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DrawItem Event

Summary

Occurs when a request is made to draw an item in an owner-drawn RasterImageList.

Syntax

C#
VB
C++
public event EventHandler<RasterImageListDrawItemEventArgs> DrawItem 
  
Public Event DrawItem As EventHandler(Of RasterImageListDrawItemEventArgs) 
public: 
event EventHandler<RasterImageListDrawItemEventArgs^>^ DrawItem 

Event Data

The event handler receives an argument of type RasterImageListDrawItemEventArgs containing data related to this event. The following RasterImageListDrawItemEventArgs properties provide information specific to this event.

PropertyDescription
Graphics The Graphics object into which the item should be drawn.
Item The RasterImageListItem to draw.
Remarks

When you set the ViewStyle property to RasterImageListViewStyle.OwnerDraw, the RasterImageList control will fire the DrawItem event for each event that needs to be drawn. The RasterImageListDrawItemEventArgs argument passed to a DrawItem event handler provides a System.Drawing.Graphics object that enables you to perform drawing and other graphical operations on the surface of the RasterImageList along with the RasterImageListItem object that needs to be drawn.

Example

This example creates an owner drawn RasterImageList.

C#
VB
using Leadtools.WinForms; 
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Drawing; 
 
class MyForm3 : Form 
{ 
   RasterImageList imageList; 
   RasterCodecs codecs; 
 
   public MyForm3(string title) 
   { 
      Text = title; 
      // Set the size of the form 
      Size = new Size(400, 200); 
 
      // Create a new RasterImageList control 
      imageList = new RasterImageList(); 
      imageList.Dock = DockStyle.Fill; 
      imageList.SelectionMode = RasterImageListSelectionMode.Single; 
      imageList.Size = Size; 
      Controls.Add(imageList); 
      imageList.BringToFront(); 
 
      codecs = new RasterCodecs(); 
 
      // Create three items 
      string imagesPath = LEAD_VARS.ImagesDir; 
 
      for (int i = 0; i < 3; i++) 
      { 
         // Load the image 
         int index = i + 1; 
         string imageFileName = Path.Combine(imagesPath, @"ImageProcessingDemo\Image" + index.ToString() + ".cmp"); 
         RasterImage image = codecs.Load(imageFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1); 
         RasterImageListItem item = new RasterImageListItem(image, 1, "Item" + index.ToString()); 
 
         // Select the first item 
         if (i == 0) 
            item.Selected = true; 
 
         // Add the item to the image list 
         imageList.Items.Add(item); 
      } 
 
      // Change the item size 
      imageList.ItemSize = new Size(200, 200); 
 
      // Change the item image size 
      imageList.ItemImageSize = new Size(120, 120); 
 
      // We are going to draw the items ourselves 
      imageList.ViewStyle = RasterImageListViewStyle.OwnerDraw; 
 
      // Add a handler to the DrawItem event 
      imageList.DrawItem += new EventHandler<RasterImageListDrawItemEventArgs>(rasterImageList_DrawItem); 
 
      // Add the RasterImageList to the control collection. 
      Controls.Add(imageList); 
   } 
 
   private void rasterImageList_DrawItem(object sender, RasterImageListDrawItemEventArgs e) 
   { 
      RasterImageListItem item = e.Item; 
      RasterImageList imageList = item.ImageList; 
      Graphics g = e.Graphics; 
 
      // get the item rectangle 
      Rectangle rc = imageList.GetItemRectangle(item); 
 
      // sanity check 
      if (rc.IsEmpty) 
         return; 
 
      // we want to draw a 1 pixel black rectangle around the item 
      // then we fill the inside of the rectangle with white if the item 
      // is not selected or lightgray if it is 
 
      g.DrawRectangle(Pens.Black, rc.Left, rc.Top, rc.Width - 1, rc.Height - 1); 
 
      // we used up 1 pixel 
      rc.Inflate(-1, -1); 
 
      Brush b; 
      if (item.Selected) 
         b = Brushes.LightGray; 
      else 
         b = Brushes.White; 
      g.FillRectangle(b, rc); 
 
      // calculate the rectangles for image and text 
      if (imageList.ShowItemText) 
      { 
         // text is visible 
         // draw the text at the bottom of the item 
         int textHeight = (int)(g.MeasureString("WWW", imageList.Font).Height + 4); 
         Rectangle textRect = Rectangle.FromLTRB( 
            rc.Left, 
            rc.Bottom - textHeight, 
            rc.Right, 
            rc.Bottom); 
 
         if (!textRect.IsEmpty) 
         { 
            StringFormat sf = new StringFormat(); 
            sf.Alignment = StringAlignment.Center; 
            sf.LineAlignment = StringAlignment.Center; 
            sf.Trimming = StringTrimming.EllipsisPath; 
            sf.FormatFlags = StringFormatFlags.NoWrap; 
 
            g.DrawString( 
               item.Text, 
               imageList.Font, 
               Brushes.Black, 
               textRect, 
               sf); 
            sf.Dispose(); 
 
            // we need to update the item rectangle for the space 
            // we used up to draw the text 
            rc.Height -= textRect.Height; 
         } 
      } 
 
      // rc is the image rectangle 
      if (!rc.IsEmpty) 
      { 
         // now rc holds the rectangle to draw the image into 
 
         // first, set the correct page 
         int savePage = -1; 
         if (item.Image.Page != item.Page) 
         { 
            // the page is different 
 
            // save current image page so we can set it back when we are done 
            savePage = item.Image.Page; 
 
            // disable the image events, we are going to set the page back, 
            // so we do not want anybody subscribing to this image Changed 
            // event to know we changed it. 
            item.Image.DisableEvents(); 
 
            // set new page 
            item.Image.Page = item.Page; 
         } 
 
         try 
         { 
            // we want to center the image into whatever left of rc 
            Size itemImageSize = imageList.ItemImageSize; 
            Rectangle imageRect = new Rectangle( 
               rc.Left + (rc.Width - itemImageSize.Width) / 2, 
               rc.Top + (rc.Height - itemImageSize.Height) / 2, 
               itemImageSize.Width, 
               itemImageSize.Height); 
 
            // we want to keep the aspect ratio 
            imageRect = RasterImageList.GetFixedAspectRatioImageRectangle( 
               item.Image.ImageWidth, 
               item.Image.ImageHeight, 
               imageRect); 
 
            // draw the image 
            LeadRect lRect = new LeadRect(imageRect.Left, imageRect.Top, imageRect.Width, imageRect.Height); 
            RasterImagePainter.Paint(item.Image, e.Graphics, lRect, imageList.PaintProperties); 
 
            // finally, draw a black rectangle around the image 
            imageRect.Inflate(1, 1); 
            g.DrawRectangle( 
               Pens.Black, 
               imageRect.Left, 
               imageRect.Top, 
               imageRect.Width - 1, 
               imageRect.Height - 1); 
         } 
         finally 
         { 
            // reset the old page 
            if (savePage != -1) 
            { 
               item.Image.Page = savePage; 
 
               // re-enable the events 
               item.Image.EnableEvents(); 
            } 
         } 
      } 
   } 
} 
 
public void RasterImageList_DrawItem(string title) 
{ 
   MyForm3 form = new MyForm3(title); 
   form.ShowDialog(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; 
} 
Imports Leadtools.WinForms 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Drawing 
 
Private Class MyForm3 : Inherits Form 
   Private imageList As RasterImageList 
   Private codecs As RasterCodecs 
 
   Public Sub New(ByVal title As String) 
      Text = title 
      ' Set the size of the form 
      Size = New Size(400, 200) 
 
      ' Create a new RasterImageList control 
      imageList = New RasterImageList() 
      imageList.Dock = DockStyle.Fill 
      imageList.SelectionMode = RasterImageListSelectionMode.Single 
      imageList.Size = Size 
      Controls.Add(imageList) 
      imageList.BringToFront() 
 
      codecs = New RasterCodecs() 
 
      ' Create three items 
      Dim imagesPath As String = LEAD_VARS.ImagesDir 
 
      For i As Integer = 0 To 2 
         ' Load the image 
         Dim index As Integer = i + 1 
         Dim imageFileName As String = Path.Combine(imagesPath, "ImageProcessingDemo\Image" & index.ToString() & ".cmp") 
         Dim image As RasterImage = codecs.Load(imageFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, 1) 
         Dim item As RasterImageListItem = New RasterImageListItem(image, 1, "Item" & index.ToString()) 
 
         ' Select the first item 
         If i = 0 Then 
            item.Selected = True 
         End If 
 
         ' Add the item to the image list 
         imageList.Items.Add(item) 
      Next i 
 
      ' Change the item size 
      imageList.ItemSize = New Size(200, 200) 
 
      ' Change the item image size 
      imageList.ItemImageSize = New Size(120, 120) 
 
      ' We are going to draw the items ourselves 
      imageList.ViewStyle = RasterImageListViewStyle.OwnerDraw 
 
      ' Add a handler to the DrawItem event 
      AddHandler imageList.DrawItem, AddressOf rasterImageList_DrawItem 
 
