main.rs

#![feature(plugin)]
#![plugin(clippy)]

extern crate comdlg32;
extern crate winapi;

const PNGS: &'static str = "PNG Image Files\0*.png\0\0";
const MAX_FILE_NAME_LENGTH: u32 = 260;

fn main() {
    println!("{:?}", get_filename());
}

fn get_filename() -> Option<String> {
    unsafe {
        use comdlg32::*;
        use winapi::*;
        use std::ptr::null;

        let mut filename = [0 as c_char; (MAX_FILE_NAME_LENGTH+1) as usize];
        let null_ptr = null::<c_void>();

        let mut opts = OPENFILENAMEA {
            lStructSize: std::mem::size_of::<OPENFILENAMEW>() as u32,
            hwndOwner: null_ptr as _,
            hInstance: null_ptr as _,
            lpstrFilter: PNGS.as_ptr() as _,
            lpstrFile: filename.as_mut_ptr(),
            nMaxFile: MAX_FILE_NAME_LENGTH,
            lpstrTitle: "Select A File To Open\0".as_ptr() as _,
            nFilterIndex: 0,
            nMaxCustFilter: 0,
            lpstrCustomFilter: null_ptr as _,
            nFileExtension: 0,
            nFileOffset: 0,
            lpstrInitialDir: null_ptr as _,
            Flags: 0,
            nMaxFileTitle: 0,
            lpstrFileTitle: null_ptr as _,
            lCustData: 0,
            lpstrDefExt: null(),
            lpfnHook: None,
            pvReserved: null_ptr as _,
            lpTemplateName: null(),
            dwReserved: 0,
            FlagsEx: 0
        };
        let res = GetOpenFileNameA(&mut opts as _);

        if res == 1 {
            let filename = &filename as &[i8];
            Some(String::from_utf8(filename.iter().map(|x|{*x as u8}).take_while(|x|{*x != 0}).collect()).expect("Couldn't decode"))
        } else {
            None
        }
    }
}