qpainter

问题 My code below currently opens a 500x500 QMainWindow that is blank. I am simply trying to draw a circle in the QWidget using QPainter. Here is my code: from PyQt4 import QtCore, QtGui, Qt from PyQt4.QtGui import QApplication, QMainWindow import sys class Ui_MainWindow(object): def setupUi(self, MainWindow): MainWindow.resize(500, 500) self.centralwidget = QtGui.QWidget(MainWindow) self.horizontalLayout = QtGui.QHBoxLayout(self.centralwidget) MainWindow.setCentralWidget(self.centralwidget) self

问题 I have a large display (about 1000x2000 pixels) and I'm doing the following to draw images to the screen: QImage *pImage = GetImage(); // from wherever QPainter painter(this); painter.drawImage((0,0), *pImage); // this line takes over 100ms to complete. The larger the screen is that I'm drawing to, the longer this paint takes. I guess the pImage is being memcpy'd and that's the difference. How can I reduce this overhead? I'm not trying to scale or anything here. Thanks. 回答1: You're painting a

问题 I am having a problem getting CutyCapt to work with SSL URLs, I have the most recent version of CutyCapt ( CutyCapt.cpp 10 2013-07-14 21:57:37Z ), it works perfect with all non-SSL URLs, when I try to grab a URL with SSL using the following command: ./xvfb-run ./CutyCapt --min-width=1280 --min-height=720 --max-wait=6000 \ --url="https://apple.com" --out="testssl.jpg" I get the following error: QPainter::begin: Paint device returned engine == 0, type: 3 QPainter::setRenderHint: Painter must be

问题 This question already has an answer here : paintEvent in QTableView derived class: Paint device returned engine == 0, type: 1 (1 answer) Closed 2 months ago . I tried to draw some more information in QChartView so I re-implement paintEvent virtual void paintEvent(QPaintEvent *event) { QChartView::paintEvent(event); OmenChart *mchr = dynamic_cast<OmenChart *>(this->chart()); if(mchr == nullptr) return; QPainter painter(this); const int labelOffset = 2 + 2; painter.setFont(this->font());

问题 I'm attempting to create a widget that consists of of a single horizontal black line. This widget will be placed in a QGridLayout such that it takes up the entire row, thus acting as a separator. As the widget upon which the layout is installed is resized, I'd like the line to change it's size to keep up. I've checked out a number of options, including QLine, QGraphicsView and QImage, but I can't seem to get the line drawn, never mind get it to resize. I'm implementing this in it's own class

问题 This question is further development of this post and is different, though may seem similar as this one. I am trying to reimplement QHeaderView::paintSection , so that the background returned from the model would be honored. I tried to do this void Header::paintSection(QPainter * painter, const QRect & rect, int logicalIndex) const { QVariant bg = model()->headerData(logicalIndex, Qt::Horizontal, Qt::BackgroundRole); // try before if(bg.isValid()) // workaround for Qt bug https://bugreports

问题 I'm painting a QPixmap inside the QItemDelegate of QListWidget. Each QListWidgetItem is of different dimensions. Inside the void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) function of QItemDelegate, I want to paint QPixmap with center Alignment inside the QListWidgetItem. option.rect() gives the geometry of the item with which I can calculate the center position and paint accordingly, but I want to know the better approach for this alignment.Can

问题 I'm trying to print Qtablewidget but it just print a blank page and application output show QPrinter::metric: Invalid metric command QPainter::begin: Paint device returned engine == 0, type: 2 QWidget::render: Cannot render with an inactive painter print function void MainWindow::on_btPrint_clicked(){ QPrinter printer(QPrinter::HighResolution); QPrintDialog printer_dialog(&printer, this); if (printer_dialog.exec() == QDialog::Rejected) return; QPainter painter(&printer); ui->table_log->render

问题 In Qt 5, I have a QDialog window on which I have drawn a circle as follows: void MyDialog::paintEvent(QPaintEvent *pe) { QPainter painter(this); painter.setRenderHint(QPainter::Antialiasing,true); QPen pen(Qt::blue,2); painter.setPen(pen); QRect r=QRect(0,0,100,100); painter.drawEllipse(r); } If I draw a larger circle, for example by using QRect(0,0,500,500); , the circle being greater than the dialog window is clipped. So I dragged a QScrollArea onto the the dialog window and decide to draw

问题 I am looking for a simple c++ 2d plotting tool for Linux (to be more honest "Cross-platform"). "koolplot" is nice but I think it's for windows only since its code includes graphics.h and windows.h. Someone suggested Qt's QPainter, but I cannot even use it to draw a single point. :'( So, if there is any help on other plotting tool or a decent tutorial on Qt's QPainter, I would be very grateful. Thanks. 回答1: Check out Qwt. It's worked well for all of my 2D applications, plus it's cross-platform