Hardware LCD Plane Library
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README.md

Microchip

Microchip Hardware LCD Plane Library

libplanes is a library that provides support for working with LCD controller hardware planes found on SAMA5 hardware. It directly uses libdrm to manipulate and control the hardware planes with support for using cairo for basic drawing primitives. It includes basic support for parsing a configuration file used to describe the layout and configuration of the planes, but this can also be done manually.

Also included are several applications that use libplanes to perform various tasks to exercise the hardware and library. These applications provide a set of examples and evaluation tests related to using hardware planes.

Terminology

The general terminology used to describe hardware planes varies. The comparison is as follows:

  • Plane (Linux/DRM/KMS)

    • Primary Plane
    • Overlay Plane
    • Cursor Plane
  • Layer (Datasheet/DirectFB)

    • Base Layer
    • Overlay Layer
    • High End Overlay (HEO)

Dependencies

  • libdrm >= 2.4.0
  • cJSON >= 1.6.0
  • lua >= 5.3.1
  • cairo >= 1.14.6
  • Python >= 2.7
  • swig
  • directfb >= 1.7.0 (optional)

Building

Make sure you have the required dependencis listed above. To cross compile, put the cross gcc path in your environment PATH variable and use the appropriate prefix for --host on the configure line. For example:

./autogen.sh
./configure --host=arm-buildroot-linux-gnueabihf
make

If you wish to statically link the applications, add the following to your configure line:

./configure --enable-static --disable-shared LDFLAGS="-static"

API Documentation

If you have doxygen installed, you can generate the API documentation by running:

make docs

The resulting documentation will be in the docs directory.

Python Bindings

Full Python bindings are provided, generated with swig. You can find examples in the python directory.

Applications

planes

Application that acts as a DRM master that takes a configuration and applies it to hardware planes and then will run a minimal engine to perform basic animation of the overlays.

./planes -v -c default.config

The config file is a simple JSON formatted file that specifies the configuration of each plane. See default.config for an example.

With this application running as a DRM master, other applications can then use the created GEM names to manipulate the plane framebuffers externally from another process.

render

Application that uses GEM names created by the planes app that can be passed to this process to write to a plane framebuffers independently. It supports setting a single background color or loading an image into the framebuffer. To run this, the planes app must already be running.

./render -n 1 -c 0xff0000ff --width 800 --height 480
./render -n 1 -f ./frog.png --width 800 --height 480

grab

Application that uses GEM names created by the planes app to capture and save the framebuffer as a PNG. To run this, the planes app must already be running.

./grab -n 1 -f capture.png --width 800 --height 480

dfblayers

Simple demo based on a DirectFB test that allocates hardware overlays using the DirectFB API and moves them around on the screen showing little CPU usage in the process.

./dfblayers

License

libplanes is released under the terms of the MIT license. See the COPYING file for more information.