add preliminary support for user configurations

1 files changed, 127 insertions, 0 deletions

diff --git a/src/useropts.rs b/src/useropts.rs
new file mode 100644
index 0000000..e6de8de
--- /dev/null
+++ b/src/useropts.rs
@@ -0,0 +1,127 @@
+//! Support for loading user defined rendering options.
+//!
+//! User options are given in a toml file, for example
+//!
+//! ```toml
+//! skill_size = 20
+//! ```
+//!
+//! The file is automatically deserialized by serde, so all fields defined in
+//! [`UserOptions`](struct.UserOptions.html) can be used.
+use image::Rgba;
+use rusttype::Font;
+use serde::{Deserialize, Serialize};
+use std::{error::Error, fmt, fs, io, path::Path};
+
+use super::render::{Alignment, RenderOptions};
+
+/// Error that can occur during loading or converting user options.
+#[derive(Debug)]
+pub enum ConfigError {
+    Io(io::Error),
+    Serialization(toml::de::Error),
+    Font(rusttype::Error),
+}
+
+error_froms! {
+    ConfigError,
+    err: io::Error => ConfigError::Io(err),
+    err: toml::de::Error => ConfigError::Serialization(err),
+    err: rusttype::Error => ConfigError::Font(err),
+}
+
+impl fmt::Display for ConfigError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "ConfigError: ")?;
+        match *self {
+            ConfigError::Io(_) => write!(f, "input/output error"),
+            ConfigError::Serialization(_) => write!(f, "serialization error"),
+            ConfigError::Font(_) => write!(f, "could not load the font"),
+        }
+    }
+}
+
+impl Error for ConfigError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match *self {
+            ConfigError::Io(ref err) => Some(err),
+            ConfigError::Serialization(ref err) => Some(err),
+            ConfigError::Font(ref err) => Some(err),
+        }
+    }
+}
+
+macro_rules! maybe_take_from {
+    (from: $from:expr, to: $to:ident, $($field:ident,)*) => {
+        $(
+            if let Some(data) = $from.$field {
+                $to.$field = data;
+            }
+        )*
+    }
+}
+
+/// A struct for deserializing user defined options.
+///
+/// This is basically a struct containing the same fields, but optional. If a field is given, it
+/// should override the corresponding field in
+/// [`RenderOptions`](../render/struct.RenderOptions.html).
+///
+/// Some fields require some pre-processing, as the proper type cannot be serialized (e.g.
+/// `image::Rgba` for `background_color`).
+#[derive(Debug, Serialize, Deserialize)]
+pub struct UserOptions {
+    pub traitline_x_offset: Option<u32>,
+    pub trait_size: Option<u32>,
+    pub line_color: Option<[u8; 4]>,
+    pub line_height: Option<u32>,
+    pub text_size: Option<u32>,
+    pub background_color: Option<[u8; 4]>,
+    pub font_path: Option<String>,
+    pub render_specialization_names: Option<bool>,
+    pub skill_alignment: Option<Alignment>,
+}
+
+impl UserOptions {
+    /// Converts this `UserOptions` to a proper
+    /// [`RenderOptions`](../render/struct.RenderOptions.html).
+    pub fn convert(self) -> Result<RenderOptions, ConfigError> {
+        let mut result = RenderOptions::default();
+
+        if let Some(data) = self.background_color {
+            result.background_color = Rgba(data);
+        }
+
+        if let Some(data) = self.line_color {
+            result.line_color = Rgba(data);
+        }
+
+        if let Some(path) = self.font_path {
+            let data = fs::read(path)?;
+            let font = Font::from_bytes(data)?;
+            result.font = font;
+        }
+
+        maybe_take_from! {
+            from: self, to: result,
+            traitline_x_offset,
+            trait_size,
+            line_height,
+            text_size,
+            render_specialization_names,
+            skill_alignment,
+        }
+
+        Ok(result)
+    }
+}
+
+/// Load user given options from the given file path.
+///
+/// This is basically a convenience function around reading the data, deserializing it from toml
+/// and returning [`UserOptions::convert`](struct.UserOptions.html#method.convert).
+pub fn load_file<P: AsRef<Path>>(path: P) -> Result<RenderOptions, ConfigError> {
+    let data = fs::read(path)?;
+    let opts = toml::from_slice::<UserOptions>(&data)?;
+    opts.convert()
+}