The ForColormap Fortran library is independent of any graphical toolkit: its main functionality is to convert a real value to RGB values that you can use with any drawing toolkit. It includes:
And it offers various methods and options to manage colormaps.
Assuming your graphical library has a setpixelgb()
-like function and you know your z
values will be for example in the [0, 2] range, you can write something like:
use forcolormap, only: Colormap, wp
...
type(Colormap) :: cmap
integer :: red, green, blue
real(wp) :: z, x, y
...
! Let's use the glasgow colormap:
call cmap%set("glasgow", 0.0_wp, 2.0_wp)
...
z = f(x,y)
call cmap%compute_RGB(z, red, green, blue)
call setpixelrgb(x, y, red, green, blue)
The library is using the precision wp=>real64
defined in the module iso_fortran_env
. And depending on the integers expected by your graphical library, you may need to convert the kinds of red, green, blue variables.
This guideline can help you choose the right kind of colormap. And you can visually choose the available colormaps in the colormaps_list/ForColormap.pdf manual or on this page (under development): https://github.com/gha3mi/forcolormap/tree/dev
You need, whatever your operating system:
If you have a GitHub account, just clone the repository. Then launch the demo example, which is creating PPM files with colormaps and colorbars for all the available colormaps:
$ git clone git@github.com:vmagnin/forcolormap.git
$ cd forcolormap
$ fpm run --example demo
To use ForColormap within your own fpm
project, add the following lines to your fpm.toml
manifest file:
[dependencies]
forcolormap = {git = "https://github.com/vmagnin/forcolormap.git"}
You can also build the project with CMake:
$ git clone git@github.com:vmagnin/forcolormap.git
$ cd forcolormap
$ mkdir build && cd build
$ cmake ..
$ make
$ sudo make install
By default, ForColormap is built as a static library by CMake. You can compile your program with the -static
option:
$ gfortran -static my_program.f90 $(pkg-config --cflags --libs forcolormap forimage)
Note that ForColormap is depending on ForImage, and for static linking you must respect that order.
There is a CMake option to obtain a shared library:
$ cmake -D BUILD_SHARED_LIBS=true ..
You can compile your program like this:
$ gfortran my_program.f90 $(pkg-config --cflags --libs forcolormap)
If you encounter linking problems, you should verify the content of your PKG_CONFIG_PATH
and LD_LIBRARY_PATH
environment variables. For example, in Ubuntu or FreeBSD the .pc
files will be installed in /usr/local/lib/pkgconfig/
and the libraries in /usr/local/lib/
.
$ export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig/
You can build the examples with:
$ cmake -D BUILD_FORCOLORMAP_EXAMPLES=true ..
$ make
$ cd example
The automatic tests can be run with:
$ cmake -D BUILD_TESTING=true ..
$ make
$ ctest
From the build
directory:
$ sudo make uninstall_forcolormap
Note that its dependency ForImage will also be uninstalled! You will have to reinstall it if needed.
You can also choose and remove files listed in build/install_manifest.txt
one by one.
See CMake basics for more information.
In the example
directory, you will find these commented demos:
demo.f90
creates demo PPM files for each built-in colormap, plus a PPM file with the corresponding colorbars. It also demonstrates how to create your own colormap defined in an array and how to download a colormap from a .txt
file.demo_reverse.f90
demonstrates the usage of the reverse=.true.
option to reverse the direction of a colormap.colormaps_list.f90
generates the colormaps_list/COLORMAPS_LIST_*.md
files.example1.f90
demonstrates how ForImage can be used to import/export PPM files.create.f90
demonstrates creating a custom colormap using methods like create_lagrange()
and create_bezier()
.extract.f90
demonstrates how to create a specific colormap by extracting a specified number of colors of a colormap.info.f90
demonstrates how to obtain information about a colormap using the Colormaps_info
class.modify.f90
demonstrates how you can modify a colormap with methods like shift()
, in concrete cases.They can be launched with the command fpm run --example name_of_the_example
(without the .f90
extension).
In the gtk-fortran-extra repository, you will also find a physical model demonstrating the use of ForColormap. It creates a movie with Turing patterns, displayed with various colormaps:
https://www.youtube.com/watch?v=cVHLCVVvZ4U
This project is under MIT license. The logo files are under license CC BY-SA 4.0.
As any work, a colormap should be cited: