autocommit 2022-02-19 19:41:18 CET

src/text.rs

@@ -0,0 +1,67 @@
+use crate::format::ARGB8888;
+use crate::render::{RenderContext, Texture};
+use crate::theme::Color;
+use crate::RenderError;
+use cairo::{ImageSurface, Operator};
+use pango::{EllipsizeMode, Layout};
+use pangocairo::cairo::Format;
+use pangocairo::pango::FontDescription;
+use pangocairo::{cairo, pango};
+use std::mem;
+use std::rc::Rc;
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum TextError {
+    #[error("Could not create a cairo image")]
+    CreateImage(#[source] cairo::Error),
+    #[error("Could not create a cairo context")]
+    CairoContext(#[source] cairo::Error),
+    #[error("Could not create a pango context")]
+    PangoContext,
+    #[error("Could not import the rendered text")]
+    RenderError(#[source] RenderError),
+    #[error("Could not access the cairo image data")]
+    ImageData,
+}
+
+pub fn render(
+    ctx: &Rc<RenderContext>,
+    width: i32,
+    height: i32,
+    font: &str,
+    text: &str,
+    color: Color,
+) -> Result<Rc<Texture>, TextError> {
+    let image = match ImageSurface::create(Format::ARgb32, width, height) {
+        Ok(s) => s,
+        Err(e) => return Err(TextError::CreateImage(e)),
+    };
+    let cctx = match cairo::Context::new(&image) {
+        Ok(c) => c,
+        Err(e) => return Err(TextError::CairoContext(e)),
+    };
+    let pctx = match pangocairo::create_context(&cctx) {
+        Some(c) => c,
+        _ => return Err(TextError::PangoContext),
+    };
+    let fd = FontDescription::from_string(font);
+    let layout = Layout::new(&pctx);
+    layout.set_width(width * pango::SCALE);
+    layout.set_ellipsize(EllipsizeMode::End);
+    layout.set_font_description(Some(&fd));
+    layout.set_text(text);
+    cctx.set_operator(Operator::Source);
+    cctx.set_source_rgba(color.r as _, color.g as _, color.b as _, color.a as _);
+    pangocairo::show_layout(&cctx, &layout);
+    let mut texture = None;
+    let _ = image.with_data(|d| unsafe {
+        let d = mem::transmute(d);
+        texture = Some(ctx.shmem_texture(d, ARGB8888, width, height, image.stride()));
+    });
+    match texture {
+        Some(Ok(t)) => Ok(t),
+        Some(Err(e)) => Err(TextError::RenderError(e)),
+        None => Err(TextError::ImageData),
+    }
+}