Copy了一份实现单指滑动手势的源码。
Qt的SwipeGesture居然是要三个手指同时操作（这里是说用widget而不是用quick控件，实际上quick控件才是Qt为移动开发打造的）。把源码拿出来看了半天，看是能够看懂，可以就是改了就无法编译了。在GitHub上用搜索功能，终于找到了直接可用的方案（神奇的GitHub）：
头文件,这里面的宏定义MINIMUM_DISTANCE = 50是可以根据需要修改的
// customGesture.h
#ifndef CUSTOMGESTURE_H
#define CUSTOMGESTURE_H
#include <QGesture>
#include <QGestureRecognizer>
#include <QSwipeGesture>
/**
* @brief The SwipeGestureRecognizer class
* needed because the defalt implementation of swipe is a little bit odd: it only triggers on 3 finger swipes! (5.3)
*
* http://developer.android.com/design/patterns/gestures.html
* http://qt-project.org/doc/qt-5/gestures-overview.html
*/
class SwipeGestureRecognizer : public QGestureRecognizer
{
public:
SwipeGestureRecognizer();
private:
#ifdef FOR_DESKTOP
static const int MINIMUM_DISTANCE = 50;
#endif
#ifdef FOR_MOBILE
static const int MINIMUM_DISTANCE = 50;
#endif
typedef QGestureRecognizer parent;
bool IsValidMove(int dx, int dy);
qreal ComputeAngle(int dx, int dy);
virtual QGesture* create(QObject* pTarget);
virtual QGestureRecognizer::Result recognize(QGesture* pGesture, QObject *pWatched, QEvent *pEvent);
void reset (QGesture *pGesture);
};
class SwipeGestureUtil {
public:
static QSwipeGesture::SwipeDirection GetHorizontalDirection(QSwipeGesture *pSwipeGesture);
static QSwipeGesture::SwipeDirection GetVerticalDirection(QSwipeGesture *pSwipeGesture);
};
#endif // CUSTOMGESTURE_H
源文件
// customGesture.cpp
#include <QMouseEvent>
#include <QDebug>
#include <cmath>
#include "customgesture.h"
SwipeGestureRecognizer::SwipeGestureRecognizer()
{
}
bool
SwipeGestureRecognizer::IsValidMove(int dx, int dy)
{
// The moved distance is to small to count as not just a glitch.
if ((qAbs(dx) < MINIMUM_DISTANCE) && (qAbs(dy) < MINIMUM_DISTANCE)) {
return false;
}
return true;
}
// virtual
QGesture*
SwipeGestureRecognizer::create(QObject* pTarget)
{
//qDebug("SwipeGestureRecognizer::create() called");
QGesture *pGesture = new QSwipeGesture(pTarget);
return pGesture;
}
// virtual
QGestureRecognizer::Result
SwipeGestureRecognizer::recognize(QGesture* pGesture, QObject *pWatched, QEvent *pEvent)
{
QGestureRecognizer::Result result = QGestureRecognizer::Ignore;
QSwipeGesture *pSwipe = static_cast<QSwipeGesture*>(pGesture);
switch(pEvent->type()) {
case QEvent::MouseButtonPress: {
QMouseEvent* pMouseEvent = static_cast<QMouseEvent*>(pEvent);
#if QT_VERSION < QT_VERSION_CHECK(5, 0, 0)
pSwipe->setProperty("startPoint", pMouseEvent->posF());
#else
pSwipe->setProperty("startPoint", pMouseEvent->localPos());
#endif
result = QGestureRecognizer::MayBeGesture;
//qDebug() << "Swipe gesture started (start point=" << pSwipe->property("startPoint").toPointF() << ")";
}
break;
case QEvent::MouseButtonRelease: {
QMouseEvent* pMouseEvent = static_cast<QMouseEvent*>(pEvent);
const QVariant& propValue = pSwipe->property("startPoint");
QPointF startPoint = propValue.toPointF();
#if QT_VERSION < QT_VERSION_CHECK(5, 0, 0)
QPointF endPoint = pMouseEvent->posF();
#else
QPointF endPoint = pMouseEvent->localPos();
#endif
// process distance and direction
int dx = endPoint.x() - startPoint.x();
int dy = endPoint.y() - startPoint.y();
//bugfix: startPoint.isNull because we sometimes get false events with startpoint 0 -> wrong swipe detected!
if ( (!IsValidMove(dx, dy)) || ( startPoint.isNull() ) ) {
// Just a click, so no gesture.
result = QGestureRecognizer::CancelGesture;
//qDebug("Swipe gesture canceled");
} else {
// Compute the angle.
