.NET (Core and Framework)

Re: Combobox - DrawItem and dragging scroll bar problem [modified]

19-Jul-09 8:26

Hi,

I haven't done any ComboBox.DrawItem myself, however I use ListBopx.DrawItem a lot, and they are documented very similarly. Never had any problems. Is your CB double-buffered? is your Form? Mine normally are.

You haven't told in any detail what is wrong with the result.

here are some suggestions:
- if the comboBox.Items are strings, no need to call ToString()
- use the entire e.Bounds in DrawString, not just X and Y
- if the visual result does not provide a clue, I would add logging code to figure for which items DrawItem gets called/doesn't get called assuming some of the items are not repainted, hence show previous content.

BTW: the MSDN example on CB.DrawItem creates and doesn't dispose of its SolidBrush and Font!

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.

David Hovey19-Jul-09 11:51

David Hovey

19-Jul-09 11:51

Ok. Well here is the info I have.
I changed the code quite a bit. Created a custom combobox at runtime. Form and combobox are doublebuffered.
It also creates a log file showing index, bounds, and time of DrawItem method being executed.

To describe the problem. It would appear that the Background is not being drawn correctly (but this only describes the appearance-I don't think this is the cause). When I quickly scroll the entire list, to the end, the majority of the items appear as a "blob" of black as if all of the items were drawn over top of eachother. The odd thing is this is intermittent. Out of the 20 items shown in the drop down maybe 3 or 4 will be displayed correctly.

The log file shows that when quickly dragging through a list, the items are only being drawn on either the last or second to the last visible item bounds. When dragging up the items are only drawn on either the top or second visible item bounds. Since this is the case, internally, either Windows or the .NET framework, would have to be storing the item graphics and then be moving the previous item graphics up or down.
But if you click on the scroll bar to get the next or previous "page" all the items will be redrawn from top to bottom...

I uploaded the log file to my website http://www.hoveytech.com/drawitemlog.txt

Not sure where to go from here.

Thanks for your quick answers and continued help!

Public Class Form1
    Private m_fBold As Font
    Private WithEvents m_cboCustom1 As CustomCombo

    Private Sub m_cboCustom1_DrawItem(ByVal sender As Object, ByVal e As System.Windows.Forms.DrawItemEventArgs) Handles m_cboCustom1.DrawItem

        If e.Index = -1 Then
            Exit Sub
        End If

        e.DrawBackground()

        If e.Index Mod 4 = 0 Then
            e.Graphics.DrawString(m_cboCustom1.Items(e.Index).ToString(), m_fBold, Brushes.Black, e.Bounds)
        Else
            e.Graphics.DrawString(m_cboCustom1.Items(e.Index).ToString(), e.Font, Brushes.Black, e.Bounds)
        End If

        LogDrawItem(e.Index, e.State, e.Bounds)

    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load


        Me.DoubleBuffered = True

        m_cboCustom1 = New CustomCombo
        m_cboCustom1.Location = New Point(30, 30)
        m_cboCustom1.DropDownStyle = ComboBoxStyle.DropDownList
        m_cboCustom1.DrawMode = DrawMode.OwnerDrawVariable
        m_cboCustom1.MaxDropDownItems = 20
        Me.Controls.Add(m_cboCustom1)

        m_fBold = New Font(m_cboCustom1.Font, FontStyle.Bold)

        Dim i As Integer

        For i = 1 To 200
            m_cboCustom1.Items.Add(i)
        Next

    End Sub

    Private Sub LogDrawItem(ByVal iIndexDrawn As Integer, ByVal iState As System.Windows.Forms.DrawItemState, ByVal rect1 As Rectangle)

        Dim sw As System.IO.StreamWriter = New System.IO.StreamWriter(Application.StartupPath & "\drawitemlog.txt", True)

        sw.WriteLine("DrawItem method ran for index: " & iIndexDrawn.ToString() & vbTab & "bounds: " & rect1.ToString() & vbTab & "at " & Now().ToLongDateString & " " & Now().ToLongTimeString())

        sw.Close()

    End Sub
End Class

Public Class CustomCombo
    Inherits System.Windows.Forms.ComboBox

    Public Sub New()

        Me.DoubleBuffered = True

    End Sub
End Class

modified on Sunday, July 19, 2009 5:58 PM

Re: Combobox - DrawItem and dragging scroll bar problem

Luc Pattyn19-Jul-09 12:17

Re: Combobox - DrawItem and dragging scroll bar problem

19-Jul-09 12:17

Hi David,

I noticed you have chosen OwnerDrawVariable, which means each item has its own height, and before DrawItem fires a MeasureItem event gets fired, asking you for the height of the item.

