Okay, so, I have a C++ project I'm working on. I've created my own custom window using Cairo (I realize Cairo might not be the best for this application but it makes a lot of tasks that my GUI needs to do easier).
It controls the window size, minimizing and everything by itself, but when I create a borderless window to put it in, it still has an opaque background (my custom window has rounded borders).
How could I get the background to be transparent on at least the 3 most popular window systems? What are the platform-specific API functions that do this so that I can abstract it myself, or, is there a lightweight library that does this and will work with Cairo?
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I am looking for some information about rendering child windows in specific about how OpenGL interop with GDI. The problem that I have is that I have basically is that I have two windows, first, the main windows are created in qt, and inside of qt, a child window is hosted that leverages an OpenGL renderer.
Now what I wanted to do is to host an overlay on top of my OpenGL window, so I use that to overlay the OpenGL window. The problem that I am having is that when I render with OpenGL, the OpenGL generated graphics seem to obscure the graphics area including and effectively undo the graphics composited by qt.
In the image below the blue area is the qt overlay, in that picture I'm using GDI (BeginPaint/EndPaint) so and the windows seem to interact fine. That is, window order seems correct, the client region is correct. The moment I start to render with Opengl the blue area gets replaced with whatever OpenGL renders.
What I did I basically created to create the overlay I created a second frameless, topmost QMainWindow, and once the platform HWND was initialized I reparent it. Basically I change the new windows parent to be the same parent of my OpenGL window.
What I believed this would do is that the every window, gets drawn separately and the desktop composition manager would make the final composition and basically avoiding the infamous airspace problem as documented by Microsoft in their WPF framework.
What I would like to know is what could cause these issues? At this point, I lack understanding why once i render with OpenGL the pixels by qt overlay are obscured, even though windows hierarchy should say make them composited. What could I do to accomplish what I want?
Mixing OpenGL and GDI drawing on a shared drawable (that also includes sibling / childwindows without the CS_OWNDC windowclass style flag) never was supported. That's not something about Qt, but simply how OpenGL and GDI interact.
But the more important issue is: Why the hell aren't you using the OpenGL support built right into Qt in the first place? Ever since Qt-5 – if available – uses OpenGL to draw everything (all the UI elements). Qt-5 makes it trivial to mix Qt stuff and OpenGL drawing.
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 general question on how to develop an image viewer plugin with Firebreath. For that, I would like to incorporate a GUI framework, like wxwidget or Qt. The GUI would be used to to fire up some dialogs, adding a toolbar on top, or to open context menus with right clicking an image.
As far as I understand I have a hwnd handle and so I can draw onto a window. I also understand that I have various events I can react on, like mouse button clicks or keyboard strokes. But it fails me how I would add graphical menus, buttons, etc. I know I could use html around the window but that's not the route I like to take.
For instance, does it makes sense to render an user interface offline (in memory) onto an image and then keep somehow track of the state internally?
Has anyone done such thing? Or can anyone give me some insight on how to accomplish adding a user interface.
Assuming you only care about windows and assuming that you don't mind using a windowed plugin, which is the easiest (but no HTML elements can float over the plugin), it should be no different than creating a GUI in any other windows application.
You are given a window that shows up with the AttachedEvent; when DetachedEvent is fired you need to stop using the window. Many people create a child window inside that parent window and use that for all their actual real code which makes it a little easier to use one of those other abstractions, but that's basically all there is to it. I don't know specifically how you'd do it with QT or wxwidget but you'd create a child window of that HWND that you are given and have the abstraction do your thing for you.
As to whether or not it would be rendering things offscreen, etc, I have no idea; that would totally depend on the window system. There is no reason that I know of that you would need to do that, and most things just draw directly to the HWND, but there are a zillion different ways you could do it. It looks to me like what you really need is to understand how drawing in Windows actually works.
I hope that helps
I guess this question has been ask before, but I have not found sufficient answer to even start poking around. Most answer refers to catching WM_PAINT method directly and do custom rendering, or use a onwer draw object. However, I did not see a centralized place that has the info. to start researching. Hence, the question.
My goal is to create a very simple GUI program with custom look into it. I prefer the way winamp does their custom look that is customizable through "skins". However, I am not interested in using some cross-platform library like GTK+, QT or wxWidget.
I have some experience in system programming, but not much for GUI. I spent most of my time developing console applications, and I just started doing some QT development. If you can point me in the right direction, I'd be very appreciated.
PS: I am interested in both windows and linux environment.
Everybody,
Sorry for the late reply. I had a chance to have a quick talk with the original developer for winamp, and this is the quick answers I have:
Using skins: Artists create skins, developer will render the skins
To the OS (Windows), winamp is just one pretty box, nothing else. There is a container windows, and that's about it
All controls (button, label, list, etc) are implemented by winamp team themselves. All messages and stuffs are passed as relative position to the container window. WinAmp and the GUI engine has to decide if a button is clicked or if the label next to it is the target, etc.
Rendering artists skins created in XML
I do not have the details on if they use any libraries to do all that, but I am suspecting they do hook a window call directly, and do custom rendering themselves.
GUI skin usually using plug-in mechanism
I guess this is exactly what you are looking for:
https://www.linux.com/learn/tutorials/428800:weekend-project-creating-qt-interfaces-with-gimp?utm_medium=twitter&utm_source=twitterfeed
I also interested in creating custom look of window and widgets.
Speaking about widgets it's not hard, just need to create subclass (if you are using C++) or some widget and implement some methods like draw, handle etc. But this solution is good only if you use some high-level library like GTK, QT, etc. If you want to implement all controls by your own, you may get any graphics library, which can create window and do any graphics inside. For example, SDL2 + Cairo. SDL2 for creating window, Cairo for vector rendering controls/widgets. Both of this libraries are for win and linux. Another option is take opengl/vulkan + some lib for rendering window. It could be SDL2, SFML, GLFW.
If you really interested how it works on low level, then search Windows API for Windows and XLib or XCB for Linux/X.Org.
Speaking about window, I still investigate it. However I have one thought: you may create an empty window and then draw whatever you want. Then you need to add handlers for resizing window on the borders. But I am not sure if it's good solution, and if it won't freezes.
I'm making a non-rectangular dialog, modelled over an image from Photoshop (the image is the background of the dialog, and the user will see trough the transparent part of the image). I'ts like a dashboard-style window for a media-app with a few custom-drawn controls. Most of the background-image is either opaque or 100% transparent - but in between there is a thin area of partially transparent pixels, ment to blend the image smootly into the background. This works great for web-graphics, but I have not found a way to make this work for Windows windows. I'm using the Windows Template Library (WTL), msvc 2008 - and the app must run on Windows XP as well as Vista and Windows 7.
Currently, I'm simply using the opaque part of the background-image to create a GDI clipping-region, but this gives pretty rough edges.
Does anyone know about any API functions to accomplish this (part of WTL, or reachable from WTL)?
Perhaps you could use layered windows? I haven't tested these with WTL but you should be able to get the effect you want. To the best of my knowledge I don't think you can add controls to a layered window so you'll need to attach it to another (non-layered) window to use controls.
Not sure how this interoperates with WTL, but have a look at the AlphaBlend function. You'll need to select your partially transparent bitmap into a DC and copy that to your dialog's DC in your paint function.
This article shows how to use layered windows with WTL and the Gdi+ API which is available on all your target platforms.