如何清除gtk、goocanvas表面？
How to clear gtk, goocanvas surface?
我正在使用 goocanvas 在 GTK 框架上绘制一个简单图表，图表尺寸基于相同 window 上的值。当用户使用微调按钮更改界面上的值时，图表应实时更改其尺寸。
我成功地在 gtk window->hbox->frame 上渲染了初始图表。
问题出在更改值时。它在绘图之上重绘。
那么有任何 "clear" 功能可用于 goo canvas 吗？
或者有什么其他方法可以达到预期的效果吗？
编辑：
当前代码：
/*
* Compile me with:
* gcc -o dia dia.c `pkg-config --libs --cflags gtk+-2.0 goocanvas` -rdynamic -I./headers/ -lm
*
*/
#include <stdio.h>
#include <gtk/gtk.h>
#include <goocanvas.h>
/*Common structs and varaibles*/
struct dia_struct
{
gdouble diam;
const gchar *tbp, *thtp, *wt;
};
struct dia_struct set_dia; /* intitializing the structure */
/* Goo canvas items */
GooCanvasItem *root, *path, *path2;
GtkWidget *canvas;
/*
* Function: ofdra
* --------------------
* This is the main function to draw the diagram on screen
*
* returns: none
*/
void ofdra (double diam)
{
double dfactor = diam*50;
path = NULL;
path2 = NULL;
double x = (465-dfactor)/2;
double y = 465-x;
char buf[100];
char buf2[100];
sprintf(buf, "M 0 %f L 1000 %f", x, x);
sprintf(buf2, "M 0 %f L 1000 %f", y, y);
path = goo_canvas_path_new (root, buf, "stroke-color", "red", NULL);
path2 = goo_canvas_path_new (root, buf2, "stroke-color", "red", NULL);
/*goo_canvas_item_update (path, TRUE, );*/
/*goo_canvas_item_update (path2);*/
}
/*
* Function: ofruta
* --------------------
* This is the main function to run when in a user changed a value.
*
* glade_wdgets: widget-object
* pObList: array of objects to go through
*
* returns: none
*/
void ofruta (GtkWidget *glade_wdgets, gpointer *pObList)
{
/* common varaibles needed */
struct dia_struct dia; /* intitializing the structure */
/* getters */
dia.diam = gtk_spin_button_get_value (GTK_SPIN_BUTTON(pObList[0])); /* diameter reading */
set_diamond.diam = diamond.diam;
gtk_spin_button_set_value(GTK_SPIN_BUTTON(pObList[0]), set_diamond.diam);
/* Loads all dynamically generated diagram drawing */
ofdra(set_diamond.diam);
}
//===========================================================================
/*
* main
*
* Program begins here
*/
int main( int argc, char **argv )
{
GtkBuilder *builder;
GtkWidget *window;
GError *error = NULL;
GtkButton *button;
GtkLabel *label;
cairo_surface_t *surface;
/* Init GTK+ */
gtk_init( &argc, &argv );
/* Create new GtkBuilder object */
builder = gtk_builder_new();
/* Load UI from file. If error occurs, report it and quit application.
