* Closes https://github.com/emilk/egui/issues/1010
### In short
You can now put interactive widgets, like buttons and hyperlinks, in an
tooltip using `on_hover_ui`. If you do, the tooltip will stay open as
long as the user hovers it.
There is a new demo for this in the egui demo app (egui.rs):

### Design
Tooltips can now contain interactive widgets, such as buttons and links.
If they do, they will stay open when the user moves their pointer over
them.
Widgets that do not contain interactive widgets disappear as soon as you
no longer hover the underlying widget, just like before. This is so that
they won't annoy the user.
To ensure not all tooltips with text in them are considered interactive,
`selectable_labels` is `false` for tooltips contents by default. If you
want selectable text in tooltips, either change the `selectable_labels`
setting, or use `Label::selectable`.
```rs
ui.label("Hover me").on_hover_ui(|ui| {
ui.style_mut().interaction.selectable_labels = true;
ui.label("This text can be selected.");
ui.add(egui::Label::new("This too.").selectable(true));
});
```
### Changes
* Layers in `Order::Tooltip` can now be interacted with
⚠️ Removes `Context::translate_layer`, replacing it with a sticky
`set_transform_layer`
Adds the capability to scale layers.
Allows interaction with scaled and transformed widgets inside
transformed layers.
I've also added a demo of how to have zooming and panning in a window
(see the video below).
This probably closes#1811. Having a panning and zooming container would
just be creating a new
`Area` with a new id, and applying zooming and panning with
`ctx.transform_layer`.
I've run the github workflow scripts in my repository, so hopefully the
formatting and `cargo cranky` is satisfied.
I'm not sure if all call sites where transforms would be relevant have
been handled. This might also be missing are transforming clipping
rects, but I'm not sure where / how to accomplish that. In the demo, the
clipping rect is transformed to match, which seems to work.
https://github.com/emilk/egui/assets/70821802/77e7e743-cdfe-402f-86e3-7744b3ee7b0f
---------
Co-authored-by: tweoss <fchua@puffer5.stanford.edu>
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
* Closes https://github.com/emilk/egui/issues/3816

Turn off with `style.interaction.multi_widget_text_select`.
There is an API for this in `LabelSelectionState`, but it's pretty
bare-bones.
This became really hairy implementation-wise, but it works decently
well.
# Limitations
* Drag-select to scroll doesn't work
* A selection disappears if you scroll past one of its end-points
* Only the text of labels and links are selectable
## TODO
* [x] An option to turn it off
* [x] An API for querying about the selected text, and to deselect it.
* [x] Scrolling past selection behaves weird
* [x] Shift-click to select a range
* Part of https://github.com/emilk/egui/issues/3556
## In short
You now almost never need to use `eframe::Frame` - instead use
`ui.input(|i| i.viewport())` for information about the current viewport
(native window), and use `ctx.send_viewport_cmd` to modify it.
## In detail
This PR removes most commands from `eframe::Frame`, and replaces them
with `ViewportCommand`.
So `frame.close()` becomes
`ctx.send_viewport_cmd(ViewportCommand::Close)`, etc.
`frame.info().window_info` is now also gone, replaced with `ui.input(|i|
i.viewport())`.
`frame.info().native_pixels_per_point` is replaced with `ui.input(|i|
i.raw.native_pixels_per_point)`.
`RawInput` now contains one `ViewportInfo` for each viewport.
Screenshots are taken with
`ctx.send_viewport_cmd(ViewportCommand::Screenshots)` and are returned
in `egui::Event` which you can check with:
``` ust
ui.input(|i| {
for event in &i.raw.events {
if let egui::Event::Screenshot { viewport_id, image } = event {
// handle it here
}
}
});
```
### Motivation
You no longer need to pass around the `&eframe::Frame` everywhere.
This also opens the door for other integrations to use the same API of
`ViewportCommand`s.
* Add `TextFormat::extra_letter_spacing`
* Add control of line height
* Add to text layout demo
* Move the text layout demo to its own window in the demo app
* Fix doclink
* Better document points vs pixels
* Better documentation and code cleanup