Both the functions SDL_GetRenderer(SDL_Window*) and SDL_CreateRenderer(SDL_Window*, int, Uint32) seem to do the same thing: return a pointer to SDL_Renderer from the window. However, what method is more appropriate for the task? The SDL Wiki does not provide much information on where which method should be used, so please explain what each method does, how they differ and where they should be used.
SDL_CreateRenderer allows you to create a renderer for a window by specifying some options. It's stored in the specific window data which you can query with SDL_GetRenderer (so the latter is equivalent to (SDL_Renderer *)SDL_GetWindowData(window, SDL_WINDOWRENDERDATA))
If you call SDL_GetRenderer without having created it beforehand, you'll get a NULL pointer.
If you call SDL_CreateRenderer on a window twice, the second call will fail with SDL_SetError("Renderer already associated with window"); (see line 805).
See here
Related
In gtkmm 4, how can one get the X Window ID of type XID as defined in X11/X.h, from inside a class, that inherits from Gtk::Widget?
Not all of them have one.
Those widgets that do will implement the GtkNative interface, which provides the gtk_native_get_surface function, allowing you to obtain a GdkSurface. In gtkmm, this will correspond to casting to to Gtk::Native and calling get_surface.
To obtain a Window handle from that, you can use the GDK_SURFACE_XID macro. For that, I don’t think a C++ wrapper exists; you will have to call Gdk::Surface::gobj to obtain a GdkSurface * and use the C API.
I wanted to add two things to the accepted answer
It is of course important to check if get_surface() returned a valid nonzero object indeed. Otherwise get the ID after the Widget's signal_realize() is emitted, which is done after the widget is assigned to a surface. This can be achieved by overriding the default handler on_realize()
Instead of casting and calling ((Gtk::Native)this)->get_surface() it is also possible to call like get_native()->get_surface().
In conclusion do
void myWidget::on_realize() {
// Call default handler
Gtk::Widget::on_realize();
XID x_window = GDK_SURFACE_XID(get_native()->get_surface()->gobj());
}
to get the X window ID as early as possible.
I have the following wxDialog parent window:
I have created that parent window by the following code:
settingsFrm settingsWindow(this, "Settings");
settingsWindow.ShowModal();
I have tried to use FindWindowByName to get the value of the first text ctrl as follow:
wxLogMessage(dynamic_cast<wxTextCtrl*>(settingsWindow->FindWindowByName("keywords_txt"))->GetValue());
But unfortunately, it doesn't work and gives me a runtime error.
I don't know if that method suitable to do what I want.
How to get the value/other of a control through its parent window?
From your comments, it seems like you expect the function to find the control from the name of the variable in your code which is not how it works and would be pretty much impossible.
FindWindowByName() uses the window name (and, as a fallback, label, but this is irrelevant here because text controls don't have labels anyhow), so for it to work you need to set the window name when creating the control, using the corresponding parameter of its ctor. This is very rarely useful in C++ code, however, as it's simpler to just store a pointer to the control in some variable and use this instead.
FindWindowByName() can often be useful when creating controls from XRC, however. If you do this, then you should specify names for your controls in XRC and pass the same name to this function.
How did you create the TextCtrl instance? You should have something like wxTextCtrl m_textCtrl1 = new wxTextCtrl(/// arguments); Accessing the value should be very easy, as wxString text = m_textCtrl1->GetValue(); You definitely don't need FindWindowByName just for what you are trying to do here.
I am experimenting with some fundamental Xlib stuff. I am creating a basic window and creating an OpenGL context for it.
I am trying to prevent the user from being able to resize or manually full screen the window. I added the code:
XSizeHints hints;
hints.min_width = hints.max_width = setup.w;
hints.min_height = hints.max_height = setup.h;
XSetWMNormalHints(dpy, win, &hints);
This worked at first. However after experimenting with it I have found that it mysteriously stops working sometimes. It is not a matter of unusual window managers or anything like that, I am using the default windows manager installed with Ubuntu. What causes it to change, strangly enough, is whether or not I include this line in main:
XWindowAttributes atts;
It does not matter where I put it. At the beginning, or inside a loop, or even after the return. As long as I put that somewhere in main the hints prevent resizing (just to be clear, any name for the variable works). It does not matter if I use it at all or not, it was initially there for a call to XGetWindowAttributes. I discovered the problem when I tried moving that into a separate function call. If I take it out, the window will have a full screen button and I will be able to shrink it. I have experimented with declaring the variable other places, such as in the struct where I contain the Window and GLXContext.
What is going on here? The way I see it I either have a very subtle and unusual bug coming from my virtual machine or something weird like that, or I have missed some obvious piece of information. Can anyone shed some light on this?