* Replace "tut.glade" with your saved project. */
if( ! gtk_builder_add_from_file( builder, "dia_glade.glade", &error ) )
{
g_warning( "%s", error->message );
g_free( error );
return( 1 );
}
/* Get main window pointer from UI */
window = GTK_WIDGET( gtk_builder_get_object( builder, "window1" ) );
gpointer spinners[] = { gtk_builder_get_object( builder, "diam" )};
/* Connect signals */
gtk_builder_connect_signals( builder, spinners );
g_signal_connect(G_OBJECT(window), "delete-event", (GCallback)gtk_main_quit, NULL);
g_signal_connect(G_OBJECT("measure"), "clicked", (GCallback)ofruta, spinners);
canvas = goo_canvas_new ();
gtk_widget_set_size_request (canvas, 600, 465);
goo_canvas_set_bounds (GOO_CANVAS (canvas), 0, 0, 1000, 1000);
gtk_widget_show (canvas);
gtk_container_add (GTK_CONTAINER (gtk_builder_get_object( builder, "draw_area" )), canvas);
root = goo_canvas_get_root_item (GOO_CANVAS (canvas));
/* Destroy builder, since we don't need it anymore */
g_object_unref( G_OBJECT( builder ) );
/* Show window. All other widgets are automatically shown by GtkBuilder */
gtk_widget_show( window );
/* Start main loop */
gtk_main();
return( 0 );
}
当单击名为 "measure" 的按钮时，它的处理程序调用了 "ofruta"
在 "ofruta" 中调用绘图函数。
这是正确的方法吗？
这是一个基于 https://developer.gnome.org/goocanvas/unstable/goocanvas-model-view-canvas.html 的例子：
#include <stdlib.h>
#include <goocanvas.h>
static gboolean on_rect_button_press (GooCanvasItem *view,
GooCanvasItem *target,
GdkEventButton *event,
gpointer data);
static gboolean on_delete_event (GtkWidget *window,
GdkEvent *event,
gpointer unused_data);
GooCanvasItemModel *root, *rect_model, *text_model, *path;
int main (int argc, char *argv[]) {
GtkWidget *window, *scrolled_win, *canvas;
GooCanvasItem *rect_item;
gtk_set_locale ();
gtk_init (&argc, &argv);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_default_size (GTK_WINDOW (window), 640, 600);
gtk_widget_show (window);
g_signal_connect (window, "delete_event", (GtkSignalFunc) on_delete_event,
NULL);
scrolled_win = gtk_scrolled_window_new (NULL, NULL);
gtk_scrolled_window_set_shadow_type (GTK_SCROLLED_WINDOW (scrolled_win),
GTK_SHADOW_IN);
gtk_widget_show (scrolled_win);
gtk_container_add (GTK_CONTAINER (window), scrolled_win);
canvas = goo_canvas_new ();
gtk_widget_set_size_request (canvas, 600, 450);
goo_canvas_set_bounds (GOO_CANVAS (canvas), 0, 0, 1000, 1000);
gtk_widget_show (canvas);
gtk_container_add (GTK_CONTAINER (scrolled_win), canvas);
root = goo_canvas_group_model_new (NULL, NULL);
rect_model = goo_canvas_rect_model_new (root, 100, 100, 400, 400,
"line-width", 10.0,
"radius-x", 20.0,
"radius-y", 10.0,
"stroke-color", "yellow",
"fill-color", "red",
NULL);
text_model = goo_canvas_text_model_new (root, "Hello World", 300, 300, -1,
GTK_ANCHOR_CENTER,
"font", "Sans 24",
NULL);
goo_canvas_item_model_rotate (text_model, 45, 300, 300);
goo_canvas_set_root_item_model (GOO_CANVAS (canvas), root);
GooCanvasLineDash *dash = goo_canvas_line_dash_new (2, 5.0, 5.0);
const char *buf = "M 0 128 L 1000 256";
path = goo_canvas_path_model_new (root, buf,
"stroke-color", "red",
"line-dash", dash,
NULL);
