cam: sdl_sink: Use libjpeg over SDL2_image

We were using the libjpeg functionality of SDL2_image only, instead just
use libjpeg directly to reduce our dependancy count, it is a more
commonly available library.

Signed-off-by: Eric Curtin <ecurtin@redhat.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

1 files changed, 64 insertions, 6 deletions

diff --git a/src/cam/sdl_texture_mjpg.cpp b/src/cam/sdl_texture_mjpg.cpp
index 69e99ad3..7eddc00c 100644
--- a/src/cam/sdl_texture_mjpg.cpp
+++ b/src/cam/sdl_texture_mjpg.cpp
@@ -7,19 +7,77 @@
 
 #include "sdl_texture_mjpg.h"
 
-#include <SDL2/SDL_image.h>
+#include <iostream>
+#include <setjmp.h>
+#include <stdio.h>
+
+#include <jpeglib.h>
 
 using namespace libcamera;
 
+struct JpegErrorManager : public jpeg_error_mgr {
+	JpegErrorManager()
+	{
+		jpeg_std_error(this);
+		error_exit = errorExit;
+		output_message = outputMessage;
+	}
+
+	static void errorExit(j_common_ptr cinfo)
+	{
+		JpegErrorManager *self =
+			static_cast<JpegErrorManager *>(cinfo->err);
+		longjmp(self->escape_, 1);
+	}
+
+	static void outputMessage([[maybe_unused]] j_common_ptr cinfo)
+	{
+	}
+
+	jmp_buf escape_;
+};
+
 SDLTextureMJPG::SDLTextureMJPG(const SDL_Rect &rect)
-	: SDLTexture(rect, SDL_PIXELFORMAT_RGB24, 0)
+	: SDLTexture(rect, SDL_PIXELFORMAT_RGB24, rect.w * 3),
+	  rgb_(std::make_unique<unsigned char[]>(pitch_ * rect.h))
 {
 }
 
+int SDLTextureMJPG::decompress(const Span<uint8_t> &data)
+{
+	struct jpeg_decompress_struct cinfo;
+
+	JpegErrorManager errorManager;
+	if (setjmp(errorManager.escape_)) {
+		/* libjpeg found an error */
+		jpeg_destroy_decompress(&cinfo);
+		std::cerr << "JPEG decompression error" << std::endl;
+		return -EINVAL;
+	}
+
+	cinfo.err = &errorManager;
+	jpeg_create_decompress(&cinfo);
+
+	jpeg_mem_src(&cinfo, data.data(), data.size());
+
+	jpeg_read_header(&cinfo, TRUE);
+
+	jpeg_start_decompress(&cinfo);
+
+	for (int i = 0; cinfo.output_scanline < cinfo.output_height; ++i) {
+		JSAMPROW rowptr = rgb_.get() + i * pitch_;
+		jpeg_read_scanlines(&cinfo, &rowptr, 1);
+	}
+
+	jpeg_finish_decompress(&cinfo);
+
+	jpeg_destroy_decompress(&cinfo);
+
+	return 0;
+}
+
 void SDLTextureMJPG::update(const Span<uint8_t> &data)
 {
-	SDL_RWops *bufferStream = SDL_RWFromMem(data.data(), data.size());
-	SDL_Surface *frame = IMG_Load_RW(bufferStream, 0);
-	SDL_UpdateTexture(ptr_, nullptr, frame->pixels, frame->pitch);
-	SDL_FreeSurface(frame);
+	decompress(data);
+	SDL_UpdateTexture(ptr_, nullptr, rgb_.get(), pitch_);
 }