I'm having a bit of trouble in my attempts to learn WXWidgets. I'm currently trying to work with file Dialogs, and I've got one opening just fine. But I run into trouble whenever I try to apply styles to the window. I get an undeclared identifier for whatever style I use.
My code is as follows (yes, I know, hello world app. I'm experimenting with all the things I need to learn to do before actually making a fully fledged app)
#include "wx/wx.h"
#include "wx/filedlg.h"
#include "HelloWorldApp.h"
IMPLEMENT_APP(HelloWorldApp)
bool HelloWorldApp::OnInit()
{
wxFrame *frame = new wxFrame((wxFrame*) NULL, -1, _T("Hello wxWidgets World"));
wxFileDialog* OpenDialog = new wxFileDialog(frame, _("Choose a file to open"), wxEmptyString, wxEmptyString,
_("Image Files (*.jpg, *.png, *.gif, *.bmp)|*.jpg;*.png;*.gif;*.bmp|Sound Files (*.wav, *.mp3)|*.wav;*.mp3"),
wxFD_MULTIPLE);
frame->CenterOnScreen();
frame->Show(true);
OpenDialog->ShowModal();
SetTopWindow(frame);
return true;
}
It runs just fine without the "wxFD_MULTIPLE" argument. I'm using version 2.8.12 of wxWidgets.
Thanks for reading. I really appreciate any help or guidance anyone can give. Sorry if it's something really obvious I'm missing.
In very old wxWidgets versions (2.6), this style was known as wxMULTIPLE but wxFD_MULTIPLE is definitely available in any 2.8.x version. You should give the (beginning of) the errors you get to allow us to understand what is really going on.
Completely independently, your code is wrong because it contains a memory leak: the dialog must be destroyed as modal dialogs are exceptions to the usual rule that all windows should be allocated on the heap and can be allocated on the stack, i.e. used as simple local variables, see the example in the documentation. Looking at the "dialogs" sample code is also strongly recommended.
Related
Hey guys I'm new in c++ wxwidgets programming.
I would like to know the easiest way to put an image into a button.
I tried :
button1 = new wxBitmapButton(side_panel, wxID_ANY, wxBitmap("image.png",wxBITMAP_TYPE_PNG), wxPoint(150,30), wxSize(30, 30),wxBORDER_NONE);
But I always get the same error:
If you expand the error dialog you see, you should see more information about the error, but my guess is that the image simply can't be found. You should check that the file image.png indeed exists in the current working directory of your program, i.e. the directory that you run it from, assuming you don't change it later.
You should also actually check for errors in your programs, even simple ones, i.e.
wxBitmap bmp("image.png");
if (!bmp.IsOk()) {
... handle the error somehow instead of blithely using an invalid bitmap ...
}
I've been trying to make a simple wxWidgets program with just a button with a picture on it. I've been able to make the button with the image on it easily enough, but my problem arises when including it.
So far, I've only been able to fetch the image during run-time (the image has to be in the same folder as the .exe file; otherwise, I get error 2: the system cannot find the file specified). With this method, I have no problems -- the program works just fine. What I'm trying to do, however, is to #include the file so that it is embedded during compile-time, so that it doesn't need to be available during run-time.
I've tried #including the file (both as .png and as .xpm), and I've also tried adding it to the resource includes (this is on Visual Studio 2017). Neither of these worked -- the first method still required the image to be in the same folder, and the second failed during compilation (as far as I can tell, it wasn't able to read the .xpm file).
Here is the relevant code, if it helps:
/*relevant includes*/
#include "happyFace.png" //this isn't working. the file is still needed
||
#include "happyFace.xpm" //ditto
/*I have also tried putting these lines in the resource includes.*/
/*code*/
wxInitAllImageHandlers();
wxBitmap bitmap("happyFace.xpm", wxBITMAP_TYPE_XPM); //only works in same directory at run-time
||
wxBitmap bitmap("happyFace.png", wxBITMAP_TYPE_PNG); //ditto
wxButton *button = new wxButton(this, ID_BMP_BUTTON);
button->SetBitmap(bitmap);
//the rest of the button programming and stuff
Sorry if I haven't provided enough information; I can provide more if necessary. I would really appreciate any help. Thanks!
Two possibilities... Number 1 is simplest. It's been a long time since I wrote the code I'm looking at, so the details are fuzzy.
In Visual Studio, Solution Explorer, add the image into the resource files. Assume the name of the resourse is sample.rc. Then it can be used like so to set the main icon...
SetIcon(wxICON(sample));
Method 1 must be used in order for MS Windows Explorer to display the main icon. I do not remember how to use .rc resources for other things, but it should be easy to figure out.
