QTableView row height animation - c++

Question

In a form, I have 2 instances of QTableView (tableView1 & tableView2) using the same model. The goal is to link items together:
In the first table view, select the object you want to define as the parent.
In the second table view, add a tick mark on the object(s) you want to define as the child. An object cannot be its own parent (it can have no parent).
The way I wanted to proceed is by hiding in tableView2 the object selected in tableView1, and to be precise, by setting the row height to 0 with an animation.
That very part works but problems start to arise when I try to implement the creation/deletion of new objects (rows get inserted or removed) or with fast change of selection with the keyboard.
Inserting a new row makes any row under it reappear if it was hidden.
Deleting the row that was selected in tableView1 makes the next row be automatically selected, with no effect on tableView2.
Selecting rows faster than the animation can handle sometimes leaves row with a different height than normal.
I strongly suspect this behavior is caused by how the selection model needs to react to new rows inserted above the selection and how in contrary, it does not need to react to the current row being deleted (the next row takes the position of the deleted one and appears to be selected instead).
Even with that in mind, I cannot get my head around it; I have tried adding more signal/slot connections (on rowsAboutToBeInserted/rowsAboutToBeRemoved) to no avail.
Below is the code I have so far.
Note: I created the sample on QtCreator because it is quicker but for some reason, the animation is extremely crappy; my actual longer code is on Visual Studio, which makes it smooth. Either some optimization is missing or using QTableWidget makes it slower than my actual code with separate QTableView and subclass of QAbstractItemModel.
Even if the animation is bad, the only way in that code for rows visible in tableView1 to appear/reappear in tableView2 is the animations.
MainWindow.h
#pragma once
#include <QtWidgets/QMainWindow>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);
public slots:
void onPrependClicked();
void onInsertClicked();
void onAppendClicked();
void onDeleteClicked();
private:
Ui::MainWindow *ui;
};
MainWindow.cpp
#include "MainWindow.h"
#include "ui_MainWindow.h"
#include <QtCore/QParallelAnimationGroup>
#include <QtCore/QVariantAnimation>
#include <QtWidgets/QStyledItemDelegate>
#include <QtWidgets/QWidget>
class RowAnimator : public QVariantAnimation {
public:
RowAnimator(QObject* parent) : QVariantAnimation(parent), Row(-1) { setDuration(500); /* for the investigation, we keep a large value to make it possible to see it */ }
int Row;
};
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
//ui->tableView1 and ui->tableView2 will share the same model().
//ui->tableView1 is set to select a single row at any one time.
auto model = ui->tableView1->model();
ui->tableView2->setModel(model);
RowAnimator* hideRowAnimator = new RowAnimator(ui->tableView2),
* showRowAnimator = new RowAnimator(ui->tableView2);
{ //Setup the RowAnimator
int rowHeight = ui->tableView2->rowHeight(0);
hideRowAnimator->setStartValue(rowHeight); hideRowAnimator->setEndValue(0);
showRowAnimator->setStartValue(0); showRowAnimator->setEndValue(rowHeight);
QObject::connect(hideRowAnimator, &QVariantAnimation::valueChanged, [=](const QVariant& value) {
if (hideRowAnimator->Row >= 0)
ui->tableView2->setRowHeight(hideRowAnimator->Row, value.toInt());
});
QObject::connect(showRowAnimator, &QVariantAnimation::valueChanged, [=](const QVariant& value) {
if (showRowAnimator->Row >= 0)
ui->tableView2->setRowHeight(showRowAnimator->Row, value.toInt());
});
//Update the RowAnimator when rows are inserted or removed
QObject::connect(model, &QAbstractItemModel::rowsAboutToBeInserted, hideRowAnimator, [hideRowAnimator](const QModelIndex&, int first, int last) {
if (first <= hideRowAnimator->Row)
hideRowAnimator->Row += (1 + last - first);
}, Qt::DirectConnection);
QObject::connect(model, &QAbstractItemModel::rowsAboutToBeInserted, showRowAnimator, [showRowAnimator](const QModelIndex&, int first, int last) {
if (first <= showRowAnimator->Row)
showRowAnimator->Row += (1 + last - first);
}, Qt::DirectConnection);
QObject::connect(model, &QAbstractItemModel::rowsAboutToBeRemoved, hideRowAnimator, [hideRowAnimator](const QModelIndex&, int first, int last) {
if (last < hideRowAnimator->Row)
hideRowAnimator->Row -= (1 + last - first);
else if (first <= hideRowAnimator->Row)
hideRowAnimator->Row = -1;
}, Qt::DirectConnection);
QObject::connect(model, &QAbstractItemModel::rowsAboutToBeRemoved, showRowAnimator, [showRowAnimator](const QModelIndex&, int first, int last) {
if (last < showRowAnimator->Row)
showRowAnimator->Row -= (1 + last - first);
else if (first <= showRowAnimator->Row)
showRowAnimator->Row = -1;
}, Qt::DirectConnection);
}
QParallelAnimationGroup* parallelAnimation = new QParallelAnimationGroup(ui->tableView2);
parallelAnimation->addAnimation(hideRowAnimator);
parallelAnimation->addAnimation(showRowAnimator);
//Setup the events to animate.
