我需要知道用 cairo 在 gtk 中绘制形状的最简单方法
I need to know the simplest way to draw a shape in gtk with cairo
有人能告诉我在 gtk 中的 window 中绘制矩形的最简单方法吗？请？简单的。这是一个挑战。编写一个文件，用几行代码绘制任何 cairo 形状。我在网上找到了可用的绘图代码，但它非常复杂，并不是所有的都是必要的。有人可以给我写代码，用几行代码绘制任何 cairo 形状，这样我就可以将它用作我的游戏参考吗？
这是一些工作代码，但过于复杂。我不需要通过单击鼠标来绘制矩形，只需从四个数字中绘制一个矩形即可。有人，请将其减少到绘制一个矩形所绝对需要的。最好我想画一个除了主要功能之外没有任何其他功能的矩形（一旦主要功能returns归零，一切都结束）
代码：
#include <gtk/gtk.h>
/* Surface to store current scribbles */
static cairo_surface_t *surface = NULL;
static void
clear_surface (void)
{
cairo_t *cr;
cr = cairo_create (surface);
cairo_set_source_rgb (cr, 1, 1, 1);
cairo_paint (cr);
cairo_destroy (cr);
}
/* Create a new surface of the appropriate size to store our scribbles */
static gboolean
configure_event_cb (GtkWidget *widget,
GdkEventConfigure *event,
gpointer data)
{
if (surface)
cairo_surface_destroy (surface);
surface = gdk_window_create_similar_surface (gtk_widget_get_window (widget),
CAIRO_CONTENT_COLOR,
gtk_widget_get_allocated_width (widget),
gtk_widget_get_allocated_height (widget));
/* Initialize the surface to white */
clear_surface ();
/* We've handled the configure event, no need for further processing. */
return TRUE;
}
/* Redraw the screen from the surface. Note that the ::draw
* signal receives a ready-to-be-used cairo_t that is already
* clipped to only draw the exposed areas of the widget
*/
static gboolean
draw_cb (GtkWidget *widget,
cairo_t *cr,
gpointer data)
{
cairo_set_source_surface (cr, surface, 0, 0);
cairo_paint (cr);
return FALSE;
}
/* Draw a rectangle on the surface at the given position */
static void
draw_brush (GtkWidget *widget,
gdouble x,
gdouble y)
{
cairo_t *cr;
/* Paint to the surface, where we store our state */
cr = cairo_create (surface);
cairo_rectangle (cr, x - 3, y - 3, 6, 6);
cairo_fill (cr);
cairo_destroy (cr);
/* Now invalidate the affected region of the drawing area. */
gtk_widget_queue_draw_area (widget, x - 3, y - 3, 6, 6);
}
/* Handle button press events by either drawing a rectangle
* or clearing the surface, depending on which button was pressed.
* The ::button-press signal handler receives a GdkEventButton
* struct which contains this information.
*/
static gboolean
button_press_event_cb (GtkWidget *widget,
GdkEventButton *event,
gpointer data)
{
/* paranoia check, in case we haven't gotten a configure event */
if (surface == NULL)
return FALSE;
if (event->button == GDK_BUTTON_PRIMARY)
{
draw_brush (widget, event->x, event->y);
}
else if (event->button == GDK_BUTTON_SECONDARY)
{
clear_surface ();
gtk_widget_queue_draw (widget);
}
/* We've handled the event, stop processing */
return TRUE;
}
/* Handle motion events by continuing to draw if button 1 is
* still held down. The ::motion-notify signal handler receives
* a GdkEventMotion struct which contains this information.
