Pregunta

I have a combobox and I need to populate it with all the available fonts in the system - their actual name, style, etc...

From all the information I can find online, I am able to put together the DrawItem event, but I keep running into the following error, "Cannot invoke non-delegate type 'System.Drawing.Font'" In fact, I borrowed line per line from other websites and made some changes. So, I thought it should have worked.

Here is how I populate the items list in the ComboBox:

method MainForm.MainForm_Load(sender: System.Object; e: System.EventArgs);
var thefont:Font;
begin
    if (ComboBox4.Items.Count>0) then
        ComboBox4.Items.Clear;

    for each oneFontFamily in FontFamily.Families do
    begin
        if (oneFontFamily.IsStyleAvailable(FontStyle.Regular)) then
            thefont := new Font(oneFontFamily.Name, 15)
        else if (oneFontFamily.IsStyleAvailable(FontStyle.Bold)) then
            thefont := new Font(oneFontFamily.Name, 15,FontStyle.Bold)
        else if (oneFontFamily.IsStyleAvailable(FontStyle.Italic)) then
            thefont := new Font(oneFontFamily.Name, 15,FontStyle.Italic)
        else if (oneFontFamily.IsStyleAvailable(FontStyle.Strikeout)) then
            thefont := new Font(oneFontFamily.Name, 15, FontStyle.Strikeout)
        else if (oneFontFamily.isStyleAvailable(FontStyle.Underline)) then
            thefont := new Font(oneFontFamily.Name, 15, FontStyle.Underline);

    if (thefont <> nil) then
        ComboBox4.Items.Add(theFont);
        end;
end;

Here is the combobox4 drawitem event:

method MainForm.comboBox4_DrawItem(sender: System.Object; e: System.Windows.Forms.DrawItemEventArgs);
begin
    if e.index = -1 then exit;

    // Draw the background of the item
    e.DrawBackground();

    // Should we draw the focus rectangle
    if ((e.State and DrawItemState.Focus) <> DrawItemState.Checked) then
        e.DrawFocusRectangle();

        // Create a new background brush.
        var b := new SolidBrush(e.ForeColor);

        // Draw the item.
        // This line raises the above mentioned error.
        e.Graphics.DrawString(FontFamily(comboBox4.Items[e.Index]).Name, font(comboBox4.Items[e.Index]), b, e.Bounds.x,e.Bounds.y);  <<===== Here is where the error is raised
end;

UPDATED: I modified the line that was causing the error and it compiles without error now but as I stated in my comment it is not drawing the fonts in their own style and size.

e.Graphics.DrawString(FontFamily(comboBox4.Items[e.Index]).Name, new font((comboBox4.Items[e.Index] as Font), (comboBox4.Items[e.Index] as Font).Style), b, e.Bounds.x,e.Bounds.y);

UPDATE: I forgot to set the DrawMode to OwnerDrawFixed. Now it is calling my DrawItem Event but still not drawing the Fonts in their own style and sizes.

I want the combobox to look like the following image:

someone else's combobox

Not like mine below:

actual Image of the winform with combobox

¿Fue útil?

Solución 2

Here is my answer with working code.

  • create a new project and open your main winform. Open your ToolBox and place a combobox on your mainform.
  • Open the property window for the combobox that you just placed on the winform.
  • Set the following properties for your combobox as follows: DrawMode = OwnerDrawFixed, DropDownStyle = DropDownList, FormattingEnabled = true, GenerateMemeber = true, IntegralHeight = false and ItemHeight = 25.
    • Create Mainform_Load method by double clicking on the main winform and copy the following code accordingly to your load method.

,

Method MainForm.MainForm_Load(sender: System.Object; e:System.EvenArgs);
var 
   thefont:Font;
begin
if (ComboBox1.Items.Count>0) then
   ComboBox1.Items.Clear;

for each oneFontFamily in FontFamily.Families do
begin
    if (oneFontFamily.IsStyleAvailable(FontStyle.Regular)) then
        thefont := new Font(oneFontFamily.Name, 12)
    else if (oneFontFamily.IsStyleAvailable(FontStyle.Bold)) then
        thefont := new Font(oneFontFamily.Name, 12,FontStyle.Bold)
    else if (oneFontFamily.IsStyleAvailable(FontStyle.Italic)) then
        thefont := new Font(oneFontFamily.Name, 12,FontStyle.Italic)
    else if (oneFontFamily.IsStyleAvailable(FontStyle.Strikeout)) then
        thefont := new Font(oneFontFamily.Name, 12, FontStyle.Strikeout)
    else if (oneFontFamily.isStyleAvailable(FontStyle.Underline)) then
        thefont := new Font(oneFontFamily.Name, 12, FontStyle.Underline);

    if (thefont <> nil) then
        ComboBox1.Items.Add(theFont);
end;
end;
  • Create DrawItem event for the your comboBox and copy the following code accordingly into your drawitem event.

'

    Method MainForm.ComboBox1_DrawItem(sender:System.Object; e: System.Windows.Forms.DrawItemEventArgs);
    var theobject:Font;
    begin
       if e.Index=-1 then exit;
       // Draw the background of the item
       e.DrawBackground();

       // Should we draw the focus rectangle
       if ((e.State and DrawItemState.Focus) <> DrawItemState.Checked) then
          e.DrawFocusRectangle();

       // Create a new background brush.
       var b := new SolidBrush(e.ForeColor);
       theobject := (ComboBox1.Items[e.Index] as font);

       // Draw the item.
       e.Graphics.DrawString(theobject.Name, theObject, b,e.Bounds);
    end;

When you have it all done and running you should have a combobox1 displaying fonts as follows:

ComboBox displaying Font Text

Otros consejos

Here is something that most probably helps you: http://www.vbaccelerator.com/home/net/code/controls/ListBox_and_ComboBox/Font_Picker/article.asp

Be sure to implement the required infrastructure from this article too, though: http://www.vbaccelerator.com/home/NET/Code/Controls/ListBox_and_ComboBox/Icon_ComboBox/article.asp

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