Completely unsafe example using SDL2

Cargo.toml

@@ -1,3 +1,7 @@
 [workspace]
-members = ["lvgl-sys", "lvgl"]
+members = [
+    "lvgl-sys",
+    "lvgl",
+    "examples/demo",
+]
 

examples/demo/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "demo"
+version = "0.1.0"
+authors = ["Rafael Caricio <crates@caric.io>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+lvgl-sys = { path = "../../lvgl-sys" }
+sdl2 = "0.33.0"

examples/demo/src/main.rs

@@ -0,0 +1,103 @@
+use std::ffi::CString;
+use std::os::raw::c_void;
+use std::time::Duration;
+use std::mem::MaybeUninit;
+
+use sdl2::event::Event;
+use sdl2::keyboard::Keycode;
+use sdl2::pixels::{Color, PixelFormat, PixelFormatEnum};
+
+use lvgl_sys;
+use lvgl_sys::{lv_btn_create, lv_color_t, lv_disp_buf_init, lv_disp_buf_t, lv_disp_drv_init, lv_disp_drv_register, lv_disp_drv_t, lv_disp_get_hor_res, lv_disp_get_scr_act, lv_disp_get_ver_res, lv_label_create, lv_label_set_text, lv_obj_set_pos, lv_obj_set_size, lv_obj_set_x, lv_obj_set_y, lv_obj_t, lv_task_handler, lv_area_t, lv_disp_flush_ready, LV_HOR_RES_MAX, lv_style_t, lv_style_copy, lv_style_btn_rel, LV_BTN_STYLE_PR, LV_BTN_STYLE_REL, lv_slider_set_style};
+
+fn main() -> Result<(), String> {
+    unsafe {
+        lvgl_sys::lv_init();
+    }
+
+    let sdl_context = sdl2::init()?;
+    let video_subsystem = sdl_context.video()?;
+
+    let hr: u32 = unsafe { lv_disp_get_hor_res(std::ptr::null_mut()) as u32 };
+    let vr: u32 = unsafe { lv_disp_get_ver_res(std::ptr::null_mut()) as u32 };
+
+    let window = video_subsystem.window("TFT Display: Demo", hr, vr)
+        .position_centered()
+        .opengl()
+        .build()
+        .map_err(|e| e.to_string())?;
+
+    let mut canvas = window.into_canvas().build().map_err(|e| e.to_string())?;
+
+    canvas.set_draw_color(Color::RGB(255, 0, 0));
+    canvas.clear();
+    canvas.present();
+    let mut event_pump = sdl_context.event_pump()?;
+
+    // Create a display buffer for LittlevGL
+    let mut disp_buf = MaybeUninit::<lv_disp_buf_t>::uninit();
+    let mut buf: [MaybeUninit<lv_color_t>;  LV_HOR_RES_MAX as usize * 10] = unsafe { MaybeUninit::uninit().assume_init()  };          /*Declare a buffer for 10 lines*/
+    unsafe {
+        lv_disp_buf_init(disp_buf.as_mut_ptr(), buf.as_mut_ptr() as *mut c_void, std::ptr::null_mut(), (hr * 10) as u32);    /*Initialize the display buffer*/
+    }
+
+    // Implement and register a function which can copy a pixel array to an area of your display:
+    unsafe {
+        unsafe extern "C" fn my_disp_flush(disp_drv: *mut lv_disp_drv_t, area: *const lv_area_t, color_p: *mut lv_color_t) {
+            let mut i = 1;
+            for y in (*area).y1..(*area).y2 {
+                for x in (*area).x1..(*area).x2 {
+                    // Put a pixel to the display.
+                    let raw_color = *color_p.add(i);
+                    let color = Color::from((raw_color.ch.red, raw_color.ch.green, raw_color.ch.blue, raw_color.ch.alpha));
+                    if raw_color.ch.blue != 255 {
+                        println!("{}x{} - {:?}", x, y, color.rgb());
+                    }
+                    i = i + 1;
+                }
+            }
+
+            lv_disp_flush_ready(disp_drv);         /* Indicate you are ready with the flushing*/
+        }
+
+        let mut disp_drv = MaybeUninit::<lv_disp_drv_t>::uninit().assume_init();                  /*Descriptor of a display driver*/
+        lv_disp_drv_init(&mut disp_drv);     /*Basic initialization*/
+        disp_drv.flush_cb = Some(my_disp_flush);                /*Set your driver function*/
+        disp_drv.buffer = disp_buf.as_mut_ptr();          /*Assign the buffer to the display*/
+        lv_disp_drv_register(&mut disp_drv); /*Finally register the driver*/
+    }
+
+    // Create screen and widgets
+    let mut screen = unsafe { lv_disp_get_scr_act(std::ptr::null_mut()) };
+    let mut btn = unsafe { lv_btn_create(screen, std::ptr::null_mut()) };
+    unsafe {
+        lv_obj_set_pos(btn, 10, 10);
+        lv_obj_set_size(btn, 200, 50)
+    }
+    let mut label = unsafe { lv_label_create(btn, std::ptr::null_mut()) };
+    unsafe {
+        lv_label_set_text(label, CString::new("Click me!").unwrap().as_ptr());
+    }
+
+    'running: loop {
+        for event in event_pump.poll_iter() {
+            match event {
+                Event::Quit { .. } | Event::KeyDown { keycode: Some(Keycode::Escape), .. } => {
+                    break 'running;
+                }
+                _ => {}
+            }
+        }
+
+        canvas.clear();
+        canvas.present();
+        ::std::thread::sleep(Duration::from_millis(300));
+        // The rest of the game loop goes here...
+
+        unsafe {
+            lv_task_handler();
+        }
+    }
+
+    Ok(())
+}