*/
static gboolean
motion_notify_event_cb (GtkWidget *widget,
GdkEventMotion *event,
gpointer data)
{
/* paranoia check, in case we haven't gotten a configure event */
if (surface == NULL)
return FALSE;
if (event->state & GDK_BUTTON1_MASK)
draw_brush (widget, event->x, event->y);
/* We've handled it, stop processing */
return TRUE;
}
static void
close_window (void)
{
if (surface)
cairo_surface_destroy (surface);
}
static void
activate (GtkApplication *app,
gpointer user_data)
{
GtkWidget *window;
GtkWidget *frame;
GtkWidget *drawing_area;
window = gtk_application_window_new (app);
gtk_window_set_title (GTK_WINDOW (window), "Drawing Area");
g_signal_connect (window, "destroy", G_CALLBACK (close_window), NULL);
gtk_container_set_border_width (GTK_CONTAINER (window), 8);
frame = gtk_frame_new (NULL);
gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
gtk_container_add (GTK_CONTAINER (window), frame);
drawing_area = gtk_drawing_area_new ();
/* set a minimum size */
gtk_widget_set_size_request (drawing_area, 100, 100);
gtk_container_add (GTK_CONTAINER (frame), drawing_area);
/* Signals used to handle the backing surface */
g_signal_connect (drawing_area, "draw",
G_CALLBACK (draw_cb), NULL);
g_signal_connect (drawing_area,"configure-event",
G_CALLBACK (configure_event_cb), NULL);
/* Event signals */
g_signal_connect (drawing_area, "motion-notify-event",
G_CALLBACK (motion_notify_event_cb), NULL);
g_signal_connect (drawing_area, "button-press-event",
G_CALLBACK (button_press_event_cb), NULL);
/* Ask to receive events the drawing area doesn't normally
* subscribe to. In particular, we need to ask for the
* button press and motion notify events that want to handle.
*/
gtk_widget_set_events (drawing_area, gtk_widget_get_events (drawing_area)
| GDK_BUTTON_PRESS_MASK
| GDK_POINTER_MOTION_MASK);
gtk_widget_show_all (window);
}
int
main (int argc,
char **argv)
{
GtkApplication *app;
int status;
app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
status = g_application_run (G_APPLICATION (app), argc, argv);
g_object_unref (app);
return status;
}
Can someone tell me the SIMPLEST way to draw like a rectangle in a
window in gtk?
是的，但您只会得到一个默认的 Gtk window，其中 cairo_rectangle 填充默认的 200x200 window，矩形周围有 10 像素的边框。绘制一个矩形并不多，（您甚至不必用单独的颜色填充它 - 尽管这使得它与正常的 window 背景无法区分）。
只需创建 gtk window 并使用 gtk window 作为容器添加 cairo 绘图区（您将无法向 window 添加任何其他内容，除非你使用像 vbox 等布局容器。）
大约最小值是：
#include <cairo.h>
#include <gtk/gtk.h>
static void draw_rect (cairo_t *cr)
{
cairo_rectangle (cr, 10, 10, 180, 180); /* set rectangle */
cairo_set_source_rgb (cr, 0.3, 0.4, 0.6); /* set fill color */
cairo_fill (cr); /* fill rectangle */
}
static gboolean on_draw_event (GtkWidget *widget, cairo_t *cr,
gpointer user_data)
{
draw_rect (cr); /* draw rectangle in window */
return FALSE;
(void)user_data, (void)widget; /* suppress -Wunused warning */
}
int main (int argc, char *argv[])
{
GtkWidget *window; /* gtk windows */
GtkWidget *darea; /* cairo drawing area */
gtk_init (&argc, &argv); /* required with every gtk app */
window = gtk_window_new (GTK_WINDOW_TOPLEVEL); /* create window */
darea = gtk_drawing_area_new(); /* create cairo area */
gtk_container_add (GTK_CONTAINER(window), darea); /* add to window */
