Added a readme and re-ordered the crate a bit

Author: sanbox-irl

README.md

@@ -1,7 +1,84 @@
 # imgui-winit-support
 
-See the examples for [`imgui-glium-renderer`][glium] or [`imgui-glow-renderer`][glow]
-for simple examples of this platform backend with different renderers
+This crate provides a winit-based backend platform for [`imgui-rs`].
 
-[glium]: ../../imgui-glium-renderer/examples
-[glow]: ../../imgui-glow-renderer/examples
+A backend platform handles window/input device events and manages their state.
+
+# Using the library
+
+There are five things you need to do to use this library correctly:
+
+1. Initialize a [`WinitPlatform`] instance.
+2. Attach it to a winit [`Window`] with [`WinitPlatform::attach_window`].
+3. Pass events to the platform (every frame) with [`WinitPlatform::handle_event`].
+4. Call the frame preparation callback [`WinitPlatform::prepare_frame`] (every frame)
+5. Call the render preparation callback [`WinitPlatform::prepare_render`] (every frame)
+
+## Complete example (without a renderer)
+
+```no_run
+use imgui::Context;
+use imgui_winit_support::{HiDpiMode, WinitPlatform};
+use std::time::Instant;
+use winit::event::{Event, WindowEvent};
+use winit::event_loop::{ControlFlow, EventLoop};
+use winit::window::Window;
+
+let mut event_loop = EventLoop::new().expect("Failed to create EventLoop");
+let mut window = Window::new(&event_loop).unwrap();
+
+let mut imgui = Context::create();
+// configure imgui-rs Context if necessary
+
+let mut platform = WinitPlatform::init(&mut imgui); // step 1
+platform.attach_window(imgui.io_mut(), &window, HiDpiMode::Default); // step 2
+
+let mut last_frame = Instant::now();
+let mut run = true;
+event_loop.run(move |event, window_target| {
+    match event {
+        Event::NewEvents(_) => {
+            // other application-specific logic
+            let now = Instant::now();
+            imgui.io_mut().update_delta_time(now - last_frame);
+            last_frame = now;
+        },
+        Event::AboutToWait => {
+            // other application-specific logic
+            platform.prepare_frame(imgui.io_mut(), &window) // step 4
+                .expect("Failed to prepare frame");
+            window.request_redraw();
+        }
+        Event::WindowEvent { event: WindowEvent::RedrawRequested, .. } => {
+            let ui = imgui.frame();
+            // application-specific rendering *under the UI*
+
+            // construct the UI
+
+            platform.prepare_render(&ui, &window); // step 5
+            // render the UI with a renderer
+            let draw_data = imgui.render();
+            // renderer.render(..., draw_data).expect("UI rendering failed");
+
+            // application-specific rendering *over the UI*
+        },
+        Event::WindowEvent { event: WindowEvent::CloseRequested, .. } => {
+            window_target.exit();
+        }
+        // other application-specific event handling
+        event => {
+            platform.handle_event(imgui.io_mut(), &window, &event); // step 3
+            // other application-specific event handling
+        }
+    }
+}).expect("EventLoop error");
+```
+
+## License
+
+Licensed under either of
+
+- Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or https://www.apache.org/licenses/LICENSE-2.0)
+- MIT license ([LICENSE-MIT](LICENSE-MIT) or https://opensource.org/licenses/MIT)
+
+at your option.