有人可以向我展示一个使用 C 语言为 Cairo 和 Gtk3 绘制单行的最小工作示例GtkDrawingArea
。我尝试testcairo.c
在 Gtk3 测试文件夹中进行修改,但无法正常工作。请不要在开罗网站上推荐教程;Zetcode.com 或 gnome.org,它们要么不适用于 Gtk3,要么不是最小的工作示例。
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16595 次
4 回答
13
我得到了它。关键区别在于,对于 gtk+3,您必须从“绘制”信号处理程序中进行绘制。使用 gtk+2 它来自“expose-event”信号处理程序。这是一个最小的工作示例。
于 2012-07-11T16:41:22.993 回答
7
这是一个完整的工作示例:
确保
gtk3-devel
已安装(在 Fedora #dnf install gtk3-devel 中)在 Ubuntu 中:
sudo apt install libgtk-3-dev
编译:gcc draw.c `pkg-config --cflags gtk+-3.0 --libs gtk+-3.0` -o draw
#include <gtk/gtk.h>
gboolean draw_callback (GtkWidget *widget, cairo_t *cr, gpointer data)
{
guint width, height;
GdkRGBA color;
GtkStyleContext *context;
context = gtk_widget_get_style_context (widget);
width = gtk_widget_get_allocated_width (widget);
height = gtk_widget_get_allocated_height (widget);
gtk_render_background(context, cr, 0, 0, width, height);
cairo_arc (cr, width/2.0, height/2.0, MIN (width, height) / 2.0, 0, 2 * G_PI);
gtk_style_context_get_color (context, gtk_style_context_get_state (context), &color);
gdk_cairo_set_source_rgba (cr, &color);
gdk_cairo_set_source_rgba (cr, &color);
cairo_fill (cr);
return FALSE;
}
gint main(int argc,char *argv[])
{
GtkWidget *window, *drawing_area;
gtk_init (&argc, &argv);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
drawing_area = gtk_drawing_area_new();
gtk_container_add (GTK_CONTAINER (window), drawing_area);
gtk_widget_set_size_request (drawing_area, 200, 100);
g_signal_connect (G_OBJECT (drawing_area), "draw", G_CALLBACK (draw_callback), NULL);
gtk_widget_show_all (window);
gtk_main ();
return 0;
}
于 2017-01-30T17:49:26.177 回答
5
任何人都在 2020 年这样做。这是重构为使用 GTK3 的 Zetcode 示例,它绘制了您想要的内容,因此线条不会奇怪地连接。我添加了评论来解释正在发生的事情。
/* To compile: gcc linetest.c -o linetest `pkg-config --cflags --libs gtk+-3.0`
* C program for basic drawing with GTK+ and cairo.
* Working 2020 example if this got you stuck, http://zetcode.com/gfx/cairo/basicdrawing/
* Note: the above command line uses backticks (`), it's right before 1 on your keyboard.
*/
#include <cairo.h>
#include <gtk/gtk.h>
//function prototypes
static gboolean on_draw_event(GtkWidget *widget, cairo_t *cr, gpointer user_data);
static void do_drawing(cairo_t *cr);
static gboolean clicked(GtkWidget *widget, GdkEventButton *event, gpointer user_data);
//end of function prototypes
/* Global variables for storing mouse coordinates,
* count is index of arrays, coordx and coordy are x and y coordinates of the mouse
*/
struct {
int count;
double coordx[100];
double coordy[100];
} glob;
/* Function: on_draw_event
*Parameters: GtkWidget, cairo_t, gpointer
*Use: This is the function we attach to the main method when we want to draw. It calls the do_drawing method.
