From 73d7718c09ef23db851d0360ce726373f0bf7ac7 Mon Sep 17 00:00:00 2001
From: Harry Jeffery <harry@exec64.co.uk>
Date: Thu, 5 Nov 2015 21:45:31 +0000
Subject: Add JPEG support

---
 Makefile |  2 +-
 jpeg.c   | 42 ++++++++++++++++++++++++++++++++++++++++++
 loader.c |  3 +++
 3 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 jpeg.c

diff --git a/Makefile b/Makefile
index 7c23259..09dded0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 .PHONY: clean
 
 CFLAGS = -g -W -Wall -std=c11 `sdl2-config --cflags`
-LDFLAGS = `sdl2-config --libs` -lpng
+LDFLAGS = `sdl2-config --libs` -lpng -ljpeg
 
 TARGET = imv
 SOURCES = $(wildcard *.c)
diff --git a/jpeg.c b/jpeg.c
new file mode 100644
index 0000000..5ec3b5f
--- /dev/null
+++ b/jpeg.c
@@ -0,0 +1,42 @@
+#include <SDL2/SDL.h>
+#include <string.h>
+#include <jpeglib.h>
+#include <setjmp.h>
+
+SDL_Texture* imv_load_jpeg(SDL_Renderer *r, const char* path)
+{
+  FILE *fp = fopen(path, "rb");
+  if(!fp) {
+    return NULL;
+  }
+
+  struct jpeg_decompress_struct cinfo;
+  jpeg_create_decompress(&cinfo);
+  struct jpeg_error_mgr jerr;
+  cinfo.err = jpeg_std_error(&jerr);
+
+  jpeg_stdio_src(&cinfo, fp);
+  jpeg_read_header(&cinfo, TRUE);
+  jpeg_start_decompress(&cinfo);
+  int row_stride = cinfo.output_width * cinfo.output_components;
+  JSAMPARRAY buffer = (*cinfo.mem->alloc_sarray)
+                ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);
+  char* pixels = (char*)malloc(row_stride*cinfo.output_height);
+  while (cinfo.output_scanline < cinfo.output_height) {
+    jpeg_read_scanlines(&cinfo, buffer, 1);
+    void *out_row = pixels + row_stride * (cinfo.output_scanline-1);
+    memcpy(out_row, buffer[0], row_stride);
+  }
+  jpeg_finish_decompress(&cinfo);
+  jpeg_destroy_decompress(&cinfo);
+  fclose(fp);
+
+  SDL_Texture *img = SDL_CreateTexture(r,
+      SDL_PIXELFORMAT_RGB24, SDL_TEXTUREACCESS_STATIC,
+      cinfo.output_width, cinfo.output_height);
+
+  SDL_Rect area = {0,0,cinfo.output_width,cinfo.output_height};
+  SDL_UpdateTexture(img, &area, pixels, row_stride);
+  free(pixels);
+  return img;
+}
diff --git a/loader.c b/loader.c
index 9f62d24..8d3015f 100644
--- a/loader.c
+++ b/loader.c
@@ -2,6 +2,7 @@
 #include <string.h>
 
 extern SDL_Texture* imv_load_png(SDL_Renderer *r, const char* path);
+extern SDL_Texture* imv_load_jpeg(SDL_Renderer *r, const char* path);
 
 SDL_Texture* imv_load_image(SDL_Renderer *r, const char* path)
 {
@@ -27,6 +28,8 @@ SDL_Texture* imv_load_image(SDL_Renderer *r, const char* path)
     return img;
   } else if(strcasecmp(ext, ".png") == 0) {
     return imv_load_png(r, path);
+  } else if(strcasecmp(ext, ".jpeg") == 0 || strcasecmp(ext, ".jpg") == 0) {
+    return imv_load_jpeg(r, path);
   }
 
   return NULL;
-- 
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