Fix cairo build (autoconf + CMake) + README's

- rewrite to use pkg-config with both autoconf + CMake
- remove hardcoded library names
- fix build dependencies and search directories
- remove or replace old and unused variables
- update README files

To be done:
- implement fallback for autoconf/configure if pkg-config is missing
- fix pango build (uses cairo internally)

1 files changed, 129 insertions, 38 deletions

diff --git a/README.Cairo.txt b/README.Cairo.txt
index d4b519d2a..47eabda4d 100644
--- a/README.Cairo.txt
+++ b/README.Cairo.txt
@@ -1,22 +1,28 @@
-README.Cairo.txt - 2011-12-10 - Cairo rendering support for FLTK
-----------------------------------------------------------------
-
+README.Cairo.txt - Cairo rendering support for FLTK
+----------------------------------------------------
 
 
  CONTENTS
 ==========
 
  1   INTRODUCTION
- 2   CAIRO SUPPORT FOR FLTK 1.3
-   2.1   Configuration
-   2.2   Currently supported features
-   2.3   Future considerations
+
+ 2   CAIRO SUPPORT FOR FLTK
+   2.1    Configuration
+   2.2    Currently supported features
+   2.3    Future considerations
+
  3   PLATFORM SPECIFIC NOTES
-   3.1  Linux
-   3.2  Windows
-   3.3  Mac OSX
- 4   DOCUMENT HISTORY
+   3.1    Linux
+   3.1.1  Debian and Derivatives (like Ubuntu)
+   3.1.2  CentOS from Greg (erco@seriss.com)
+   3.2    Windows
+   3.3    macOS
+   3.3.1  Install Xcode Commandline Tools
+   3.3.2  Install Homebrew for Cairo and other Library Support
+   3.3.3  Install CMake and Build with CMake
 
+ 4   DOCUMENT HISTORY
 
 
  INTRODUCTION
@@ -28,14 +34,13 @@ primitives for 2-dimensional drawing across a number of different
 backends. Cairo is designed to use hardware acceleration when available.
 
 
- CAIRO SUPPORT FOR FLTK 1.3
-============================
+ CAIRO SUPPORT FOR FLTK
+========================
 
-It is now possible to integrate cairo rendering in your FLTK application
+It is now possible to integrate Cairo rendering in your FLTK application
 more easily and transparently.
-In 1.3, we provide minimum support for Cairo,
-in particular, no "total" cairo rendering layer support is achieved,
-as in fltk2.
+Since FLTK 1.3 we provide minimum support for Cairo; no "total" Cairo
+rendering layer support is achieved.
 
 
  Configuration
@@ -53,25 +58,25 @@ variable OPTION_CAIRO:BOOL=ON is set.
     integration of a Cairo draw callback without the need to subclass Fl_Window.
 
 (2) Adding a Fl::cairo_make_current(Fl_Window*) function only providing
-    transparently a cairo context to your custom Fl_Window derived class.
+    transparently a Cairo context to your custom Fl_Window derived class.
     This function is intended to be used in your overloaded draw() method.
 
-(3) Adding an optional cairo autolink context mode support which permits
+(3) Adding an optional Cairo autolink context mode support which permits
     complete and automatic synchronization of OS dependent graphical context
-    and cairo contexts, thus furthering a valid cairo context anytime,
+    and Cairo contexts, thus furthering a valid Cairo context anytime,
     in any current window.
 
     This feature should be only necessary in the following cases:
-    - Intensive and almost systematic use of cairo in an FLTK application
-    - Creation of a new cairo based scheme for FLTK
-    - Other uses of cairo necessitating the FLTK internal instrumentation
-      to automatically making possible the use of a cairo context
+    - Intensive and almost systematic use of Cairo in an FLTK application
+    - Creation of a new Cairo based scheme for FLTK
+    - Other uses of Cairo necessitating the FLTK internal instrumentation
+      to automatically making possible the use of a Cairo context
       in any FLTK window.
 
     This feature must be enabled with 'configure --enable-cairoext' or the
     CMake variable OPTION_CAIROEXT:BOOL=ON (Default: OFF).
 
-(4) A new cairo demo that is available in the test subdirectory and has
+(4) A new Cairo demo that is available in the test subdirectory and has
     been used as a testcase during the multiplatform tests.
 
 For more details, please have a look to the doxygen documentation,
@@ -83,16 +88,16 @@ in the Modules section.
 
 From Bill:
 First there is the FLTK_HAVE_CAIRO configuration option. This indicates that
-any cairo calls are available. In this case you get something like this:
+any Cairo calls are available. In this case you get something like this:
 
-// static variable holding the last cairo context FLTK set:
+// static variable holding the last Cairo context FLTK set:
 cairo_t* Fl::cr;
 
 // Make cr draw in this window. This hides the ugly platform-dependent
-// part of getting cairo going:
+// part of getting Cairo going:
 void Fl::cairo_make_current(Fl_Window*)
 
-*** POST 1.3 potential cairo use:
+*** POST 1.3 potential Cairo use:
 // Set cr to something you made yourself. This lets you reuse functions
 // that use cr, and also tells FLTK that cr is not one of its own and
 // thus cannot be destroyed or reused for a different window:
@@ -117,19 +122,19 @@ on the various supported operating systems.
     3.1 Linux
     ---------
 
-    3.1.1 Debian and derivatives (like Ubuntu)
-    -----------------------------------------------------
+    3.1.1 Debian and Derivatives (like Ubuntu)
+    -------------------------------------------
 
       Run from a terminal command line:
         sudo apt install libcairo2-dev
 
-    Then build fltk using the cairo additional option using:
+    Then build fltk using the Cairo support option using:
       cmake -G"Unix Makefiles" -DOPTION_CAIRO:BOOL=ON -S <fltk_dir> -B <your_build_dir>
       cd <your_build_dir>
       make
 
     3.1.2 CentOS from Greg (erco@seriss.com)
-    ---------------------------------------------------
+    -----------------------------------------
 
     To get FLTK 1.3.x (r9204) to build on Centos 5.5, I found that
     I only needed to install the "cairo-devel" package, ie:
@@ -158,7 +163,7 @@ on the various supported operating systems.
     ..then another 'make' should finish the build without errors.
     You should be able to then run the test/cairo_test program.
 