Suggestion:
- try OwnerDrawFixed;
- or provide a MeasureItem handler.

With this fixed it works fine for me (also remove the logging in DrawItem for good responsiveness).

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.

David Hovey19-Jul-09 12:33

David Hovey

19-Jul-09 12:33

Thanks for your help!
It works now!!

loading text [modified]

deadcell_618-Jul-09 8:50

18-Jul-09 8:50

im wanting to click on a item in a listbox and load the txt file into a richtextbox from the folder my main program resides in

can anyone show me how to do this in c#?

modified on Saturday, July 18, 2009 3:01 PM

Luc Pattyn18-Jul-09 9:07

Re: loading text [modified]

18-Jul-09 9:07

What hzve you done so far? Which part of Pete's earlier and fine reply are you having trouble with?

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.

deadcell_618-Jul-09 9:11

18-Jul-09 9:11

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
if (listBox1.SelectedItem == (object)"New DVD")
{
TextBox1. <---- i want to load a text file here from this programs Data folder

modified on Saturday, July 18, 2009 3:19 PM

Luc Pattyn18-Jul-09 9:21

18-Jul-09 9:21

deadcell_6 wrote:
private void listBox1_SelectedIndexChanged(object sender, EventArgs e)

that is OK

deadcell_6 wrote:
if (listBox1.SelectedItem == (object)"New DVD")

that is terrible. Why would you cast to an object?
why would you include a literal string?

I guess your ListBox is showing filenames? if so, get the filename from the selected item.
Could be as easy as

if (listBox1.SelectedIndex>=0) {
    string filename=listBox1.Items[listBox1.SelectedIndex];
    string s=File.ReadAllText(filename);
    myTextBox.Text=s;
}

It probably could use some error handling and some refinement, but that is how it goes.

If all of this is new to you, I strongly recommend you this advice[^]. And do consider reading some CodeProject articles as well!

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.

deadcell_618-Jul-09 9:30

18-Jul-09 9:30

thank you

now say i have 10 text files and my code is

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
if (listBox1.SelectedItem == (object)"DVD 1")
{
TextBox1 <--- and i want to display dvd 1.txt

}
else if (listBox1.SelectedItem == (object)"DVD 2")
TextBox1 <---- and i want to display dvd 2.txt

else if (listBox1.SelectedItem == (object)"DVD 3")
TextBox1

else if (listBox1.SelectedItem == (object)"DVD 4")
TextBox1
......

sry im very new Smile | :)

this is what i have now and i think it would be easier to update the txt files as i get more dvds

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
if (listBox1.SelectedItem == (object)"DVD 1")
{
TextBox1.Text = "horror" +Environment.NewLine + "actors:";
}

molesworth18-Jul-09 10:02

molesworth

18-Jul-09 10:02

deadcell_6 wrote:
private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
if (listBox1.SelectedItem == (object)"DVD 1")
{
TextBox1 <--- and i want to display dvd 1.txt

}
else if (listBox1.SelectedItem == (object)"DVD 2")
TextBox1 <---- and i want to display dvd 2.txt

else if (listBox1.SelectedItem == (object)"DVD 3")
...

Eeek!!

Seriously, you need to learn some more of the basics of how to organise and manage data first.

How do you think an application that handles hundreds , or thousands, of pieces of information works? It certainly isn't by having a seaprate "if..." for each one.

Find out about structures, arrays, and file handling (then eventually maybe databases) and think about what information you have and how you want to organise it.

There are three kinds of people in the world - those who can count and those who can't...