//When a row gets selected in tableView1 -> hide the corresponding row in tableView2 + show the previously hiidden row.
QObject::connect(ui->tableView1->selectionModel(), &QItemSelectionModel::selectionChanged, parallelAnimation,
[hideRowAnimator, showRowAnimator, parallelAnimation](const QItemSelection& selected) {
if (selected.isEmpty() || selected.indexes().isEmpty()) {
showRowAnimator->Row = hideRowAnimator->Row;
hideRowAnimator->Row = -1;
}
else if (QModelIndex selectedIndex = selected.indexes().first(); selectedIndex.isValid()) {
showRowAnimator->Row = hideRowAnimator->Row;
hideRowAnimator->Row = selectedIndex.row();
}
else {
showRowAnimator->Row = hideRowAnimator->Row;
hideRowAnimator->Row = -1;
}
parallelAnimation->start();
}
);
}
void MainWindow::onPrependClicked()
{
auto model = ui->tableView1->model();
model->insertRow(0, QModelIndex());
// This makes the hidden row reappear
}
void MainWindow::onInsertClicked()
{
auto model = ui->tableView1->model();
model->insertRow(1, QModelIndex());
// This makes the hidden row reappear except if it was row 0 (only rows under the inserted one reappear).
}
void MainWindow::onAppendClicked()
{
auto model = ui->tableView1->model();
model->insertRow(model->rowCount(), QModelIndex());
// Apparently no animation (there is no row are under that new one).
}
void MainWindow::onDeleteClicked()
{
auto selectionModel = ui->tableView1->selectionModel();
if (selectionModel->currentIndex().isValid()) {
auto model = ui->tableView1->model();
model->removeRow(selectionModel->currentIndex().row());
}
//This triggers an animation on the row right under the one being deleted.
//At the end, that row is shown (showRowAnimator is evaluated last) even though deleting a row apparently changes the selection.
//The correct behavior is either to have nothing selected or have the newly selected row hidden in tableView2.
}
MainWindow.ui
<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>MainWindow</class>
<widget class="QMainWindow" name="MainWindow">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>800</width>
<height>600</height>
</rect>
</property>
<property name="windowTitle">
<string>MainWindow</string>
</property>
<widget class="QWidget" name="centralwidget">
<layout class="QGridLayout" name="gridLayout">
<item row="0" column="0">
<widget class="QTableWidget" name="tableView1">
<property name="mouseTracking">
<bool>false</bool>
</property>
<property name="focusPolicy">
<enum>Qt::WheelFocus</enum>
</property>
<property name="styleSheet">
<string notr="true">QTableView { outline:none; }
QTableView::item:selected { background:#0078D7; }</string>
</property>
<property name="locale">
<locale language="English" country="UnitedStates"/>
</property>
<property name="inputMethodHints">
<set>Qt::ImhLatinOnly</set>
</property>
<property name="autoScroll">
<bool>false</bool>
</property>
<property name="editTriggers">
<set>QAbstractItemView::NoEditTriggers</set>
</property>
<property name="tabKeyNavigation">
<bool>false</bool>
</property>
<property name="showDropIndicator" stdset="0">
<bool>false</bool>
</property>
<property name="dragDropOverwriteMode">
<bool>false</bool>
</property>
<property name="selectionMode">
<enum>QAbstractItemView::SingleSelection</enum>
</property>
<property name="selectionBehavior">
<enum>QAbstractItemView::SelectRows</enum>
</property>
<property name="showGrid">
<bool>false</bool>
</property>
<property name="gridStyle">
<enum>Qt::NoPen</enum>
