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  • QPainter declared inside a run function creates artifact.

    - by yan bellavance
    I am rendering a QPixmap inside of a QThread. the code to paint is inside a function. If I declare the painter inside the drawChart function everything seems ok but if I declare the painter inside the run function the image is wrong in the sense that at the edge of a black and white area, the pixels at the interface are overlapped to give a grey. Does anyone know why this is so? Could it be because of the nature of the run function itself? //This is ok void RenderThread::run() { QImage image(resultSize, QImage::Format_RGB32); drawChart(&image); emit renderedImage(image, scaleFactor); } drawChart(&image){ QPainter painter(image); painter.doStuff()(; ... } //This gives a image that seems to have artifacts void RenderThread::run() { QImage image(resultSize, QImage::Format_RGB32); QPainter painter(image); drawChart(painter); emit renderedImage(image, scaleFactor); } drawChart(&painter){ painter.doStuff()(; ... }

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  • Integrating Jython Cpython

    - by eric.frederich
    I am about to begin a project where I will likely use PyQt or Pyside. I will need to interface with a buggy 3rd party piece of server software that provides C++ and Java APIs. The Java APIs are a lot easier to use because you get Exceptions where with the C++ libraries you get segfaults. Also, the Python bindings to the Java APIs are automatic with Jython whereas the Python bindings for the C++ APIs don't exist. So, how would a CPython PyQt client application be able to communicate with these Java APIs? How would you go about it? Would you have another separate Java process on the client that serializes / pickles objects and communicates with the PyQt process over a socket? I don't want to re-invent the wheel... is there some sort of standard interface for these types of things? Some technology I should look into? RPC, Corba, etc? Thanks, ~Eric

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  • getting keyboard events with pyqt

    - by Moayyad Yaghi
    hello i converted recently from wxpython to pyqt and im still facing alot of problems since im still noob in pyqt so is it possible to detected if user pressed (CTRL+key ) in pyqt ? and how ? i've been trying to find an answer for this for 3 days . if you know website or a good place to learn pyqt, it will be highly appreciated thanx in advance

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  • Changing the color of a QTextBlock that is within a QTextDocument

    - by yan bellavance
    Is there any other way to change the QTextLayout of a QTextBlock that is within a QTextDocument without having to subclass QAbstractTextDocumentLayout and call its documentChanged? I know that on a call to QTextBlock::layout() const ; the returned QTextLayout object can only be modified from the documentChanged implementation of a QAbstractTextDocumentLayout subclass but I was wodering if there was any other way before I implemented it.

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  • Strange problem with vectors.

    - by Catalin Dumitru
    I have a really strange problem with stl vectors in which the wrong destructor is called for the right object when I call the erase method if that makes any sense. My code looks something like this: for(vector<Category>::iterator iter = this->children.begin(); iter != this->children.end(); iter++) { if((*iter).item == item) { this->children.erase(iter); return; } ------------------------- } It's just a simple function that finds the element in the vector which has some item to be searched, and removes said element from the vector. My problem is than when the erase function is called, and thus the object which the iterator is pointing at is being destroyed, the wrong destructor is being called. More specific the destructor of the last element in the vector is being called, and not of the actual object being removed. Thus the memory is being removed from the wrong object, which will still be an element in the vector, and the actual object which is removed from the vector, still has all of it's memory intact. The costructor of the object looks like this: Category::Category(const Category &from) { this->name = from.name; for(vector<Category>::const_iterator iter = from.children.begin(); iter != from.children.end(); iter++) this->children.push_back((*iter)); this->item = new QTreeWidgetItem; } And the destructor Category::~Category() { this->children.clear(); if(this->item != NULL) { QTreeWidgetItem* parent = this->item->parent(); if(parent != NULL) parent->removeChild(this->item); delete this->item; } }

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  • Encrypt/Decrypt SQLite-database and use it "on the fly"

    - by Berschi
    Here's the thing: In my Qt4.6-Project, I use a SQLite-Database. This database shouldn't be unencrypted on my harddrive. So I want, that on every start of my program, the user gets asked to enter a password to decrypt the database. Of course the database never should appear "in clear" (not encrypted) on my harddrive. So is there any possibility to decrypt a SQLite-database "on the fly" and read and write data? What algorithm is here the best (maybe AES)? When it's not possible (or very slow), maybe it's better to encrypt every string in the database and decrypt the string when the password was right (so that a user could open the database, but has no clue what all the entrys could mean)?

