We have a lot of code written that makes use of the standard template library. I would like to integrate some of our apps into the windows shell, which should provide a better experience for our users.
One piece of integration involves a Shell Preview provider, the code is very straight forward, however, I’m stuck on the best way to implement something.
The shell is giving me, via my preview handler, an IStream object and I need to convert/adapt it to an std::ifstream object, primarily so that std::getline can get called further down the callstack.
I was wondering if there was a “standard” way of doing the adapting or do I need to role up my sleeves and code?
TIA.
Faffed around with this for a while:
std::stringstream buff;
BYTE ib[2048];
ULONG totread=0, read=0, sbuff = 2048;
HRESULT hr;
do {
hr = WinInputStream->Read(ib, sbuff, &read);
buff.write(ib, read);
totread+=read;
} while((sbuff == read) && SUCCEEDED(hr));
if(totread == 0) return false;
ifstream i;
TCHAR* ncbuff = const_cast<TCHAR*>(buff.str().c_str());
i.rdbuf()->pubsetbuf(ncbuff, buff.str().length());
But didn't like having to read it all into memory, for it to be processed again.
So I implemented my preview handler using IInitializeWithFile instead.
Related
I am using an embedded system to send data from 25 sensors to a putty terminal on my computer. Works great.
I wanted to add a read from terminal functionality to the embedded system (so I can send commands). So I tried using getchar() to read whatever I would write on my putty terminal. First I just wanted to getchar and print the character back on putty. It kinda works, but my sensor data, which is supposed to print every 500ms, does not print until I type a char in putty. It is as if my code was stuck on getchar() and stuck in a while loop until getchar() reads something.
Here is my forever loop in my int main(). I am not sharing the rest as it is not really needed and too bulky (its just initializing modules). In this loop I am reading a sensor, trying to read from putty, writing to putty, and starting my next scan:
for(;;)
{
CapSense_ProcessAllWidgets(); // Process all widgets
CapSense_RunTuner(); // To sync with Tuner application
read_sensor(curr_elem); //read curr_elem
(curr_elem < RX4_TX4)?(curr_elem++):(curr_elem = 0, touchpad_readings_flag++);
// Here is the part to read I added which blocks until I type in something.
// If I remove this if and all of what's in it, I print to putty every 500ms
if(touchpad_readings_flag)
{
char received_char = getchar();
if (received_char) //if something was returned, received_char != 0
{
printf("%c", received_char);
}
}
//Here I write to putty. works fine when I remove getchar()
if (print_counter_flag && touchpad_readings_flag)
{
print_counter_flag = 0;
touchpad_readings_flag = 0;
for (int i = 0; i < 25; i++)
{
printf("\n");
printf("%c", 97 + i);
printf("%c", val[i] >> 8);
printf("%c", val[i] & 0x00ff); // For raw counts
printf("\r");
}
}
/* Start next scan */
CapSense_UpdateAllBaselines();
CapSense_ScanAllWidgets();
}
Apparently, your getchar() call is blocking unless there is input data to retrieve.
One solution to change this behaviour has been given by another article on different SE board.
Please also note that getchar() is a wrapper for getc() that is acting on stdin as this site1 describes.
For getc() you find further discussions.
In one of those, it is pointed out that some important implementations even wait for a newline character until input is delivered to your function. I think this depends on standard libraries/kind of embedded system you actually use - please check the documentation of your toolchain vendor.2
1
I didn't look up a normative source, this is just my first google hit.
2
The question doesn't specify the kind of embedded system, so a generic answer is wanted instead of a discussion of particular target/toolchain combinations, IMO.
I’m working under kubuntu 12.10 and developping an application into which i need to generate some sound into a QIODevice, then play it with QAudioOutput.
I’ve read all the litterature around speaking of how to properly do that, and I think to have done so.
