112 lines
3.8 KiB
Plaintext
112 lines
3.8 KiB
Plaintext
README.Cairo.txt - 2010-10-25 - 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 DOCUMENT HISTORY
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iINTRODUCTION
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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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wbackends. 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.
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For non configure based platforms/ide, the FLTK_HAVE_CAIRO preprocess var.
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has to be defined.
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All configure based build files has now this feature integrated,
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also vc2005 build files have 2 new build modes "Release Cairo" and
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"Debug Cairo".
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Others IDE's will be updated progressively.
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Currently supported features
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------------------------------
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- Adding a new Fl_Cairo_Window class permitting transparent and easy
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integration of a Cairo draw callback without the need to achieve subclassing.
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- 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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- Adding an optional cairo autolink context mode support (disabled by default)
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which permits complete & automatic synchronization of OS dependent graphical
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context 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 contexts 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 necessiting the flk internals 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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- A new cairo demo that is available in the test subdirectory and has been
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used as a testcase durings 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 it's 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 if
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FLTK_USE_CAIRO does not, and so that turning on FLTK_USE_CAIRO does not break any
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programs written for FLTK_HAVE_CAIRO.
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DOCUMENT HISTORY
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==================
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Dec 20 2010 - matt: restructured document
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