GUAC-236: Implement JPEG.

src/guacenc/jpeg.c

@@ -22,13 +22,66 @@
 
 #include "config.h"
 #include "jpeg.h"
+#include "log.h"
+
+#include <stdio.h>
+#include <unistd.h>
 
 #include <cairo/cairo.h>
+#include <jpeglib.h>
 
 #include <stdlib.h>
 
 cairo_surface_t* guacenc_jpeg_decoder(unsigned char* data, int length) {
-    /* STUB */
+
+    struct jpeg_decompress_struct cinfo;
+    struct jpeg_error_mgr jerr;
+
+    /* Create decompressor with standard error handling */
+    jpeg_create_decompress(&cinfo);
+    cinfo.err = jpeg_std_error(&jerr);
+
+    /* Read JPEG directly from memory buffer */
+    jpeg_mem_src(&cinfo, data, length);
+
+    /* Read and validate JPEG header */
+    if (!jpeg_read_header(&cinfo, TRUE)) {
+        guacenc_log(GUAC_LOG_WARNING, "Invalid JPEG data");
+        jpeg_destroy_decompress(&cinfo);
         return NULL;
+    }
+
+    /* Begin decompression */
+    cinfo.out_color_space = JCS_EXT_BGRX;
+    jpeg_start_decompress(&cinfo);
+
+    /* Pull JPEG dimensions from decompressor */
+    int width = cinfo.output_width;
+    int height = cinfo.output_height;
+
+    /* Create blank Cairo surface (no transparency in JPEG) */
+    cairo_surface_t* surface = cairo_image_surface_create(CAIRO_FORMAT_RGB24,
+            width, height);
+
+    /* Pull underlying buffer and its stride */
+    int stride = cairo_image_surface_get_stride(surface);
+    unsigned char* row = cairo_image_surface_get_data(surface);
+
+    /* Read JPEG into surface */
+    while (cinfo.output_scanline < height) {
+        unsigned char* buffers[1] = { row };
+        jpeg_read_scanlines(&cinfo, buffers, 1);
+        row += stride;
+    }
+
+    /* End decompression */
+    jpeg_finish_decompress(&cinfo);
+
+    /* Free decompressor */
+    jpeg_destroy_decompress(&cinfo);
+
+    /* JPEG was read successfully */
+    return surface;
+
 }