So far I’ve done :
QVector <double> * soundData = SoundGenerator::getSound();
soundBuffer->open(QIODevice::ReadWrite);
QDataStream writeStream(soundBuffer);
foreach(double d, *soundData) {
char value = d * (2 << 7);
// qDebug() << "Value : " << (short int)value;
writeStream << value;
}
QAudioFormat format;
// Set up the format, eg.
format.setSampleRate(SoundGenerator::getAudioSampleRate());
format.setChannelCount(1);
format.setSampleSize(8);
format.setCodec("audio/pcm");
format.setByteOrder(QAudioFormat::LittleEndian);
format.setSampleType(QAudioFormat::SignedInt);
QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());
audio = new QAudioOutput(format, this);
if (audio->error() != QAudio::NoError) {
qDebug() << "Problem playing sound";
}
connect(audio, SIGNAL(stateChanged(QAudio::State)), this, SLOT(aboutToFinish(QAudio::State)));
I have also a call to
audio->start(soundBuffer)
—
from another slot
I do not have any error in the initialization of the QAudioOutput
And I have NO SOUND AT ALL (all other applications have sound, and I’m porting a Qt4 app to Qt5, in Qt4 everything is ok with Phonon)
The aboutToFinish slot is called at the beggining with ActiveState as state, and NoError when calling QAudioOutput::error, but it’s not called anymore, even if waiting far more than the expected generated sound duration.
The sound generation process is not to be put in question, it has been tested by writing wav files, and it works.
Moreover, I have built the multimedia example from Qt’s sources, when it comes to pure audio there is no output (for example in the sprectrum example), on another hand, video plays with the sound perfectly.
Is there any known issue concerning that ? Is that a bug ? Am I doing something wrong ?
Thanks in advance ;)
This does not work because you have set 8 bit sample size and signed integer format.
SOLUTION: You have to set the sample type to unsigned for 8-bit resolution:
format.setSampleType(QAudioFormat::UnsignedInt);
This is not a Qt bug. Why? The answer is that in the WAV spec', 8-bit samples are always unsigned, whereas 16-bit samples are always signed. Any other combination does not work.
So for 16-bit samples you would have to put:
format.setSampleType(QAudioFormat:SignedInt);
(IMHO the fact that Qt does not take care of handling these cases by forcing the correct format is a flaw but not a lack in functionnality).
You can learn more about this in the notes section of this page: https://ccrma.stanford.edu/courses/422/projects/WaveFormat/
And also the solution to this very similar question (same problem but with 16-bit): Qt QAudioOutput push mode
Try to add:
QEventLoop loop;
loop.exec();
Hey, I am making some stuff in Objective-C++... And I must say that I am a total newbie when it comes to the Objective-C part... I don't really want to learn it, I kinda just need it for accessing a few Mac APIs (ObjC is such a dumb language).
So - compiling with g++ -x objective-c++ - and I somehow keep getting this warning:
XXX may not respond to YYY
First it was with a NSScreen, now it is with a NSWindow:
NSWindow may not respond to +initWithContentRect:styleMask:backing:defer:
I saw somewhere that I should cast it to id, but didn't work, throwing absolutely cryptic errors...
So - WHAT does this warning actually mean and HOW am I supposed to make it stop?
EDIT: Okay, apparently I need to ALLOCATE an instance first, then I can call its init function... Anyways, now the GCC is reporting:
confused by earlier errors, bailing out
And NOTHING else. This is the ONLY error that it reports. I figured that there is some error in my code that doesn't get reported... So I will post the whole file where the problem is here:
ONXeWindow::ONXeWindow(int px, int py, int sw, int sh, bool resizable){
NSRect wr = NSMakeRect(px, py, sw, sh);
int wf = 1; // titled
wf += 2; // closable
wf += 4; // miniaturizable
wf += (resizable ? 8 : 0); // resizable
wf += (false ? 128 : 0); // metal bg
useWindow = [[NSWindow alloc] initWithContentRect:wr styleMask:wf backing:2 defer:YES];
}
Also, YES, framework AppKit was imported (in the header file) - I am not going to confuse you with my weird file scheme here.
The message isn't really cryptic, you just don't know the language (and don't care to, by your own admission).
