implement get_printers for windows

Author: atzhukov

Cargo.lock

@@ -18,6 +18,9 @@ doctest = false
 strum = { version = "0.27.2", features = ["derive"] }
 thiserror = "2.0.12"
 
+[target.'cfg(windows)'.dependencies]
+windows = { version = "0.52", features = ["Win32_Foundation", "Win32_Graphics_Printing"] }
+
 [dev-dependencies]
 trybuild = "1.0.110"
 uuid = { version = "1.17.0", features = ["v4"] }

paperjet/Cargo.toml

@@ -1,12 +1,59 @@
+use std::collections::HashMap;
 use std::io::Read;
+use std::slice;
+
+use windows::Win32::Graphics::Printing::{self, EnumPrintersW};
 
 use crate::error::PrintError;
 use crate::options::PrintOptions;
 use crate::{CrossPlatformApi, PlatformSpecificApi, Printer};
 
 impl CrossPlatformApi for PlatformSpecificApi {
 	fn get_printers() -> Vec<Printer> {
-		todo!("Not supported on Windows yet")
+		let mut buf_size = 0u32;
+		let mut printers_len = 0u32;
+
+		// First call to determine the buffer size (we use level 4 here, thus this is fast)
+		// SAFETY: the only pointers we pass in are `buf_size` and `printers_len`, which are valid.
+		let _ = unsafe {
+			EnumPrintersW(
+				Printing::PRINTER_ENUM_LOCAL | Printing::PRINTER_ENUM_CONNECTIONS,
+				None,
+				4,
+				None,
+				&mut buf_size,
+				&mut printers_len,
+			)
+		};
+		// Second call to populate the buffer
+		// SAFETY: all pointers we pass in are valid again, and `buf` is of required size, as determined
+		// by the previous call to `EnumPrintersW`.
+		let mut buf = vec![0u8; buf_size as usize];
+		let result = unsafe {
+			EnumPrintersW(
+				Printing::PRINTER_ENUM_LOCAL | Printing::PRINTER_ENUM_CONNECTIONS,
+				None,
+				4,
+				Some(&mut buf),
+				&mut buf_size,
+				&mut printers_len,
+			)
+		};
+
+		if result.is_err() {
+			// TODO: return result
+			return vec![];
+		}
+
+		unsafe {
+			slice::from_raw_parts(
+				buf.as_ptr() as *mut Printing::PRINTER_INFO_4W,
+				printers_len as usize,
+			)
+		}
+		.iter()
+		.map(map_printer_info_4_to_printer)
+		.collect::<Vec<_>>()
 	}
 
 	fn get_printer(_name: &str) -> Option<Printer> {
@@ -25,3 +72,14 @@ impl CrossPlatformApi for PlatformSpecificApi {
 		todo!("Not supported on Windows yet")
 	}
 }
+
+/// Converts the [`PRINTER_INFO_4W`] instance to a [`Printer`] instance.
+fn map_printer_info_4_to_printer(info: &Printing::PRINTER_INFO_4W) -> Printer {
+	Printer {
+		identifier: unsafe { info.pPrinterName.to_string().unwrap() },
+		name: unsafe { info.pPrinterName.to_string().unwrap() },
+		instance: None,
+		is_default: false,
+		options: HashMap::new(),
+	}
+}