Backup project on read and exit (#3)

Can be turned off in `src/conf.zig`.

README.md

@@ -90,6 +90,12 @@ Modes:
 * Shift + right click: rectangle unselection.
 * Left or right click while un·selecting: end selection.
 
+# Backups
+*Can be disabled in the configuration.*
+Safety backups are made when:
+* Reading operation is started (`backup_read.kble`)
+* The program exit (`backup_exit.kble`)
+
 # License
 Copyright (c) 2021 KikooDX
 

src/conf.zig

@@ -26,6 +26,10 @@ pub const mouse_right_btn: c_int = 1;
 // * true: click to enter, draw, release to exit.
 pub const mouse_graphic_tablet: bool = false;
 
+// The editor will save the level before reading, exiting and other
+// dangerous operations to avoid unexpected data loss.
+pub const safety_backup = true;
+
 pub const default_grid_size = .{
     .width = 16,
     .height = 16,

src/level.zig

@@ -169,6 +169,9 @@ pub fn write(self: Self, kble_file_path: [*:0]const u8) !void {
 
 /// Wrapper around `init_read`.
 pub fn action_read(self: *Self, allocator: *std.mem.Allocator, kble_file_path: [*:0]const u8) void {
+    // Safety backup before reading.
+    if (conf.safety_backup)
+        self.action_write(allocator, "backup_read.kble");
     self.deinit(allocator);
     self.* = Self.init_read(allocator, kble_file_path) catch unreachable;
 }

src/main.zig

@@ -272,6 +272,9 @@ pub fn main() void {
             mouse.draw(scale, camera);
         //ray.DrawFPS(0, 0);
     }
+    // Safety backup before exiting.
+    if (conf.safety_backup)
+        level.write("backup_exit.kble") catch unreachable;
 }
 
 fn add_key_to_buffer(input_buffer: *[input_buffer_len]u32, input_cursor: *u8, key: c_int) void {