1 files changed, 83 insertions, 0 deletions
diff --git a/src/apps/cam/sdl_texture_mjpg.cpp b/src/apps/cam/sdl_texture_mjpg.cpp
new file mode 100644
index 00000000..da958e03
--- /dev/null
+++ b/src/apps/cam/sdl_texture_mjpg.cpp
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2022, Ideas on Board Oy
+ *
+ * sdl_texture_mjpg.cpp - SDL Texture MJPG
+ */
+
+#include "sdl_texture_mjpg.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, rect.w * 3),
+	  rgb_(std::make_unique<unsigned char[]>(stride_ * rect.h))
+{
+}
+
+int SDLTextureMJPG::decompress(Span<const 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 * stride_;
+		jpeg_read_scanlines(&cinfo, &rowptr, 1);
+	}
+
+	jpeg_finish_decompress(&cinfo);
+
+	jpeg_destroy_decompress(&cinfo);
+
+	return 0;
+}
+
+void SDLTextureMJPG::update(const std::vector<libcamera::Span<const uint8_t>> &data)
+{
+	decompress(data[0]);
+	SDL_UpdateTexture(ptr_, nullptr, rgb_.get(), stride_);
+}