Didj and Explorer SDL image

From eLinux.org
Revision as of 13:55, 5 November 2010 by Reggie (Talk | contribs)

Jump to: navigation, search

How to install SDL_Image library

A short tutorial on how to build, install and get started with the SDL_Image handling library, adding .jpg and .png support to your apps/games.

I'd like to thank Nirvous, NullMoogleCable, PhillKll, Claude, JKent, Jburks, GrizzlyAdams and anyone I may have forgotten for their help :)


A working toolchain
LX Kernel sources and ThirdParty tarball unpacked to your harddrive
correct environment variables set 
zlib (installed as part of this tutorial)
libpng (installed as part of this tutorial)
libjpg (installed as part of this tutorial)
libSDL (should already be installed)

SDL_Image requires a few libraries to be installed, namely the image formats that you want supported and any libraries they are dependent on. I have chosen libjpg as its a very popular format and libpng as we already have .png files on the Didj/LX.

Luckily for us, all 3 of these libraries are provided for us, zlib and libpng are in the packages directory and libjpeg is part of the Third Party tarball.

Installing zlib and libpng

first we need to install zlib, this is the same procedure used for all /package apps. go to your /packages directory, make sure your env vars are set correctly and do:


you should end up with the headers and lib files in their appropriate directories under ROOTFS_PATH/usr/include and /lib respectively.

Do the same for libpng:


Installing libjpeg

go to where you unpacked the ThirdParty folder, I unpacked mine into the same folder that /scripts and /packages are in the LX kernel sources. Next go into the /libJPEG/Source folder.

Now do the usual to start the installation, slightly different filename this time though:

CLEAN=1 ./setup-libjpeg.sh

the libJPEG lib and header files should be in ROOTFS_PATH/usr/lib and /include folders respectively.

Now that we have the libs and headers installed we can go ahead and make our SDL_image library, to do this we will need a folder in PROJECT_PATH/packages and an install.sh file, so make the directory and enter it:

mkdir $PROJECT_PATH/packages/SDLimage
cd $PROJECT_PATH/packages/SDLimage

Copy the following and paste it into a text file, save it as install.sh in your $PROJECT_PATH/packages/SDLimage folder:

export CFLAGS='-I${ROOTFS_PATH}/usr/include -I${ROOTFS_PATH}/usr/include/SDL'
export LD_FLAGS='-L${ROOTFS_PATH}/usr/lib'
export CC=arm-linux-uclibcgnueabi-gcc
export CXX=arm-linux-uclibcgnueabi-g++ 
if [ "$CLEAN" == "1" ]; then
rm -rf ./SDL_image-1.2.10
rm ./SDL_image-1.2.10.tar.gz
wget http://www.libsdl.org/projects/SDL_image/release/SDL_image-1.2.10.tar.gz
tar -xf SDL_image-1.2.10.tar.gz
cd ./SDL_image-1.2.10
./configure CPPFLAGS="-I${ROOTFS_PATH}/usr/include" --prefix=$ROOTFS_PATH/usr --build=`uname -m` --host=arm-linux --enable-shared --with-sdl-prefix=${ROOTFS_PATH}/usr --libdir=${ROOTFS_PATH}/usr/lib --includedir= ${ROOTFS_PATH}/usr/include --enable-jpg
make -j3
make -j3 install

next you just have to run the install.sh script (make sure your environment variables are set):

CLEAN=1 ./install.sh

this should now build and install SDL_Image to your ROOTFS_PATH/usr/lib and include folders, if you want to add other libraries, then compile and install them (use the install.sh files for libjpg and libpng for hints on what to do), then re-run the SDLimage/install.sh file again

You can now build an app with SDL_image support by adding the following to your .c file:

#include "SDL/SDL_image.h"

and to compile an app with SDL_image support, try the following:

arm-linux-uclibcgnueabi-gcc -o mysdlApp mysdlApp.c -I${ROOTFS_PATH}/usr/include -L${ROOTFS_PATH}/usr/lib -lSDL -lSDL_image -ljpeg -lpng -lz -lpthread 

Obviously change the arm-linux-uclibcgnueabi-gcc to your chosen cross compiler. If you added extra image formats don't forget to add a -l for each extra lib and support lib that is needed.