kaka.farm

commit 4a0791da47fc65cbd73d3f3fe1b58d74add5a527
parent 56146db34daa0f718194ece5201a6870d1001563
Author: Yuval Langer <yuval.langer@gmail.com>
Date:   Sat, 29 Jan 2022 02:55:15 +0200

Add Python/GTK GtkScale value-changed event handler stuff.

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content/2022-01-29-python-gtk-scale-value-changed-event-handler.md
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diff --git a/content/2022-01-29-python-gtk-scale-value-changed-event-handler.md b/content/2022-01-29-python-gtk-scale-value-changed-event-handler.md
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+title: Handling Python/GTK's GtkScale value-changed event.
+date: 2022-01-29
+
+It took me way too long, but now I know how to handle the value-changed event of GtkScale.
+
+In Glade:
+
+1. Create a GtkScale widget. We will ID it `foo_scale`.
+2. In the `Signals -> GtkRange -> value-changed` line change the `Handler`
+    field to something sensible like `on_foo_scale_value_changed`. That will
+    be the name of the handler.
+2. Make a new Adjustment in:
+
+    ```
+    General ->
+    Adjustment ->
+    (little pen button in the field) ->
+    Choose a [sic] Adjustment in this project ->
+    New
+    ```
+
+3. Rename the adjustment to something sensible like `foo_adjustment` and set
+    the `Value`, `Minimum Value`, `Maximum Value`, etc. Those are kind of self
+    explanatory…
+4. In Python, your handler will be called with a single argument - the signal
+    emitting object, which is the GtkScale object itself. It has a method,
+    `get_value()`, used to get its current value:
+
+    ```python
+    def on_foo_scale_value_changed(emitter):
+        scale_value = emitter.get_value()
+	do_stuff_with_scale_value(scale_value)
+    ```
+
+Fin.