      ' Add the RasterImageList to the control collection. 
      Controls.Add(imageList) 
   End Sub 
 
   Private Sub rasterImageList_DrawItem(ByVal sender As Object, ByVal e As RasterImageListDrawItemEventArgs) 
      Dim item As RasterImageListItem = e.Item 
      Dim imageList As RasterImageList = item.ImageList 
      Dim g As Graphics = e.Graphics 
 
      ' get the item rectangle 
      Dim rc As Rectangle = imageList.GetItemRectangle(item) 
 
      ' sanity check 
      If rc.IsEmpty Then 
         Return 
      End If 
 
      ' we want to draw a 1 pixel black rectangle around the item 
      ' then we fill the inside of the rectangle with white if the item 
      ' is not selected or lightgray if it is 
 
      g.DrawRectangle(Pens.Black, rc.Left, rc.Top, rc.Width - 1, rc.Height - 1) 
 
      ' we used up 1 pixel 
      rc.Inflate(-1, -1) 
 
      Dim b As Brush 
      If item.Selected Then 
         b = Brushes.LightGray 
      Else 
         b = Brushes.White 
      End If 
      g.FillRectangle(b, rc) 
 
      ' calculate the rectangles for image and text 
      If imageList.ShowItemText Then 
         ' text is visible 
         ' draw the text at the bottom of the item 
         Dim textHeight As Integer = CInt(g.MeasureString("WWW", imageList.Font).Height + 4) 
         Dim textRect As Rectangle = Rectangle.FromLTRB(rc.Left, rc.Bottom - textHeight, rc.Right, rc.Bottom) 
 
         If (Not textRect.IsEmpty) Then 
            Dim sf As StringFormat = New StringFormat() 
            sf.Alignment = StringAlignment.Center 
            sf.LineAlignment = StringAlignment.Center 
            sf.Trimming = StringTrimming.EllipsisPath 
            sf.FormatFlags = StringFormatFlags.NoWrap 
 
            g.DrawString(item.Text, imageList.Font, Brushes.Black, textRect, sf) 
            sf.Dispose() 
 
            ' we need to update the item rectangle for the space 
            ' we used up to draw the text 
            rc.Height -= textRect.Height 
         End If 
      End If 
 
      ' rc is the image rectangle 
      If (Not rc.IsEmpty) Then 
         ' now rc holds the rectangle to draw the image into 
 
         ' first, set the correct page 
         Dim savePage As Integer = -1 
         If item.Image.Page <> item.Page Then 
            ' the page is different 
 
            ' save current image page so we can set it back when we are done 
            savePage = item.Image.Page 
 
            ' disable the image events, we are going to set the page back, 
            ' so we do not want anybody subscribing to this image Changed 
            ' event to know we changed it. 
            item.Image.DisableEvents() 
 
            ' set new page 
            item.Image.Page = item.Page 
         End If 
 
         Try 
            ' we want to center the image into whatever left of rc 
            Dim itemImageSize As Size = imageList.ItemImageSize 
            Dim imageRect As Rectangle = New Rectangle(rc.Left + (rc.Width - itemImageSize.Width) \ 2, rc.Top + (rc.Height - itemImageSize.Height) \ 2, 
                                                       itemImageSize.Width, itemImageSize.Height) 
 
            ' we want to keep the aspect ratio 
            imageRect = RasterImageList.GetFixedAspectRatioImageRectangle(item.Image.ImageWidth, item.Image.ImageHeight, imageRect) 
 
            ' draw the image 
            Dim lRect As LeadRect = New LeadRect(imageRect.Left, imageRect.Top, imageRect.Width, imageRect.Height) 
            RasterImagePainter.Paint(item.Image, e.Graphics, lRect, imageList.PaintProperties) 
 
            ' finally, draw a black rectangle around the image 
            imageRect.Inflate(1, 1) 
            g.DrawRectangle(Pens.Black, imageRect.Left, imageRect.Top, imageRect.Width - 1, imageRect.Height - 1) 
         Finally 
            ' reset the old page 
            If savePage <> -1 Then 
               item.Image.Page = savePage 
 
               ' re-enable the events 
               item.Image.EnableEvents() 
            End If 
         End Try 
      End If 
   End Sub 
End Class 
 
Public Sub RasterImageList_DrawItem(ByVal title As String) 
   Dim form As MyForm3 = New MyForm3(title) 
   form.ShowDialog() 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class 

Requirements

Target Platforms

Help Version 19.0.2017.10.27
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Leadtools.WinForms Assembly