rect_item = goo_canvas_get_item (GOO_CANVAS (canvas), rect_model);
g_signal_connect (rect_item, "button_press_event",
(GtkSignalFunc) on_rect_button_press, NULL);
goo_canvas_line_dash_unref(dash);
gtk_main ();
return 0;
}
static gboolean on_rect_button_press (GooCanvasItem *item,
GooCanvasItem *target,
GdkEventButton *event,
gpointer data) {
g_print ("rect item received button press event\n");
static float a = 128, b = 256;
a += 16, b += 16;
char buf[64];
snprintf(buf, sizeof(buf), "M 0 %f L 1000 %f", a, b);
g_object_set(G_OBJECT(path), "data", buf, NULL);
return TRUE;
}
static gboolean on_delete_event (GtkWidget *window,
GdkEvent *event,
gpointer unused_data) {
exit (0);
}
通过将路径的 data 属性 修改为 g_object_set 它会在单击矩形时移动。属性名称应取自文档，例如https://developer.gnome.org/goocanvas/unstable/GooCanvasPathModel.html
我正在使用 goocanvas 在 GTK 框架上绘制一个简单图表，图表尺寸基于相同 window 上的值。当用户使用微调按钮更改界面上的值时，图表应实时更改其尺寸。
我成功地在 gtk window->hbox->frame 上渲染了初始图表。
问题出在更改值时。它在绘图之上重绘。
那么有任何 "clear" 功能可用于 goo canvas 吗？
或者有什么其他方法可以达到预期的效果吗？
编辑：
当前代码：
/*
* Compile me with:
* gcc -o dia dia.c `pkg-config --libs --cflags gtk+-2.0 goocanvas` -rdynamic -I./headers/ -lm
*
*/
#include <stdio.h>
#include <gtk/gtk.h>
#include <goocanvas.h>
/*Common structs and varaibles*/
struct dia_struct
{
gdouble diam;
const gchar *tbp, *thtp, *wt;
};
struct dia_struct set_dia; /* intitializing the structure */
/* Goo canvas items */
GooCanvasItem *root, *path, *path2;
GtkWidget *canvas;
/*
* Function: ofdra
* --------------------
* This is the main function to draw the diagram on screen
*
* returns: none
*/
void ofdra (double diam)
{
double dfactor = diam*50;
path = NULL;
path2 = NULL;
double x = (465-dfactor)/2;
double y = 465-x;
char buf[100];
char buf2[100];
sprintf(buf, "M 0 %f L 1000 %f", x, x);
sprintf(buf2, "M 0 %f L 1000 %f", y, y);
path = goo_canvas_path_new (root, buf, "stroke-color", "red", NULL);
path2 = goo_canvas_path_new (root, buf2, "stroke-color", "red", NULL);
/*goo_canvas_item_update (path, TRUE, );*/
/*goo_canvas_item_update (path2);*/
}
/*
* Function: ofruta
* --------------------
* This is the main function to run when in a user changed a value.
*
* glade_wdgets: widget-object
* pObList: array of objects to go through
*
* returns: none
*/
void ofruta (GtkWidget *glade_wdgets, gpointer *pObList)
{
/* common varaibles needed */
struct dia_struct dia; /* intitializing the structure */
/* getters */
dia.diam = gtk_spin_button_get_value (GTK_SPIN_BUTTON(pObList[0])); /* diameter reading */
set_diamond.diam = diamond.diam;
gtk_spin_button_set_value(GTK_SPIN_BUTTON(pObList[0]), set_diamond.diam);
/* Loads all dynamically generated diagram drawing */
ofdra(set_diamond.diam);
}
//===========================================================================
/*
* main
*
* Program begins here
*/
int main( int argc, char **argv )
{
GtkBuilder *builder;
GtkWidget *window;
GError *error = NULL;
GtkButton *button;
GtkLabel *label;
cairo_surface_t *surface;
/* Init GTK+ */
gtk_init( &argc, &argv );
/* Create new GtkBuilder object */
builder = gtk_builder_new();
/* Load UI from file. If error occurs, report it and quit application.
