allow js to set jpeg quality

backend/src/JPEGEncoder.ts

@@ -14,6 +14,7 @@ export class JPEGEncoder {
 			width: rect.width,
 			height: rect.height,
 			stride: displaySize.width,
+			quality: gJpegQuality,
 			buffer: canvas.subarray(offset)
 		});
 	}

jpeg-rs/index.d.ts

@@ -1,15 +1,15 @@
 //
 
 interface JpegInputArgs {
-	width: number,
-	height: number,
-	stride: number, // The width of your input framebuffer OR your image width (if encoding a full image)
-	buffer: Buffer
+	width: number;
+	height: number;
+	stride: number; // The width of your input framebuffer OR your image width (if encoding a full image)
+	quality: number | undefined;
+	buffer: Buffer;
 
 	// TODO: Allow different formats, or export a boxed ffi object which can store a format
 	// (i.e: new JpegEncoder(FORMAT_xxx)).
 }
 
 /// Performs JPEG encoding.
-export function jpegEncode(input: JpegInputArgs) : Promise<Buffer>;
-
+export function jpegEncode(input: JpegInputArgs): Promise<Buffer>;

jpeg-rs/src/jpeg_js.rs

@@ -31,6 +31,11 @@ fn jpeg_encode_impl<'a>(cx: &mut FunctionContext<'a>) -> JsResult<'a, JsPromise>
     let width: u64 = input.get::<JsNumber, _, _>(cx, "width")?.value(cx) as u64;
     let height: u64 = input.get::<JsNumber, _, _>(cx, "height")?.value(cx) as u64;
     let stride: u64 = input.get::<JsNumber, _, _>(cx, "stride")?.value(cx) as u64;
+	let quality : u64 = if let Ok(val) = input.get::<JsNumber, _, _>(cx, "quality") {
+		val.value(cx) as u64
+	} else {
+		35u64
+	};
     let buffer: Handle<JsBuffer> = input.get(cx, "buffer")?;
 
     let (deferred, promise) = cx.promise();
@@ -65,7 +70,7 @@ fn jpeg_encode_impl<'a>(cx: &mut FunctionContext<'a>) -> JsResult<'a, JsPromise>
 
         let vec = COMPRESSOR.with(|lazy| {
             let mut b = lazy.borrow_mut();
-            b.set_quality(35);
+            b.set_quality(quality as u32);
             b.set_subsamp(turbojpeg_sys::TJSAMP_TJSAMP_420);
             b.compress_buffer(&image)
         });