<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <meta name="Generator" content="Microsoft Exchange Server">  <style></style> </head> <body> <font face="Calibri, sans-serif" size="2"> <div style="padding-left: 70pt; ">Hi,</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">New to the list and already my first question….</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">I'd like to have the recording surface grab colours to playback from a parent..</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">E.g. </div> <div style="padding-left: 70pt; ">draw…</div> <div style="padding-left: 70pt; ">set color to X</div> <div style="padding-left: 70pt; ">paint</div> <div style="padding-left: 70pt; ">set color to Y</div> <div style="padding-left: 70pt; ">draw…</div> <div style="padding-left: 70pt; ">paint</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">When playing it back I'd like to be able to vary X. Like an Andy Warhol pic be able to play back in BLUE, RED,…</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">There are other clear applications.. In PDF, for example, we have something called Xobjects. These contain a number of</div> <div style="padding-left: 70pt; ">drawing operations and get their stroking and non-stroking (fill) colours from the context into which they are being played</div> <div style="padding-left: 70pt; ">back into.</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">At the current stage I suspect the only means would be to extend cairo with something like</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">typedef cairo_status_t (*cairo_callback_func_t) (int which, cairo_t *cr, void *data);</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">cairo_status_t cairo_callback_set (cairo_t *cr, cairo_callback_func_t callback);</div> <div style="padding-left: 70pt; ">cairo_status_t cairo_callback_call (cairo_t *cr, int which, void *data);</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">(data is not really needed but I figure maybe it can't hurt even if its means one needs to store a pointer)</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">the callback could then in the above example set the colors (which choosing which one).. or be used for a host of other</div> <div style="padding-left: 70pt; ">applications, even attach/fetch the user data from surface backing the context.. Putting the callback function into gstate even</div> <div style="padding-left: 70pt; ">lets one push/pop them to one delight..</div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">This extension would be simple enough to do.. </div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; ">Or is there already a means to handle my use case without extending Cairo and I'm just missing the trivial?</div> <div style="padding-left: 70pt; "> </div> <div><font color="#210058"> </font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">_________________________________________________________________</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">Edward C. Zimmermann</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">Softwareentwicklung</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">–––</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">CIB software GmbH</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">Elektrastr. 6a</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">81925 München</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">–––</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">T +49 (0)89 / 1 43 60 - 156</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">F +49 (0)89 / 1 43 60 -100</font></div> <div><a href="mailto:edward.zimmermann@cib.de"><font face="Verdana, sans-serif" size="2" color="#0000FF"><u>edward.zimmermann@cib.de</u></font></a></div> <div><a href="http://www.cib.de/"><font face="Verdana, sans-serif" size="2" color="#0000FF"><u>www.cib.de</u></font></a></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">–––</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">Sitz: München </font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">Registergericht München, HRB 123286</font></div> <div><font face="Verdana, sans-serif" size="2" color="#210058">Geschäftsführer: Dipl.-Ing. Ulrich Brandner</font></div> <div> </div> <div style="padding-left: 70pt; "> </div> <div style="padding-left: 70pt; "> </div> </font> </body> </html>