Method tile_view_info

egui_plot/src/items/heatmap.rs:330–389

(&self, ui: &Ui, transform: &PlotTransform, index: usize)

    }

    fn tile_view_info(&self, ui: &Ui, transform: &PlotTransform, index: usize) -> (Rect, Color32, Shape) {
        let v = self.values[index];

        let mut fill_color = if let Some(mapping) = &self.custom_mapping {
            mapping(v)
        } else {
            // convert to value in [0.0, 1.0]
            let v_rel = (v - self.min) / (self.max - self.min);

            // convert to color palette index
            let palette_index = (v_rel * (self.palette.len() - 1) as f64).round() as usize;

            self.palette[palette_index]
        };

        if self.highlight {
            let fill = Rgba::from(fill_color);
            let fill_alpha = (2.0 * fill.a()).at_most(1.0);
            let fill = fill.to_opaque().multiply(fill_alpha);
            fill_color = fill.into();
        }

        let x = index % self.cols;
        let y = index / self.cols;
        let tile_rect = transform.rect_from_values(
            &PlotPoint {
                x: self.pos.x + self.tile_size.x as f64 * x as f64,
                y: self.pos.y + self.tile_size.y as f64 * y as f64,
            },
            &PlotPoint {
                x: self.pos.x + self.tile_size.x as f64 * (x + 1) as f64,
                y: self.pos.y + self.tile_size.y as f64 * (y + 1) as f64,
            },
        );
        // Text

        let text: WidgetText = (self.formatter)(v).into();

        // calculate color that is readable on coloured tiles
        let luminance =
            0.2126 * fill_color.r() as f32 + 0.7151 * fill_color.g() as f32 + 0.0721 * fill_color.b() as f32;

        let inverted_color = if luminance < 140.0 {
            Color32::WHITE
        } else {
            Color32::BLACK
        };

        let text = text.color(inverted_color);
        let galley = text.into_galley(
            ui,
            Some(egui::TextWrapMode::Truncate),
            f32::INFINITY,
            TextStyle::Monospace,
        );
        let text_pos = tile_rect.center() - galley.size() / 2.0;

        let text = Shape::galley(text_pos, Arc::clone(&galley), Color32::WHITE);