我想使 Gtk+ 窗口的背景透明,以便只有窗口中的小部件可见。我找到了一些教程:
http://mikehearn.wordpress.com/2006/03/26/gtk-windows-with-alpha-channels/
http://macslow.thepimp.net/?p=26
但它们似乎都在监听“暴露”事件,然后委托(delegate)给 Cairo 进行渲染。这意味着添加到窗口的其他小部件不会呈现(例如,我也尝试将按钮添加到窗口)。
我看到 GtkWidget 上有一个方法 modify-bg: http://library.gnome.org/devel/gtk/stable/GtkWidget.html#gtk-widget-modify-bg
但是,GdkColor 似乎不接受透明度参数:http://library.gnome.org/devel/gdk/stable/gdk-Colormaps-and-Colors.html
我也尝试过 GtkWindow.set_opacity 方法,但这也设置了窗口内容的不透明度,这不是我想要的。
如果有人能提供这方面的任何指导,我将不胜感激。
最佳答案
我更改了 alphademo例如绘制一个按钮而不是红色圆圈。
此应用程序在 400x400 透明窗口上绘制按钮。
当您单击窗口时,应用程序会显示/隐藏标题栏。
#include <gtk/gtk.h>
#include <gdk/gdkscreen.h>
#include <cairo.h>
static void screen_changed(GtkWidget *widget, GdkScreen *old_screen, gpointer user_data);
static gboolean expose(GtkWidget *widget, GdkEventExpose *event, gpointer user_data);
static void clicked(GtkWindow *win, GdkEventButton *event, gpointer user_data);
int main(int argc, char **argv)
{
gtk_init(&argc, &argv);
GtkWidget *window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
gtk_window_set_default_size(GTK_WINDOW(window), 400, 400);
gtk_window_set_title(GTK_WINDOW(window), "Alpha Demo");
g_signal_connect(G_OBJECT(window), "delete-event", gtk_main_quit, NULL);
gtk_widget_set_app_paintable(window, TRUE);
g_signal_connect(G_OBJECT(window), "expose-event", G_CALLBACK(expose), NULL);
g_signal_connect(G_OBJECT(window), "screen-changed", G_CALLBACK(screen_changed), NULL);
gtk_window_set_decorated(GTK_WINDOW(window), FALSE);
gtk_widget_add_events(window, GDK_BUTTON_PRESS_MASK);
g_signal_connect(G_OBJECT(window), "button-press-event", G_CALLBACK(clicked), NULL);
GtkWidget* fixed_container = gtk_fixed_new();
gtk_container_add(GTK_CONTAINER(window), fixed_container);
GtkWidget* button = gtk_button_new_with_label("button1");
gtk_widget_set_size_request(button, 100, 100);
gtk_container_add(GTK_CONTAINER(fixed_container), button);
screen_changed(window, NULL, NULL);
gtk_widget_show_all(window);
gtk_main();
return 0;
}
gboolean supports_alpha = FALSE;
static void screen_changed(GtkWidget *widget, GdkScreen *old_screen, gpointer userdata)
{
/* To check if the display supports alpha channels, get the colormap */
GdkScreen *screen = gtk_widget_get_screen(widget);
GdkColormap *colormap = gdk_screen_get_rgba_colormap(screen);
if (!colormap)
{
printf("Your screen does not support alpha channels!\n");
colormap = gdk_screen_get_rgb_colormap(screen);
supports_alpha = FALSE;
}
else
{
printf("Your screen supports alpha channels!\n");
supports_alpha = TRUE;
}
gtk_widget_set_colormap(widget, colormap);
}
static gboolean expose(GtkWidget *widget, GdkEventExpose *event, gpointer userdata)
{
cairo_t *cr = gdk_cairo_create(widget->window);
if (supports_alpha)
cairo_set_source_rgba (cr, 1.0, 1.0, 1.0, 0.0); /* transparent */
else
cairo_set_source_rgb (cr, 1.0, 1.0, 1.0); /* opaque white */
/* draw the background */
cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
cairo_paint (cr);
cairo_destroy(cr);
return FALSE;
}
static void clicked(GtkWindow *win, GdkEventButton *event, gpointer user_data)
{
/* toggle window manager frames */
gtk_window_set_decorated(win, !gtk_window_get_decorated(win));
}
在 Ubuntu 10.04 上编译:
gcc alpha.c -o alpha -I/usr/include/gtk-2.0 -I/usr/lib/gtk-2.0/include -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/cairo -I/usr/include/pango-1.0 -I/usr/include/atk-1.0 -lgtk-x11-2.0
关于c - 如何使 Gtk+ 窗口背景透明?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/3908565/