Languages

Menu
Sites
Language
I can not show a canvas

Hi to all,

I have two questions, first and more basic, I have this code, supose to show some shapes in the screen, but is not showing nothing:

Evas_Object *img;
    img = evas_object_image_filled_add(evas_object_evas_get(ad->win));
    evas_object_show(img);
    cairo_surface_t *surface;
    cairo_t *cairo;
    evas_object_geometry_get(ad->win, NULL, NULL, &screen_size_w, &screen_size_h);
    surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, screen_size_w, screen_size_h);
    cairo = cairo_create (surface);
    cairo_set_source_rgba(cairo, 1, 1, 1, 1);
        cairo_paint(cairo);

        cairo_translate(cairo,100, 100);
        cairo_set_line_width(cairo,2);
        cairo_set_source_rgba(cairo, 0.0, 0.0, 1.0, 1.0);
        cairo_move_to (cairo, 200 , 200);
            cairo_line_to (cairo, 400, 300);
            cairo_rel_line_to (cairo, 200 , 100);
        cairo_surface_flush(surface);
        unsigned char * imageData = cairo_image_surface_get_data(cairo_get_target(cairo));
            evas_object_image_data_set(img, imageData);
            evas_object_image_data_update_add(img, 0, 0, screen_size_w, screen_size_h);

 

Second question, Is possible to use the canvas object to draw, not on the window, to draw on a, for example, label object?

Thanks to all!!

View Selected Answer
List

Responses

2 Replies
Mark as answer
Shaswati Saha

Add the line below in the create_base_gui() function.
 

evas_object_event_callback_add(ad->win, EVAS_CALLBACK_RESIZE, win_resize_cb, ad);

Write the win_resize_cb() as below:

static void
win_resize_cb(void *data, Evas *e , Evas_Object *obj , void *event_info)
{
    appdata_s *ad = data;

	if(ad->surface)
	{
		cairo_surface_destroy(ad->surface);
		cairo_destroy(ad->cairo);
		ad->surface = NULL;
		ad->cairo = NULL;
	}

	evas_object_geometry_get(obj, NULL, NULL, &ad->width, &ad->height);
	evas_object_image_size_set(ad->img, ad->width, ad->height);
	evas_object_resize(ad->img, ad->width, ad->height);
	evas_object_show(ad->img);

	if(!ad->surface)
	{
		ad->surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, ad->width, ad->height);
		ad->cairo = cairo_create (ad->surface);
		cairo_drawing(ad);
	}
}

Write cairo_drawing() function as below:

void cairo_drawing(void *data)
{
    appdata_s *ad = data;


	/* clear background as white */
	cairo_set_source_rgba(ad->cairo, 1, 1, 1, 1);
	cairo_paint(ad->cairo);

	cairo_translate(ad->cairo, 100,100);
	cairo_set_line_width(ad->cairo,2);
	cairo_set_source_rgba(ad->cairo, 0.0, 0.0, 1.0, 1.0);

	cairo_move_to (ad->cairo, 200 , 200);
	cairo_line_to (ad->cairo,400, 300);
	cairo_rel_line_to (ad->cairo, 200, 100);
	//cairo_arc (ad->cairo, 0.4 * d, 0.4 * d, 0.2* d * sqrt(2), -0.25 * M_PI, 0.25 * M_PI);

	cairo_stroke(ad->cairo);
	cairo_surface_flush(ad->surface);

	/* display cairo drawin on screen */
	unsigned char * imageData = cairo_image_surface_get_data(cairo_get_target(ad->cairo));
	evas_object_image_data_set(ad->img, imageData);
	evas_object_image_data_update_add(ad->img, 0, 0, ad->width, ad->height);
}

Note: I didn't find the below line in your code. 

cairo_stroke(ad->cairo);
Carlos Dominguez

Thanks!