Well, I have no explanation for why declaring a XWindowAttributes instance in main was making it work, but I did figure out what was wrong with my code and I was able to make it behave as expected when I made the following changes:
Do not create XSizeHints directly as shown above. Create it as follows:
XSizeHints *hints = XAllocSizeHints();
Set flags in the object specifying which variables are used:
hints->flags = PMinSize|PMaxSize;
Use XSetWMNormalHints and XSetWMSizeHints:
XSetWMNormalHints(dpy, win, hints);
XSetWMSizeHints(dpy, win, hints, PMinSize|PMaxSize);
I also put a pointer to the hints in my struct containing data about the window. All together the code above became:
XSizeHints *hints = wind->hints = XAllocSizeHints();
hints->flags = PMinSize|PMaxSize;
hints->min_width = hints->max_width = setup.w;
hints->min_height = hints->max_height = setup.h;
XSetWMNormalHints(dpy, win, hints);
XSetWMSizeHints(dpy, win, hints, PMinSize|PMaxSize);
For those that came here:
1. Communicating with the Windows Manager
It's all about convention like said at 12.3 in the "Xlib Programming Manual VOL1". Some WM will completely ignore hints like max & min size, because eg they manage Windows as Tiled Windows. So, how YOUR Window Manager will get your choices is an issue.
2. Make things in the right order.
This will perhaps answer your question : "What is going on here?"
Most difficulties with X comes from the order you make things. I encountered the same trouble as yours, and solve it because I saw I didn't follow the right process.
Chapter 12.3.1 from the "Xlib Prog Manual" says:
'Once the client has created the windows, BUT BEFORE IT MAPS THEM, it must place properties to help WM manage them effectively'
In your case, it means you cannot use XSetWM* functions AFTER your window is mapped. Some properties will have an effect, some others not, and sometimes some will be overridden with bad values.
3. The right order. (AFAIK)
a. Set an Error Handler
b. Get a Display
c. Init your Context (here GLX) & get a Visual from it.
d. set Window Attributes (events mask, ...)
e. Create your Window
e. Set WM Properties (eg your sizehints, min/max size, class, title, ...)
e.1 always init pointers you need with XAlloc* when possible
e.2 use X11r4 XSetWMProperties that will put them all at once, avoid use of deprecated functions.
e.3 XFree your 'pointers'
f. Set the Wm Protocols you are interested in (WM_DELETE_WINDOW, ...)
g. set some others properties according to your needs (eg _NET_WM_PID, ...)
h. Finally, Map your Window
4. See what happens : use xprop
xprop will report how your window is known by your Windows Manager.
If your size hints were properly set, you will see some lines like:
WM_NORMAL_HINTS(WM_SIZE_HINTS):
user specified location: 550, 200
user specified size: 500 by 500
program specified minimum size: 500 by 500
program specified maximum size: 65535 by 65535
Hope it helps future users,
(PS: the previous answer TS#Oct 27 '14 at 15:26 has an error: XSetWMSizeHints expect an Atom as 3rd arg.).
I've just used cocos2d-x for creating some games. When I read the HelloWorld.cpp, I saw this line
Scene* HelloWorld::createScene()
That's strange for me. How does it work? A method named creatScene that takes no parameters and returns a pointer to a Scene ?
In different libraries, there are different methods to initialize library or some part of that. So, in this case, it maybe create a new context inside library and return it without any argument. It maybe needs no arguments (use defaults) it this step of get them from somewhere else like configuration file. And note that this is convenient to use this type of initializing. Like this:
rc = redis.Redis() #uses default values for server address
It is really an easy question even it cannot be called as question when you check the source code.
In cocos2d-x, CCScene always create this way.
1. create a Layer, which coded by yourself with a lot of other widgets.
2. create a Scene
3. add the layer to the scene
4. return the scene you create.
In my WTL app Im trying to change the font of a static label. But CreatePointFont returns NULL. Why might this be?
CFont font;
font.CreatePointFont(120, _T("Segoe UI"));
text.Attach(GetDlgItem(IDC_MAINTEXT));
text.SetFont(font);
Are you sure that CreatePointFont is returning NULL?
For a font to be set, it must remain in memory, whereas from your code snippet it appears that the variable font is destroyed directly after setting it.
Declare the variable somewhere that will not be deleted during the lifetime of the text object, such as the class if you are using an MFC object.
The nPointSize argument to CreatePointFont() is in tenths of a point, perhaps your size of 12/10 = 1.2 points is too small. You probably meant to pass in 120.
On a lighter note, you may also want to visit the ban comic sans web site, if you're using this for a business application.
The documentation is not too verbose on the fail conditions, but my guess it you don't have the named font on the machine
Check if it is listed by the EnumFontFamilies function (quote form the documentation):
The Windows EnumFontFamilies function can be used to enumerate all currently available fonts