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  • Qwt setAxisScale() locks up application when given numbers less than 2e-07 and greater than 0

    - by Dane Larsen
    I'm using Qwt for some scientific graphing, and I'm working with some fairly small numbers, the smallest being around 1.0e-22. I'm trying to call setAxisScale(xaxis, xmin, xmax) //xmin = 0, xmax = 2.0e-10 But when I do, the application locks up. I haven't found anything in the documentation that refers to a minimum value. Xmin and xmax are both doubles, so that shouldn't be a problem. Is this a bug in Qwt, or am I doing something wrong? Thanks in advance

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  • How to fetch output when calling R using Qprocess or system

    - by SYK
    Hi Experts, I would like to execute a R script simply as R --file=x.R It runs well on the command line. However when I try the system call in C++ by QProcess::execute("R --file=x.R"); or system("R --file=x.R"); the program R runs and quits but I can't see the output the program is supposed to generate. If a program uses no stdout (such as R), how do I fetch the output after a system call either as a output file or in the program's own console? Thanks for your time.

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  • Subclassing QGraphicsItemGroup

    - by onurozcelik
    Hi everyone I have system that has classes derived from QGraphicsWidget. I manage derived class objects in layouts on QGraphicsScene. Now I need a compound item that contain two or more QGraphicsWidget in it and also I need to put that item inside my layout. So I choose QGraphicsItemGroup and write I class like this. class CompositeItem : public QGraphicsItemGroup,public QGraphicsLayoutItem { ... }; I only implemented sizeHint function again. When add CompositeItem instance to layout it does not shown. What may cause this? Where I made wrong?

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  • Quartz Window Services equivalent for Windows and X11?

    - by Jake Petroules
    What is the equivalent of Quartz Window Services for Windows and X11? I want to be able to capture individual windows with their decorations, shadows, etc., completely independent from each other. Basically what the Son of Grab example is able to do. http://developer.apple.com/mac/library/samplecode/SonOfGrab/Introduction/Intro.html Also it seems like it's not possible to capture non-top-level windows with QWS in Mac. For example I want to be able to capture a Java or Flash applet running inside Firefox. What other library would I need to use instead?

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  • HowTo stick QDialog to Screen Borders like Skype do?

    - by mosg
    Hello. A long time ago I tried to find method how to stick QDialog window to screen borders for my small projects like Skype windows do it, but I failed. May be I was looking this code not in the right place, so now I'm looking the solution here, on stack! :) So, does any one have a deal with some kind of such code, links, samples? In my opinion, we have to reimplement QDialog moveEvent function, like below, but that code does not working: void CDialog::moveEvent(QMoveEvent * event) { QRect wndRect; int leftTaskbar = 0, rightTaskbar = 0, topTaskbar = 0, bottomTaskbar = 0; // int top = 0, left = 0, right = 0, bottom = 0; wndRect = this->frameGeometry(); // Screen resolution int screenWidth = QApplication::desktop()->width(); int screenHeight = QApplication::desktop()->height(); int wndWidth = wndRect.right() - wndRect.left(); int wndHeight = wndRect.bottom() - wndRect.top(); int posX = event->pos().x(); int posY = event->pos().y(); // Snap to screen border // Left border if (posX >= -m_nXOffset + leftTaskbar && posX <= leftTaskbar + m_nXOffset) { //left = leftTaskbar; this->move(leftTaskbar, posY); return; } // Top border if (posY >= -m_nYOffset && posY <= topTaskbar + m_nYOffset) { //top = topTaskbar; this->move(posX, topTaskbar); return; } // Right border if (posX + wndWidth <= screenWidth - rightTaskbar + m_nXOffset && posX + wndWidth >= screenWidth - rightTaskbar - m_nXOffset) { //right = screenWidth - rightTaskbar - wndWidth; this->move(screenWidth - rightTaskbar - wndWidth, posY); return; } // Bottom border if (posY + wndHeight <= screenHeight - bottomTaskbar + m_nYOffset && posY + wndHeight >= screenHeight - bottomTaskbar - m_nYOffset) { //bottom = screenHeight - bottomTaskbar - wndHeight; this->move(posX, screenHeight - bottomTaskbar - wndHeight); return; } QDialog::moveEvent(event); } Thanks.

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  • Qwt setAxisScale() seems to lock up application when given numbers with greater precision than 2e-07

    - by Dane Larsen
    I'm using Qwt for some scientific graphing, and I'm working with some fairly small numbers, the smallest being around 1.0e-22. I'm trying to call setAxisScale(xaxis, xmin, xmax) //xmin = 0, xmax = 2.0e-10 But when I do, the application locks up. I haven't found anything in the documentation that refers to a minimum value. Xmin and xmax are both doubles, so that shouldn't be a problem. Is this a bug in Qwt, or am I doing something wrong? Thanks in advance

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  • QAbstractTableModel as a model for one QTableView and few QListViews

    - by ??????
    community. Briefly. I wrote usual model over QAbstractTableModel and using it in usual way for QTableView. But I think I need to use some columns of this model for the few QListViews in QWizard to fill main table in the right way (for user). For example: use the column2 as the QListView's model on the page1 of the wizard; column3 for page2 for its QListView etc. Please, help me to understand just two things: Am I on the right way? If yes then how can I make it simply and explicitly?

