add example

Cargo.lock

@@ -4983,6 +4983,15 @@ dependencies = [
  "linked-hash-map",
 ]
 
+[[package]]
+name = "z_order"
+version = "0.1.0"
+dependencies = [
+ "eframe",
+ "log",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "zbus"
 version = "3.6.0"

examples/z_order/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "z_order"
+version = "0.1.0"
+authors = ["Max Stoumen <max@mxs.dev>"]
+license = "MIT OR Apache-2.0"
+edition = "2021"
+rust-version = "1.65"
+publish = false
+
+
+[dependencies]
+eframe = { path = "../../crates/eframe", features = [
+    "__screenshot", # __screenshot is so we can dump a screenshot using EFRAME_SCREENSHOT_TO
+] }
+log = "0.4.17"
+tracing-subscriber = "0.3"

examples/z_order/README.md

@@ -0,0 +1,7 @@
+Example for how to set Z-order for drawing and interaction.
+
+```sh
+cargo run -p z_order
+```
+
+![](screenshot.png)

examples/z_order/src/main.rs

@@ -0,0 +1,82 @@
+#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")] // hide console window on Windows in release
+
+use eframe::{
+    egui::{self, layers::ZOrder, Sense, Ui},
+    epaint::{Color32, Rect, Rounding, Vec2},
+};
+
+fn main() -> Result<(), eframe::Error> {
+    // Log to stdout (if you run with `RUST_LOG=debug`).
+    tracing_subscriber::fmt::init();
+
+    let options = eframe::NativeOptions {
+        initial_window_size: Some(egui::vec2(220.0, 150.0)),
+        ..Default::default()
+    };
+    eframe::run_native(
+        "Z Order Test",
+        options,
+        Box::new(|_cc| Box::new(MyApp::default())),
+    )
+}
+
+#[derive(Default)]
+struct MyApp {}
+
+impl eframe::App for MyApp {
+    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
+        egui::CentralPanel::default().show(ctx, |ui| {
+            ui.label("The left example should show blue over green. The right should show green over blue.");
+
+            egui::Frame::default()
+                .fill(ui.style().visuals.window_fill)
+                .inner_margin(10.0)
+                .show(ui, |ui| {
+                    const SIZE: Vec2 = Vec2::new(50.0, 50.0);
+                    const DELTA: Vec2 = Vec2::new(20.0, 20.0);
+
+                    fn draw_squares(
+                        ui: &mut Ui,
+                        shift: Vec2,
+                        order1: ZOrder,
+                        order2: ZOrder,
+                    ) {
+                        let pos = ui.max_rect().left_top();
+
+                        ui.with_z(order1, |ui| {
+                            let response = ui.allocate_rect(
+                                Rect::from_min_size(pos + shift, SIZE),
+                                Sense::click(),
+                            );
+
+                            let painter = ui.painter_at(response.rect);
+                            painter.rect_filled(response.rect, Rounding::none(), Color32::GREEN);
+
+                            if response.clicked() {
+                                log::info!("Clicked green");
+                            }
+                        });
+
+                        ui.with_z(order2, |ui| {
+                            let response = ui.allocate_rect(
+                                Rect::from_min_size(pos + DELTA + shift, SIZE),
+                                Sense::click(),
+                            );
+                            let painter = ui.painter_at(response.rect);
+                            painter.rect_filled(response.rect, Rounding::none(), Color32::BLUE);
+
+                            if response.clicked() {
+                                log::info!("Clicked blue");
+                            }
+                        });
+                    }
+
+                    let base = ZOrder::base();
+                    let above = base.above();
+
+                    draw_squares(ui, Vec2::new(0.0, 0.0), base, above);
+                    draw_squares(ui, Vec2::new(100.0, 0.0), above, base);
+                })
+        });
+    }
+}