feat(custom): progress bar widget.

Resolves partially #68.

docs/modules/Custom.md

@@ -17,11 +17,11 @@ You can think of these like HTML elements and their attributes.
 
 Every widget has the following options available; `type` is mandatory.
 
-| Name    | Type                                                | Default | Description                   |
-|---------|-----------------------------------------------------|---------|-------------------------------|
-| `type`  | `box` or `label` or `button` or `image` or `slider` | `null`  | Type of GTK widget to create. |
-| `name`  | `string`                                            | `null`  | Widget name.                  |
-| `class` | `string`                                            | `null`  | Widget class name.            |
+| Name    | Type                                                              | Default | Description                   |
+|---------|-------------------------------------------------------------------|---------|-------------------------------|
+| `type`  | `box` or `label` or `button` or `image` or `slider` or `progress` | `null`  | Type of GTK widget to create. |
+| `name`  | `string`                                                          | `null`  | Widget name.                  |
+| `class` | `string`                                                          | `null`  | Widget class name.            |
 
 #### Box
 
@@ -86,9 +86,6 @@ If your input program requires an integer, you will need to round it.
 | `max`         | `float`                                            | `100`        | Maximum slider value.                                                        | 
 | `length`      | `integer`                                          | `null`       | Slider length. GTK will automatically size if left unset.                    |
 
-Note that `on_change` will provide the **floating point** value as an argument. 
-If your input program requires an integer, you will need to round it. 
-
 The example slider widget below shows a volume control for MPC, 
 which updates the server when changed, and polls the server for volume changes to keep the slider in sync.
 