//qDebug() << " startPoint= " << startPoint << " endPoint=" << endPoint << " dx=" << dx << " dy=" << dy;
qreal angle = ComputeAngle(dx, dy);
pSwipe->setSwipeAngle(angle);
result = QGestureRecognizer::FinishGesture;
//qDebug("Swipe gesture finished");
}
}
break;
default:
break;
}
return result;
}
void
SwipeGestureRecognizer::reset(QGesture *pGesture)
{
pGesture->setProperty("startPoint", QVariant(QVariant::Invalid));
parent::reset(pGesture);
}
qreal
SwipeGestureRecognizer::ComputeAngle(int dx, int dy)
{
double PI = 3.14159265;
// Need to convert from screen coordinates direction
// into classical coordinates direction.
dy = -dy;
double result = atan2((double)dy, (double)dx) ;
result = (result * 180) / PI;
// Always return positive angle.
if (result < 0) {
result += 360;
}
return result;
}
/*
==========================================================================
*/
QSwipeGesture::SwipeDirection
SwipeGestureUtil::GetHorizontalDirection(QSwipeGesture *pSwipeGesture)
{
qreal angle = pSwipeGesture->swipeAngle();
if (0 <= angle && angle <= 45) {
return QSwipeGesture::Right;
}
if (135 <= angle && angle <= 225) {
return QSwipeGesture::Left;
}
if (315 <= angle && angle <= 360) {
return QSwipeGesture::Right;
}
return QSwipeGesture::NoDirection;
}
QSwipeGesture::SwipeDirection
SwipeGestureUtil::GetVerticalDirection(QSwipeGesture *pSwipeGesture)
{
qreal angle = pSwipeGesture->swipeAngle();
if (45 < angle && angle < 135) {
return QSwipeGesture::Up;
}
if (225 < angle && angle < 315) {
return QSwipeGesture::Down;
}
return QSwipeGesture::NoDirection;
}
使用代码就很简单了，比如某个窗体的头文件
class rangeReport : public QWidget
{
Q_OBJECT
// ...
private:
// ...
SwipeGestureRecognizer *fftRecognizer;
Qt::GestureType fftType;
void swipeTriggered(QSwipeGesture *gesture);
bool event(QEvent *event);
bool gestureEvent(QGestureEvent *event);
int currentGraph;
void registerGesture();
};
而源文件就是要注册这个手势识别器，并实现手势之后的响应
rangeReport::rangeReport(rangeType type):
ui(new Ui::rangeReport)
{
ui->setupUi(this);
registerGesture();
// ...
}
// ...
bool rangeReport::event(QEvent *event)
{
if (event->type() == QEvent::Gesture){
//qDebug()<<"grab!";
return gestureEvent(static_cast<QGestureEvent*>(event));
}
return QWidget::event(event);
}
void rangeReport::swipeTriggered(QSwipeGesture *gesture)
{
if (gesture->state() == Qt::GestureFinished) {
if (gesture->horizontalDirection() == QSwipeGesture::Left
|| gesture->verticalDirection() == QSwipeGesture::Up) {
if(currentGraph != chart.size() - 1){
currentGraph ++;
ui->graph1->setChart(chart[currentGraph]);
}
} else {
if(currentGraph != 0){
currentGraph --;
ui->graph1->setChart(chart[currentGraph]);
} //?ui->tabWidget->count():ui->tabWidget->currentIndex() + 1 );
}
update();
}
}
bool rangeReport::gestureEvent(QGestureEvent *event)
{
//qDebug() << "gestureEvent():" << event;
if (QGesture *swipe = event->gesture(Qt::SwipeGesture))
swipeTriggered(static_cast<QSwipeGesture *>(swipe));
else if (QGesture *pan = event->gesture(Qt::PanGesture))
//panTriggered(static_cast<QPanGesture *>(pan));
return true;
}
void rangeReport::registerGesture()
{
fftRecognizer = new SwipeGestureRecognizer();
fftType = QGestureRecognizer::registerRecognizer(fftRecognizer);
grabGesture(fftType);
}
最后还是要吐槽一下sqlite:我觉得这个数据库的性能特别好，查询速度很快，占用资源也少。不过为什么不支持全外连接语句
让我用连接和并集写全外连接不是白白增加工作量吗？