
        private StringBuilder elementDescription = new StringBuilder();
        private Label label1 = new Label();
        private TreeView treeView1 = new TreeView();
        private DomainUpDown domainUpDown1 = new DomainUpDown();
        private bool drawElement = false;

        public ElementViewer()
            : base()
        {
            this.Location = new Point(10, 10);
            this.Size = new Size(650, 500);
            this.Text = "VisualStyleElement Viewer";
            this.Font = SystemFonts.IconTitleFont;
            this.BackColor = Color.White;
            this.BorderStyle = BorderStyle.Fixed3D;
            this.AutoSize = true;
            this.Load += new EventHandler(ElementViewer_Load);
        }

        void ElementViewer_Load(object sender, EventArgs e)
        {
            // Make sure the visual styles are enabled before 
            // going any further.
            if (!Application.RenderWithVisualStyles)
            {
                return;
            }

            label1.Location = new Point(320, 10);
            label1.Size = new Size(300, 60);
            label1.Text = "Expand the element class nodes " +
                "in the tree view to access visual style elements. " +
                "Click an element name to draw the element below. To " +
                "change the size of a resizable element, use the " +
                "spin control.";

            domainUpDown1.Location = new Point(320, 80);
            domainUpDown1.Size = new Size(70, 30);
            domainUpDown1.ReadOnly = true;
            domainUpDown1.Items.Add(elementSizes.Large);
            domainUpDown1.Items.Add(elementSizes.Medium);
            domainUpDown1.Items.Add(elementSizes.TrueSize);
            domainUpDown1.SelectedIndex = 2;
            domainUpDown1.SelectedItemChanged +=
                new EventHandler(domainUpDown1_SelectedItemChanged);
            domainUpDown1.DownButton();

            descriptionRect = new Rectangle(320, 120, 250, 50);
            displayRect = new Rectangle(320, 160, 0, 0);
            displayRectFull = new Rectangle(320, 160, 300, 200);

            // Initialize the element and renderer to known good values.
            element = VisualStyleElement.Button.PushButton.Normal;
            renderer = new VisualStyleRenderer(element);

            SetupElementCollection();
            SetupTreeView();

            this.Controls.AddRange(new Control[] { treeView1, 
                domainUpDown1, label1 });
        }

        // Use reflection to build a Dictionary of all 
        // VisualStyleElement objects exposed in the 
        // System.Windows.Forms.VisualStyles namespace.
        private void SetupElementCollection()
        {
            StringBuilder elementName = new StringBuilder();
            VisualStyleElement currentElement;
            int plusSignIndex = 0;

            // Get array of first-level nested types within 
            // VisualStyleElement; these are the element classes.
            Type[] elementClasses =
                typeof(VisualStyleElement).GetNestedTypes();

            foreach (Type elementClass in elementClasses)
            {
                // Get an array of second-level nested types within
                // VisualStyleElement; these are the element parts.
                Type[] elementParts = elementClass.GetNestedTypes();

                // Get the index of the first '+' character in 
                // the full element class name.
                plusSignIndex = elementClass.FullName.IndexOf('+');

                foreach (Type elementPart in elementParts)
                {
                    // Get an array of static property details 
                    // for  the current type. Each of these types have 
                    // properties that return VisualStyleElement objects.
                    PropertyInfo[] elementProperties =
                        elementPart.GetProperties(BindingFlags.Static |
                        BindingFlags.Public);

                    // For each property, insert the unique full element   
                    // name and the element into the collection.
                    foreach (PropertyInfo elementProperty in
                        elementProperties)
                    {
                        // Get the element.
                        currentElement =
                            (VisualStyleElement)elementProperty.
                            GetValue(null, BindingFlags.Static, null,
                            null, null);

                        // Append the full element name.
                        elementName.Append(elementClass.FullName,
                            plusSignIndex + 1,
                            elementClass.FullName.Length -
                            plusSignIndex - 1);
                        elementName.Append("." +
                            elementPart.Name.ToString() + "." +
                            elementProperty.Name);

                        // Add the element and element name to 
                        // the Dictionary.
                        elementDictionary.Add(elementName.ToString(),
                            currentElement);

                        // Clear the element name for the 
                        // next iteration.
                        elementName.Remove(0, elementName.Length);
                    }
                }
            }
        }

        // Initialize the tree view with the element names.
        private void SetupTreeView()
        {
            treeView1.Location = new Point(10, 10);
            treeView1.Size = new Size(300, 450);
            treeView1.BorderStyle = BorderStyle.FixedSingle;
            treeView1.BackColor = Color.WhiteSmoke;
            treeView1.SelectedNode = null;
            treeView1.AfterSelect +=
                new TreeViewEventHandler(treeView1_AfterSelect);

            treeView1.BeginUpdate();

