Qt5开发及实例-CH1102.rar,Qt5实现键盘控制图标的移动来介绍键盘事件的应用的代码

#include "keyevent.h" #include <QPainter> KeyEvent::KeyEvent(QWidget *parent) : QWidget(parent) { setWindowTitle(tr("键盘事件")); setAutoFillBackground(true); QPalette palette = this->palette(); palette.setColor(QPalette::Window,Qt::white); setPalette(palette); setMinimumSize(512,256); setMaximumSize(512,256); width=size().width(); height=size().height(); pix = new QPixmap(width,height); pix->fill(Qt::white); image.load("../image/image.png"); startX=100; startY=100; step=20; drawPix(); resize(512,256); } void KeyEvent::drawPix() { pix->fill(Qt::white); //重新刷新pix对象为白色底色 QPainter *painter = new QPainter; //创建一个QPainter对象 QPen pen(Qt::DotLine); //(a) for(int i=step;i<width;i=i+step) //按照步进值的间隔绘制纵向的网格线 { painter->begin(pix); //指定pix为绘图设备 painter->setPen(pen); painter->drawLine(QPoint(i,0),QPoint(i,height)); painter->end(); } for(int j=step;j<height;j=j+step) //按照步进值的间隔绘制横向的网格线 { painter->begin(pix); painter->setPen(pen); painter->drawLine(QPoint(0,j),QPoint(width,j)); painter->end(); } painter->begin(pix); painter->drawImage(QPoint(startX,startY),image); //(b) painter->end(); } void KeyEvent::keyPressEvent(QKeyEvent *event) { if(event->modifiers()==Qt::ControlModifier) //(a) { if(event->key()==Qt::Key_Left) //(b) { startX=(startX-1<0)?startX:startX-1; } if(event->key()==Qt::Key_Right) //(c) { startX=(startX+1+image.width()>width)?startX:startX+1; } if(event->key()==Qt::Key_Up) //(d) { startY=(startY-1<0)?startY:startY-1; } if(event->key()==Qt::Key_Down) //(e) { startY=(startY+1+image.height()>height)?startY:startY+1; } } else //对【Ctrl】键没有按下的处理 { /* 首先调节图标左上顶点的位置至网格的顶点上 */ startX=startX-startX%step; startY=startY-startY%step; if(event->key()==Qt::Key_Left) //(f) { startX=(startX-step<0)?startX:startX-step; } if(event->key()==Qt::Key_Right) //(g) { startX=(startX+step+image.width()>width)?startX:startX+step; } if(event->key()==Qt::Key_Up) //(h) { startY=(startY-step<0)?startY:startY-step; } if(event->key()==Qt::Key_Down) //(i) { startY=(startY+step+image.height()>height)? startY:startY+step; } if(event->key()==Qt::Key_Home) //(j) { startX=0; startY=0; } if(event->key()==Qt::Key_End) //(k) { startX=width-image.width(); startY=height-image.height(); } } drawPix(); //根据调整后的图标位置重新在pix中绘制图像 update(); //触发界面重画 } void KeyEvent::paintEvent(QPaintEvent *) { QPainter painter; painter.begin(this); painter.drawPixmap(QPoint(0,0),*pix); painter.end(); } KeyEvent::~KeyEvent() { }