bendns' repos / fimg
fast image operations
Diffstat (limited to 'src/drawing/text.rs')
-rw-r--r--src/drawing/text.rs88
1 files changed, 88 insertions, 0 deletions
diff --git a/src/drawing/text.rs b/src/drawing/text.rs
new file mode 100644
index 0000000..7c9cf27
--- /dev/null
+++ b/src/drawing/text.rs
@@ -0,0 +1,88 @@
+//! text raster
+
+use crate::Image;
+use fontdue::{layout::TextStyle, Font};
+use umath::FFloat;
+
+impl<T: AsMut<[u8]> + AsRef<[u8]>> Image<T, 4> {
+ /// Draw text.
+ ///
+ /// ```
+ /// # use fimg::Image;
+ /// let font = fontdue::Font::from_bytes(
+ /// &include_bytes!("../../tdata/CascadiaCode.ttf")[..],
+ /// fontdue::FontSettings {
+ /// scale: 200.0,
+ /// ..Default::default()
+ /// },
+ /// ).unwrap();
+ /// let mut i: Image<_, 4> = Image::alloc(750, 250).boxed();
+ /// i.text(50, 10, 200.0, &font, "hello", [0, 0, 0, 255]);
+ /// assert_eq!(i.buffer(), include_bytes!("../../tdata/text.imgbuf"));
+ /// ```
+ pub fn text(&mut self, x: u32, y: u32, size: f32, font: &Font, text: &str, color: [u8; 4]) {
+ let mut lay =
+ fontdue::layout::Layout::new(fontdue::layout::CoordinateSystem::PositiveYDown);
+ lay.append(&[font], &TextStyle::new(text, size, 0));
+ for glpyh in lay.glyphs() {
+ let (metrics, bitmap) = font.rasterize(glpyh.parent, size);
+ for i in 0..metrics.width {
+ for j in 0..metrics.height {
+ // SAFETY: the rasterizer kinda promises that metrics width and height are in bounds
+ let fg = [color[0], color[1], color[2], unsafe {
+ *bitmap.get_unchecked(j * metrics.width + i)
+ }];
+ let x = x + i as u32 + glpyh.x as u32;
+ if x >= self.width() {
+ continue;
+ }
+ let y = y + j as u32 + glpyh.y as u32;
+ if y >= self.height() {
+ continue;
+ }
+ // SAFETY: we clampin
+ let bg = unsafe { self.pixel_mut(x, y) };
+
+ blend(bg.try_into().unwrap(), fg);
+ }
+ }
+ }
+ }
+}
+
+pub fn blend(bg: &mut [u8; 4], fg: [u8; 4]) {
+ if fg[3] == 0 {
+ return;
+ }
+ if fg[3] == 255 {
+ *bg = fg;
+ return;
+ }
+ #[allow(clippy::multiple_unsafe_ops_per_block)]
+ // SAFETY: no u8 can possibly become INF / NAN
+ unsafe {
+ let max = FFloat::new(255.0);
+ let bg_a = FFloat::new(bg[3] as f32) / max;
+ let fg_a = FFloat::new(fg[3] as f32) / max;
+ let a = bg_a + fg_a - bg_a * fg_a;
+ if a == 0.0 {
+ return;
+ };
+ // could turn it into array::map
+ *bg = [
+ *(max
+ * ((((FFloat::new(fg[0] as f32) / max) * fg_a)
+ + ((FFloat::new(bg[0] as f32) / max) * bg_a) * (FFloat::new(1.0) - fg_a))
+ / a)) as u8,
+ *(max
+ * ((((FFloat::new(fg[1] as f32) / max) * fg_a)
+ + ((FFloat::new(bg[1] as f32) / max) * bg_a) * (FFloat::new(1.0) - fg_a))
+ / a)) as u8,
+ *(max
+ * ((((FFloat::new(fg[2] as f32) / max) * fg_a)
+ + ((FFloat::new(bg[2] as f32) / max) * bg_a) * (FFloat::new(1.0) - fg_a))
+ / a)) as u8,
+ *(max * a) as u8,
+ ]
+ }
+}