            // An index into the top-level tree nodes.
            int nodeIndex = 0;

            // An index into the first '.' character in an element name.
            int firstDotIndex = 0;

            // Initialize the element class name to compare 
            // with the class name of the first element  
            // in the Dictionary, and set this name to the first 
            // top-level node.
            StringBuilder compareClassName =
                new StringBuilder("Button");
            treeView1.Nodes.Add(
                new TreeNode(compareClassName.ToString()));

            // The current element class name.
            StringBuilder currentClassName = new StringBuilder();

            // The text for each second-level node.
            StringBuilder nodeText = new StringBuilder();

            foreach (KeyValuePair<string, VisualStyleElement> entry
                in elementDictionary)
            {
                // Isolate the class name of the current element.
                firstDotIndex = entry.Key.IndexOf('.');
                currentClassName.Append(entry.Key, 0, firstDotIndex);

                // Determine whether we need to increment to the next 
                // element class.
                if (currentClassName.ToString() !=
                    compareClassName.ToString())
                {
                    // Increment the index to the next top-level node 
                    // in the tree view.
                    nodeIndex++;

                    // Get the new class name to compare with.
                    compareClassName.Remove(0, compareClassName.Length);
                    compareClassName.Append(entry.Key);
                    compareClassName.Remove(firstDotIndex,
                        compareClassName.Length - firstDotIndex);

                    // Add a new top-level node to the tree view.
                    treeView1.Nodes.Add(
                        new TreeNode(compareClassName.ToString()));
                }

                // Get the text for the new second-level node.
                nodeText.Append(entry.Key, firstDotIndex + 1,
                    entry.Key.Length - firstDotIndex - 1);

                // Create and insert the new second-level node.
                TreeNode newNode = new TreeNode(nodeText.ToString());
                newNode.Name = entry.Key;
                treeView1.Nodes[nodeIndex].Nodes.Add(newNode);

                currentClassName.Remove(0, currentClassName.Length);
                nodeText.Remove(0, nodeText.Length);
            }

            treeView1.EndUpdate();
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

            // Do nothing further if visual styles are disabled.
            if (!Application.RenderWithVisualStyles)
            {
                this.Text = "Visual styles are disabled.";
                TextRenderer.DrawText(e.Graphics, this.Text, this.Font,
                    this.Location, this.ForeColor);
                return;
            }

            // Draw the element description.
            TextRenderer.DrawText(e.Graphics, elementDescription.ToString(),
                this.Font, descriptionRect, this.ForeColor,
                TextFormatFlags.WordBreak);

            // Draw the element, if an element is selected.
            if (drawElement)
            {
                renderer.DrawBackground(e.Graphics, this.displayRect);
            }
        }

        // Set the element to draw.
        void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
        {
            // Clear the element description.
            elementDescription.Remove(0, elementDescription.Length);

            // If the user clicked a first-level node, disable drawing.
            if (e.Node.Nodes.Count > 0)
            {
                drawElement = false;
                elementDescription.Append("No element is selected");
                domainUpDown1.Enabled = false;
            }

            // The user clicked an element node.
            else
            {
                // Add the element name to the description.
                elementDescription.Append(e.Node.Text);

                // Get the element that corresponds to the selected  
                // node's name.
                String key = e.Node.Name;
                element = elementDictionary[key];

                // Disable resizing if the element is not defined.
                if (!VisualStyleRenderer.IsElementDefined(element))
                {
                    drawElement = false;
                    elementDescription.Append(" is not defined.");
                    domainUpDown1.Enabled = false;
                }
                else
                {
                    // Set the element to the renderer.
                    drawElement = true;
                    renderer.SetParameters(element);
                    elementDescription.Append(" is defined.");

                    // Get the system-defined size of the element.
                    Graphics g = this.CreateGraphics();
                    currentTrueSize = renderer.GetPartSize(g,
                        ThemeSizeType.True);
                    g.Dispose();
                    displayRect.Size = currentTrueSize;

                    domainUpDown1.Enabled = true;
                    domainUpDown1.SelectedIndex = 2;
                }
            }

            Invalidate();
        }

        // Resize the element display area.
        void domainUpDown1_SelectedItemChanged(object sender,
            EventArgs e)
        {
            switch ((int)domainUpDown1.SelectedItem)
            {
                case (int)elementSizes.TrueSize:
                    displayRect.Size = currentTrueSize;
                    break;
                case (int)elementSizes.Medium:
                    displayRect.Size =
                        new Size(displayRectFull.Width / 2,
                        displayRectFull.Height / 2);
                    break;
                case (int)elementSizes.Large:
                    displayRect.Size = displayRectFull.Size;
                    break;
            }

