Question

我想让Gtk +窗口的背景透明，以便只有窗口中的窗口小部件可见。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

但他们似乎都在听“揭露”事件，然后委托开罗进行渲染。这意味着添加到窗口的其他窗口小部件不会呈现（例如，我也尝试向窗口添加按钮）。

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。

我很感激任何人都可以提供任何指导。

Answer 1

我更改了alphademo示例以绘制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

Answer 2

感谢代码，正是我正在寻找的东西虽然需要修改才能使用GTK3。曝光事件也需要改为“平局”。让它运作的事件。所以这是我为GTK3修改的代码贡献：

gcc alpha.c -o alpha  `pkg-config --cflags --libs glib-2.0` `pkg-config --cflags --libs gtk+-3.0`

这是我在Ubuntu 15.04上编译的方式：

{{1}}

希望这有助于其他人试图让它在GTK3上运行。

Answer 3

感谢您的回答。我在python + GTK3中重写了代码：

#!/usr/bin/env python3

import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk, Gdk
import cairo


supports_alpha = False


def screen_changed(widget, old_screen, userdata=None):
    global supports_alpha

    screen = widget.get_screen()
    visual = screen.get_rgba_visual()

    if visual is None:
        print("Your screen does not support alpha channels!")
        visual = screen.get_system_visual()
        supports_alpha = False
    else:
        print("Your screen supports alpha channels!")
        supports_alpha = True

    widget.set_visual(visual)


def expose_draw(widget, event, userdata=None):
    global supports_alpha

    cr = Gdk.cairo_create(widget.get_window())

    if supports_alpha:
        print("setting transparent window")
        cr.set_source_rgba(1.0, 1.0, 1.0, 0.0) 
    else:
        print("setting opaque window")
        cr.set_source_rgb(1.0, 1.0, 1.0)

    cr.set_operator(cairo.OPERATOR_SOURCE)
    cr.paint()

    return False


def clicked(window, event, userdata=None):
    # toggle window manager frames
    window.set_decorated(not window.get_decorated())


if __name__ == "__main__":
    window = Gtk.Window()
    window.set_position(Gtk.WindowPosition.CENTER)
    window.set_default_size(400, 400)
    window.set_title("Alpha Demo")
    window.connect("delete-event", Gtk.main_quit)

    window.set_app_paintable(True)

    window.connect("draw", expose_draw)
    window.connect("screen-changed", screen_changed)

    window.set_decorated(False)
    window.add_events(Gdk.EventMask.BUTTON_PRESS_MASK)
    window.connect("button-press-event", clicked)

    fixed_container = Gtk.Fixed()
    window.add(fixed_container)
    button = Gtk.Button.new_with_label("button1")
    button.set_size_request(100, 100)
    fixed_container.add(button)

    screen_changed(window, None, None)

    window.show_all()
    Gtk.main()

Answer 4

对于那些使用golang的人，这是一个使用gotk3（https://github.com/gotk3/gotk3）的人：

"fingerprintjs2": "^2"

如何让Gtk +窗口背景透明？

4 个答案: