drag and drop working for save states

README.md

@@ -23,7 +23,7 @@ ___________________
 -------------------
 Save state: F5
 Load state: F9
-(Only one save state at a time supported currently: saving a second time overwrites the first.)
+(Saving state a second time overwrites the first unless you copy/rename the `.dat` file. You can drag and drop any `.dat` file onto the window to load it.)
 ```
 The code aims to follow the explanations from the [NES dev wiki](https://wiki.nesdev.com/w/index.php/NES_reference_guide) where possible, especially in the PPU, and the comments quote from it often. Thanks to everyone who contributes to that wiki/forum, and to Michael Fogleman's [NES](https://github.com/fogleman/nes) and Scott Ferguson's [Fergulator](https://github.com/scottferg/Fergulator) for getting me unstuck at several points.
 
@@ -47,9 +47,9 @@ The code aims to follow the explanations from the [NES dev wiki](https://wiki.ne
 
 - DMC audio channel, high- and low-pass filters
 
-- Better GUI and distributable solution
+- Better GUI
 
-- Save states
+- Better save state handling
 
 - Player 2 controller?
 

src/apu/serialize.rs

@@ -2,8 +2,7 @@ pub type ApuData = super::Apu;
 
 impl super::Apu{
     pub fn save_state(&self) -> ApuData {
-        let x: ApuData = self.clone();
-        x
+        self.clone()
     }
 
     pub fn load_state(&mut self, data: ApuData) {

src/main.rs

@@ -13,13 +13,14 @@ use apu::Apu;
 use cartridge::get_mapper;
 use input::poll_buttons;
 use screen::{init_window, draw_pixel, draw_to_window};
-use state::{save_state, load_state};
+use state::{save_state, load_state, change_file_extension};
 
 use std::sync::{Arc, Mutex};
 use std::time::{Instant, Duration};
 use sdl2::keyboard::Keycode;
 use sdl2::event::Event;
 use sdl2::pixels::PixelFormatEnum;
+use std::path::Path;
 
 // use cpuprofiler::PROFILER;
 
@@ -96,12 +97,20 @@ fn main() -> Result<(), String> {
                         Event::Quit {..} | Event::KeyDown { keycode: Some(Keycode::Escape), .. }
                             => break 'running,
                         Event::KeyDown{ keycode: Some(Keycode::F5), .. } => {
-                            let res: Result<(), String> = save_state(&cpu, &filename)
+                            let dat_filename = state::change_file_extension(&filename, "dat").unwrap();
+                            let res: Result<(), String> = save_state(&cpu, dat_filename)
                                 .or_else(|e| {println!("{}", e); Ok(())});
                             res.unwrap();
                         },
                         Event::KeyDown{ keycode: Some(Keycode::F9), .. } => {
-                            let res: Result<(), String> = load_state(&mut cpu, &filename)
+                            let dat_filename = state::change_file_extension(&filename, "dat").unwrap();
+                            let res: Result<(), String> = load_state(&mut cpu, dat_filename)
+                                .or_else(|e| {println!("{}", e); Ok(())});
+                            res.unwrap();
+                        },
+                        Event::DropFile{ timestamp: _t, window_id: _w, filename: f } => {
+                            let p = Path::new(&f).to_path_buf();
+                            let res: Result<(), String> = load_state(&mut cpu, p)
                                 .or_else(|e| {println!("{}", e); Ok(())});
                             res.unwrap();
                         },

src/state.rs

@@ -4,7 +4,7 @@ use super::apu;
 
 use std::fs::File;
 use std::io::{Read, Write};
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use serde::{Serialize, Deserialize};
 
 #[derive(Serialize, Deserialize)]
@@ -14,7 +14,7 @@ struct SaveState {
     apu: apu::serialize::ApuData,
 }
 
-pub fn save_state(cpu: &cpu::Cpu, filename: &str) -> Result<(), String> {
+pub fn save_state(cpu: &cpu::Cpu, save_file: PathBuf) -> Result<(), String> {
     let data = SaveState{
         cpu: cpu.save_state(),
         ppu: cpu.ppu.save_state(),
@@ -22,16 +22,6 @@ pub fn save_state(cpu: &cpu::Cpu, filename: &str) -> Result<(), String> {
     };
     let serialized = serde_json::to_string(&data)
         .map_err(|e| e.to_string())?;
-    let path = match Path::new(&filename).parent() {
-        Some(p) => p,
-        None => return Err("couldn't convert filename to path".to_string()),
-    };
-    let stem = match Path::new(&filename).file_stem() {
-        Some(s) => s,
-        None => return Err("couldn't get file stem".to_string()),
-    };
-    let mut save_file = path.join(stem);
-    save_file.set_extension("dat");
     println!("state saved to file: {:?}", save_file);
     let mut f = File::create(&save_file)
         .expect("could not create output file for save state");
@@ -39,19 +29,7 @@ pub fn save_state(cpu: &cpu::Cpu, filename: &str) -> Result<(), String> {
         .map_err(|_| "couldn't write serialized data to file".to_string())
 }
 
-pub fn load_state(cpu: &mut cpu::Cpu, filename: &str) -> Result<(), String> {
-    // load file, deserialize to cpudata, set cpu fields to data fields
-    let path = match Path::new(&filename).parent() {
-        Some(p) => p,
-        None => return Err("couldn't convert filename to path".to_string()),
-    };
-    let stem = match Path::new(&filename).file_stem() {
-        Some(s) => s,
-        None => return Err("couldn't get file stem".to_string()),
-    };
-    let mut save_file = path.join(stem);
-    save_file.set_extension("dat");
-
+pub fn load_state(cpu: &mut cpu::Cpu, save_file: PathBuf) -> Result<(), String> {
     if Path::new(&save_file).exists() {
         let mut f = File::open(save_file.clone())
             .map_err(|e| e.to_string())?;
@@ -71,3 +49,11 @@ pub fn load_state(cpu: &mut cpu::Cpu, filename: &str) -> Result<(), String> {
         Err(format!("no save state file at {:?}", save_file))
     }
 }
+
+pub fn change_file_extension(filename: &str, extension: &str) -> Option<PathBuf> {
+    let path = Path::new(filename).parent()?;
+    let stem = Path::new(&filename).file_stem()?;
+    let mut save_file = path.join(stem);
+    save_file.set_extension(extension);
+    Some(save_file)
+}