            Invalidate();
        }

        // These values represent the options in the UpDown control.
        private enum elementSizes
        {
            TrueSize,
            Medium,
            Large
        };
    }
}

Imports System.Text
Imports System.Drawing
Imports System.Collections.Generic
Imports System.Reflection
Imports System.Windows.Forms
Imports System.Windows.Forms.VisualStyles

Namespace VisualStyleElementViewer

    Class Form1
        Inherits Form

        Public Sub New()
            Dim ElementViewer1 As New ElementViewer()
            With Me
                .Controls.Add(ElementViewer1)
                .Text = ElementViewer1.Text
                .Size = New Size(700, 550)
            End With
        End Sub

        <STAThread()> Shared Sub Main()
            Application.EnableVisualStyles()
            Application.Run(New Form1())
        End Sub
    End Class

    Public Class ElementViewer
        Inherits UserControl

        Private element As VisualStyleElement
        Private renderer As VisualStyleRenderer
        Private elementDictionary As New Dictionary(Of String, _
            VisualStyleElement)
        Private descriptionRect As Rectangle
        Private displayRect As Rectangle
        Private displayRectFull As Rectangle
        Private currentTrueSize As New Size()
        Private elementDescription As New StringBuilder()
        Private label1 As New Label()
        Private WithEvents treeView1 As New TreeView()
        Private WithEvents domainUpDown1 As New DomainUpDown()
        Private drawElement As Boolean = False

        Public Sub New()
            With Me
                .Location = New Point(10, 10)
                .Size = New Size(650, 500)
                .Text = "VisualStyleElement Viewer"
                .Font = SystemFonts.IconTitleFont
                .BackColor = Color.White
                .BorderStyle = BorderStyle.Fixed3D
                .AutoSize = True
            End With
        End Sub

        Private Sub ElementViewer_Load(ByVal sender As Object, _
            ByVal e As EventArgs) Handles Me.Load

            ' Make sure the visual styles are enabled before 
            ' going any further.
            If Not Application.RenderWithVisualStyles Then
                Return
            End If

            With label1
                .Location = New Point(320, 10)
                .Size = New Size(300, 60)
                .Text = "Expand the element class nodes in the " + _
                    "tree view to access visual style elements. " + _
                    "Click an element name to draw the element " + _
                    "below. To change the size of a resizable " + _
                    "element, use the spin control."
            End With

            With domainUpDown1
                .Location = New Point(320, 80)
                .Size = New Size(70, 30)
                .ReadOnly = True
                .Items.Add(elementSizes.Large)
                .Items.Add(elementSizes.Medium)
                .Items.Add(elementSizes.TrueSize)
                .SelectedIndex = 2
                .DownButton()
            End With

            descriptionRect = New Rectangle(320, 120, 250, 50)
            displayRect = New Rectangle(320, 160, 0, 0)
            displayRectFull = New Rectangle(320, 160, 300, 200)

            ' Initialize the element and renderer to known good values.
            element = VisualStyleElement.Button.PushButton.Normal
            renderer = New VisualStyleRenderer(element)

            SetupElementCollection()
            SetupTreeView()

            Me.Controls.AddRange(New Control() {treeView1, _
                domainUpDown1, label1})
        End Sub

        ' Use reflection to build a Dictionary of all 
        ' VisualStyleElement objects exposed in the 
        ' System.Windows.Forms.VisualStyles namespace.
        Private Sub SetupElementCollection()
            Dim elementName As New StringBuilder()
            Dim currentElement As VisualStyleElement
            Dim tempObject As Object
            Dim plusSignIndex As Integer = 0

            ' Get array of first-level nested types within 
            ' VisualStyleElement; these are the element classes.
            Dim elementClasses As Type() = _
                GetType(VisualStyleElement).GetNestedTypes()

            Dim elementClass As Type
            For Each elementClass In elementClasses

                ' Get an array of second-level nested types within
                ' VisualStyleElement; these are the element parts.
                Dim elementParts As Type() = _
                    elementClass.GetNestedTypes()

                ' Get the index of the first '+' character in 
                ' the full element class name.
                plusSignIndex = elementClass.FullName.IndexOf("+")

