text: add metrics and dynamic height

src/text.rs

@@ -76,14 +76,21 @@ pub fn measure(
     text: &str,
     markup: bool,
     scale: Option<f64>,
-) -> Result<Rect, TextError> {
+    full: bool,
+) -> Result<TextMeasurement, TextError> {
     let data = create_data(font, 1, 1, scale)?;
     if markup {
         data.layout.set_markup(text);
     } else {
         data.layout.set_text(text);
     }
-    Ok(data.layout.inc_pixel_rect())
+    let mut res = TextMeasurement::default();
+    res.ink_rect = data.layout.inc_pixel_rect();
+    if full {
+        res.logical_rect = data.layout.logical_pixel_rect();
+        res.baseline = data.layout.pixel_baseline();
+    }
+    Ok(res)
 }
 
 pub fn render(
@@ -96,13 +103,14 @@ pub fn render(
     scale: Option<f64>,
 ) -> Result<Rc<Texture>, TextError> {
     render2(
-        ctx, 1, width, height, 1, font, text, color, true, false, scale,
+        ctx, 1, None, width, height, 1, font, text, color, true, false, scale,
     )
 }
 
 fn render2(
     ctx: &Rc<RenderContext>,
     x: i32,
+    y: Option<i32>,
     width: i32,
     height: i32,
     padding: i32,
@@ -128,8 +136,8 @@ fn render2(
     data.cctx.set_operator(CAIRO_OPERATOR_SOURCE);
     data.cctx
         .set_source_rgba(color.r as _, color.g as _, color.b as _, color.a as _);
-    data.cctx
-        .move_to(x as f64, ((height - font_height) / 2) as f64);
+    let y = y.unwrap_or((height - font_height) / 2);
+    data.cctx.move_to(x as f64, y as f64);
     data.layout.show_layout();
     data.image.flush();
     let bytes = match data.image.data() {
@@ -144,19 +152,44 @@ fn render2(
 
 pub fn render_fitting(
     ctx: &Rc<RenderContext>,
-    height: i32,
+    height: Option<i32>,
     font: &str,
     text: &str,
     color: Color,
     markup: bool,
     scale: Option<f64>,
 ) -> Result<Rc<Texture>, TextError> {
-    let rect = measure(font, text, markup, scale)?;
-    render2(
+    render_fitting2(ctx, height, font, text, color, markup, scale, false).map(|(a, _)| a)
+}
+
+#[derive(Debug, Copy, Clone, Default)]
+pub struct TextMeasurement {
+    pub ink_rect: Rect,
+    pub logical_rect: Rect,
+    pub baseline: i32,
+}
+
+pub fn render_fitting2(
+    ctx: &Rc<RenderContext>,
+    height: Option<i32>,
+    font: &str,
+    text: &str,
+    color: Color,
+    markup: bool,
+    scale: Option<f64>,
+    include_measurements: bool,
+) -> Result<(Rc<Texture>, TextMeasurement), TextError> {
+    let measurement = measure(font, text, markup, scale, include_measurements)?;
+    let y = match height {
+        Some(_) => None,
+        _ => Some(measurement.ink_rect.y1().neg()),
+    };
+    let res = render2(
         ctx,
-        rect.x1().neg(),
-        rect.width(),
-        height,
+        measurement.ink_rect.x1().neg(),
+        y,
+        measurement.ink_rect.width(),
+        height.unwrap_or(measurement.ink_rect.height()),
         0,
         font,
         text,
@@ -164,5 +197,6 @@ pub fn render_fitting(
         false,
         markup,
         scale,
-    )
+    );
+    res.map(|r| (r, measurement))
 }