Tag: widget

QTableWidget cell related signals

Use a piece of code to detail the relevant signals emitted when QTableWidget’s cells are clicked (including single-click and double-click) and the content is edited. (1) Mainly include cellChanged, cellActivated, cellClicked, cellDoubleClicked, cellEntered, cellPressed and corresponding item class signals (2) Timing of sending each signal (3) The order in which signals are sent Through the […]

[Qt control QDockWidget] use

Overview The QDockWidget class provides a widget that can be docked in QMainWindow or displayed as a floating top-level window on the desktop. QDockWidget provides the concept of a dock window, also known as a tool staging area or utility window. The dock window is a secondary window placed in the dock window area around […]

Various refresh widgets in Flutter

1.FutureBuilder Very useful widget for handling asynchronous operations and building interfaces. It is typically used with Future objects to build the interface after an asynchronous operation has completed. import ‘package:flutter/material.dart’; void main() => runApp(MyApp()); class MyApp extends StatelessWidget {<!– –> @override Widget build(BuildContext context) {<!– –> return MaterialApp( home: MyHomePage(), ); } } class MyHomePage […]

QWidget|QFrame sets the background to be transparent and can have a border color

QWidget|QFrame sets the background to be transparent and can have a border color Chapter1 “Qt” part 6 QSS Qt style sheet – interface beautification 1($$$) Chapter2 [QT] QSS beautification – basic knowledge Chapter3 QWidget|QFrame sets the background to be transparent and can have a border color Reference link Chapter4 Several methods for setting form (QWidget) […]

[PyQt5] Open Excel, CSV, convert tableWidget to dataframe, add options to listWidget, for loop list derivation–list/dict

untitled.py # -*- coding: utf-8 -*- # Form implementation generated from reading ui file ‘untitled.ui’ # # Created by: PyQt5 UI code generator 5.15.9 # # WARNING: Any manual changes made to this file will be lost when pyuic5 is # run again. Do not edit this file unless you know what you are doing. […]

pcl+vtk (9) QVTKOpenGLNativeWidget displays point cloud and model at the same time

1. Load point cloud pcl::PointCloud<pcl::PointXYZ>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZ>); //Create point cloud pointer QString fileName = QFileDialog::getOpenFileName(this, “Open PointCloud”, “.”, “Open PCD files(*.pcd)”); if(fileName == “”) return; pcl::io::loadPCDFile(fileName.toStdString(),*cloud); vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New(); vtkSmartPointer<vtkCellArray> vertices = vtkSmartPointer<vtkCellArray>::New(); for (int i = 0; i<cloud->size(); i + + ) { vtkIdType pid[1]; pid[0] = points->InsertNextPoint(cloud->at(i).x, cloud->at(i).y, cloud->at(i).z); vertices->InsertNextCell(1, pid); } […]

Flutter view principle StatefulWidget, InheritedWidget

Directory StatefulElement 1.Constructor 2.build 3._firstBuild 3.didChangeDependencies 4.setState InheritedElement 1.Elementclass 2._updateInheritance 3.InheritedWidgetdataispasseddownward 3.1dependOnInheritedWidgetOfExactType 4.StatebindingofInheritedWidget 4.1.ProxyElement Intheflutterproject,StatelessWidget,StatefulWidget,andInheritedWidgetarecommonwidgets.Today,wewillanalyzehowtheyareimplementedthroughthesourcecode. Thecorrespondingfunctionsarebasicallyimplementedinelements,andwidgetsonlyprovidecomponentconfiguration.Therefore,whenexplainingStatefulWidgetandInheritedWidget,wemainlyanalyzetheimplementationofthecorrespondingelements. StatefulElement StatefulWidgetisaWidgetwithstate.UnlikestatelessWidget,thecreationofWidgetisdelegatedtostateinsteadofbeingcreateddirectlyusingwidget.build.ThepreviouschapterofStatelessWidgetcodehasalreadytalkedabouttheestablishmentprocessofthreetrees,soignoreit. )) 1.Constructor ComparetheconstructorofstatelessElement: classStatefulElementextendsComponentElement{<!—-> ///Createsanelementthatusesthegivenwidgetasitsconfiguration. StatefulElement(StatefulWidgetwidget) :_state=widget.createState(), super(widget){<!—-> assert(state._element==null); state._element=this; state._widget=widget; assert(state._debugLifecycleState==_StateLifecycle.created); } //…omitted } Intheconstructor,widget.createState()iscalleddirectly.Anewstateiscreated.Themembervariablesofstateincludeelement,andwidgetsareallprivatemembers.Atthistime,thelifecycleofstateshouldbecreated,state._debugLifecycleState==_StateLifecycle.created 2.build Usestatetocreatewidgets: Widgetbuild()=>state.build(this); 3._firstBuild void_firstBuild(){<!—-> //…omitted state.didChangeDependencies(); assert((){<!—-> state._debugLifecycleState=_StateLifecycle.ready; }()); super._firstBuild(); } Thisfunctioncalloccurswhenanelementisgeneratedforthefirsttime.Itistriggeredwhentheelementismounted.Atthistime,thestate’sdidChangeDependenciesmethodwillbecalledback.AnothersituationisthattheremaybeacallbackduringperformRebuild(),whichwillbediscussedbelow. Lookatthispictureagain: 3.didChangeDependencies ThedidChangeDependenciesfunctionisthecallbackinterfaceofelement.Thisinterfaceiscalledbyparentnotificationwhendependencieschange.Itwillmodify_didChangeDependencies=true;,andthentheperformRebuild()functionwilltriggerstate.didChangeDependencies.();‘scallback. bool_didChangeDependencies=false; @override voiddidChangeDependencies(){<!—-> super.didChangeDependencies(); _didChangeDependencies=true; […]