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OT: gtk rectangle with opacity

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Patrick Shirkey

27 Dec 2009 27 Dec '09

1:31 p.m.

Hi, Does anyone have an example in c of drawing a gdk_rectangle with opacity in the foreground color? There's several examples in python floating around that use the cairo but I can't find a nice example in c. Cheers. -- Patrick Shirkey Boost Hardware Ltd

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hermann

27 Dec 27 Dec

2:39 p.m.

gboolean box_expose(GtkWidget *wi, GdkEventExpose *ev, gpointer data) { cairo_t *cr; // create a cairo context // cr = gdk_cairo_create(wi->window); double x0 = wi->allocation.x; double y0 = wi->allocation.y; double rect_width = wi->allocation.width; double rect_height = wi->allocation.height; cairo_rectangle (cr, x0,y0,rect_width,rect_height+3); cairo_set_source_rgba (cr, 0, 0, 0, 0.5); // a set the opacity level cairo_fill (cr); cairo_destroy(cr); } draw a transparent black rectangle to the calling widget. You can connect it with to make sure it will redraw when needed. g_signal_connect(widget, "expose-event", G_CALLBACK(box_expose), NULL); more examples you could found here http://cairographics.org/samples/ regards hermann Am Montag, den 28.12.2009, 04:30 +1100 schrieb Patrick Shirkey:

Hi, Does anyone have an example in c of drawing a gdk_rectangle with opacity in the foreground color? There's several examples in python floating around that use the cairo but I can't find a nice example in c. Cheers.

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hermann

2:43 p.m.

Am Sonntag, den 27.12.2009, 19:39 +0100 schrieb hermann:

gboolean box_expose(GtkWidget *wi, GdkEventExpose *ev, gpointer data) { cairo_t *cr; // create a cairo context // cr = gdk_cairo_create(wi->window); double x0 = wi->allocation.x; double y0 = wi->allocation.y; double rect_width = wi->allocation.width; double rect_height = wi->allocation.height; cairo_rectangle (cr, x0,y0,rect_width,rect_height+3); cairo_set_source_rgba (cr, 0, 0, 0, 0.5); // a set the opacity level cairo_fill (cr); cairo_destroy(cr);

// EDIT:// don't forget to return false; //

} draw a transparent black rectangle to the calling widget. You can connect it with to make sure it will redraw when needed. g_signal_connect(widget, "expose-event", G_CALLBACK(box_expose), NULL); more examples you could found here http://cairographics.org/samples/ regards hermann Am Montag, den 28.12.2009, 04:30 +1100 schrieb Patrick Shirkey:

Hi, Does anyone have an example in c of drawing a gdk_rectangle with opacity in the foreground color? There's several examples in python floating around that use the cairo but I can't find a nice example in c. Cheers.

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Patrick Shirkey

2:59 p.m.

On 12/28/2009 05:43 AM, hermann wrote:

Am Sonntag, den 27.12.2009, 19:39 +0100 schrieb hermann:

gboolean box_expose(GtkWidget *wi, GdkEventExpose *ev, gpointer data) { cairo_t *cr; // create a cairo context // cr = gdk_cairo_create(wi->window); double x0 = wi->allocation.x; double y0 = wi->allocation.y; double rect_width = wi->allocation.width; double rect_height = wi->allocation.height; cairo_rectangle (cr, x0,y0,rect_width,rect_height+3); cairo_set_source_rgba (cr, 0, 0, 0, 0.5); // a set the opacity level cairo_fill (cr); cairo_destroy(cr);

// EDIT:// don't forget to return false; // > } > draw a transparent black rectangle to the calling widget. > You can connect it with to make sure it will redraw when needed. > > g_signal_connect(widget, "expose-event", G_CALLBACK(box_expose), NULL); > > more examples you could found here > http://cairographics.org/samples/ > > regards hermann >

Thanks. That's what I was looking for. I was getting close but this code definitely saves me some time. FYI, I am have merged the gtkmeter.c and gtkmeterscale.c classes into one widget. With the transparent levels it looks very nice now. If anyone wants this class let me know. Cheers. Patrick Shirkey Boost Hardware Ltd

Am Montag, den 28.12.2009, 04:30 +1100 schrieb Patrick Shirkey:

Hi, Does anyone have an example in c of drawing a gdk_rectangle with opacity in the foreground color? There's several examples in python floating around that use the cairo but I can't find a nice example in c. Cheers.

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hermann
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