Plotter: add control on how to resolve the axes origin label drawing …

…and possibility to override axes text adaptive contrast behaviour (#2)

* allow for selecting which axis has priority when having to resolve a label conflict (i.e.: not displaying the 0 label on both axes)

* add stroke overrides for axes, nasty hack

* comment

* spelling mistakes

* pr feedback

* pr feedback, remove custom colors and use bool to drive adaptive contrast

crates/egui_extras/src/table.rs

@@ -546,7 +546,7 @@ pub struct Table<'a> {
 
 /// Returned from [`Table::body`]. Contains information about the way the table has been built by the context.
 pub struct TableOutput {
-    /// The response recieved upon the creation of the table's header, if one was defined.
+    /// The response received upon the creation of the table's header, if one was defined.
     pub header_response: Option<Response>,
 
     /// The output of the [`ScrollArea`] containing the table body's contents.

crates/egui_plot/src/lib.rs

@@ -236,8 +236,14 @@ pub struct Plot {
     show_y: bool,
     label_formatter: LabelFormatter,
     coordinates_formatter: Option<(Corner, CoordinatesFormatter)>,
+<<<<<<< HEAD:crates/egui_plot/src/lib.rs
     x_axes: Vec<AxisHints>, // default x axes
     y_axes: Vec<AxisHints>, // default y axes
+=======
+    axis_formatters: [AxisFormatter; 2],
+    x_axis_origin_label_has_priority: bool,
+    axis_text_use_adaptive_contrast: [bool; 2],
+>>>>>>> e76d03b9 (Plotter: add control on how to resolve the axes origin label drawing and possibility to override axes text adaptive contrast behaviour (#2)):crates/egui/src/widgets/plot/mod.rs
     legend_config: Option<Legend>,
     show_background: bool,
     show_axes: AxisBools,
@@ -278,8 +284,14 @@ impl Plot {
             show_y: true,
             label_formatter: None,
             coordinates_formatter: None,
+<<<<<<< HEAD:crates/egui_plot/src/lib.rs
             x_axes: vec![Default::default()],
             y_axes: vec![Default::default()],
+=======
+            axis_formatters: [None, None], // [None; 2] requires Copy
+            x_axis_origin_label_has_priority: true,
+            axis_text_use_adaptive_contrast: [true, true],
+>>>>>>> e76d03b9 (Plotter: add control on how to resolve the axes origin label drawing and possibility to override axes text adaptive contrast behaviour (#2)):crates/egui/src/widgets/plot/mod.rs
             legend_config: None,
             show_background: true,
             show_axes: true.into(),
@@ -446,6 +458,62 @@ impl Plot {
         self
     }
 
+<<<<<<< HEAD:crates/egui_plot/src/lib.rs
+=======
+    /// Provide a function to customize the labels for the X axis based on the current visible value range.
+    ///
+    /// This is useful for custom input domains, e.g. date/time.
+    ///
+    /// If axis labels should not appear for certain values or beyond a certain zoom/resolution,
+    /// the formatter function can return empty strings. This is also useful if your domain is
+    /// discrete (e.g. only full days in a calendar).
+    pub fn x_axis_formatter(
+        mut self,
+        func: impl Fn(f64, &RangeInclusive<f64>) -> String + 'static,
+    ) -> Self {
+        self.axis_formatters[0] = Some(Box::new(func));
+        self
+    }
+
+    /// Provide a function to customize the labels for the Y axis based on the current value range.
+    ///
+    /// This is useful for custom value representation, e.g. percentage or units.
+    ///
+    /// If axis labels should not appear for certain values or beyond a certain zoom/resolution,
+    /// the formatter function can return empty strings. This is also useful if your Y values are
+    /// discrete (e.g. only integers).
+    pub fn y_axis_formatter(
+        mut self,
+        func: impl Fn(f64, &RangeInclusive<f64>) -> String + 'static,
+    ) -> Self {
+        self.axis_formatters[1] = Some(Box::new(func));
+        self
+    }
+
+    /// Set the priority of the X axis origin label. Default: `true`.
+    /// This defines which label has display priority when resolving the overlapping of the origin (0.0) labels.
+    pub fn x_axis_origin_label_has_priority(mut self, val: bool) -> Self {
+        self.x_axis_origin_label_has_priority = val;
+        self
+    }
+
+    /// Overrides the default behaviour of the X axis' text rendering.
+    /// Always use the ui foreground color instead of calculating the color of the stroke using the `color_from_contrast` calculations,
+    /// which blends the background and foreground colors according to a defined contrast
+    pub fn x_axis_text_adaptive_contrast(mut self, val: bool) -> Self {
+        self.axis_text_use_adaptive_contrast[0] = val;
+        self
+    }
+
+    /// Overrides the default behaviour of the Y axis' text rendering.
+    /// Always use the ui foreground color instead of calculating the color of the stroke using the `color_from_contrast` calculations,
+    /// which blends the background and foreground colors according to a defined contrast
+    pub fn y_axis_text_adaptive_contrast(mut self, val: bool) -> Self {
+        self.axis_text_use_adaptive_contrast[1] = val;
+        self
+    }
+
+>>>>>>> e76d03b9 (Plotter: add control on how to resolve the axes origin label drawing and possibility to override axes text adaptive contrast behaviour (#2)):crates/egui/src/widgets/plot/mod.rs
     /// Configure how the grid in the background is spaced apart along the X axis.
     ///
     /// Default is a log-10 grid, i.e. every plot unit is divided into 10 other units.
@@ -719,8 +787,14 @@ impl Plot {
             mut show_y,
             label_formatter,
             coordinates_formatter,
+<<<<<<< HEAD:crates/egui_plot/src/lib.rs
             x_axes,
             y_axes,
+=======
+            axis_formatters,
+            x_axis_origin_label_has_priority,
+            axis_text_use_adaptive_contrast,
+>>>>>>> e76d03b9 (Plotter: add control on how to resolve the axes origin label drawing and possibility to override axes text adaptive contrast behaviour (#2)):crates/egui/src/widgets/plot/mod.rs
             legend_config,
             reset,
             show_background,
@@ -1179,6 +1253,9 @@ impl Plot {
             grid_spacers,
             sharp_grid_lines,
             clamp_grid,
+
+            x_axis_origin_label_has_priority,
+            axis_text_use_adaptive_contrast,
         };
 