/* connect callbacks to draw rectangle and close window/quit app */
g_signal_connect (G_OBJECT(darea), "draw",
G_CALLBACK(on_draw_event), NULL);
g_signal_connect (G_OBJECT(window), "destroy",
G_CALLBACK(gtk_main_quit), NULL);
gtk_widget_show_all (window); /* show all windows */
gtk_main(); /* pass control to gtk event-loop */
}
(注意： 你可以删除 (void)user_data, (void)widget; 行，它只是抑制未使用的参数警告)
编译
gcc -Wall -Wextra -pedantic -std=c11 -O3 `pkg-config --cflags --libs gtk+-3.0`
例子Use/Output
$ ./bin/cairo_rectangle_min
有人能告诉我在 gtk 中的 window 中绘制矩形的最简单方法吗？请？简单的。这是一个挑战。编写一个文件，用几行代码绘制任何 cairo 形状。我在网上找到了可用的绘图代码，但它非常复杂，并不是所有的都是必要的。有人可以给我写代码，用几行代码绘制任何 cairo 形状，这样我就可以将它用作我的游戏参考吗？
这是一些工作代码，但过于复杂。我不需要通过单击鼠标来绘制矩形，只需从四个数字中绘制一个矩形即可。有人，请将其减少到绘制一个矩形所绝对需要的。最好我想画一个除了主要功能之外没有任何其他功能的矩形（一旦主要功能returns归零，一切都结束）
代码：
#include <gtk/gtk.h>
/* Surface to store current scribbles */
static cairo_surface_t *surface = NULL;
static void
clear_surface (void)
{
cairo_t *cr;
cr = cairo_create (surface);
cairo_set_source_rgb (cr, 1, 1, 1);
cairo_paint (cr);
cairo_destroy (cr);
}
/* Create a new surface of the appropriate size to store our scribbles */
static gboolean
configure_event_cb (GtkWidget *widget,
GdkEventConfigure *event,
gpointer data)
{
if (surface)
cairo_surface_destroy (surface);
surface = gdk_window_create_similar_surface (gtk_widget_get_window (widget),
CAIRO_CONTENT_COLOR,
gtk_widget_get_allocated_width (widget),
gtk_widget_get_allocated_height (widget));
/* Initialize the surface to white */
clear_surface ();
/* We've handled the configure event, no need for further processing. */
return TRUE;
}
/* Redraw the screen from the surface. Note that the ::draw
* signal receives a ready-to-be-used cairo_t that is already
* clipped to only draw the exposed areas of the widget
*/
static gboolean
draw_cb (GtkWidget *widget,
cairo_t *cr,
gpointer data)
{
cairo_set_source_surface (cr, surface, 0, 0);
cairo_paint (cr);
return FALSE;
}
/* Draw a rectangle on the surface at the given position */
static void
draw_brush (GtkWidget *widget,
gdouble x,
gdouble y)
{
cairo_t *cr;
/* Paint to the surface, where we store our state */
cr = cairo_create (surface);
cairo_rectangle (cr, x - 3, y - 3, 6, 6);
cairo_fill (cr);
cairo_destroy (cr);
/* Now invalidate the affected region of the drawing area. */
gtk_widget_queue_draw_area (widget, x - 3, y - 3, 6, 6);
}
/* Handle button press events by either drawing a rectangle
* or clearing the surface, depending on which button was pressed.
* The ::button-press signal handler receives a GdkEventButton
* struct which contains this information.
*/
static gboolean
button_press_event_cb (GtkWidget *widget,
GdkEventButton *event,
gpointer data)
{
/* paranoia check, in case we haven't gotten a configure event */
if (surface == NULL)
return FALSE;
if (event->button == GDK_BUTTON_PRIMARY)
{
draw_brush (widget, event->x, event->y);
}
else if (event->button == GDK_BUTTON_SECONDARY)
{
clear_surface ();
gtk_widget_queue_draw (widget);
}
/* We've handled the event, stop processing */
return TRUE;
}
/* Handle motion events by continuing to draw if button 1 is
* still held down. The ::motion-notify signal handler receives
* a GdkEventMotion struct which contains this information.
