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winformsfontsdispose

Windows Form Fonts Questions Part 2

Continue to my previous question (link)

What if I want to assign the font of a new user control to its creator's font. Should I do this a):

newControl = new MyControl(...);
...    
newControl.Font = this.Font;

or this b)?

newControl = new MyControl(...);
...
newControl.Font = (Font)this.Font.Clone();

If answer is a), what will happen to the new user control's font if the creator's font get disposed (for example, a window closed by user)?

Thanks,

Gilbert

Solution

  • The Font class actually encapsulates two things:

    • A text style

    • A GDI handle that may be used to draw text with that style

    The text style encapsulated by a Font class is immutable; the handle is "disposable immutable", meaning that it will never encapsulate any GDI handle other than the one with which it was created, but once the Font is disposed it will cease to encapsulate any font handle (it becomes truly immutable, albeit useless, at that point).

    Setting the Font property of the controls in the Framework will cause it to grab two things:

    • The identity of the Font object used to set the property, which is used solely by the Font property getter

    • The text style, which the control will use to create its own private Font object.

    Because each Framework control will inherently clone any Font instance used to set its Font property, there's generally no need for user code to clone a font before using it to set another control's Font property.