Added stairs plot support

README.md

@@ -61,6 +61,7 @@ created for 64-bit floats.
   - [x] Bar plot
     - [x] Vertical
     - [x] Horizontal
+  - [x] Stairs plot
   - [ ] Shaded plot
   - [ ] Stem plots
   - [ ] Images
@@ -70,7 +71,6 @@ created for 64-bit floats.
   - [ ] Heatmap
   - [ ] Pie chart
   - [ ] Digital data
-  - [ ] Stairs plot
   - [ ] Annotations
   - [ ] Dragline
   - [ ] Dragpoint

implot-examples/examples-shared/src/lib.rs

@@ -1,6 +1,7 @@
 pub mod bar_plots;
 pub mod line_plots;
 pub mod scatter_plots;
+pub mod stairs_plots;
 pub mod text_plots;
 
 use imgui::Ui;
@@ -11,4 +12,5 @@ pub fn show_demos(ui: &Ui, plot_ui: &PlotUi) {
     line_plots::show_demo_window(ui, plot_ui);
     scatter_plots::show_demo_window(ui, plot_ui);
     text_plots::show_demo_window(ui, plot_ui);
+    stairs_plots::show_demo_window(ui, plot_ui);
 }

implot-examples/examples-shared/src/stairs_plots.rs

@@ -0,0 +1,40 @@
+//! This example demonstrates how stairs plots are to be used. They are almost the same as line
+//! plots, so head over to the line plots example for more info.
+//!
+use imgui::{im_str, CollapsingHeader, Condition, Ui, Window};
+use implot::{Plot, PlotStairs, PlotUi};
+
+pub fn show_basic_plot(ui: &Ui, plot_ui: &PlotUi) {
+    ui.text_wrapped(im_str!(
+        "This header just plots a stairs-style line with as little code as possible."
+    ));
+    let content_width = ui.window_content_region_width();
+    Plot::new("Simple stairs plot")
+        // The size call could also be omitted, though the defaults don't consider window
+        // width, which is why we're not doing so here.
+        .size(content_width, 300.0)
+        .build(plot_ui, || {
+            // If this is called outside a plot build callback, the program will panic.
+            let x_positions = vec![0.1, 0.2, 0.5];
+            let y_positions = vec![0.1, 0.3, 0.9];
+            PlotStairs::new("legend label").plot(&x_positions, &y_positions);
+        });
+}
+
+pub fn show_demo_window(ui: &Ui, plot_ui: &PlotUi) {
+    Window::new(im_str!("Stairs plots example"))
+        .size([430.0, 450.0], Condition::FirstUseEver)
+        .build(ui, || {
+            ui.text(im_str!("Hello from implot-rs!"));
+            ui.text_wrapped(im_str!(
+                "The headers here demo the stairs plotting features of the library. \
+                 Have a look at the example source code to see how they are implemented.\n\
+                 Check out the demo from ImPlot itself first \
+                 for instructions on how to interact with ImPlot plots."
+            ));
+
+            if CollapsingHeader::new(im_str!("Basic stairs plot")).build(&ui) {
+                show_basic_plot(&ui, &plot_ui);
+            }
+        });
+}

src/plot_elements.rs

@@ -40,6 +40,40 @@ impl PlotLine {
     }
 }
 
+/// Struct to provide functionality for plotting a line in a plot with stairs style.
+pub struct PlotStairs {
+    /// Label to show in the legend for this line
+    label: String,
+}
+
+impl PlotStairs {
+    /// Create a new line to be plotted. Does not draw anything yet.
+    pub fn new(label: &str) -> Self {
+        Self {
+            label: label.to_owned(),
+        }
+    }
+
+    /// Plot a stairs style line. Use this in closures passed to
+    /// [`Plot::build()`](struct.Plot.html#method.build)
+    pub fn plot(&self, x: &Vec<f64>, y: &Vec<f64>) {
+        // If there is no data to plot, we stop here
+        if x.len().min(y.len()) == 0 {
+            return;
+        }
+        unsafe {
+            sys::ImPlot_PlotStairsdoublePtrdoublePtr(
+                im_str!("{}", self.label).as_ptr() as *const i8,
+                x.as_ptr(),
+                y.as_ptr(),
+                x.len().min(y.len()) as i32, // "as" casts saturate as of Rust 1.45. This is safe here.
+                0,                           // No offset
+                std::mem::size_of::<f64>() as i32, // Stride, set to one f64 for the standard use case
+            );
+        }
+    }
+}
+
 /// Struct to provide functionality for creating a scatter plot
 pub struct PlotScatter {
     /// Label to show in the legend for this scatter plot