                Dim elementPart As Type
                For Each elementPart In elementParts

                    ' Get an array of Shared property details 
                    ' for  the current type. Each of these types have 
                    ' properties that return VisualStyleElement objects.
                    Dim elementProperties As PropertyInfo() = _
                        elementPart.GetProperties( _
                        (BindingFlags.Static Or BindingFlags.Public))

                    ' For each property, insert the unique full element   
                    ' name and the element into the collection.
                    Dim elementProperty As PropertyInfo
                    For Each elementProperty In elementProperties

                        ' Get the element.
                        tempObject = elementProperty.GetValue( _
                            Nothing, BindingFlags.Static, Nothing, _
                            Nothing, Nothing)
                        currentElement = CType(tempObject, _
                            VisualStyleElement)

                        ' Append the full element name.
                        elementName.Append(elementClass.FullName, _
                            plusSignIndex + 1, _
                            elementClass.FullName.Length - _
                            plusSignIndex - 1)
                        elementName.Append(("." + _
                            elementPart.Name.ToString() + _
                            "." + elementProperty.Name))

                        ' Add the element and element name to 
                        ' the Dictionary.
                        elementDictionary.Add(elementName.ToString(), _
                            currentElement)

                        ' Clear the element name for the next iteration.
                        elementName.Remove(0, elementName.Length)
                    Next elementProperty
                Next elementPart
            Next elementClass
        End Sub

        ' Initialize the tree view with the element names.
        Private Sub SetupTreeView()

            With treeView1
                .Location = New Point(10, 10)
                .Size = New Size(300, 450)
                .BorderStyle = BorderStyle.FixedSingle
                .BackColor = Color.WhiteSmoke
                .SelectedNode = Nothing
                .BeginUpdate()
            End With

            ' An index into the top-level tree nodes.
            Dim nodeIndex As Integer = 0

            ' An index into the first '.' character in an element name.
            Dim firstDotIndex As Integer = 0

            ' Initialize the element class name to compare 
            ' with the class name of the first element 
            ' in the Dictionary, and set this name to the first 
            ' top-level node.
            Dim compareClassName As New StringBuilder("Button")
            treeView1.Nodes.Add( _
                New TreeNode(compareClassName.ToString()))

            ' The current element class name.
            Dim currentClassName As New StringBuilder()

            ' The text for each second-level node.
            Dim nodeText As New StringBuilder()

            Dim entry As KeyValuePair(Of String, VisualStyleElement)
            For Each entry In elementDictionary

                ' Isolate the class name of the current element.
                firstDotIndex = entry.Key.IndexOf(".")
                currentClassName.Append(entry.Key, 0, firstDotIndex)

                ' Determine whether we need to increment to the next 
                ' element class.
                If currentClassName.ToString() <> _
                    compareClassName.ToString() Then

                    ' Increment the index to the next top-level node 
                    ' in the tree view.
                    nodeIndex += 1

                    ' Update the class name to compare with.
                    compareClassName.Remove(0, compareClassName.Length)
                    compareClassName.Append(entry.Key)
                    compareClassName.Remove(firstDotIndex, _
                        compareClassName.Length - firstDotIndex)

                    ' Add a new top-level node to the tree view.
                    Dim node As New TreeNode(compareClassName.ToString())
                    treeView1.Nodes.Add(node)
                End If

                ' Get the text for the new second-level node.
                nodeText.Append(entry.Key, firstDotIndex + 1, _
                    entry.Key.Length - firstDotIndex - 1)

                ' Create and insert the new second-level node.
                Dim newNode As New TreeNode(nodeText.ToString())
                newNode.Name = entry.Key
                treeView1.Nodes(nodeIndex).Nodes.Add(newNode)

                currentClassName.Remove(0, currentClassName.Length)
                nodeText.Remove(0, nodeText.Length)
            Next entry

            treeView1.EndUpdate()
        End Sub

        Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
            MyBase.OnPaint(e)

            ' Do nothing further if visual styles are disabled.
            If Not Application.RenderWithVisualStyles Then
                Me.Text = "Visual styles are disabled."
                TextRenderer.DrawText(e.Graphics, Me.Text, Me.Font, _
                    Me.Location, Me.ForeColor)
                Return
            End If

            ' Draw the element description.
            TextRenderer.DrawText(e.Graphics, _
                elementDescription.ToString(), Me.Font, _
                descriptionRect, Me.ForeColor, _
                TextFormatFlags.WordBreak)

            ' Draw the element, if an element is selected.
            If drawElement Then
                renderer.DrawBackground(e.Graphics, Me.displayRect)
            End If
        End Sub

        ' Set the element to draw.
        Private Sub treeView1_AfterSelect(ByVal sender As Object, _
            ByVal e As TreeViewEventArgs) Handles treeView1.AfterSelect

