{"id":2747,"date":"2010-08-27T01:40:21","date_gmt":"2010-08-26T20:10:21","guid":{"rendered":"http:\/\/www.jeffrin.in\/?p=2747"},"modified":"2010-08-27T01:40:21","modified_gmt":"2010-08-26T20:10:21","slug":"cairo-graphics-1-1-beautification","status":"publish","type":"post","link":"https:\/\/www.trueangle.org\/index.php\/2010\/08\/27\/cairo-graphics-1-1-beautification\/","title":{"rendered":"cairo graphics 1.1 beautification"},"content":{"rendered":"

\"\"<\/a>
\n
\n\/* Jeffrin Jose Licensed GPL v3 Copyright
\nAugust 2010 GPL --> http:\/\/www.gnu.org\/copyleft\/gpl.html *\/<\/p>\n

#include
\n#include
\n#include
\n#include<\/p>\n

\/\/the global pixmap that will serve as our buffer
\nstatic GdkPixmap *pixmap = NULL;<\/p>\n

gboolean on_window_configure_event(GtkWidget * da, GdkEventConfigure * event, gpointer user_data){
\n static int oldw = 0;
\n static int oldh = 0;
\n \/\/make our selves a properly sized pixmap if our window has been resized
\n if (oldw != event->width || oldh != event->height){
\n \/\/create our new pixmap with the correct size.
\n GdkPixmap *tmppixmap = gdk_pixmap_new(da->window, event->width, event->height, -1);
\n \/\/copy the contents of the old pixmap to the new pixmap. This keeps ugly uninitialized
\n \/\/pixmaps from being painted upon resize
\n int minw = oldw, minh = oldh;
\n if( event->width width; }
\n if( event->height height; }
\n gdk_draw_drawable(tmppixmap, da->style->fg_gc[GTK_WIDGET_STATE(da)], pixmap, 0, 0, 0, 0, minw, minh);
\n \/\/we're done with our old pixmap, so we can get rid of it and replace it with our properly-sized one.
\n g_object_unref(pixmap);
\n pixmap = tmppixmap;
\n }
\n oldw = event->width;
\n oldh = event->height;
\n return TRUE;
\n}<\/p>\n

gboolean on_window_expose_event(GtkWidget * da, GdkEventExpose * event, gpointer user_data){
\n gdk_draw_drawable(da->window,
\n da->style->fg_gc[GTK_WIDGET_STATE(da)], pixmap,
\n \/\/ Only copy the area that was exposed.
\n event->area.x, event->area.y,
\n event->area.x, event->area.y,
\n event->area.width, event->area.height);
\n return TRUE;
\n}<\/p>\n

static int currently_drawing = 0;
\n\/\/do_draw will be executed in a separate thread whenever we would like to update
\n\/\/our animation
\nvoid *do_draw(void *ptr){<\/p>\n

currently_drawing = 1;<\/p>\n

int width, height;
\n gdk_threads_enter();
\n gdk_drawable_get_size(pixmap, &width, &height);
\n gdk_threads_leave();<\/p>\n

\/\/create a gtk-independant surface to draw on
\n cairo_surface_t *cst = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
\n cairo_t *cr = cairo_create(cst);<\/p>\n

\/\/Vertical Line
\n cairo_move_to(cr, 200,30);
\n cairo_line_to(cr,200,200);<\/p>\n

\/\/Horizontal Line
\n cairo_move_to(cr, 120,120);
\n cairo_line_to(cr,290,120);<\/p>\n

cairo_rectangle(cr,80,25,300,220);<\/p>\n

\/\/do some time-consuming drawing
\n static int i = 0;
\n ++i; i = i % 300; \/\/give a little movement to our animation
\n cairo_set_source_rgb (cr, .9, .9, .9);
\n cairo_paint(cr);
\n cairo_set_source_rgb (cr, 0.8, 0.5, 0.9);
\n cairo_move_to(cr, 50,50);<\/p>\n

int j,k;
\nk=0;
\n\/* for(k=0; k<100; ++k){*\/ \/\/lets just redraw lots of times to use a lot of proc power
\n for(j=0; j 100)
\n {
\n cairo_move_to(cr, 200,76);
\n cairo_arc(cr, 200+i,76+i,0,0,0);
\n }
\nelse
\n{
\n cairo_arc(cr, 100+i,76,0,0,0);
\n}<\/p>\n