* Replace "tut.glade" with your saved project. */
if( ! gtk_builder_add_from_file( builder, "dia_glade.glade", &error ) )
{
g_warning( "%s", error->message );
g_free( error );
return( 1 );
}
/* Get main window pointer from UI */
window = GTK_WIDGET( gtk_builder_get_object( builder, "window1" ) );
gpointer spinners[] = { gtk_builder_get_object( builder, "diam" )};
/* Connect signals */
gtk_builder_connect_signals( builder, spinners );
g_signal_connect(G_OBJECT(window), "delete-event", (GCallback)gtk_main_quit, NULL);
g_signal_connect(G_OBJECT("measure"), "clicked", (GCallback)ofruta, spinners);
canvas = goo_canvas_new ();
gtk_widget_set_size_request (canvas, 600, 465);
goo_canvas_set_bounds (GOO_CANVAS (canvas), 0, 0, 1000, 1000);
gtk_widget_show (canvas);
gtk_container_add (GTK_CONTAINER (gtk_builder_get_object( builder, "draw_area" )), canvas);
root = goo_canvas_get_root_item (GOO_CANVAS (canvas));
/* Destroy builder, since we don't need it anymore */
g_object_unref( G_OBJECT( builder ) );
/* Show window. All other widgets are automatically shown by GtkBuilder */
gtk_widget_show( window );
/* Start main loop */
gtk_main();
return( 0 );
}
当单击名为 "measure" 的按钮时，它的处理程序调用了 "ofruta" 在 "ofruta" 中调用绘图函数。
这是正确的方法吗？
这是一个基于 https://developer.gnome.org/goocanvas/unstable/goocanvas-model-view-canvas.html 的例子：
#include <stdlib.h>
#include <goocanvas.h>
static gboolean on_rect_button_press (GooCanvasItem *view,
GooCanvasItem *target,
GdkEventButton *event,
gpointer data);
static gboolean on_delete_event (GtkWidget *window,
GdkEvent *event,
gpointer unused_data);
GooCanvasItemModel *root, *rect_model, *text_model, *path;
int main (int argc, char *argv[]) {
GtkWidget *window, *scrolled_win, *canvas;
GooCanvasItem *rect_item;
gtk_set_locale ();
gtk_init (&argc, &argv);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_default_size (GTK_WINDOW (window), 640, 600);
gtk_widget_show (window);
g_signal_connect (window, "delete_event", (GtkSignalFunc) on_delete_event,
NULL);
scrolled_win = gtk_scrolled_window_new (NULL, NULL);
gtk_scrolled_window_set_shadow_type (GTK_SCROLLED_WINDOW (scrolled_win),
GTK_SHADOW_IN);
gtk_widget_show (scrolled_win);
gtk_container_add (GTK_CONTAINER (window), scrolled_win);
canvas = goo_canvas_new ();
gtk_widget_set_size_request (canvas, 600, 450);
goo_canvas_set_bounds (GOO_CANVAS (canvas), 0, 0, 1000, 1000);
gtk_widget_show (canvas);
gtk_container_add (GTK_CONTAINER (scrolled_win), canvas);
root = goo_canvas_group_model_new (NULL, NULL);
rect_model = goo_canvas_rect_model_new (root, 100, 100, 400, 400,
"line-width", 10.0,
"radius-x", 20.0,
"radius-y", 10.0,
"stroke-color", "yellow",
"fill-color", "red",
NULL);
text_model = goo_canvas_text_model_new (root, "Hello World", 300, 300, -1,
GTK_ANCHOR_CENTER,
"font", "Sans 24",
NULL);
goo_canvas_item_model_rotate (text_model, 45, 300, 300);
goo_canvas_set_root_item_model (GOO_CANVAS (canvas), root);
GooCanvasLineDash *dash = goo_canvas_line_dash_new (2, 5.0, 5.0);
const char *buf = "M 0 128 L 1000 256";
path = goo_canvas_path_model_new (root, buf,
"stroke-color", "red",
"line-dash", dash,
NULL);
rect_item = goo_canvas_get_item (GOO_CANVAS (canvas), rect_model);
g_signal_connect (rect_item, "button_press_event",
(GtkSignalFunc) on_rect_button_press, NULL);
goo_canvas_line_dash_unref(dash);
gtk_main ();
return 0;
}
static gboolean on_rect_button_press (GooCanvasItem *item,
GooCanvasItem *target,
GdkEventButton *event,
gpointer data) {
g_print ("rect item received button press event\n");
static float a = 128, b = 256;
a += 16, b += 16;
char buf[64];
snprintf(buf, sizeof(buf), "M 0 %f L 1000 %f", a, b);
g_object_set(G_OBJECT(path), "data", buf, NULL);
return TRUE;
}
static gboolean on_delete_event (GtkWidget *window,
GdkEvent *event,
gpointer unused_data) {
exit (0);
}
通过将路径的 data 属性 修改为 g_object_set 它会在单击矩形时移动。属性名称应取自文档，例如https://developer.gnome.org/goocanvas/unstable/GooCanvasPathModel.html