         let plot_cursors = prepared.ui(ui, &response);
@@ -1552,7 +1629,11 @@ pub struct GridInput {
 }
 
 /// One mark (horizontal or vertical line) in the background grid of a plot.
+<<<<<<< HEAD:crates/egui_plot/src/lib.rs
 #[derive(Debug, Clone, Copy)]
+=======
+#[derive(Debug)]
+>>>>>>> e76d03b9 (Plotter: add control on how to resolve the axes origin label drawing and possibility to override axes text adaptive contrast behaviour (#2)):crates/egui/src/widgets/plot/mod.rs
 pub struct GridMark {
     /// X or Y value in the plot.
     pub value: f64,
@@ -1624,6 +1705,9 @@ struct PreparedPlot {
 
     sharp_grid_lines: bool,
     clamp_grid: bool,
+
+    x_axis_origin_label_has_priority: bool,
+    axis_text_use_adaptive_contrast: [bool; 2],
 }
 
 impl PreparedPlot {
@@ -1807,6 +1891,61 @@ impl PreparedPlot {
                     line_strength,
                 ));
             }
+<<<<<<< HEAD:crates/egui_plot/src/lib.rs
+=======
+
+            const MIN_TEXT_SPACING: f32 = 40.0;
+            if spacing_in_points > MIN_TEXT_SPACING {
+                let text_strength =
+                    remap_clamp(spacing_in_points, MIN_TEXT_SPACING..=150.0, 0.0..=1.0);
+
+                let color = if self.axis_text_use_adaptive_contrast[axis] {
+                    color_from_contrast(ui, text_strength)
+                } else {
+                    ui.visuals().widgets.open.fg_stroke.color
+                };
+
+                let text: String = if let Some(formatter) = axis_formatters[axis].as_deref() {
+                    formatter(value_main, &axis_range)
+                } else {
+                    emath::round_to_decimals(value_main, 5).to_string() // hack
+                };
+
+                // Skip origin label for the axis that doesn't have priority, if the axis with priority is already showing it (otherwise it's displayed twice)
+                let priority_axis_idx = if self.x_axis_origin_label_has_priority {
+                    0
+                } else {
+                    1
+                };
+                let skip_low_priority_origin =
+                    axis != priority_axis_idx && other_axis_shown && value_main == 0.0;
+
+                // Custom formatters can return empty string to signal "no label at this resolution"
+                if !text.is_empty() && !skip_low_priority_origin {
+                    let galley = ui.painter().layout_no_wrap(text, font_id.clone(), color);
+
+                    let mut text_pos = pos_in_gui + vec2(1.0, -galley.size().y);
+
+                    // Make sure we see the labels, even if the axis is off-screen:
+                    text_pos[1 - axis] = text_pos[1 - axis]
+                        .at_most(transform.frame().max[1 - axis] - galley.size()[1 - axis] - 2.0)
+                        .at_least(transform.frame().min[1 - axis] + 1.0);
+
+                    shapes.push((Shape::galley(text_pos, galley), text_strength));
+                }
+            }
+        }
+
+        fn color_from_contrast(ui: &Ui, contrast: f32) -> Color32 {
+            let bg = ui.visuals().extreme_bg_color;
+            let fg = ui.visuals().widgets.open.fg_stroke.color;
+            let mix = 0.5 * contrast.sqrt();
+            Color32::from_rgb(
+                lerp((bg.r() as f32)..=(fg.r() as f32), mix) as u8,
+                lerp((bg.g() as f32)..=(fg.g() as f32), mix) as u8,
+                lerp((bg.b() as f32)..=(fg.b() as f32), mix) as u8,
+            )
+>>>>>>> e76d03b9 (Plotter: add control on how to resolve the axes origin label drawing and possibility to override axes text adaptive contrast behaviour (#2)):crates/egui/src/widgets/plot/mod.rs
         }
     }