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  • Events with QGraphicsItemGroup

    - by onurozcelik
    In my application I want to use QGraphicsItemGroup for grouping items into one item. I played with it a little and not sure using it because when I want to catch events, events are merged together but I want to handle specific event with specific child. How can I achieve this?

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  • subclassing QList and operator+ overloading

    - by Milen
    I would like to be able to add two QList objects. For example: QList<int> b; b.append(10); b.append(20); b.append(30); QList<int> c; c.append(1); c.append(2); c.append(3); QList<int> d; d = b + c; For this reason, I decided to subclass the QList and to overload the operator+. Here is my code: class List : public QList<int> { public: List() : QList<int>() {} // Add QList + QList friend List operator+(const List& a1, const List& a2); }; List operator+(const List& a1, const List& a2) { List myList; myList.append(a1[0] + a2[0]); myList.append(a1[1] + a2[1]); myList.append(a1[2] + a2[2]); return myList; } int main(int argc, char *argv[]) { QCoreApplication a(argc, argv); List b; b.append(10); b.append(20); b.append(30); List c; c.append(1); c.append(2); c.append(3); List d; d = b + c; List::iterator i; for(i = d.begin(); i != d.end(); ++i) qDebug() << *i; return a.exec(); } , the result is correct but I am not sure whether this is a good approach. I would like to ask whether there is better solution?

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  • what is the mistake in my code

    - by Solitaire
    class myslot { public: Q_OBJECT myslot() { } ~myslot() { } typedef enum Emycars{volvo,benz,tata}cars; public slots: void hellowslot(myslot::cars); }; void myslot::hellowslot(myslot::cars cars1) { } class mysignal { public: Q_OBJECT public: mysignal(myslot *ourslot) { bool val = QObject::connect(this,SIGNAL(hellowsignal(myslot::Emycars)),ourslot,SLOT(hellowslot(myslot::Emycars))); } ~mysignal() { } signals: void hellowsignal(myslot::Emycars); }; int main(int argc, char *argv[]) { QApplication a(argc, argv); myslot slot; mysignal sig(&slot); // DeleteNow w; // w.showMaximized(); return a.exec(); } what is the mistake in mycode, the way which i have written connect for the function which recive enum is right or not? please let me know where i am wrong.

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  • How to know coordinates in a real image from a scaled image.

    - by ocell
    Hi folks, First of all thanks for your time reading my question :-) I have an original image (w': 2124, h': 3204) and the same image scaled (w: 512, h: 768). The ratio for width is 4.14 (rw) and the ratio for height is 4.17 (rh). I'm trying to know the coordinates (x', y') in the original image when I receive the coordinates in the scaled image (x, y). I'm using the formula: x' = x * rw and y' = y * rh. But when I'm painting a line, or a rectangle always appears a shift that is incremented when x or y is higher. Please anybody knows how to transform coordinates without loosing of accuracy. Thanks in advance! Oscar.

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  • How to delete a QProcess instance correctly?

    - by Kopfschmerzen
    Hi everyone! I have a class looking like this: class FakeRunner : public QObject { Q_OBJECT private: QProcess* proc; public: FakeRunner(); int run() { if (proc) return -1; proc = new QProcess(); QStringList args; QString programName = "fake.exe"; connect(comp, SIGNAL(started()), this, SLOT(procStarted())); connect(comp, SIGNAL(error(QProcess::ProcessError)), this, SLOT(procError(QProcess::ProcessError))); connect(comp, SIGNAL(finished(int, QProcess::ExitStatus)), this, SLOT(procFinished(int, QProcess::ExitStatus))); proc->start(programName, args); return 0; }; private slots: void procStarted() {}; void procFinished(int, QProcess::ExitStatus) {}; void procError(QProcess::ProcessError); } Since "fake.exe" does not exist on my system, proc emits the error() signal. If I handle it like following, my program crashes: void FakeRunner::procError(QProcess::ProcessError rc) { delete proc; proc = 0; } It works well, though, if I don't delete the pointer. So, the question is how (and when) should I delete the pointer to QProcess? I believe I have to delete it to avoid a memory leak. FakeRunner::run() can be invoked many times, so the leak, if there is one, will grow. Thanks!

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  • Set bold rows in a QTreeView

    - by taynaron
    I have a custom subclass of a QTreeView in a pyqt application. I'm trying to give the user the ability to highlight and "lowlight" (for lack of a better term) rows. Highlighted rows should have bold text and (optionally) a different background color. Any ideas? I'm considering StyleSheets as an option, but have so far been unable to get that to work. If I set the QTreeView's stylesheet: self.setStyleSheet("QTreeView::item:selected {border: 1px solid #567dbc;}") I can't figure out how to manually enable 'states' that would keep only the desired rows at a particular state. If I try setting an individual item's stylesheet: #modelIndex is a valid QModelIndex modelIndex.internalPointer().setStyleSheet() I get a segfault. I'm not convinced stylesheets are the way to go, I'm open to all ideas. Thanks!

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