Switch to concrete error type

Author: siefkenj

examples/layout.rs

@@ -9,8 +9,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     root.fill(&full_palette::WHITE)?;
 
     let mut chart = ChartLayout::new(&root);
-    chart.set_title_text("Chart Title").unwrap();
-    chart.draw().unwrap();
+    chart.set_title_text("Chart Title")?.draw()?;
 
     Ok(())
 }

src/chart/layout/mod.rs

@@ -1,8 +1,8 @@
 use crate::coord::Shift;
 
-use crate::drawing::DrawingArea;
+use crate::drawing::{DrawingArea, DrawingAreaErrorKind};
 use crate::style::IntoFont;
-use crate::style::{colors, TextStyle};
+use crate::style::TextStyle;
 
 use plotters_backend::DrawingBackend;
 
@@ -32,7 +32,7 @@ impl<'a, 'b, DB: DrawingBackend> ChartLayout<'a, 'b, DB> {
         }
     }
 
-    pub fn draw(&mut self) -> Result<&mut Self, Box<dyn std::error::Error + 'a>> {
+    pub fn draw(&mut self) -> Result<&mut Self, DrawingAreaErrorKind<DB::ErrorType>> {
         let (x_range, y_range) = self.root_area.get_pixel_range();
         let (x_top, y_top) = (x_range.start, y_range.start);
         let (w, h) = (x_range.end - x_top, y_range.end - y_top);
@@ -54,11 +54,12 @@ impl<'a, 'b, DB: DrawingBackend> ChartLayout<'a, 'b, DB> {
     pub fn set_title_text<S: AsRef<str>>(
         &mut self,
         title: S,
-    ) -> Result<&mut Self, Box<dyn std::error::Error + 'a>> {
+    ) -> Result<&mut Self, DrawingAreaErrorKind<DB::ErrorType>> {
         self.title_text = Some(title.as_ref().to_string());
         let (w, h) = self
             .root_area
-            .estimate_text_size(&self.title_text.as_ref().unwrap(), &self.title_style)?;
+            .estimate_text_size(&self.title_text.as_ref().unwrap(), &self.title_style)
+            .unwrap();
         self.nodes.set_chart_title_size(w as i32, h as i32)?;
         Ok(self)
     }
@@ -87,4 +88,4 @@ mod test {
         let mut chart = ChartLayout::new(&drawing_area);
     }
 }
-*/
+*/

src/chart/layout/nodes.rs

@@ -66,7 +66,7 @@ macro_rules! impl_set_size {
                 &mut self,
                 w: i32,
                 h: i32,
-            ) -> Result<(), Box<dyn std::error::Error>> {
+            ) -> Result<(), stretch::Error> {
                 self.stretch_context.set_measure(
                     self.$name,
                     Some(new_measure_func_with_min_sizes(w as f32, h as f32)),
@@ -83,7 +83,7 @@ macro_rules! impl_set_size {
                 &mut self,
                 w: i32,
                 h: i32,
-            ) -> Result<(), Box<dyn std::error::Error>> {
+            ) -> Result<(), stretch::Error> {
                 self.stretch_context.set_measure(
                     self.$name.$sub_part,
                     Some(new_measure_func_with_min_sizes(w as f32, h as f32)),
@@ -106,7 +106,7 @@ pub(crate) struct CenteredLabelLayout {
 impl CenteredLabelLayout {
     /// Create an inner node that is `justify-content: center` with respect
     /// to its outer node.
-    fn new(stretch_context: &mut Stretch) -> Result<Self, Box<dyn std::error::Error>> {
+    fn new(stretch_context: &mut Stretch) -> Result<Self, stretch::Error> {
         let inner = stretch_context.new_leaf(
             Default::default(),
             Box::new(|constraint| {
@@ -127,7 +127,7 @@ impl CenteredLabelLayout {
         Ok(Self { inner, outer })
     }
     /// Create an inner node that is horizontally centered in its 100% width parent.
-    fn new_row_layout(stretch_context: &mut Stretch) -> Result<Self, Box<dyn std::error::Error>> {
+    fn new_row_layout(stretch_context: &mut Stretch) -> Result<Self, stretch::Error> {
         let layout = Self::new(stretch_context)?;
         // If the layout is placed in a row, the outer should have 100% width.
         let outer_style = *stretch_context.style(layout.outer)?;
@@ -142,7 +142,7 @@ impl CenteredLabelLayout {
         Ok(layout)
     }
     /// Create an inner node that is vertically centered in its 100% height parent.
-    fn new_col_layout(stretch_context: &mut Stretch) -> Result<Self, Box<dyn std::error::Error>> {
+    fn new_col_layout(stretch_context: &mut Stretch) -> Result<Self, stretch::Error> {
         let layout = Self::new(stretch_context)?;
         // If the layout is placed in a row, the outer should have 100% width.
         let outer_style = *stretch_context.style(layout.outer)?;
@@ -232,7 +232,7 @@ pub(crate) struct ChartLayoutNodes {
 impl ChartLayoutNodes {
     /// Create a new `ChartLayoutNodes`. All margins/padding/sizes are set to 0
     /// and should be overridden as needed.
-    pub fn new() -> Result<Self, Box<dyn std::error::Error>> {
+    pub fn new() -> Result<Self, stretch::Error> {
         // Set up the layout engine
         let mut stretch_context = Stretch::new();
 
