RichTextBox changing Font Color using CFM_COLOR code

Question

I am developing a text editor in Windows Forms, for which I use RichTextBox widget. I came across a problem where, when selecting different styled text pieces, the selection would return a null value, which prevented me from, let's say, changing the size of a text that has parts of Verdana and Arial in it.

To solve this problem I created a new class that manipulates CHARFORMAT structure, and sends messages according to the style I want to change. Now I need to make a function that changes the font color of the user selection. For that, I need the CFM_COLOR tag, which I have no idea what it is, and I can't seem to find it anywhere.

    [Browsable(false)] 
    [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
    public Color SelectionFontColor
    {
        set
        {
            CHARFORMAT cf = new CHARFORMAT();
            cf.cbSize = Marshal.SizeOf(cf);
            cf.dwMask = CFM_COLOR;
            // There might be some missing code
            ???
            SendMessage(Handle, EM_SETCHARFORMAT, SCF_SELECTION, ref cf);
        }
    }

Answer 1

从referencesource.microsoft.com上的RichTextBoxConstants.cs ：

internal const int CFM_COLOR               = 0x40000000;

Answer 2

I came across a problem where, when selecting different styled text pieces, the selection would return a null value

I cannot reproduce your problem : for example, I select text with differents styles, and I colorize in Orange the selected text with richTextBox1.SelectionColor =>