-    According to the cairo site, "For Debian and Debian derivatives including
+    According to the Cairo site, "For Debian and Debian derivatives including
     Ubuntu" you need to install libcairo2-dev, i.e.
 
         sudo apt-get install libcairo2-dev
@@ -167,16 +172,101 @@ on the various supported operating systems.
     installs libpixman-1-dev, so that dependencies on this should be resolved
     as well.
 
+    As of Feb 2021 (FLTK 1.4.0) dependencies like pixman-1 will be detected by
+    configure or CMake automatically using pkg-config.
+
+    Note 1: CMake builds *require* the use of pkg-config.
+
+    Note 2: As of Feb 2021 autoconf/configure/make builds require pkg-config
+    as well but there are plans to implement a fallback mechanism so you can
+    build FLTK w/o having to install and use pkg-config. This will be done if
+    possible (but not guaranteed).
+
 
     3.2 Windows
-    -----------
+    ------------
     TBD
 
 
-    3.3 Mac OSX
-    -----------
-    TBD
+    3.3 macOS
+    ----------
+    As under Linux you can use both build options, i.e. autoconf/make or CMake
+    to build FLTK with Cairo support. One option is to install Homebrew and
+    add the required libraries with `brew install ...'. It is always required
+    to install the "Xcode commandline tools" but a full installation of Xcode
+    is not necessary. If you choose to use Xcode you can generate the Xcode
+    IDE files with CMake.
+
+    The following instructions are intentionally terse. More detailed
+    information can be found in README.macOS.md and README.CMake.txt.
+
+
+    3.3.1 Install Xcode Commandline Tools
+    --------------------------------------
+    Launch a "Terminal" and execute `xcode-select --install', then select to
+    install the Xcode commandline tools. This installs the required compilers
+    and build tools, for instance `git' (commandline only) and `clang'.
+
+    With these tools installed it is already possible to download and build
+    a current FLTK tarball or snapshot. All you need to do is unpack the
+    tarball and run `make' in the root directory. This will run `configure',
+    generate the necessary files, and build FLTK in its standard configuration.
+
+    Note 1: this requires an existing `configure' file which is included in
+    FLTK releases and snapshots but not in the FLTK Git repository.
+
+    Note 2: to build current FLTK downloaded from Git using configure + make
+    you need to run `autoconf' to generate 'configure'. If autoconf is not
+    available on your system you can download a FLTK snapshot, unpack it,
+    and copy the 'configure' file from the snapshot to your Git worktree.
+
+
+    3.3.2 Install Homebrew for Cairo and other Library Support
+    -----------------------------------------------------------
+    There are several options to install additional library support under
+    macOS. macOS does not provide a package manager to install such software.
+    This README is about installing and using Homebrew as a package manager
+    to build FLTK with Cairo, everything else (for instance "Fink") is beyond
+    the scope of this README.
+
+    This was tested on a MacBook Air 2020 (M1) with the new Apple Silicon M1
+    (ARM) processor.
+
+    Go to https://brew.sh/ and follow the instructions under "Install Homebrew".
+    Before you do this, read about the security implications - the FLTK team
+    is not responsible for your system security. Read their docs on how to
+    install and use Homebrew.
+
+    If you installed Homebrew correctly you can use `brew search cairo' or any
+    other software (package) name to see if it can be installed. If yes, run
+    `brew install cairo' (or other name) to install it.
+
+    Other helpful packages are 'autoconf' and other Unix (Linux) tools, for
+    instance 'git-gui' (installs 'gitk' and 'git gui' commands). The Xcode
+    commandline tools mentioned above install only the git commandline tool.
+
+
+    3.3.3 Install CMake and Build with CMake
+    -----------------------------------------
+    Either use `brew install cmake' or go to https://cmake.org/download/
+    and download the latest stable CMake release for macOS, for instance
+    'cmake-3.19.6-macos-universal.dmg' (at the time of this writing). Open
+    (mount) this .dmg file in the Finder. In the shown window you can either
+    run CMake directly or drag the CMake application to the "Applications"
+    folder to install it (recommended). Then you can run CMake from your
+    Applications folder or using "launchpad". See README.macOS.md for
+    instructions to install the downloaded CMake GUI tool for use with the
+    commandline.
+
+    Once you start the CMake GUI version you can select your source folder
+    (where you downloaded FLTK) and the build folder (either a subdirectory,
+    e.g. 'build' or another folder anywhere else) and click "configure".
+    Follow the instructions and select either "native compilers" or Xcode or
+    whatever you like to build your FLTK library. In the CMake GUI you need
+    to select OPTION_CAIRO (ON) to build with basic Cairo support. Finally
+    click "generate" to create the build files.
 
+    For more information on using CMake to build FLTK see README.CMake.txt.
 
 
  DOCUMENT HISTORY
@@ -186,3 +276,4 @@ Dec 20 2010 - matt: restructured document
 Dec 09 2011 - greg: Updates for Centos 5.5 builds
 Dec 10 2011 - Albrecht: Updates for Ubuntu and Debian, fixed typos.
 Jul 05 2017 - Albrecht: Added CMake config info, fixed typos.
+Feb 28 2021 - Albrecht: Update for FLTK 1.4, add macOS instructions.