Since Objective-C methods are dispatched dynamically at run-time, you can call a method that the compiler doesn't have any knowledge of, however, the compiler is warning you that you're doing so. The + in the beginning of the method name means that you're calling a class method (a - would indicate that you're calling a method on an instance). Since NSWindow has no class method named initWithContentRect:styleMask:backing:defer:, the compiler is giving you a warning, and in this case, it's a pretty good one.
You probably wrote something like:
NSWindow* myWindow = [NSWindow initWithContentRect:rect styleMask:0 backing:0 defer:NO];
when you meant to write something like:
NSWindow* myWindow = [[NSWindow alloc] initWithContentRect:rect styleMask:0 backing:0 defer:NO];
The first one sends the message directly to the class, but this is an instance method. You need to allocate an instance of NSWindow first, then send the init message. Also, clang tends to give much better warning and error messages than gcc. Clang 2.0 also handles C++ and ObjC++ pretty well, so it might be worth it to switch to clang.
Checkout this example, looks like you are not allocating your objects.
So, I'm using the HTTPConnection Class, like so:
HttpConnection c =
(HttpConnection)Connector.open("http://147.117.66.165:8000/eggs.3gp");
Following what LOOKS like the right way to do things in the Blackberry JDE API.
However, my code crashes if I try to do just about anything with the variable 'c'.
.getType()
.getInputStream()
.getStatus()
all cause it to crash.
I can, however get the URL from it, and I can look at the variable 'c' itself to know that it did, in fact, get created.
Did I manage to create a broken Connection? Do I need to do something else to actually do things with the connection? Under what circumanstances will this happen (I know the link is good, I can use the blackberry's browser to visit it).
Am I just using HttpConnection wrong? How would I do things correctly?
What error is it throwing when it crashes? You may want to try adding the "Connector.READ_WRITE" as a second argument to your open call - even if it's just a "read only" connection like a GET, some OSes such as 4.6 will throw an exception unless you open it in read/write mode.
I figured out what was wrong by finding some sample code that was using HttpConnection, (at least, I think I did, at least, I can access all those variables, now). Before, I wasn't ever casting it as a "Stream Connection" (the examples I saw had it cast from Connector to HTTPConnection).
StreamConnection s = null;
s = (StreamConnection)Connector.open("http://10.252.9.15/eggs.3gp");
HttpConnection c = (HttpConnection)s;
InputStream i = c.openInputStream();
System.out.println("~~~~~I have a connection?~~~~~~" + c);
System.out.println("~~~~~I have a URL?~~~~" + c.getURL());
System.out.println("~~~~~I have a type?~~~~" + c.getType());
System.out.println("~~~~~I have a status?~~~~~~" + c.getResponseCode());
System.out.println("~~~~~I have a stream?~~~~~~" + i);
player = Manager.createPlayer(i, c.getType());
Even though the stream is now successfully being created, I'm still having problems USING it, but that might be because my connection is so slow.
The API documentation for HttpConnection suggests the first call should be to c.getResponseCode(), try that.
You should find everything you need in my blog post "An HttpRequest and HttpResponse library for BB OS5+"
And for invoking media within your application you can do either a browser invokation or directly from app. You would probably be best to use the browser like so:
BrowserSession invokeHighQuality = Browser.getDefaultSession();
invokeHighQuality.displayPage("URL goes here");
OR you can try this:
// CHAPI invocation
Invocation invoke = new Invocation(_data.getUrl(), null, BlackBerryContentHandler.ID_MEDIA_CONTENT_HANDLER, false,
null);
try {
Registry.getRegistry(YourAppClass.class.getName()).invoke(invoke);
} catch (Throwable t) {
}
I have a problem with Lucene.NET. During an index, I receive the error 'Access to the path segments is denied'. Or sometimes 'Access to the path deletable is denied'. I eventually gave 'Everyone' full security rights to the index directory, but the problem still existed.
