EasyVG

EasyVG provides an abstraction layer above native OpenVG, for quickly and easily creating OpenVG contexts and drawing shapes, images, and text.

EasyVG follows standard C and EGL API naming conventions.

EasyVG is fully compatible with the Raspberry Pi.

This project is a fork of OpenVG by Anthony Starks

Text & Fonts

EasyVG is capable of rendering text.

To use custom TrueType fonts, developers should convert the font into C code use the font2openvg library, and then load it the font using loadfont().

There are plans to support loading a font directly from a .ttf file.

Using font2openvg

The font2openvg repository contains build instructions for building the font2openvg source. Once the library is built, compile a TrueType font file. For the below demonstrations, it will be assumed that you are using a source font file named DejaVuSans.ttf and a compiled output named DejaVuSans.inc.

Once a font is compiled, it can be included in your code like so:

    #include "DejaVuSans.inc"
    Fontinfo DejaFont

    loadfont(DejaVuSans_glyphPoints,
            DejaVuSans_glyphPointIndices,
            DejaVuSans_glyphInstructions,
            DejaVuSans_glyphInstructionIndices,
            DejaVuSans_glyphInstructionCounts,
            DejaVuSans_glyphAdvances,
            DejaVuSans_characterMap,
            DejaVuSans_glyphCount);

    // Unload the font when done
    unloadfont(DejaFont.Glyphs, DejaFont.Count);

Build and Run Examples

Note that you will need at least 64 MB of GPU RAM. You will also need the DejaVu fonts, and the jpeg and freetype libraries.

pi@raspberrypi ~ $ sudo apt-get install libfreetype6-dev libjpeg8-dev ttf-dejavu-core

Next, build the library:

pi@raspberrypi ~ $ git clone https://github.com/mgthomas99/easy-vg
pi@raspberrypi ~ $ cd easy-vg
pi@raspberrypi ~/easy-vg $ make
 g++ -I/usr/include/freetype2 fontutil/font2openvg.cpp -o font2openvg -lfreetype
 ./font2openvg /usr/share/fonts/truetype/ttf-dejavu/DejaVuSans.ttf DejaVuSans.inc DejaVuSans
 224 glyphs written
 gcc -O2 -Wall -I/opt/vc/include -I/opt/vc/include/interface/vmcs_host/linux -I/opt/vc/include/interface/vcos/pthreads -c libshapes.c
 gcc -O2 -Wall -I/opt/vc/include -I/opt/vc/include/interface/vmcs_host/linux -I/opt/vc/include/interface/vcos/pthreads -c oglinit.c

Next, build the examples:

pi@raspberrypi ~/easy-vg/client $ cd example
pi@raspberrypi ~/easy-vg/client $ make hello
 cc -Wall -I/opt/vc/include -I/opt/vc/include/interface/vcms_host/linux -I/opt/vc/include/interface/vcos/pthreads -I.. hello.c -o hello ../build/libshapes.o ../build/oglinit.o -L/opt/vc/lib -lEGL -lGLESv2 -lbcm_host -ljpeg -lpthread
pi@raspberrypi ~/easy-vg/client $ ./hello

Installing as a Global Library

To install the library as a system-wide shared library:

pi@raspberrypi ~/easy-vg $ make library
pi@raspberrypi ~/easy-vg $ sudo make install

The EasyVG shapes library can now be used in C code by including shapes.h and fontinfo.h, and linking with libshapes.so:

#include <shapes.h>
#include <fontinfo.h>

pi@raspberrypi ~ $ gcc -I/opt/vc/include -I/opt/vc/include/interface/vmcs_host/linux -I/opt/vc/include/interface/vcos/pthreads anysource.c -o anysource -lshapes
pi@raspberrypi ~ $ ./anysource

License

See the LICENSE file for license information.