lvgl-sys/build.rs

@@ -8,6 +8,7 @@ fn main() {
         .unwrap();
     let root_dir = project_dir.parent().unwrap();
     let vendor = root_dir.join("vendor");
+    let lvgl_sys_src = root_dir.join("lvgl-sys").join("src");
     let src = vendor.join("lvgl").join("src");
 
     // TODO: Make it configurable! Needs to be linked to final proj defs, define as an env var.
@@ -29,14 +30,13 @@ fn main() {
         .include(&lvgl_config_path)
         .compile("lvgl");
 
-    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
     let cc_args = ["-DLV_CONF_INCLUDE_SIMPLE=1", "-I", lvgl_config_path.to_str().unwrap()];
     bindgen::Builder::default()
         .header(src.parent().unwrap().join("lvgl.h").to_str().unwrap())
         .clang_args(&cc_args)
         .generate()
         .expect("Unable to generate bindings")
-        .write_to_file(out_path.join("bindings.rs"))
+        .write_to_file(lvgl_sys_src.join("bindings.rs"))
         .expect("Can't write bindings!");
 }
 

lvgl-sys/src/lib.rs

@@ -2,7 +2,8 @@
 #![allow(non_camel_case_types)]
 #![allow(non_upper_case_globals)]
 
-include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
+pub mod bindings;
+pub use bindings::*;
 
 #[cfg(test)]
 mod tests {
@@ -13,11 +14,11 @@ mod tests {
         unsafe {
             lv_init();
 
-            let hres = lv_disp_get_hor_res(std::ptr::null_mut());
-            assert_eq!(hres, 480);
+            let horizontal_resolution = lv_disp_get_hor_res(std::ptr::null_mut());
+            assert_eq!(horizontal_resolution, 480);
 
-            let vres = lv_disp_get_ver_res(std::ptr::null_mut());
-            assert_eq!(vres, 320);
+            let vertical_resolution = lv_disp_get_ver_res(std::ptr::null_mut());
+            assert_eq!(vertical_resolution, 320);
         }
     }
 }