@@ -312,7 +312,7 @@ impl ChartLayoutNodes {
     }
     /// Compute the layout of all items to fill a container of width
     /// `w` and height `h`.
-    pub fn layout(&mut self, w: u32, h: u32) -> Result<(), Box<dyn std::error::Error>> {
+    pub fn layout(&mut self, w: u32, h: u32) -> Result<(), stretch::Error> {
         // Compute the initial layout
         self.stretch_context.compute_layout(
             self.outer_container,
@@ -381,7 +381,7 @@ impl ChartLayoutNodes {
         &mut self,
         w: i32,
         h: i32,
-    ) -> Result<(), Box<dyn std::error::Error>> {
+    ) -> Result<(), stretch::Error> {
         self.stretch_context.set_measure(
             self.chart_area,
             Some(new_measure_func_with_min_sizes(w as f32, h as f32)),
@@ -420,7 +420,7 @@ impl ChartLayoutNodes {
 fn packed_title_label_area(
     stretch_context: &mut Stretch,
     flex_direction: FlexDirection,
-) -> Result<(Node, CenteredLabelLayout, Node), Box<dyn std::error::Error>> {
+) -> Result<(Node, CenteredLabelLayout, Node), stretch::Error> {
     let title = match flex_direction {
         FlexDirection::Row | FlexDirection::RowReverse => {
             // If the title and the label are packed in a row, the title should be centered in a *column*.

src/drawing/area.rs

@@ -141,6 +141,8 @@ pub enum DrawingAreaErrorKind<E: Error + Send + Sync> {
     SharingError,
     /// The error caused by invalid layout
     LayoutError,
+    /// Layout error coming from the Stretch library
+    StretchError(stretch::Error),
 }
 
 impl<E: Error + Send + Sync> std::fmt::Display for DrawingAreaErrorKind<E> {
@@ -151,12 +153,19 @@ impl<E: Error + Send + Sync> std::fmt::Display for DrawingAreaErrorKind<E> {
                 write!(fmt, "Multiple backend operation in progress")
             }
             DrawingAreaErrorKind::LayoutError => write!(fmt, "Bad layout"),
+            DrawingAreaErrorKind::StretchError(e) => e.fmt(fmt),
         }
     }
 }
 
 impl<E: Error + Send + Sync> Error for DrawingAreaErrorKind<E> {}
 
+impl<E: Error + Send + Sync> From<stretch::Error> for DrawingAreaErrorKind<E> {
+    fn from(err: stretch::Error) -> Self {
+        DrawingAreaErrorKind::StretchError(err)
+    }
+}
+
 #[allow(type_alias_bounds)]
 type DrawingAreaError<T: DrawingBackend> = DrawingAreaErrorKind<T::ErrorType>;