Last modified on 7 September 2012, at 08:14

Aros/Developer/Cairo

Navbar for the Aros wikibook
Aros User Docs
Aros User Docs
Aros User FAQs
Aros User Applications
Aros User DOS Shell
Aros/User/AmigaLegacy
Aros Dev Docs
Aros Developer Docs
Porting Software from AmigaOS/SDL
For Zune Beginners
Zune .MUI Classes
For SDL Beginners
Aros Developer BuildSystem
Specific platforms
68k Support
PPC Power Architecture Support
Arm Raspberry Pi Support
Android support
Linux and FreeBSD Support
Windows Mingw and MacOSX Support
Aros x86 Installing
Aros x86 Audio/Video Support
Aros x86 Network Support
Aros x86 Complete System HCL
Aros Storage Support IDE SATA etc
Aros Poseidon USB Support
x86-64 Support
misc
Aros Public License

There are currently two ports (1.5 and 1.12) of the Cairo graphics library. Both are located in the Aros contrib sources.

You'll find a quite recent version in "contrib/development/libs/cairo". It is a patch to Cairo version 1.12.0. This version builds into a static link library.

To compile the link library run the following commands in your Aros source directory:

make development-fontconfig

fc-cache

make development-cairo

This will build the dependencies and the Cairo and Pixman library.



Cairo 1.12 examplesEdit

Cairo 1.12, using directly the image surface (that processes everything in system memory) gives much faster results, say probably about 60% faster than the old 1.5.

Using the image surface, blit the rgba data to your custom area class in draw method, using cairo_image_get_data().



Cairo 1.5 examplesEdit

The Cairo version (1.5) in "contrib/gfx/libs/cairo/" is rather old. But in contrast to the other version it has the great advantage that it support Aros as a native backend. This means it comes with a function "cairo_aros_surface_create" that can render to Intuition RastPorts. First parameter was the pointer to the RastPort, the other parameters specified X/Y-offset, width and height. Also this port builds into a Aros shared library. In the Aros-Exec Archives you'll also find a static link library of Cairo that supports "cairo_aros_surface_create".

The old 1.5 version was entirely software-driven and it involved reads from the bitmap in video ram, which is highly inefficient.


The second example below shows a simple example of how native Aros surfaces are created and used.

Simple Cairo example that creates a PNG image

Compile with: gcc test.c -lcairo -lpixman -lfreetype2 -lfontconfig -liconv -lxml2 -lz -lpng

#include <cairo/cairo.h>
 
int main (int argc, char *argv[])
{
cairo_surface_t *surface;
cairo_t *cr;
 
surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 470, 80);
cr = cairo_create (surface);
 
        cairo_select_font_face (cr, "DejaVu Sans", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_BOLD);
        cairo_set_font_size (cr, 50.0);
        cairo_set_source_rgb (cr, 1.0, 0.0, 0.0);
        cairo_move_to (cr, 50, 50);
        cairo_show_text (cr, "Hello, AROS :-)");
 
cairo_destroy (cr);
cairo_surface_write_to_png (surface, "helloamiga.png");
cairo_surface_destroy (surface);
 
return 0;
}


Simple Cairo example using Aros native RastPort backend

#include <exec/types.h>
#include <exec/exec.h>
#include <intuition/intuition.h>
 
#include <proto/intuition.h>
#include <proto/dos.h>
#include <proto/exec.h>
 
#include <cairo/cairo.h>
#include <cairo/cairo-aros.h>
 
#define WIDTH 400
#define HEIGHT 120
 
struct Window *appwin;
struct IntuitionBase *IntuitionBase;
 
cairo_surface_t *surface;
cairo_t *cr;
 
int main()
{
    IntuitionBase = (struct IntuitionBase *) OpenLibrary("intuition.library",0L);
 
    if (IntuitionBase != NULL)
    {
        appwin = OpenWindowTags(NULL,
                                WA_Left, 100,
                                WA_Top, 100,
                                WA_Width, WIDTH,
                                WA_Height, HEIGHT,
                                WA_Title, "Cairo - AROS",
                                WA_CloseGadget, TRUE,
                                WA_DragBar, TRUE,
                                WA_DepthGadget, TRUE,
                                WA_IDCMP, IDCMP_CLOSEWINDOW,
                                WA_Activate, TRUE,
                                WA_GimmeZeroZero, TRUE,
                                TAG_DONE);
 
        surface = cairo_aros_surface_create (appwin->RPort, 0, 0, WIDTH, HEIGHT);
        cr      = cairo_create (surface);
 
        cairo_select_font_face (cr, "DejaVu Sans", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_BOLD);
        cairo_set_font_size (cr, 50.0);
        cairo_set_source_rgb (cr, 1.0, 0.0, 0.0);
        cairo_move_to (cr, 50, 50);
        cairo_show_text (cr, "Hello, AROS :-)");
 
        if (appwin != NULL)
        {
            Wait(1L << appwin->UserPort->mp_SigBit);
 
            CloseWindow(appwin);
        }
    }
 
    if (IntuitionBase != NULL) CloseLibrary((struct Library *)IntuitionBase);
 
    return 0;
}



ReferenceEdit

Direct Access FunctionsEdit

cairo_image_get_data() and other direct access functions are often misused by applications because they don't call cairo_surface_flush() and/or cairo_surface_mark_dirty() around the code which accesses the surface data directly. You must call cairo_surface_flush() before reading from or writing to the surface and that you must use cairo_surface_mark_dirty() after modifying it.



void
modify_image_surface (cairo_surface_t *surface)
{
  unsigned char *data;
  int width, height, stride;

  // flush to ensure all writing to the image was done
  cairo_surface_flush (surface);

  // modify the image
  data = cairo_image_surface_get_data (surface);
  width = cairo_image_surface_get_width (surface);
  height = cairo_image_surface_get_height (surface);
  stride = cairo_image_surface_get_stride (surface);
  modify_image_data (data, width, height, stride);

  // mark the image dirty so Cairo clears its caches.
  cairo_surface_mark_dirty (surface);
}


Cairo Library Calls



SurfaceEdit

cairo_surface_create_similar cairo_surface_create_similar_image cairo_surface_create_for_rectangle cairo_surface_reference cairo_surface_destroy cairo_surface_status cairo_surface_finish cairo_surface_flush cairo_surface_get_device cairo_surface_get_font_options cairo_surface_get_content cairo_surface_mark_dirty cairo_surface_mark_dirty_rectangle cairo_surface_set_device_offset cairo_surface_get_device_offset cairo_surface_set_fallback_resolution cairo_surface_get_fallback_resolution cairo_surface_get_type cairo_surface_get_reference_count cairo_surface_set_user_data cairo_surface_get_user_data cairo_surface_copy_page cairo_surface_show_page cairo_surface_has_show_text_glyphs cairo_surface_set_mime_data cairo_surface_get_mime_data cairo_surface_supports_mime_type cairo_surface_map_to_image cairo_surface_unmap_image


DevicesEdit

cairo_device_reference cairo_device_destroy cairo_device_status cairo_device_finish cairo_device_flush cairo_device_get_type cairo_device_get_reference_count cairo_device_set_user_data cairo_device_get_user_data cairo_device_acquire cairo_device_release