</property>
<property name="wordWrap">
<bool>false</bool>
</property>
<property name="cornerButtonEnabled">
<bool>false</bool>
</property>
<attribute name="horizontalHeaderVisible">
<bool>true</bool>
</attribute>
<attribute name="verticalHeaderVisible">
<bool>true</bool>
</attribute>
<row>
<property name="text">
<string>1</string>
</property>
</row>
<row>
<property name="text">
<string>2</string>
</property>
</row>
<row>
<property name="text">
<string>3</string>
</property>
</row>
<column>
<property name="text">
<string>1</string>
</property>
</column>
<column>
<property name="text">
<string>2</string>
</property>
</column>
<item row="0" column="0">
<property name="text">
<string>Item 1,1</string>
</property>
</item>
<item row="0" column="1">
<property name="text">
<string>Item 1,2</string>
</property>
</item>
<item row="1" column="0">
<property name="text">
<string>Item 2,1</string>
</property>
</item>
<item row="1" column="1">
<property name="text">
<string>Item 2,2</string>
</property>
</item>
<item row="2" column="0">
<property name="text">
<string>Item 3,1</string>
</property>
</item>
<item row="2" column="1">
<property name="text">
<string>Item 3,2</string>
</property>
</item>
</widget>
</item>
<item row="1" column="0">
<widget class="QPushButton" name="appendButton">
<property name="text">
<string>Append</string>
</property>
</widget>
</item>
<item row="0" column="1">
<widget class="QTableView" name="tableView2"/>
</item>
<item row="2" column="0">
<widget class="QPushButton" name="insertButton">
<property name="text">
<string>Insert</string>
</property>
</widget>
</item>
<item row="1" column="1">
<widget class="QPushButton" name="prependButton">
<property name="text">
<string>Prepend</string>
</property>
</widget>
</item>
<item row="2" column="1">
<widget class="QPushButton" name="deleteButton">
<property name="text">
<string>Delete</string>
</property>
</widget>
</item>
</layout>
</widget>
<widget class="QMenuBar" name="menubar">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>800</width>
<height>21</height>
</rect>
</property>
</widget>
<widget class="QStatusBar" name="statusbar"/>
</widget>
<resources/>
<connections>
<connection>
<sender>appendButton</sender>
<signal>clicked()</signal>
<receiver>MainWindow</receiver>
<slot>onAppendClicked()</slot>
<hints>
<hint type="sourcelabel">
<x>202</x>
<y>530</y>
</hint>
<hint type="destinationlabel">
<x>399</x>
<y>299</y>
</hint>
</hints>
</connection>
<connection>
<sender>insertButton</sender>
<signal>clicked()</signal>
<receiver>MainWindow</receiver>
<slot>onInsertClicked()</slot>
<hints>
<hint type="sourcelabel">
<x>202</x>
<y>559</y>
</hint>
<hint type="destinationlabel">
<x>399</x>
<y>299</y>
</hint>
</hints>
</connection>
<connection>
<sender>prependButton</sender>
<signal>clicked()</signal>
<receiver>MainWindow</receiver>
<slot>onPrependClicked()</slot>
<hints>
<hint type="sourcelabel">
<x>596</x>
<y>530</y>
</hint>
<hint type="destinationlabel">
<x>399</x>
<y>299</y>
</hint>
</hints>
</connection>
<connection>
<sender>deleteButton</sender>
<signal>clicked()</signal>
<receiver>MainWindow</receiver>
<slot>onDeleteClicked()</slot>
<hints>
<hint type="sourcelabel">
<x>596</x>
<y>559</y>
</hint>
<hint type="destinationlabel">
<x>399</x>
<y>299</y>
</hint>
</hints>
</connection>
</connections>
<slots>
<slot>onAppendClicked()</slot>
<slot>onInsertClicked()</slot>
<slot>onPrependClicked()</slot>
<slot>onDeleteClicked()</slot>
</slots>
</ui>