@@ -107,6 +104,40 @@ $slider = {
 }
 ```
 
+#### Progress
+
+A progress bar.
+
+> Type: `progress`
+
+Note that `value` expects a numeric value **between 0-`max`** as output.
+
+| Name          | Type                                               | Default      | Description                                                                     |
+|---------------|----------------------------------------------------|--------------|---------------------------------------------------------------------------------|
+| `src`         | `image`                                            | `null`       | Image source. See [here](images) for information on images.                     |
+| `size`        | `integer`                                          | `null`       | Width/height of the image. Aspect ratio is preserved.                           |
+| `orientation` | `horizontal` or `vertical` (shorthand: `h` or `v`) | `horizontal` | Orientation of the slider.                                                      |
+| `value`       | `Script`                                           | `null`       | Script to run to get the progress bar value. Output must be a valid percentage. |
+| `max`         | `float`                                            | `100`        | Maximum progress bar value.                                                     | 
+| `length`      | `integer`                                          | `null`       | Slider length. GTK will automatically size if left unset.                       |
+
+The example below shows progress for the current playing song in MPD, 
+and displays the elapsed/length timestamps as a label above:
+
+```corn
+$progress = { 
+    type = "custom" 
+    bar = [
+        {
+            type = "progress"
+            value = "500:mpc | sed -n 2p | awk '{ print $4 }' | grep -Eo '[0-9]+'"
+            label = "{{500:mpc | sed -n 2p | awk '{ print $3 }'}} elapsed"
+            length = 200
+        }
+    ] 
+}
+```
+
 ### Label Attributes
 
 > ℹ This is different to the `label` widget, although applies to it.

src/modules/custom/mod.rs

@@ -2,6 +2,7 @@ mod r#box;
 mod button;
 mod image;
 mod label;
+mod progress;
 mod slider;
 
 use self::image::ImageWidget;
@@ -10,6 +11,7 @@ use self::r#box::BoxWidget;
 use self::slider::SliderWidget;
 use crate::config::CommonConfig;
 use crate::modules::custom::button::ButtonWidget;
+use crate::modules::custom::progress::ProgressWidget;
 use crate::modules::{Module, ModuleInfo, ModuleUpdateEvent, ModuleWidget, WidgetContext};
 use crate::popup::WidgetGeometry;
 use crate::script::Script;
@@ -52,6 +54,7 @@ pub enum Widget {
     Button(ButtonWidget),
     Image(ImageWidget),
     Slider(SliderWidget),
+    Progress(ProgressWidget),
 }
 
 #[derive(Clone, Copy)]
@@ -76,6 +79,7 @@ impl Widget {
             Widget::Button(widget) => parent.add(&widget.into_widget(context)),
             Widget::Image(widget) => parent.add(&widget.into_widget(context)),
             Widget::Slider(widget) => parent.add(&widget.into_widget(context)),
+            Widget::Progress(widget) => parent.add(&widget.into_widget(context)),
         }
     }
 }

src/modules/custom/progress.rs

@@ -0,0 +1,93 @@
+use super::{try_get_orientation, CustomWidget, CustomWidgetContext};
+use crate::dynamic_string::DynamicString;
+use crate::script::{OutputStream, Script, ScriptInput};
+use crate::send;
+use gtk::prelude::*;
+use gtk::{Orientation, ProgressBar};
+use serde::Deserialize;
+use tokio::spawn;
+use tracing::error;
+
+#[derive(Debug, Deserialize, Clone)]
+pub struct ProgressWidget {
+    name: Option<String>,
+    class: Option<String>,
+    orientation: Option<String>,
+    label: Option<String>,
+    value: Option<ScriptInput>,
+    #[serde(default = "default_max")]
+    max: f64,
+    length: Option<i32>,
+}
+
+const fn default_max() -> f64 {
+    100.0
+}
+
+// TODO: Reduce duplication with slider, other widgets.
+impl CustomWidget for ProgressWidget {
+    type Widget = ProgressBar;
+
+    fn into_widget(self, context: CustomWidgetContext) -> Self::Widget {
+        let mut builder = ProgressBar::builder();
+
+        if let Some(name) = self.name {
+            builder = builder.name(name);
+        }
+
+        if let Some(orientation) = self.orientation {
+            builder = builder
+                .orientation(try_get_orientation(&orientation).unwrap_or(context.bar_orientation));
+        }
+
+        if let Some(length) = self.length {
+            builder = match context.bar_orientation {
+                Orientation::Horizontal => builder.width_request(length),
+                Orientation::Vertical => builder.height_request(length),
+                _ => builder,
+            }
+        }
+
+        let progress = builder.build();
+
+        if let Some(class) = self.class {
+            progress.style_context().add_class(&class);
+        }
+
+        if let Some(value) = self.value {
+            let script = Script::from(value);
+            let progress = progress.clone();
+
+            let (tx, rx) = glib::MainContext::channel(glib::PRIORITY_DEFAULT);
+
+            spawn(async move {
+                script
+                    .run(None, move |stream, _success| match stream {
+                        OutputStream::Stdout(out) => match out.parse::<f64>() {
+                            Ok(value) => send!(tx, value),
+                            Err(err) => error!("{err:?}"),
+                        },
+                        OutputStream::Stderr(err) => error!("{err:?}"),
+                    })
+                    .await;
+            });
+
+            rx.attach(None, move |value| {
+                progress.set_fraction(value / self.max);
+                Continue(true)
+            });
+        }
+
+        if let Some(text) = self.label {
+            let progress = progress.clone();
+            progress.set_show_text(true);
+
+            DynamicString::new(&text, move |string| {
+                progress.set_text(Some(&string));
+                Continue(true)
+            });
+        }
+
+        progress
+    }
+}

src/modules/custom/slider.rs

@@ -1,4 +1,4 @@
-use crate::modules::custom::{try_get_orientation, CustomWidget, CustomWidgetContext, ExecEvent};
+use super::{try_get_orientation, CustomWidget, CustomWidgetContext, ExecEvent};
 use crate::popup::Popup;
 use crate::script::{OutputStream, Script, ScriptInput};
 use crate::{send, try_send};