Displaying the image with a click-through window

[mertyildiran]

Is there a way to display the image without blocking mouse events? I mean, I would like to be able to click things inside the window that just behind the image. Imagine that we are displaying the image like a watermark on the screen. Is there a way to do that?

[phillipberndt]

Tricky. This definitively depends on your desktop environment - I'm assuming you're running pqiv under X11? Do you want the whole window to be "click-through", or just the transparent part? (The latter is easy, the former requires you to manually pass the events to the underlying window, which requires some Xlib hacking)

[mertyildiran]

@phillipberndt yes, I'm looking that for Ubuntu based distros (I think that means X11 Window System).

If you provide the information for both of the scenarios then I would be so happy 😊 Because if the
hard option is too hard then I will go with "just the transparent part" option. Also the image can be semi-transparent if it helps...

[phillipberndt]

Turns out that it's not so simple with semitransparent parts either. That makes the other solution simpler, actually. See this SO thread for what must be done. Actually, if you don't plan to use pqiv for anything else, I think that writing a plain Xlib application might be the simplest solution, because you can then simply feed the Xlib events directly back into the XSendEvent call. (And since you mentioned Python, Xlib has working Python bindings.)

Edit: This seems to be a good place to start.

[mertyildiran]

@phillipberndt thank you so much! 😊 I wasn't even know where to look. Now I will make some research about Xlib. Thanks for enlightening me.

[phillipberndt]

All right. Let me know if you're stuck, maybe I can help..

[mertyildiran]

@phillipberndt I just found this blog post and from that blog post I found this Gist. It's able create a click-through region inside the window.

To compile it you need this library: sudo apt-get install libxpm-dev

(Light green region is click through)

If it's not Always on Top then it will minimize so make it Always on Top using your system dialog:

Now there are only two things I should achieve drawing the image and making it Always on Top. Could you help me about drawing the image? At the end of the day we will be able to bring real HUD to linux 🏆

[phillipberndt]

That's useful. Here's a patch to apply this to pqiv:

diff --git a/GNUmakefile b/GNUmakefile
index 1127864..ac43446 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -95,7 +95,7 @@ endif
 
 # We need X11 to workaround a bug, see http://stackoverflow.com/questions/18647475
 ifeq ($(filter x11, $(shell pkg-config --errors-to-stdout --variable=target gtk+-$(GTK_VERSION).0; pkg-config --errors-to-stdout --variable=targets gtk+-$(GTK_VERSION).0)), x11)
-       LIBS+=x11
+       LIBS+=x11 xext
 endif
 
 # Add backend-specific libraries and objects
diff --git a/pqiv.c b/pqiv.c
index fcfd3b7..f9a8e54 100644
--- a/pqiv.c
+++ b/pqiv.c
@@ -56,6 +56,7 @@
 #ifdef GDK_WINDOWING_X11
        #include <gdk/gdkx.h>
        #include <X11/Xlib.h>
+       #include <X11/extensions/shape.h>
        #include <cairo/cairo-xlib.h>
 
        #if GTK_MAJOR_VERSION < 3
@@ -4944,7 +4945,7 @@ gboolean window_draw_callback(GtkWidget *widget, cairo_t *cr_arg, gpointer user_
                        // to speed up rotations on scaled images
                        cairo_surface_t *temporary_scaled_image_surface = get_scaled_image_surface_for_current_image();
                        cairo_set_source_surface(cr, temporary_scaled_image_surface, 0, 0);
-                       cairo_paint(cr);
+                       cairo_paint_with_alpha(cr, .5);
                        cairo_surface_destroy(temporary_scaled_image_surface);
                }
 
@@ -6360,6 +6361,16 @@ gboolean window_configure_callback(GtkWidget *widget, GdkEventConfigure *event,
        }
        #endif
 
+       // Adjust shape
+       Display *display = GDK_SCREEN_XDISPLAY(gdk_screen_get_default());
+       unsigned long window_xid = gdk_x11_window_get_xid(gtk_widget_get_window(GTK_WIDGET(main_window)));
+       Region region = XCreateRegion();
+       XRectangle rectangle = { 0, 0, 1, 1 };
+       XUnionRectWithRegion(&rectangle, region, region);
+       XShapeCombineRegion(display, window_xid, ShapeInput, 0, 0, region, ShapeSet);
+       XDestroyRegion(region);
+
+
        return FALSE;
 }/*}}}*/
 void handle_input_event(guint key_binding_value);
@@ -6883,6 +6894,8 @@ void create_window() { /*{{{*/
        if(option_transparent_background) {
                window_screen_activate_rgba();
        }
+
+       gtk_window_set_keep_above(main_window, TRUE);
 }/*}}}*/
 gboolean initialize_gui() {/*{{{*/
        setup_checkerboard_pattern();

To make an Xlib application stay on top, see this SO answer. To draw an image, see this one, though it might be simpler to use an external library like cairo for that.

[mertyildiran]

@phillipberndt that's working perfectly, thank you so much! 🏆

Now the problem is how can I integrate this into our project Dragonfire. I compiled click-through part with distutils/setuptools. But when I import the library with import realhud I'm getting this error:

ImportError: /home/mertyildiran/Downloads/realhud-test/realhud.so: undefined symbol: XLookupString

Try it yourself, clone this repository and install it sudo pip install -e .

I'm also considering the option that compiling and installing a modified version of your project pqiv on post-installation but I'm not sure what's the best option.

Could you please join to our Gitter chat room and guide me about what to do? OR you could even choose to integrate that feature to Dragonfire by yourself and send a PR. I would be so glad to see you as a contributor. 😊

[phillipberndt]

But when I import the library with import realhud I'm getting this error

Works like a charm here. The message indicates that the library isn't liked to Xlib:

$ ldd realhud.so
...
libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f8bce41e000)

should be missing for you. I don't really understand why though, your setup.py looks fine to me. If you build verbosely (setup.py build -v after deleting the build folder), does the last line linking the final shared object contain -lX11 after realhud.o?

[mertyildiran]

@phillipberndt Interestingly installing it with setup.py build and setup.py install changed everything and now it's working 😄

If I face with problems while drawing the image then I will knock at your door again, thank you so much! 👍 😊

[mertyildiran]

@phillipberndt I have implemented a simple version of your program (by following your suggestions) in here, please take a look....

and this avatar/visualization is the result of that program:

Many thanks for your support 🏆