I did it this way before I discovered VS resource (.rc) files. Compile the file-image into the program "by hand." In other words, write a program that will read an image file and produce bit-for-bit copy in a .cpp file. Then compile that .cpp into the program. Here I have the file-image in memory as an object named dj::main_cursor. Note that the in-memory version is a bit-for-bit copy of a .cur file.
dj::captured_file &c1file(dj::main_cursor);
wxMemoryInputStream cistr(c1file.contents, c1file.size);
cursor1 = wxCursor(wxImage(cistr, wxBITMAP_TYPE_CUR));
FYI, I defined the structure dj::captured_file like so:
struct captured_file {
const char *name;
const unsigned long size;
const void *contents;
captured_file(const char*fn, size_t sz, const void*c)
: name(fn)
, contents(c)
, size(sz)
{}
};
See also, Embedding PNG Images into Windows RC Files
I found some other documentation.
Resources and Application Icon All applications using wxMSW should
have a Windows resource file (.rc extension) and this file should
include include/wx/msw/wx.rc file which defines resources used by
wxWidgets itself.
Among other things, wx.rc defines some standard icons, all of which
have names starting with the "wx" prefix. This normally ensures that
any icons defined in the application's own resource file come before
them in alphabetical order which is important because Explorer
(Windows shell) selects the first icon in alphabetical order to use as
the application icon which is displayed when viewing its file in the
file manager. So if all the icons defined in your application start
with "x", "y" or "z", they won't be used by Explorer. To avoid this,
ensure that the icon which is meant to be used as the main application
icon has a name preceding "wxICON" in alphabetical order.
http://docs.wxwidgets.org/3.1.0/page_port.html
Here is how you should do it:
#include "happyFace.xpm"
wxBitmap bitmap = wxBitmap( happyFace ); // assuming the variable name is "happyFace" inside the xpm
Then you will use bitmap object just like usual. Assuming that the file happyFace.xpm is available for compilation.
I'm writing a C++ MFC program on VS2008 and I'm getting this "Debug Assertion Error" when I first run the program sometimes. When I try to debug it, it takes me to this winhand.cpp file which is not part of the program I wrote so I'm not sure how to debug this.
It takes the error to this place in winhand.cpp
CObject* pTemp = LookupTemporary(h);
if (pTemp != NULL)
{
// temporary objects must have correct handle values
HANDLE* ph = (HANDLE*)((BYTE*)pTemp + m_nOffset); // after CObject
ASSERT(ph[0] == h || ph[0] == NULL);
if (m_nHandles == 2)
ASSERT(ph[1] == h);
}
So why does this error happen? Why does it only happen sometimes (50% of the time)? How would I debug this?
I'll provide some code if is needed.
THANKS!
The code that is asserting is part of MFC's CHandleMap class. MFC deals with windows as CWnd objects, but Windows deals with them as HWND handles. the handle map allows MFC to 'convert' an HWND into a pointer to the MFC object representing that object.
What the assertion seems to be doing is checking that when a lookup of the handle finds an MFC object, that the MFC object also thinks it's wrapping the same handle.
If they're different, then you get the assertion.
So it would appear that something is corrupting the handle map or the MFC object for that handle or you're doing something incorrect that gets these 2 data structures out of sync.
Some things you might do to try to debug the problem is to determine:
what MFC object is being found in the lookup (that's what's being pointed to by pObject)
what the MFC object thinks it's wrapping (that's the handle ph[0] and/or ph[1] - I'm not sure why there can be 2 of them)
what the handle is for (that's h)
Do the handles look like handle values or do they look like garbage? Does pObject point to something that looks like an MFC object, or garbage? Do any of these these things seem related?
The answers to these questions may point to what you need to do next (maybe set a debug write breakpoint on the item that looks like it's trashed).
I got this same assertion few days ago, and after some google search,
I found the solution for my case here:
http://forums.codeguru.com/showthread.php?216770-What-would-cause-this-assertion
In my case, change to misused
CDC* dc = GetDC();
CSize spaceSize = dc->GetTextExtent(" ");
dc->DeleteDC();
to
CDC* dc = GetDC();
CSize spaceSize = dc->GetTextExtent(" ");
ReleaseDC(dc);
would fix it.
Look out for code along those lines (from memory from Stroustrup's book):
c1 = (t2+t3).c_str();
(in spirit, could be other commands and expressions of course).Temporary objects are destroyed after their enclosing full expression has been evaluated, or at least the standard allows them to be. That means that what you would like to allocate to c1 may, or may not, still be in memory where it can be assigned to c1. The compiler may alert you to this issue, and the issue may or may not arise depending on what exactly you assign and other circumstances (I am not compiler writer), which would also explain why you get this error message only sometimes.
So in your shoes, I'd scan my code for similar expressions and clean them up.
When the debugger breaks, head up the call stack to the first bit of your code (if there is any - hopefully there is!). Ideally it's as simple as something in your code calling a library function incorrectly, and the library is catching the error with an assert and alerting you to that. (I don't think anyone will be able to tell what's wrong from the library code, we need to see your code.)
Otherwise, you're in for some tricky debugging: you're doing something wrong with the library that is asserting (looks like MFC) so go back and review all your MFC code and make sure everything is correct and according to the documentation.
This looks suspiciously like an error I had this morning. Is this happening in OnIdle()?
I know this is a very old post, but hoping that someone may get a little help from my answer.
I also faced a similar issue recently because of my simple mistake, then I came across this post and got a hint from "pac"'s post.
What I found is that if I use DeleteDC() to release DC returned from GetWindowDC() or GetDC() I will get the above assertion in MFC frame once CPaintDC object instance goes out of scope.
CDC * pDC = GetWindowDC();
...
ReleaseDC(pDC);
You have to use DeleteDC() only in conjunction with CreateDC() API.
CDC * pDC = new CDC();
pDC->CreateDC();
....
pDC->DeleteDC();
We had this problem when some of our project dlls were linking MFC as static library and some as shared library (check "Use of MFC" in Project settings)
I am trying to load a Nib from a C++ constructor with Objective C++. I have searched and found enough examples to get some code together but it doesn't display the window. Or any windows for that matter.
Here is an example of the contructor:
JokeSystem::JokeSystem() : fileSystem("/Library/Application Support/Jokes/")
{
try
{
randSystem = new RandSelect<std::string>
(fileSystem.getAllFileContents("%\n"));
}
catch (std::ifstream::failure)
{
NSWindowController * errorWindowControl = [[NSWindowController alloc]
initWithWindowNibName:#"ErrorWindow"];
[errorWindowControl showWindow: nil];
}
}
The purpose of the contructor is to load the contents of a directory into a string. What I am try to do is display the error window when the files fail to open.
ErrorWindow.nib has a single window with an OK button and a NSTextView for the error, I set up a NSWindowController in the nib and connected it to the window.
My only link has been that most examples show this [errorWindowControl showWindow: self];
rather than showWindow: nil but because this is a C++ constructor I it doesn't have self and this doesn't work.
If it matters this contructor is called from the awakeFromNib method of the MainMenu.nib's primary NSObject.
Thanks
A bit of an odd way to approach Cocoa. I would encourage you to step back, learn Objective-C and then write your application with an Objective-C based Cocoa UI layer on top of whatever backing store or model layer you have.
In any case, there isn't anything particularly wrong with that code (save for the odd design).
The first thing to check is the return value of -initWithWindowNibName:. Is errorWindowControl actually non-nil? If it is nil, then the NIB failed to load.
How are you writing the Cocoa application itself? Standard app bundle using Xcode, I hope?
Also, you shouldn't be hardcoding the path to /Library/Application Support/. Actually, your application shouldn't use that directory as the only storage location; many users won't have write access to that directory and won't be able to install your app without administrator access.
My MFC application using the "ESRI MapObjects LT2" ActiveX plugin throws an ASSERT at me when closing it.
The error occurs in cmdtarg.cpp:
CCmdTarget::~CCmdTarget()
{
#ifndef _AFX_NO_OLE_SUPPORT
if (m_xDispatch.m_vtbl != 0)
((COleDispatchImpl*)&m_xDispatch)->Disconnect();
ASSERT(m_dwRef <= 1); //<--- Fails because m_dwRef is 3
#endif
m_pModuleState = NULL;
}
I built the (native C++) application with VC9.
When I compile the application with VC6, it behaves nicely.
What could be the reason for this?
That looks like a reference count. Could this "target" be referenced by something else, something that's not releasing it?
You can trace the Addref and Release calls defining _ATL_DEBUG_INTERFACES
from http://msdn.microsoft.com/en-us/library/sycfy8ec(VS.80).aspx
_ATL_DEBUG_INTERFACES
Define this macro before including any ATL header files to trace all AddRef and Release calls on your components' interfaces to the output window.
Using _ATL_DEBUG_INTERFACES did not yield any additional output...
I defined it on the first line of stdafx.h, directly after #pragma once so I guess this is early enough.
Maybe the reason is how I am using the ActiveX control:
I'm not calling AddRef() or Release() by myself.
The MapObjects Installer comes with sample code with lots of wrapper classes which must have been generated by VC6 or something earlier.
I tried to generate wrapper classes myself with VC9 but there occured errors which I wasn't able to fix.
I use the control by letting one of my windows have a member of type CMap1 (derived from CWnd), which is one of those generated wrapper classes. In CMyWnd::OnCreate() I also call CMap1::Create() and that's it, I'm finished: I can add a layer and the control displays a world map.
I have pretty much no idea what the reference-count stuff is about as I have not added or released any references. At least not knowingly...
The control is pretty old: The .OCX file has the year 2000 in its version information.
It's also not officially supported anymore but I don't have any substitue.
The following solved it for me:
In the window that contains the control, add an OnDestroy() handler:
void CMyWnd::OnDestroy()
{
// Apparently we have to disconnect the (ActiveX) Map control manually
// with this undocumented method.
COleControlSite* pSite = GetOleControlSite(MY_DIALOG_CONTROL_ID);
if(NULL != pSite)
{
pSite->ExternalDisconnect();
}
CWnd::OnDestroy();
}