假设我绘制了一个模型火车布局的线图。更新工程图时,可以更改各种工程图组件的颜色,例如指示警报情况。我想在图中添加几个“开关”小部件,“切换”按钮等,以便我可以使用Raspberry Pi(受工业过程控制启发)来打开/关闭电气项目。这可能吗? ...还是有更好的方法?
一种不同但不那么好的方法是在良好的常规窗口中显示GtkImage图形,然后在图形上方安装小部件。这种方法有效,但是您不能像在Drawing_Area小部件中那样更改单个图形组件的颜色。为了更改图形,您必须进行屏幕截图,然后裁剪图像,然后将图像另存为适当大小的JPEG,然后以某种方式更新GtkImage。
在Drawing_Area上显示小部件会更好。 …有什么想法吗?
这里您是队友。比以往任何时候都更好...;)
#include <gtk/gtk.h>
#include <math.h>
GtkWidget *window;
GtkWidget *layout;
GtkWidget *canvas;
GtkWidget *image;
GtkWidget *eventbox;
static gboolean on_window_draw (GtkWidget *da, GdkEventExpose *event, gpointer data)
{
GdkWindow *window;
GdkDrawingContext *drawingContext;
cairo_region_t *cairoRegion;
cairo_t *cr;
cairoRegion = cairo_region_create();
window = gtk_layout_get_bin_window(GTK_LAYOUT(layout));
drawingContext = gdk_window_begin_draw_frame(window, cairoRegion);
cr = gdk_drawing_context_get_cairo_context(drawingContext);
cairo_set_line_width(cr, 9);
cairo_set_source_rgb(cr, 0.69, 0.19, 0);
cairo_translate(cr, 300/2, 200/2);
cairo_arc(cr, 0, 0, 50, 0, 2 * M_PI);
cairo_stroke_preserve(cr);
cairo_set_source_rgb(cr, 0.3, 0.4, 0.6);
cairo_fill(cr);
gdk_window_end_draw_frame(window, drawingContext);
cairo_region_destroy(cairoRegion);
return FALSE;
}
int main ( int argc, char **argv)
{
GtkWidget *button;
gtk_init (&argc , &argv);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_widget_set_size_request (window, 300, 200);
g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit) , NULL);
canvas = gtk_drawing_area_new ();
layout = gtk_layout_new(NULL,NULL);
gtk_container_add (GTK_CONTAINER (layout), canvas);
gtk_container_add (GTK_CONTAINER (window), layout);
button = gtk_button_new_with_label("I feel alone...");
gtk_container_add(GTK_CONTAINER(layout), button);
gtk_layout_move(GTK_LAYOUT(layout), button, 90, 50);
g_signal_connect (canvas, "draw", (GCallback) on_window_draw, NULL);
gtk_widget_show_all (window);
gtk_main ();
return 0;
}