ARM: PNG support missing in Graphics Component

Information in this knowledgebase article applies to:

• MDK-ARM Middleware Graphics Component

SYMPTOM

In my application I want to use the Graphics Component from the MDK-ARM middleware to display a PNG image. To do this I call e. g. the function GUI_PNG_DrawEx(). The source compiles fine. But at the link step the linker reports an error like this:

Example.axf: Error: L6218E: Undefined symbol GUI_PNG_DrawEx (referred from main.o).

CAUSE

The Graphics Component from the MDK-ARM middleware is based on the emWin library from Segger, which uses 'libpng'. The adaptation of this for the emWin library is separately available on the Segger website: www.segger.com/link/emwin_png.zip

RESOLUTION

Download this archive file and extract it somewhere. Then add all the source file relating to the Graphics Component version you have in use, preferably in a separate group, to the project and build again. The build should now be successful.

The files in the PNG source code generate a number of warnings, which could be suppressed by adding a option:

--diag_suppress=1294

in the Options for Group - C/C++ - Misc Controls field.

MORE INFORMATION

• emWin manual, section "8.4 PNG file support"
• libpng.org/pub/png/libpng.html

Last Reviewed: Wednesday, June 3, 2015