\/* cairo_rectangle(cr,50+i,50+i,50,50); *\/<\/p>\n

cairo_stroke(cr);
\n }
\n \/* }*\/
\n cairo_destroy(cr);<\/p>\n

\/\/When dealing with gdkPixmap's, we need to make sure not to
\n \/\/access them from outside gtk_main().
\n gdk_threads_enter();<\/p>\n

cairo_t *cr_pixmap = gdk_cairo_create(pixmap);
\n cairo_set_source_surface (cr_pixmap, cst, 0, 0);
\n cairo_paint(cr_pixmap);
\n cairo_destroy(cr_pixmap);<\/p>\n

gdk_threads_leave();<\/p>\n

cairo_surface_destroy(cst);<\/p>\n

currently_drawing = 0;<\/p>\n

return NULL;
\n}<\/p>\n

gboolean timer_exe(GtkWidget * window){<\/p>\n

static gboolean first_execution = TRUE;<\/p>\n

\/\/use a safe function to get the value of currently_drawing so
\n \/\/we don't run into the usual multithreading issues
\n int drawing_status = g_atomic_int_get(&currently_drawing);<\/p>\n

\/\/if we are not currently drawing anything, launch a thread to
\n \/\/update our pixmap
\n if(drawing_status == 0){
\n static pthread_t thread_info;
\n int iret;
\n if(first_execution != TRUE){
\n pthread_join(thread_info, NULL);
\n }
\n iret = pthread_create( &thread_info, NULL, do_draw, NULL);
\n }<\/p>\n

\/\/tell our window it is time to draw our animation.
\n int width, height;
\n gdk_drawable_get_size(pixmap, &width, &height);
\n gtk_widget_queue_draw_area(window, 0, 0, width, height);<\/p>\n

first_execution = FALSE;<\/p>\n

return TRUE;<\/p>\n

}<\/p>\n

int main (int argc, char *argv[]){<\/p>\n

\/\/we need to initialize all these functions so that gtk knows
\n \/\/to be thread-aware
\n if (!g_thread_supported ()){ g_thread_init(NULL); }
\n gdk_threads_init();
\n gdk_threads_enter();<\/p>\n

gtk_init(&argc, &argv);<\/p>\n

GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
\n GdkColor color;
\n color.red = 0xffff;
\n color.green = 0xffff;
\n color.blue = 0;
\n gtk_widget_set_size_request (GTK_WIDGET (window), 500, 400);
\n gtk_widget_modify_bg(window, GTK_STATE_NORMAL, &color);
\n g_signal_connect(G_OBJECT(window), \"destroy\", G_CALLBACK(gtk_main_quit), NULL);
\n g_signal_connect(G_OBJECT(window), \"expose_event\", G_CALLBACK(on_window_expose_event), NULL);
\n g_signal_connect(G_OBJECT(window), \"configure_event\", G_CALLBACK(on_window_configure_event), NULL);<\/p>\n

\/\/this must be done before we define our pixmap so that it can reference
\n \/\/the colour depth and such
\n gtk_widget_show_all(window);<\/p>\n

\/\/set up our pixmap so it is ready for drawing
\n pixmap = gdk_pixmap_new(window->window,700,700,-1);
\n \/\/because we will be painting our pixmap manually during expose events
\n \/\/we can turn off gtk's automatic painting and double buffering routines.
\n gtk_widget_set_app_paintable(window, TRUE);
\n gtk_widget_set_double_buffered(window, FALSE);<\/p>\n

(void)g_timeout_add(33, (GSourceFunc)timer_exe, window);<\/p>\n

gtk_main();
\n gdk_threads_leave();<\/p>\n

return 0;
\n}
\n<\/code><\/p>\n","protected":false},"excerpt":{"rendered":"

\/* Jeffrin Jose Licensed GPL v3 Copyright August 2010 GPL –> http:\/\/www.gnu.org\/copyleft\/gpl.html *\/ #include #include #include #include \/\/the global pixmap that will serve as our buffer static GdkPixmap *pixmap = NULL; gboolean on_window_configure_event(GtkWidget * da, GdkEventConfigure * event, gpointer user_data){ static int oldw = 0; static int oldh = 0; \/\/make our selves a properly … <\/p>\n

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