*Example: g_signal_connect(G_OBJECT(darea), "draw", G_CALLBACK(on_draw_event), NULL);
*/
static gboolean on_draw_event(GtkWidget *widget, cairo_t *cr, gpointer user_data)
{
do_drawing(cr);
return FALSE;
}
/* Function: do_drawing
*Parameters: cairo_t
*Use: It sets cairo canvas settings, and draws shapes with a for loop
*Settings: are commented
*Note: printf is used during debugging to find mouse click coordinates :)
*/
static void do_drawing(cairo_t *cr)
{
cairo_set_source_rgb(cr, 0, 0, 0);//Line colour
cairo_set_line_width(cr, 0.5);//Line width
if (glob.count > 1) {
cairo_move_to(cr, glob.coordx[0], glob.coordy[0]);
//printf("from: x:%f, y:%f\n",glob.coordx[0],glob.coordy[0]);
}
//Connect lines.
for (int i = 1; i < glob.count; ++i) {
cairo_line_to(cr, glob.coordx[i], glob.coordy[i]);
//printf("to: x:%f, y:%f\n",glob.coordx[i],glob.coordy[i]);
}
// Draw the above.
cairo_stroke(cr);
//resets array so shape can be drawn again.
glob.count = 0;
}
/* Function: clicked
*Parameters: GtkWidget, GdkEventButton, gpointer
*Use: Registers mouse clicks, 1 is right, 3 is left on laptop. Clicks may be 1, 2 or 3 on a desktop
*Note: printf is used during debugging to find mouse click coordinates :)
*/
static gboolean clicked(GtkWidget *widget, GdkEventButton *event,
gpointer user_data)
{
if (event->button == 1) {
// printf("Right Click");
glob.coordx[glob.count] = event->x;
glob.coordy[glob.count++] = event->y;
// int i;
// for (i =0; i <= glob.count-1; i++) {
// printf("%f\n", glob.coordx[i]);
// }
}
if (event->button == 3) {
//printf("left Click");
gtk_widget_queue_draw(widget);
}
return TRUE;
}
//Main method.
int main(int argc, char *argv[])
{
//widget variables, window and drawing area.
GtkWidget *window;
GtkWidget *darea;
//Set global count 0, so array is at beginning whenver program starts.
glob.count = 0;
//Always have this to start GTK.
gtk_init(&argc, &argv);
//Set new window, set new drawing area.
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
darea = gtk_drawing_area_new();
//Add the drawing area to the window.
gtk_container_add(GTK_CONTAINER(window), darea);
//You need this to register mouse clicks.
gtk_widget_add_events(window, GDK_BUTTON_PRESS_MASK);
//Attaching draw function to the main method.
g_signal_connect(G_OBJECT(darea), "draw",
G_CALLBACK(on_draw_event), NULL);
//You can close window when you exit button.
g_signal_connect(window, "destroy",
G_CALLBACK(gtk_main_quit), NULL);
//Register if left or right mouse click.
g_signal_connect(window, "button-press-event",
G_CALLBACK(clicked), NULL);
//Set window position, default size, and title.
gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
gtk_window_set_default_size(GTK_WINDOW(window), 400, 300);
gtk_window_set_title(GTK_WINDOW(window), "Lines");
//Show all widgets.
gtk_widget_show_all(window);
//start window
gtk_main();
return 0;
}
于 2020-06-20T12:12:10.143 回答
0
// compila con valac --pkg gtk+-3.0 nombre_archivo.gs
uses
Gtk
Cairo
init
Gtk.init (ref args)
var TestCairo = new Ventana ()
TestCairo.show_all ()
Gtk.main ()
class Ventana : Window
area: Gtk.DrawingArea
init
title = "Test Genie + GTK + Cairo"
set_default_size (400, 400)
window_position = WindowPosition.CENTER
destroy.connect(Gtk.main_quit)
// área de dibujo
area: Gtk.DrawingArea = new Gtk.DrawingArea ()
// conecta el área de dibujo al método dibujar
area.draw.connect (dibujar)
// añade el área de dibujo a la ventana
add (area)
def dibujar (context : Context) : bool
context.set_source_rgba (1, 0, 0, 1)
context.set_line_width (2)
context.move_to (200, 100)
context.line_to (200, 300)
context.move_to (100, 200)
context.line_to (300, 200)
context.stroke ()
return true
http://genie.webierta.skn1.com中的更多 Genie + Gtk + Cairo 示例
于 2017-01-31T16:44:19.730 回答