            ' Clear the element description.
            elementDescription.Remove(0, elementDescription.Length)

            ' If the user clicked a first-level node, disable drawing.
            If e.Node.Nodes.Count > 0 Then
                drawElement = False
                elementDescription.Append("No element is selected")
                domainUpDown1.Enabled = False

            ' The user clicked an element node.
            Else
                ' Add the element name to the description.
                elementDescription.Append(e.Node.Text)

                ' Get the element that corresponds to the selected  
                ' node's name.
                Dim key As String = e.Node.Name
                element = elementDictionary(key)

                ' Disable resizing if the element is not defined.
                If Not VisualStyleRenderer.IsElementDefined(element) Then
                    drawElement = False
                    elementDescription.Append(" is not defined.")
                    domainUpDown1.Enabled = False
                Else
                    ' Set the element to the renderer.
                    drawElement = True
                    renderer.SetParameters(element)
                    elementDescription.Append(" is defined.")

                    ' Get the system-defined size of the element.
                    Dim g As Graphics = Me.CreateGraphics()
                    currentTrueSize = renderer.GetPartSize(g, _
                        ThemeSizeType.True)
                    g.Dispose()
                    displayRect.Size = currentTrueSize

                    domainUpDown1.Enabled = True
                    domainUpDown1.SelectedIndex = 2
                End If
            End If
            Invalidate()
        End Sub

        ' Resize the element display area.
        Private Sub domainUpDown1_SelectedItemChanged(ByVal sender As Object, _
            ByVal e As EventArgs) _
            Handles domainUpDown1.SelectedItemChanged

            Select Case CInt(domainUpDown1.SelectedItem)
                Case CInt(elementSizes.TrueSize)
                    displayRect.Size = currentTrueSize
                Case CInt(elementSizes.Medium)
                    displayRect.Size = _
                        New Size(displayRectFull.Width / 2, _
                        displayRectFull.Height / 2)
                Case CInt(elementSizes.Large)
                    displayRect.Size = displayRectFull.Size
            End Select

            Invalidate()
        End Sub

        ' These values represent the options in the UpDown control.
        Private Enum elementSizes
            TrueSize
            Medium
            Large
        End Enum

    End Class
End Namespace

Opmerkingen

De klasse VisualStyleElement identificeert een element Windows besturingselement of gebruikersinterface (UI) dat is gedefinieerd door de huidige visuele stijl van het besturingssysteem. Een element van een visuele stijl wordt gedefinieerd in termen van klasse, onderdeel en status:

• De klasse identificeert een groep gerelateerde visuele stijlelementen die doorgaans samen worden getrokken. De klasse wordt opgegeven door de ClassName eigenschap.

• Het onderdeel definieert een discreet lid van een klasse. Het onderdeel wordt opgegeven door de Part eigenschap.

• De status beschrijft de huidige visuele status van het element dat is gedefinieerd door de klasse en het onderdeel. De status wordt opgegeven door de State eigenschap.

De System.Windows.Forms.VisualStyles naamruimte bevat honderden VisualStyleElement-objecten die de besturingselementen en elementen van de gebruikersinterface vertegenwoordigen die kunnen worden gedefinieerd door een visuele stijl. Deze objecten worden weergegeven als static eigenschappen van geneste klassen van VisualStyleElement. Voor elke eigenschap vertegenwoordigt de gekwalificeerde naam van de klasse die eigenaar is de klasse en het deel van het getekende element en de eigenschapsnaam de status van het element. De eigenschap retourneert bijvoorbeeld VisualStyleElement.Button.PushButton.Pressed een VisualStyleElement knop die kan worden gebruikt om een knop te tekenen met visuele stijlen. De Pressed eigenschapsnaam komt overeen met de status, PushButton komt overeen met het deel en Button identificeert de klasse van het element van de visuele stijl.

Als u een element van een visuele stijl wilt tekenen, maakt u een VisualStyleRendererelement, stelt u dit in op het element VisualStyleElement dat u wilt tekenen en roept u de DrawBackground methode aan. Als u wilt bepalen of de huidige visuele stijl een definitie voor een bepaald element biedt, roept u de IsElementDefined methode aan met het element als argument.

VisualStyleElement en VisualStyleRenderer verpakt de functionaliteit van de API voor visuele stijlen vanuit het Windows Shell-gedeelte van de Windows Platform SDK. Zie Visuele stijlen voor meer informatie over visuele stijlen.

Zie ook

• VisualStyleRenderer
• VisualStyleInformation