RichTextBox sometimes does not assign Font in GraphicsUnit.Pixel

zequion 151

In WinForms, I create a Font System.Drawing.Font using System.Drawing.GraphicsUnit.Pixel and assign it to a RichTextBox.Font or RichTextBox.SelectionFont control

As I am now working more with this command, I have noticed that sometimes when running MyRichTextBox.Font = MyFont; assigns all values except GraphicsUnit.Pixel and assigns GraphicsUnit.Point

I've been testing this problem for several days and I can't find any sense in it.

In addition, I am seeing that RichTextBox.SelectionFont only uses points even if pixels are indicated. I show it in this example.
According to Microsoft: "If no text is currently selected, the font specified in this property is applied to the current insertion point and to all text that is typed into the control after the insertion point." So it should always be assignable even if no text is selected.

I need SelectionFont to use Pixels as units because I use a combobox that shows the size of the text in the place where the cursor is located and since SelectionFont uses points, it shows the value wrong and then I should use a function that converts points to pixels and I prefer not do it.

Can someone look at the RichTextBox source code to find out why? I've looked a bit but as they constantly use the SendMessage command I don't know anything. Why use that command?

ThRControl_ = new System.Windows.Forms.RichTextBox();  
  
System.Drawing.Font MyFont  = new System.Drawing.Font("Microsoft Sans Serif", 12, System.Drawing.GraphicsUnit.Pixel);  
System.Drawing.Font MyFont1 = new System.Drawing.Font("Arial", 22, System.Drawing.GraphicsUnit.Pixel);  
  
ThRControl_.Font = MyFont;  
ThRControl_.SelectionFont = MyFont1;

Viorel 112.1K Reputation points

2022-09-02T08:09:23.627+00:00

I think that it is better to use points instead of pixels, because the size in pixels looks differently on other monitors. (The height of text will depend on resolution).

In addition, the RTF file format, which is associated with RichTextBox, uses half-points to define the size.

The Font class has the SizeInPoints member, which can be used in your combobox.

The WordPad application (included in Windows), which is based on RichTextBox, seems to use points.

Therefore, maybe it has sense to use points instead of pixels.
zequion 151 Reputation points

2022-09-02T09:56:09.343+00:00

There is a Combobox where the user enters the font size. I don't know if points are used in other countries, but here in Spain only pixels are used. Anyone knows how big a font is going to be at 12px and no one knows what it will be like at 12pt. In any case, it is not explained that SelectionFont only uses points when, for example, when assigning "Font", it detects it and assigns the font and translates from pixels to points.

In any case, it would be necessary to know if there is a function to convert from any format to another. Now I have the problem that if the user enters 12px in the ComboBox, it will translate to points. So when hovering the SelectionFont is detected and I have to translate from dots to pixels and using decimals the user might see 11.99 instead of 12 or 12.49 instead of 12.5 and so on. It's not that easy to make it perfect as the user entered it.
Jack J Jun 24,286 Reputation points Microsoft Vendor

2022-09-30T02:45:42.827+00:00

@zequion , Welcome to Microsoft Q&A, sorry for the late response, let me confirm your question again, now do you want to want a function to get the decimal like 11.99?
zequion 91 Reputation points

2022-09-30T03:46:21.43+00:00

You can close the topic.