mirror of https://github.com/fltk/fltk
176 lines
5.2 KiB
Plaintext
176 lines
5.2 KiB
Plaintext
README.Cairo.txt - 2011-12-10 - Cairo rendering support for FLTK
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CONTENTS
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==========
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1 INTRODUCTION
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2 CAIRO SUPPORT FOR FLTK 1.3
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2.1 Configuration
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2.2 Currently supported features
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2.3 Future considerations
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3 PLATFORM SPECIFIC NOTES
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3.1 Linux
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3.2 Windows
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3.3 Mac OSX
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4 DOCUMENT HISTORY
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INTRODUCTION
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==============
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Cairo is a software library used to provide a vector graphics-based,
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device-independent API for software developers. It is designed to provide
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primitives for 2-dimensional drawing across a number of different
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backends. Cairo is designed to use hardware acceleration when available.
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CAIRO SUPPORT FOR FLTK 1.3
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============================
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It is now possible to integrate cairo rendering in your FLTK application
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more easily and transparently.
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In 1.3, we provide minimum support for Cairo,
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in particular, no "total" cairo rendering layer support is achieved,
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as in fltk2.
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Configuration
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---------------
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All the changes are *inactive* as long as the new configuration
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option --enable-cairo is not added to the configure command or the CMake
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variable OPTION_CAIRO:BOOL=ON is set.
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Currently supported features
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------------------------------
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(1) Adding a new Fl_Cairo_Window class permitting transparent and easy
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integration of a Cairo draw callback without the need subclass Fl_Window.
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(2) Adding a Fl::cairo_make_current(Fl_Window*) function only providing
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transparently a cairo context to your custom Fl_Window derived class.
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This function is intended to be used in your overloaded draw() method.
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(3) Adding an optional cairo autolink context mode support which permits
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complete and automatic synchronization of OS dependent graphical context
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and cairo contexts, thus furthering a valid cairo context anytime,
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in any current window.
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This feature should be only necessary in the following cases:
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- Intensive and almost systematic use of cairo in an FLTK application
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- Creation of a new cairo based scheme for FLTK
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- Other uses of cairo necessitating the FLTK internal instrumentation
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to automatically making possible the use of a cairo context
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in any FLTK window.
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This feature must be enabled with 'configure --enable-cairoext' or the
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CMake variable OPTION_CAIROEXT:BOOL=ON (Default: OFF).
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(4) A new cairo demo that is available in the test subdirectory and has
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been used as a testcase during the multiplatform tests.
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For more details, please have a look to the doxygen documentation,
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in the Modules section.
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Future considerations
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-----------------------
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From Bill:
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First there is the FLTK_HAVE_CAIRO configuration option. This indicates that
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any cairo calls are available. In this case you get something like this:
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// static variable holding the last cairo context FLTK set:
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cairo_t* Fl::cr;
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// Make cr draw in this window. This hides the ugly platform-dependent
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// part of getting cairo going:
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void Fl::cairo_make_current(Fl_Window*)
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*** POST 1.3 potential cairo use:
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// Set cr to something you made yourself. This lets you reuse functions
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// that use cr, and also tells FLTK that cr is not one of its own and
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// thus cannot be destroyed or reused for a different window:
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void Fl::cairo_make_current(cairo_t*)
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Second there is the FLTK_USE_CAIRO configuration option. This means that all
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drawing is done using Cairo. In this case when a widget draw() method is
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called, it is exactly as though cairo_make_current(window) has been done.
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***
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Note that it should be possible to compile so FLTK_HAVE_CAIRO works even
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if FLTK_USE_CAIRO does not, and so that turning on FLTK_USE_CAIRO does not
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break any programs written for FLTK_HAVE_CAIRO.
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PLATFORM SPECIFIC NOTES
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=========================
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The following are notes about building FLTK with Cairo support
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on the various supported operating systems.
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3.1 Linux
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---------
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From Greg (erco@seriss.com):
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To get FLTK 1.3.x (r9204) to build on Centos 5.5, I found that
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I only needed to install the "cairo-devel" package, ie:
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sudo yum install cairo-devel
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..and then rebuild FLTK:
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make distclean
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./configure --enable-cairo
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make
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If you get this error:
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[..]
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Linking cairo_test...
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/usr/bin/ld: cannot find -lpixman-1
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collect2: ld returned 1 exit status
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make[1]: *** [cairo_test] Error 1
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..remove "-lpixman-1" from FLTK's makeinclude file, i.e. change this line:
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-CAIROLIBS = -lcairo -lpixman-1
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+CAIROLIBS = -lcairo
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..then another 'make' should finish the build without errors.
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You should be able to then run the test/cairo_test program.
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According to the cairo site, "For Debian and Debian derivatives including
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Ubuntu" you need to install libcairo2-dev, i.e.
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sudo apt-get install libcairo2-dev
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This has been tested and works with Ubuntu 11.10. Note that this also
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installs libpixman-1-dev, so that dependencies on this should be resolved
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as well.
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3.2 Windows
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-----------
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TBD
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3.3 Mac OSX
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-----------
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TBD
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DOCUMENT HISTORY
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==================
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Dec 20 2010 - matt: restructured document
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Dec 09 2011 - greg: Updates for Centos 5.5 builds
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Dec 10 2011 - Albrecht: Updates for Ubuntu and Debian, fixed typos.
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Jul 05 2017 - Albrecht: Added CMake config info, fixed typos.
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