android: jpeg: Split and pass the thumbnail planes to encoder

After multi-planar support was introduced for jpeg encoding as well,
EncoderLibJpeg::encode() expects a vector of planes as the source of
framebuffer to be encoded. Currently, we are passing a contiguous buffer
which is treated as only one plane (instead of two, as thumbnail is NV12).

Hence, split the thumbnail data into respective planes according to NV12.
This fixes a crash in encoding of thumbnails.

Fixes: 894ca69f6043("android: jpeg: Support multi-planar buffers")
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

src/android/jpeg/post_processor_jpeg.cpp

@@ -72,7 +72,22 @@ void PostProcessorJpeg::generateThumbnail(const FrameBuffer &source,
 		 */
 		thumbnail->resize(rawThumbnail.size());
 
-		int jpeg_size = thumbnailEncoder_.encode({ rawThumbnail },
+		/*
+		 * Split planes manually as the encoder expects a vector of
+		 * planes.
+		 *
+		 * \todo Pass a vector of planes directly to
+		 * Thumbnailer::createThumbnailer above and remove the manual
+		 * planes split from here.
+		 */
+		std::vector<Span<uint8_t>> thumbnailPlanes;
+		const PixelFormatInfo &formatNV12 = PixelFormatInfo::info(formats::NV12);
+		size_t YPlaneSize = formatNV12.planeSize(targetSize, 0);
+		size_t UVPlaneSize = formatNV12.planeSize(targetSize, 1);
+		thumbnailPlanes.push_back({ rawThumbnail.data(), YPlaneSize });
+		thumbnailPlanes.push_back({ rawThumbnail.data() + YPlaneSize, UVPlaneSize });
+
+		int jpeg_size = thumbnailEncoder_.encode(thumbnailPlanes,
 							 *thumbnail, {}, quality);
 		thumbnail->resize(jpeg_size);