new text

src/drawing/text.rs

@@ -5,17 +5,22 @@ use crate::definitions::{Clamp, Image};
 use crate::drawing::Canvas;
 use crate::pixelops::weighted_sum;
 
-use ab_glyph::{point, Font, GlyphId, OutlinedGlyph, PxScale, Rect, ScaleFont};
+use ab_glyph::{point, Font, GlyphId, OutlinedGlyph, PxScale, ScaleFont};
 
 fn layout_glyphs(
     scale: impl Into<PxScale> + Copy,
     font: &impl Font,
     text: &str,
-    mut f: impl FnMut(OutlinedGlyph, Rect),
+    mut f: impl FnMut(OutlinedGlyph, (i32, i32)),
 ) -> (u32, u32) {
+    if text.is_empty() {
+        return (0, 0);
+    }
     let font = font.as_scaled(scale);
 
-    let mut w = 0f32;
+    let first_char = text.chars().next().unwrap();
+    let first_glyph = font.glyph_id(first_char);
+    let mut w = font.h_side_bearing(first_glyph).abs();
     let mut prev: Option<GlyphId> = None;
 
     for c in text.chars() {
@@ -28,11 +33,17 @@ fn layout_glyphs(
             }
             prev = Some(glyph_id);
             let bb = g.px_bounds();
-            f(g, bb);
+            let bbx = bb.min.x as i32;
+            let bby = bb.min.y as i32;
+            f(g, (bbx, bby));
         }
     }
 
-    (w as u32, font.height() as u32)
+    let w = w.ceil();
+    let h = font.height().ceil();
+    assert!(w >= 0.0);
+    assert!(h >= 0.0);
+    (w as u32, h as u32)
 }
 
 /// Get the width and height of the given text, rendered with the given font and scale.
@@ -64,6 +75,7 @@ where
     draw_text_mut(&mut out, color, x, y, scale, font, text);
     out
 }
+
 #[doc=generate_mut_doc_comment!("draw_text")]
 pub fn draw_text_mut<C>(
     canvas: &mut C,
@@ -80,12 +92,12 @@ pub fn draw_text_mut<C>(
     let image_width = canvas.width() as i32;
     let image_height = canvas.height() as i32;
 
-    layout_glyphs(scale, font, text, |g, bb| {
-        let bbx = x + bb.min.x.round() as i32;
-        let bby = y + bb.min.y.round() as i32;
+    layout_glyphs(scale, font, text, |g, (bbx, bby)| {
+        let x_shift = x + bbx;
+        let y_shift = y + bby;
         g.draw(|gx, gy, gv| {
-            let image_x = gx as i32 + bbx;
-            let image_y = gy as i32 + bby;
+            let image_x = gx as i32 + x_shift;
+            let image_y = gy as i32 + y_shift;
 
             if (0..image_width).contains(&image_x) && (0..image_height).contains(&image_y) {
                 let image_x = image_x as u32;
@@ -98,3 +110,43 @@ pub fn draw_text_mut<C>(
         })
     });
 }
+
+//#[cfg(not(miri))]
+#[cfg(test)]
+mod proptests {
+    use super::*;
+    use crate::{
+        proptest_utils::arbitrary_image_with,
+        rect::{Rect, Region},
+    };
+    use ab_glyph::FontRef;
+    use image::Luma;
+    use proptest::prelude::*;
+
+    const FONT_BYTES: &[u8] = include_bytes!("../../tests/data/fonts/DejaVuSans.ttf");
+
+    proptest! {
+        #[test]
+        fn proptest_text_size(
+            x in 0..100,
+            y in 0..100,
+            scale in 0.0..100f32,
+            ref text in "[0-9a-zA-Z]*",
+            img in arbitrary_image_with::<Luma<u8>>(Just(0), 0..=100, 0..=100),
+        ) {
+            let font = FontRef::try_from_slice(FONT_BYTES).unwrap();
+            let background = Luma([0]);
+            let text_color = Luma([255u8]);
+
+            let img = draw_text(&img, text_color, x, y, scale, &font, text);
+
+            let (text_w, text_h) = text_size(scale, &font, text);
+            let rect = Rect::at(x, y).of_size(1 + text_w, 1 + text_h);  // TODO: fix Rect::contains
+            for (px, py, &p) in img.enumerate_pixels() {
+                if !rect.contains(px as i32, py as i32) {
+                    assert_eq!(p, background, "pixel_position: {:?}, rect: {:?}", (px, py), rect);
+                }
+            }
+        }
+    }
+}