I'm writing a desktop. I already know the basics of Qt and GTK+ through Python but I don't understand how to display the finished Desktop. How do you make it the root window of a Window Manager, or is there a method for displaying the desktop I'm not familiar with?
You don't make it the root window. X has one root window which you can't change. There are a number of ways to do what you want
X Root window
The old way was that the desktop was just the standard X root window. Icons were just individual borderless windows.
Desktop Window
Now most systems open a large window, and mark it as being a desktop window. Most window managers then know never to raise it above any other windows. The X root window is still behind it, but it is hidden. This means you can do anything you want on this window, draw to it, include icons or widgets or anything else your toolkit can do.
If you are using Gtk+ then the relevant information is found in the GdkWindowTypeHint enum, specifically the GDK_WINDOW_TYPE_HINT_DESKTOP. The documentation can be found here: GdkWindow
Compositor
However, there is a newer way that desktops like Gnome3 or Unity use, which is called the Compositor Overlay Window. When a compositor is running there is an overlay window which covers all the windows on the system. It is then up to the compositor to draw the actual contents of the windows on this overlay. However, the overlay can draw whatever it wishes on this overlay window. For example, in Gnome3 when you enter the window selector and the windows arrange themselves into a grid the windows aren't really moving and shrinking, the compositor has just decided to draw them that way. In reality, the windows are still in the same position they were before, but hidden under this overlay.
This is a very advanced way to do things, and certainly not for the novice developer. You probably want to be focusing on the second method.
Related
I'm building a UI in Qt 5.9 that needs to run on an X11 display. I'm trying to add drop shadows to my dialog windows - but they don't work over X11.
The approach I'm taking is from zeFree's answer in This Question. (Put everything in the window in one widget, set the window translucent, and create a dropshadow effect on the widget).
setAttribute(Qt::WA_TranslucentBackground); //enable Window to be transparent
QGraphicsDropShadowEffect* effect = new QGraphicsDropShadowEffect();
effect->setBlurRadius(5);
ui->widget->setGraphicsEffect(effect);
It works great in my redhat vm:
RedHat Dropshadow
But when I send to the X11 display I, it looks like the transparency isn't supported, and I get the shadow on black instead:
X11 Dropshadow
My question is: Is there a way to make my Dialogs project a drop shadow onto my main window instead of onto their own (transparent) background? My application will be full screen on the X11 display so I don't need to worry about shadow effects outside of the window.
Any answer that gives me a clean way to get a drop shadow effect on this X11 display will be accepted.
If your window manage doesn't support transparency you are out of luck IMO. At least with your current approach.
There is theoretically a way to fake it, provided you can grab the pixel values from the underlying window manager composite that is under your application, then draw those pixels from your application, filling the black void, with the shadow composed over that, and finally your GUI stuff.
There is also the more viable course of giving up on native windowed dialogs and fake the dialog using a regular floating widget. This has the disadvantage that it will only be able to move within the confines of your main window, but this way you will have complete control over the drawing and not fall victim to platform limitations.
I was looking at how sometimes when you right click, the menu goes outside of the window.
Is this implemented with a separate window? If so, how can I get this functionality. I am trying to use GLFW, but I understand if it isn't possible.
Currently I am on windows, but I like keeping my options open, which is why GLFW would be preferable.
I noticed that GLUT has such a feature. If you are confused to what I am looking at then look at that.
Thanks for any help!!
Overlapping menus (in MS Windows) have to be implemented as a new top-level window, you would have a new OpenGL rendering context and draw the menu in that space - yes, it's a fair bit of work all for the edge-case of a menu overspilling the parent window,
However this isn't often a problem in OpenGL programming because if you're working on a full-screen game then the menu will always be displayed within the main window, and even if it isn't a full-screen a game your users really won't notice them as games tend to use different UI concepts like radial-menus which wouldn't overspill the parent window.
Or if you're working on a non-game title, chances are it isn't full-screen and is going to be an OpenGL rendering area within a larger application that is rendered using a native UI toolkit (e.g. 3ds Max, AutoCAD, etc), in which case no problem: just use native menus.
You can, of course, use native menus in an OpenGL application anyway, provided you do the necessary plumbing for native window messages.
I have a large OpenGL canvas in a Visual C++ MFC application. An edit box control sits over the OpenGL canvas. However, whenever the OpenGL canvas is redrawn, it obliterates the part of the edit box which sits above it, ignoring the specified window Z-order. How can I prevent this?
You don't.
Having other windows interact with an OpenGL window is not a good idea. They don't interact well; it's best to keep child windows clear of OpenGL windows.
I want to create a widget in Mac OS X that exists on the desktop background rather than the dashboard. The widget will be interactive (the widget will be able talk through text boxes when the user clicks on it, similar to Clippy) and I need it to be floating (always been on top of all windows). The widget should also be able to be flexible- by this I mean it can change shapes (i.e. how Clippy always moves). It should almost be like a character from a game on the desktop.
I have absolutely not idea how to do this, nor do I could I find any resources that instructed me how to.
Does anyone know how I could create an interactive widget on the desktop background on all major versions of Mac OS X (i.e. Snow Leopard, Lion) that floats using either C++ or Obj-C? (C++ is much more preferable)
Borderless Windows, and HUDs can be used to simulate a widget by creating a transparent, floating window.
For more info, refer to: How to create transparent notification window?
I've seen things like this and I was wondering if this was possible, say I run my application
and it will show the render on whatever is below it.
So basically, rendering on the screen without a window.
Possible or a lie?
Note: Want to do this on windows and in c++.
It is possible to use your application to draw on other application's windows. Once you have found the window you want, you have it's HWND, you can then use it just like it was your own window for the purposes of drawing. But since that window doesn't know you have done this, it will probably mess up whatever you have drawn on it when it tries to redraw itself.
There are some very complicated ways of getting around this, some of them involve using windows "hooks" to intercept drawing messages to that window so you know when it has redrawn so that you can do your redrawing as well.
Another option is to use clipping regions on a window. This can allow you to give your window an unusual shape, and have everything behind it still look correct.
There are also ways to take over drawing of the desktop background window, and you can actually run an application that draws animations and stuff on the desktop background (while the desktop is still usable). At least, this was possible up through XP, not sure if it has changed in Vista/Win7.
Unfortunately, all of these options are too very complex to go in depth without more information on what you are trying to do.
You can use GetDesktopWindow(), to get the HWND of the desktop. But as a previous answer says (SoapBox), be careful, you may mess up the desktop because the OS expects that it owns it.
I wrote an open source project a few years ago to achieve this on the desktop background. It's called Uberdash. If you follow the window hierarchy, the desktop is just a window in a sort of "background" container. Then there is a main container and a front container. The front container is how windows become full screen or "always on top." You may be able to use Aero composition to render a window with alpha in the front container, but you will need to pass events on to the lower windows. It won't be pretty.
Also, there's a technology in some video cards called overlays/underlays. You used to be able to render directly to an overlay. Your GPU would apply it directly, with no interference to main memory. So even if you took a screen capture, your overlay/underlay would not show up in the screen cap. Unfortunately MS banned that technology in Vista...