fix: text sensor placement (#13)

Fixes #11

CHANGELOG.md

@@ -9,18 +9,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 _Changes in the next release_
 
+### Fixed
+- Misplaced text sensors in custom panels (#11).
+
 ### Added
-- Simple sensor panel with a file-based data source (#6) 
-- Initial support for fan-, progress-, & pointer-sensors (#8)
-- Use [mdBook](https://rust-lang.github.io/mdBook/) for documentation and publish user guide to GitHub pages (#10)
+- Simple sensor panel with a file-based data source (#6). 
+- Initial support for fan-, progress-, & pointer-sensors (#8).
+- Use [mdBook](https://rust-lang.github.io/mdBook/) for documentation and publish user guide to GitHub pages (#10).
 
 ### Changed
-- Project structure using a Cargo workspace
+- Project structure using a Cargo workspace.
 
 ---
 
 ## v0.1.0 - 2025-08-02
 ### Added
-- Initial `asterctl` tool release for controlling the LCD: on, off, display an image
+- Initial `asterctl` tool release for controlling the LCD: on, off, display an image.
 - systemd service file to switch off LCD on system start.
-- Demo mode
+- Demo mode.

crates/asterctl/src/render.rs

@@ -212,8 +212,10 @@ impl PanelRenderer {
         };
         let font_size = sensor.font_size.unwrap_or(14) as f32;
         // TODO verify pixel scaling! Is font_size point size or pixel size?
-        // This is still a bit off compared to the original AOOSTAR-X. Only tested with HarmonyOS_Sans_SC_Bold!
-        let adjustment_hack = 0.7;
+        // TODO some font size calculation is missing, dpi scaling? internal padding?
+        //      The adjustment hack is required to get the correct size of the rendered text.
+        //      However, the y-position requires the regular value (see multiplication by 1.33 below)
+        let adjustment_hack = 0.75;
         let scale = font.pt_to_px_scale(font_size * adjustment_hack).unwrap();
 
         let text = format_value(
@@ -223,14 +225,19 @@ impl PanelRenderer {
             unit,
         );
         let size = text_size(scale, &font, &text);
-        // TODO verify x & y-coordinate handling
+        let width = sensor.width.unwrap_or_default() as i32;
+        let height = sensor.height.unwrap_or_default() as i32;
         let x = match sensor.text_align.unwrap_or_default() {
             TextAlign::Left => sensor.x,
-            TextAlign::Center => sensor.x - (size.0 / 2) as i32,
-            TextAlign::Right => sensor.x - size.0 as i32,
+            TextAlign::Center => sensor.x + width / 2 - (size.0 / 2) as i32,
+            TextAlign::Right => sensor.x + width - size.0 as i32,
         };
-        let y = (sensor.y as f32 - scale.y / 2f32) as i32;
-        // let y = sensor.y as i32 - (size.1 / 2) as i32;
+        // FIXME figure out font scaling factor / padding / dpi etc. See above for y-adjustment hack.
+        // This work quite ok for most panels, but not all!
+        // Some work better with `sensor.y + height / 2 - size.1 as i32;`
+        // The y parameter in `draw_text_mut` is still a mystery: drawing text at position (0,0)
+        // renders a huge gap at the top, about the size of half the font-height!?
+        let y = sensor.y + height / 2 - (size.1 as f32 * 1.3333 / 2f32) as i32;
 
         debug!(
             "Sensor({:03},{:03}), pixel({x:03},{y:03}), size{size:?}: {text}",