*/
static gboolean
motion_notify_event_cb (GtkWidget *widget,
GdkEventMotion *event,
gpointer data)
{
/* paranoia check, in case we haven't gotten a configure event */
if (surface == NULL)
return FALSE;
if (event->state & GDK_BUTTON1_MASK)
draw_brush (widget, event->x, event->y);
/* We've handled it, stop processing */
return TRUE;
}
static void
close_window (void)
{
if (surface)
cairo_surface_destroy (surface);
}
static void
activate (GtkApplication *app,
gpointer user_data)
{
GtkWidget *window;
GtkWidget *frame;
GtkWidget *drawing_area;
window = gtk_application_window_new (app);
gtk_window_set_title (GTK_WINDOW (window), "Drawing Area");
g_signal_connect (window, "destroy", G_CALLBACK (close_window), NULL);
gtk_container_set_border_width (GTK_CONTAINER (window), 8);
frame = gtk_frame_new (NULL);
gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_IN);
gtk_container_add (GTK_CONTAINER (window), frame);
drawing_area = gtk_drawing_area_new ();
/* set a minimum size */
gtk_widget_set_size_request (drawing_area, 100, 100);
gtk_container_add (GTK_CONTAINER (frame), drawing_area);
/* Signals used to handle the backing surface */
g_signal_connect (drawing_area, "draw",
G_CALLBACK (draw_cb), NULL);
g_signal_connect (drawing_area,"configure-event",
G_CALLBACK (configure_event_cb), NULL);
/* Event signals */
g_signal_connect (drawing_area, "motion-notify-event",
G_CALLBACK (motion_notify_event_cb), NULL);
g_signal_connect (drawing_area, "button-press-event",
G_CALLBACK (button_press_event_cb), NULL);
/* Ask to receive events the drawing area doesn't normally
* subscribe to. In particular, we need to ask for the
* button press and motion notify events that want to handle.
*/
gtk_widget_set_events (drawing_area, gtk_widget_get_events (drawing_area)
| GDK_BUTTON_PRESS_MASK
| GDK_POINTER_MOTION_MASK);
gtk_widget_show_all (window);
}
int
main (int argc,
char **argv)
{
GtkApplication *app;
int status;
app = gtk_application_new ("org.gtk.example", G_APPLICATION_FLAGS_NONE);
g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
status = g_application_run (G_APPLICATION (app), argc, argv);
g_object_unref (app);
return status;
}
Can someone tell me the SIMPLEST way to draw like a rectangle in a window in gtk?
是的，但您只会得到一个默认的 Gtk window，其中 cairo_rectangle 填充默认的 200x200 window，矩形周围有 10 像素的边框。绘制一个矩形并不多，（您甚至不必用单独的颜色填充它 - 尽管这使得它与正常的 window 背景无法区分）。
只需创建 gtk window 并使用 gtk window 作为容器添加 cairo 绘图区（您将无法向 window 添加任何其他内容，除非你使用像 vbox 等布局容器。）
大约最小值是：
#include <cairo.h>
#include <gtk/gtk.h>
static void draw_rect (cairo_t *cr)
{
cairo_rectangle (cr, 10, 10, 180, 180); /* set rectangle */
cairo_set_source_rgb (cr, 0.3, 0.4, 0.6); /* set fill color */
cairo_fill (cr); /* fill rectangle */
}
static gboolean on_draw_event (GtkWidget *widget, cairo_t *cr,
gpointer user_data)
{
draw_rect (cr); /* draw rectangle in window */
return FALSE;
(void)user_data, (void)widget; /* suppress -Wunused warning */
}
int main (int argc, char *argv[])
{
GtkWidget *window; /* gtk windows */
GtkWidget *darea; /* cairo drawing area */
gtk_init (&argc, &argv); /* required with every gtk app */
window = gtk_window_new (GTK_WINDOW_TOPLEVEL); /* create window */
darea = gtk_drawing_area_new(); /* create cairo area */
gtk_container_add (GTK_CONTAINER(window), darea); /* add to window */
/* connect callbacks to draw rectangle and close window/quit app */
g_signal_connect (G_OBJECT(darea), "draw",
G_CALLBACK(on_draw_event), NULL);
g_signal_connect (G_OBJECT(window), "destroy",
G_CALLBACK(gtk_main_quit), NULL);
gtk_widget_show_all (window); /* show all windows */
gtk_main(); /* pass control to gtk event-loop */
}
(注意： 你可以删除 (void)user_data, (void)widget; 行，它只是抑制未使用的参数警告)
编译
gcc -Wall -Wextra -pedantic -std=c11 -O3 `pkg-config --cflags --libs gtk+-3.0`
例子Use/Output
$ ./bin/cairo_rectangle_min