test: use the XRGB sample from the spec

It's unclear where the RGB_BUFFER was coming from, it's better to use
the one from the spec, like the YCBCR buffers.

Unfortunately, we don't match with the reference data after conversion.
This doesn't seem a big issue in practice.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

Author: elmarco

crates/ironrdp-graphics/src/color_conversion.rs

@@ -1,12 +1,29 @@
 use std::io;
 
 use yuvutils_rs::{
-    rdp_abgr_to_yuv444, rdp_argb_to_yuv444, rdp_bgra_to_yuv444, rdp_rgba_to_yuv444, rdp_yuv444_to_bgra, BufferStoreMut,
-    YuvPlanarImage, YuvPlanarImageMut,
+    rdp_abgr_to_yuv444, rdp_argb_to_yuv444, rdp_bgra_to_yuv444, rdp_rgba_to_yuv444, rdp_yuv444_to_argb,
+    rdp_yuv444_to_bgra, BufferStoreMut, YuvPlanarImage, YuvPlanarImageMut,
 };
 
 use crate::image_processing::PixelFormat;
 
+// FIXME: used for the test suite, we may want to drop it
+pub fn ycbcr_to_argb(input: YCbCrBuffer<'_>, output: &mut [u8]) -> io::Result<()> {
+    let len = u32::try_from(output.len()).map_err(io::Error::other)?;
+    let width = len / 4;
+    let planar = YuvPlanarImage {
+        y_plane: input.y,
+        y_stride: width,
+        u_plane: input.cb,
+        u_stride: width,
+        v_plane: input.cr,
+        v_stride: width,
+        width,
+        height: 1,
+    };
+    rdp_yuv444_to_argb(&planar, output, len).map_err(io::Error::other)
+}
+
 pub fn ycbcr_to_bgra(input: YCbCrBuffer<'_>, output: &mut [u8]) -> io::Result<()> {
     let len = u32::try_from(output.len()).map_err(io::Error::other)?;
     let width = len / 4;