I then found out that during the index run, lucene renames the segments file to 'segments.new', and then this error happens. I guess some process still tries to read from the old segments file after it has been renamed? I have no clue as to why this happens, or how to fix this. Strangely enough, my co-developers can run the index on their computer without a problem.
The error happens at happens in Lucene.Net.Index.IndexModifier.AddDocument(Document).
Any ideas would be much appreciated.
I suspect that your IndexModifier is in contention with a Searcher.
Here's how I use Lucene.Net in my bug tracking app, BugTracker.NET, which seems to be working ok.
I create the index at app startup.
I create a searcher and keep it around so that the index isn't reloaded with each search. All threads share the same searcher. When the searcher searches, it grabs a lock, searches, then releases the lock, so that another thread can search. Forces the searches into single file is doable in my app because Lucene.NET is quick and a bug tracking system isn't THAT busy.
Meanwhile, I have an IndexWriter that updates the index when there is a data change. It is just changing a little bit so it does its task quick too. When it needs to run, it grabs the same lock, destroys the searcher, updates the index, and the re-recreates the searcher. The new searcher stays around until the next update of the index. The searcher always is working with an up-to-date index.
You can get the BugTracker.NET source and look at the files my_lucene.cs and search_text.aspx. It's all in those two files, and there isn't that much code.
This problem is caused by an online virus scanner locking the segments(.new) file. I have had to write a custom Lucene Directory implementation to work around this.
I think i found a solution.. well at least it worked for me..
I was testing for the "segments.new" problem and below you have the code .. so as you can see in a loop i created thousands of lucene documents (6000).. At about 1360 document an error appears saying that he couldn´t rename blablabla.. The code is written in c#.. basically you just have to insert a try catch (inside the loop) for the error and when the error pops up you just try again subtracting the int loop nunmber(y) by one (y = y - 1) ..
//-----------------Problem -------------------------------------
for (int y = 0; y < 6000; y++)
{
Document doc = new Document();
doc.Add(new Field("URL", "C:/Users/blabla/(convert-csharp)/IMssg", Field.Store.YES, Field.Index.TOKENIZED));
writer.AddDocument(doc);
}
//--------------------Solution----------------------------------------
IndexWriter writer = new IndexWriter("C:/Users/blabla/(convert-csharp)/IMssg", new StandardAnalyzer(), false);
for (int y = 0; y < 6000; y++)
{
try
{
Document doc = new Document();
doc.Add(new Field("URL", "C:/Users/blabla/(convert-csharp)/IMssg", Field.Store.YES, Field.Index.TOKENIZED));
writer.AddDocument(doc);
}
catch (Exception t)
{
y = (y < 0) ? 0 : y - 1;
string gfff = t.Message.ToString();
}
}
writer.Close();
Im not a english guy so im sory if there´s any error in some word...
by now
regards immanouel
I second Imma's solution. I had this problem also. The fix for me was to put the try/catch around IndexWriter.AddDocument(doc):
int attemptNo = 0;
while (attemptNo < 2)
{
try
{
writer.AddDocument(doc);
break;
}
catch (Exception e)
{
String ErrMsg = String.Format("{0} ({1}): While adding Document {2}/{3}, caught {4}", DateTime.Now, attemptNo, doc.GetField("kanji").StringValue(), doc.GetField("kana").StringValue(), e.Message);
attemptNo++;
System.Threading.Thread.Sleep(30);
Application.Current.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Normal, (Action)delegate()
{
ViewModel.Log.Add(ErrMsg);
});
}
reference: http://issues.apache.org/jira/browse/LUCENE-665:
"The gist of the issue is: on Windows, you sometimes see intermittant
"Access Denied" errors in renaming segments.new to segments or
deletable.new to deletable, etc. Lucene typically writes files first
to X.new and then renames then to X."
I read about this. However, I do not have any virus scanners running. I also disabled Vista Search Index for the index directory, killed the search index process from the task manager, to make sure no other process is locking the file. Unfortunately, to no avail. Moreover, the problem seems more to be that the 'segments' file it tries to access, is gone (since lucene renamed it to segments.new). I'm not sure if they are the same problems...