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egui_extras: enable virtual scroll for heterogenous rows

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Introduce `TableBody.heterogenous_rows` and `TableRowBuilder`, the former of which takes as an argument the latter. `TableRowBuilder` provides two methods that enable virtual scrolling for rows with non-uniform heights. Those methods are:

* `TableRowBuilder.row_heights` which returns an iterator over `f32` to allow incremental virtual scroll buffer calculation.
* `TableRowBuilder.populate_row` which `TableBody.heterogenous_rows` uses to allow `TableRowBuilder` implementations to, you guessed it, populate rows that are visible.

One thought that occurs to me while writing this description is that
`TableBody.heterogenous_rows` could look more like the following:

```
    pub fn heterogenous_rows(
        mut self,
        row_heights: impl Iterator<Item = f32> + '_,
        mut row: impl FnMut(usize, TableRow<'_, '_>),
    )
```

This could potentially be easier to use, considering all the trouble I had coming up with and implementing the trait. Happy to make this change if the maintainers prefer.
This commit is contained in:
Wayne Warren
2022-04-03 00:18:04 -06:00
parent 5dff1e42c6
commit e81a92d32d
2 changed files with 132 additions and 43 deletions
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90
egui_demo_lib/src/apps/demo/table_demo.rs
View File

@@ -1,5 +1,5 @@
use egui::TextStyle;
use egui_extras::{Size, StripBuilder, TableBuilder};
use egui_extras::{Size, StripBuilder, TableBuilder, TableRow, TableRowBuilder};
/// Shows off a table with dynamic layout
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
@@ -75,7 +75,7 @@ impl TableDemo {
});
});
})
.body(|mut body| {
.body(|body| {
if self.virtual_scroll {
body.rows(text_height, 100_000, |row_index, mut row| {
row.col(|ui| {
@@ -91,37 +91,71 @@ impl TableDemo {
});
});
} else {
for row_index in 0..20 {
let thick = row_index % 6 == 0;
let row_height = if thick { 30.0 } else { 18.0 };
body.row(row_height, |mut row| {
row.col(|ui| {
ui.centered_and_justified(|ui| {
ui.label(row_index.to_string());
});
});
row.col(|ui| {
ui.centered_and_justified(|ui| {
ui.label(clock_emoji(row_index));
});
});
row.col(|ui| {
ui.centered_and_justified(|ui| {
ui.style_mut().wrap = Some(false);
if thick {
ui.heading("Extra thick row");
} else {
ui.label("Normal row");
}
});
});
});
}
let row_builder = DemoRowBuilder {
row_count: 100000,
};
body.heterogenous_rows(row_builder);
}
});
}
}
struct DemoRowBuilder {
row_count: usize,
}
struct DemoRows {
row_count: usize,
current_row: usize,
}
impl Iterator for DemoRows {
type Item = f32;
fn next(&mut self) -> Option<Self::Item> {
if self.current_row < self.row_count {
let thick = self.current_row % 6 == 0;
self.current_row += 1;
Some(if thick { 30.0 } else { 18.0 })
} else {
None
}
}
}
impl TableRowBuilder for DemoRowBuilder {
fn row_heights(&self, _: &Vec<f32>) -> Box<dyn Iterator<Item = f32>> {
Box::new(DemoRows{
row_count: self.row_count,
current_row: 0,
})
}
fn populate_row(&self, index: usize, mut row: TableRow<'_, '_>) {
let thick = index % 6 == 0;
row.col(|ui| {
ui.centered_and_justified(|ui| {
ui.label(index.to_string());
});
});
row.col(|ui| {
ui.centered_and_justified(|ui| {
ui.label(clock_emoji(index));
});
});
row.col(|ui| {
ui.centered_and_justified(|ui| {
ui.style_mut().wrap = Some(false);
if thick {
ui.heading("Extra thick row");
} else {
ui.label("Normal row");
}
});
});
}
}
fn clock_emoji(row_index: usize) -> String {
char::from_u32(0x1f550 + row_index as u32 % 24)
.unwrap()