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Add Lua API to convert Canvas::Color to Cairo RGBA

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This commit is contained in:
Robin Gareus 2017-02-17 23:28:03 +01:00
parent b4dd020139
commit 3bbb4b76f7
1 changed files with 30 additions and 0 deletions
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30
gtk2_ardour/luainstance.cc
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@ -21,6 +21,7 @@
#include <pango/pangocairo.h>
#include "gtkmm2ext/gui_thread.h"
#include "canvas/colors.h"
#include "ardour/audioengine.h"
#include "ardour/diskstream.h"
@ -312,6 +313,30 @@ class PangoLayout {
Glib::RefPtr<Pango::Layout> _layout;
};
/** expand RGBA color to parameters
*
* convert a Canvas::Color (uint32_t 0xRRGGBBAA) into
* double RGBA values which can be passed as parameters to
* Cairo::Context::set_source_rgba
*
* @returns r, g, b, a
*/
static int color_to_rgba (lua_State *L)
{
int top = lua_gettop (L);
if (top < 1) {
return luaL_argerror (L, 1, "invalid number of arguments, color_to_rgba (uint32_t)");
}
uint32_t color = luabridge::Stack<uint32_t>::get (L, 1);
double r, g, b, a;
ArdourCanvas::color_to_rgba (color, r, g, b, a);
luabridge::Stack <double>::push (L, r);
luabridge::Stack <double>::push (L, g);
luabridge::Stack <double>::push (L, b);
luabridge::Stack <double>::push (L, a);
return 4;
}
}; // namespace
////////////////////////////////////////////////////////////////////////////////
@ -515,6 +540,11 @@ LuaInstance::bind_cairo (lua_State* L)
.addConst ("WordChar", Pango::WRAP_WORD_CHAR)
.endNamespace ()
.endNamespace ()
.beginNamespace ("LuaCairo")
.addCFunction ("color_to_rgba", &LuaCairo::color_to_rgba)
.endNamespace ();
/* Lua/cairo bindings operate on Cairo::Context, there is no Cairo::RefPtr wrapper [yet].