The width of a Label.

[Chris Dams]

Dear all,

After I change the text of a Label I would like to know what the width
of the Label is going to become. If I call the get_width() method it
only gives the right width if the text is changed is such a way that
the width does not change. If the width actually changes by modifying
the text then get_width() always returns the value 1. (This may have
something to do with the fact that the set_label() method is called
from an event handler.) Maybe there is a Pango call to find out the
width that some text is going to have?

The reason that I want to know this is that I have a Label of which
the text needs to change very frequently. The width of this Label is
one of the things that determines the width of my window. I don't like
the fact that changing the text of the label results in a change of
the width of the window all the time. Therefore, I would like to allow
the window to grow when the text doesn't fit anymore but not to shrink
when the text becomes less wide. I could do this if I know the natural
width of the text.

Thank you for your information!
Chris
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[milosz derezynski]

This is basically the "TreeView problem", namely so that TreeView, in order to determine certain drawing parameters, needs to make the cells actually render the text they are going to finally display in order for them to be able to provide the required size.

What you would need to do is to create a Pango::Layout (there's Gtk::Widget::create_pango_layout), set the parameters of that Layout so that they match all the parameters of the Label, then use Pango::Layout::get_pixel_extents() and use the logical extents to determine size and eventually account for any padding the Gtk::Label might use in any way.

HTH
Milosz

2008/8/18 Chris Dams <[e-mail]>

Dear all,

After I change the text of a Label I would like to know what the width
of the Label is going to become. If I call the get_width() method it
only gives the right width if the text is changed is such a way that
the width does not change. If the width actually changes by modifying
the text then get_width() always returns the value 1. (This may have
something to do with the fact that the set_label() method is called
from an event handler.) Maybe there is a Pango call to find out the
width that some text is going to have?

The reason that I want to know this is that I have a Label of which
the text needs to change very frequently. The width of this Label is
one of the things that determines the width of my window. I don't like
the fact that changing the text of the label results in a change of
the width of the window all the time. Therefore, I would like to allow
the window to grow when the text doesn't fit anymore but not to shrink
when the text becomes less wide. I could do this if I know the natural
width of the text.

Thank you for your information!
Chris
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