LinkLabel Proposal

First of all I know that toga is not aimed to support widget primitives.

But there is already Label widget that serves for quite low level purposes:

• form inputs short description (like label in html)
• putting any text here or there (like paragraph in html (however there is need for MultiLineLabel https://github.com/beeware/toga/issues/766))

So I think it may be useful as useful is html tag.

Label-inherited POC for Winforms:

from toga_winforms.libs import WinForms
from toga_winforms.widgets.label import Label as WinFormsLabel


class WinformsLinkLabel(WinFormsLabel):
    def create(self):
        self.native = WinForms.LinkLabel()
        self.native.LinkClicked += WinForms.LinkLabelLinkClickedEventHandler(
            self.interface._link_clicked
        )
    

class LinkLabel(toga.Label):
    def __init__(self, text, link=None, id=None, style=None, factory=None):
        toga.Widget.__init__(self, id=id, style=style, factory=factory)

        self._impl = WinformsLinkLabel(interface=self)
        # self._impl = self.factory.Label(interface=self)

        self.link = link
        self.text = text
    
    @property
    def link(self):
        if self._link is None:
            return self.text
        return self._link
    
    @link.setter
    def link(self, link):
        self._link = link
    
    def _link_clicked(self, el, _):
        webbrowser.open(self.link)

My usecase: a dead simple GUI - with link to my repository. I wanted to avoid strange Button with URL inside (alternatively clickable github icon would be OK but not supported currently #774 outside of native commands palette), or create Group named “About” inside which will be “See on github” action, as it would be the only one command and on Windows it feels strange.

[samschott]

The API doesn’t need to be that complex, though

Fair point. Also, there is yet another option: have a single text attribute and a text_format attribute which can be for instance “plain”, “html” or another markup language such as “markdown” if this should be supported in the future. This works around having two different properties that hold the displayed text while still preventing ambiguity.

I’ll look into stripping certain html tags. Python’s XML parser may have trouble with self-closing html tags.

[freakboy3742]

That’s what I was afraid of - if we can’t get the size of the underlying text, then we can’t use the size of the text in layout calculations.

The HTMLLabel widget looks interesting. If I’m reading that right, it’s going back to basics - literally drawing all the component text. That seems slighly overkill under the circumstances, though.

In which case, having the Windows implementation be “concatenation of Winforms.Label” (and Winforms.LinkLabel, as needed) might be the easiest path forward.

As an aside/simplification, you should find that you can assign attributes directly, rather than invoking set_ methods - self.native.set_ReadOnly(True) should be equivalent to self.native.ReadOnly = True.