[英]How to use cairo with gtk2 in C?
I have a huge problem with cairo and gtk2. 我对cairo和gtk2有很大的疑问。 I was following this tutorial: http://zetcode.com/gfx/cairo/cairobackends/ (GTK Window header).
我正在关注本教程:http: //zetcode.com/gfx/cairo/cairobackends/ (GTK窗口标题)。 Unfortunately nothing appears in the window.
不幸的是,窗口中没有任何内容。
Code from tutorial: 教程中的代码:
#include <cairo.h>
#include <gtk/gtk.h>
static void do_drawing(cairo_t *);
static gboolean on_draw_event(GtkWidget *widget, cairo_t *cr,
gpointer user_data)
{
do_drawing(cr);
return FALSE;
}
static void do_drawing(cairo_t *cr)
{
cairo_set_source_rgb(cr, 0, 0, 0);
cairo_select_font_face(cr, "Sans", CAIRO_FONT_SLANT_NORMAL,
CAIRO_FONT_WEIGHT_NORMAL);
cairo_set_font_size(cr, 40.0);
cairo_move_to(cr, 10.0, 50.0);
cairo_show_text(cr, "Disziplin ist Macht.");
}
int main(int argc, char *argv[])
{
GtkWidget *window;
GtkWidget *darea;
gtk_init(&argc, &argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
darea = gtk_drawing_area_new();
gtk_container_add(GTK_CONTAINER(window), darea);
g_signal_connect(G_OBJECT(darea), "draw",
G_CALLBACK(on_draw_event), NULL);
g_signal_connect(window, "destroy",
G_CALLBACK(gtk_main_quit), NULL);
gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
gtk_window_set_default_size(GTK_WINDOW(window), 400, 90);
gtk_window_set_title(GTK_WINDOW(window), "GTK window");
gtk_widget_show_all(window);
gtk_main();
return 0;
}
I figured out that I should use "expose_event" istead of "draw", but there is still problem. 我发现应该使用“ expose_event”而不是“ draw”,但是仍然存在问题。
I found something like this: 我发现了这样的事情:
gboolean
expose_event_callback (GtkWidget *widget, GdkEventExpose *event, gpointer data)
{
gdk_draw_arc (widget->window,
widget->style->fg_gc[gtk_widget_get_state (widget)],
TRUE,
0, 0, widget->allocation.width, widget->allocation.height,
0, 64 * 360);
return TRUE;
}
[...]
GtkWidget *drawing_area = gtk_drawing_area_new ();
gtk_widget_set_size_request (drawing_area, 100, 100);
g_signal_connect (G_OBJECT (drawing_area), "expose_event",
G_CALLBACK (expose_event_callback), NULL);
This piece of code works, it draws something. 这段代码有效,它可以画些东西。 Could you tell me what should I do to have a working functions like in the first example with one where I can put a code I want to draw (something like do_drawing).
您能告诉我如何实现第一个示例中的工作功能,并在其中放置我想绘制的代码(类似于do_drawing)。 Thanks in advance.
提前致谢。
Try to create a new cairo context in the expose event callback with : 尝试在暴露事件回调中使用以下命令创建一个新的cairo上下文:
gdk_cairo_create (gtk_widget_get_window (widget));
Look this question : 看这个问题:
How to create a cairo_t on a Gtk 2 window 如何在Gtk 2窗口上创建cairo_t
I haven't make any tests but I think that it could help you 我没有做任何测试,但我认为它可以帮助您
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