C#.net Display

eyeshield2118-Jul-09 5:55

eyeshield21

18-Jul-09 5:55

I develop the application using C#.net in windows xp (english version)
when I run the application the display (image) still good
but when I deploy to another computer which using windows xp (chinese version)
the display (image) become not good

does anyone knows why it happen and how to solve it?

regards,
andy

Re: C#.net Display

Luc Pattyn18-Jul-09 9:08

Re: How to create a set up

18-Jul-09 9:08

eyeshield21 wrote:
the display (image) become not good

sure, that must be because your code is not good.

read my sig!

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

The quality and detail of your question reflects on the effectiveness of the help you are likely to get.
Show formatted code inside PRE tags, and give clear symptoms when describing a problem.

Re: C#.net Display

Eddy Vluggen18-Jul-09 9:14

Eddy Vluggen

18-Jul-09 9:14

Is the image localized?

Printable DataGrid

danishkhawar18-Jul-09 4:47

danishkhawar

18-Jul-09 4:47

can we make printable grid of simple dot net grid, and can we print our form objects with grid? I am trying to create my own report builder for C# forms application

Re: Printable DataGrid

Ravi Bhavnani18-Jul-09 6:10

Ravi Bhavnani

18-Jul-09 6:10

Does this[^] article help?

/ravi

My new year resolution: 2048 x 1536
Home | Articles | My .NET bits | Freeware
ravib(at)ravib(dot)com

How to create a set up

ksss_maheshece17-Jul-09 23:21

ksss_maheshece

17-Jul-09 23:21

Hello friends,
I waana create a set for my window based apllication.I should include some com components like crystal report,ms word-2005.Can u explain me in detail.Thank u.

Cheers,
MAHESH

Abhijit Jana18-Jul-09 1:40

Abhijit Jana

18-Jul-09 1:40

Visual Studio Windows Application Setup Project
and

Creating Setup and Deployment Projects in VS.NET

cheers,
Abhijit
CodeProject MVP
Web Site:abhijitjana.net
My Latest Article : IIS Remote Debugging

Re: How to create a set up

ksss_maheshece18-Jul-09 6:43

ksss_maheshece

18-Jul-09 6:43

Thank u for your help.It's really Useful for me.

Re: How to create a set up

Abhijit Jana19-Jul-09 0:15

Abhijit Jana

19-Jul-09 0:15

Nice to know its help you. Thumbs Up | :thumbsup:

cheers,
Abhijit
CodeProject MVP
Web Site:abhijitjana.net
My Latest Article : IIS Remote Debugging

Listbox help please

deadcell_617-Jul-09 21:37

How to Set Order of Properties in Property Grid VB.NET 2

17-Jul-09 21:37

i want to have a listbox with a bunch of dvds i own, and when i click a dvd i want it to display info about the movie in a richtextbox in C#.net

Re: Listbox help please

Pete O'Hanlon17-Jul-09 22:45

Pete O'Hanlon

17-Jul-09 22:45

deadcell_6 wrote:
i want to have a listbox with a bunch of dvds i own, and when i click a dvd i want it to display info about the movie in a richtextbox in C#.net

So retrieve your data from a database, bind it to the listbox and react to the selection changed index.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

My blog | My articles | MoXAML PowerToys | Onyx

luongmai17-Jul-09 5:54

luongmai

17-Jul-09 5:54

I have an expandable property, TextLength, with six properties.

TextLength.All = 0
TextLength.ACCAComment = 60
TextLength.AxisDescription = 60
TextLength.Footer = 60
TextLength.GraphicsComment = 60
TextLength.Title = 60

VB.NET 2.0 displays the properties sorted as:

TextLength.ACCAComment = 60
TextLength.All = 0
TextLength.AxisDescription = 60
TextLength.Footer = 60
TextLength.GraphicsComment = 60
TextLength.Title = 60

How can I set the order as:

TextLength.All = 0
TextLength.ACCAComment = 60
TextLength.AxisDescription = 60
TextLength.Footer = 60
TextLength.GraphicsComment = 60
TextLength.Title = 60

In VB.Net 3.5, we can use PropertyOrder(number)

Thanks

Re: How to Set Order of Properties in Property Grid VB.NET 2

Luc Pattyn17-Jul-09 10:39