"QT5 Development and examples" 32, the implementation of keyboard monitoring operation

Keyevent.h

/*** Book: "QT5 Development and examples" * Function: Implement keyboard control * file: keyevent.h* time: February 8, 2015 11:48:47* Author: cutter_point*/#ifndef keyevent_h#define Keyevent_h#include <QWidget> #include <QKeyEvent>    /keyboard # include <QPaintEvent>//    Painting Events # Include <qpainter>class keyevent:public qwidget{  q_objectpublic:  keyevent (Qwidget *parent = 0);  ~keyevent ();  void Drawpix ();   Painting image  void Keypressevent (Qkeyevent *event);    Keyboard corresponding  void PaintEvent (qpaintevent *);p rivate:  qpixmap *pix;   Buffered images  qimage image;    Picture  int StartX;  int starty;  int width;  int height;  int step;   Size of each step}; #endif//Keyevent_h

Keyevent.cpp

/*** Book: "QT5 Development and examples" * Function: Implement keyboard control * file: keyevent.cpp* time: February 8, 2015 11:48:47* Author: cutter_point*/#include "keyevent.h" keyevent  :: KeyEvent (Qwidget *parent): Qwidget (parent) {Setwindowtitle (TR ("keyboard event"));  This->setautofillbackground (TRUE);   Qpalette palette = This->palette ();    Get Palette Palette.setcolor (Qpalette::window, qt::white);    Sets the background default color This->setpalette (palette);  Set a good palette, using the palette this->setminimumsize (512, 256);  This->setmaximumsize (512, 256);  width = this->size (). width ();   Height = this->size (). height ();     Get the corresponding long and high pix = new Qpixmap (width, height);  The size of the buffered graphic Pix->fill (qt::white);   Image.load (":/image.png");  Load picture StartX = 100;  Starty = 100;  Step = 20;    Drawpix (); Drawing Resize (512, 256);}   void Drawpix ();  Painting image void KeyEvent::d Rawpix () {Pix->fill (qt::white);   Qpainter *painter = new Qpainter;      Painting Tool Qpen Pen (Qt::D otline);    Dashed for (int i = step; i < width; i = i + Step)//Draw vertical Line {painter->begin (pix);   Set drawing objects   Painter->setpen (pen);   Brush Painter->drawline (Qpoint (i, 0), Qpoint (i, height));    Draw from one point to another point painter->end ();      }//Draw horizontal for (int j = Step; j < height; j = j + Step) {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); Picture drawing Painter->end ();}    Keypressevent (Qkeyevent *event);       keyboard corresponding void Keyevent::keypressevent (Qkeyevent *event) {if (event->modifiers () = = Qt::controlmodifier)//whether there is a hold down CTRL {        if (event->key () = = Qt::key_left)//left {StartX = (startX-1 < 0)? startx:startx-1; } if (Event->key () = = qt::key_right)//Right {StartX = (StartX + image.width () > width)? s        Tartx:startx + 1; } if (Event->key () = = qt::key_up)//on {Starty = (startY-1 < 0)? starty:starty-1; } if (Event->key () = = Qt::key_down)//under {Starty = (Starty + image.height () > height)? start        Y:starty + 1;      }} else {StartX = startx-startx% Step;      As a multiple of step, the back good judgment starty = starty-starty% Step;        if (event->key () = = Qt::key_left)//left {StartX = (Startx-step < 0)? Startx:startx-step; } if (Event->key () = = qt::key_right)//Right {StartX = (StartX + step + image.width () > Wid TH)?        Startx:startx + step; } if (Event->key () = = qt::key_up)//on {Starty = (Starty-step < 0)? starty:starty-step        ; } if (Event->key () = = Qt::key_down)//under {Starty = (Starty + image.height () + Step > height) ?        Starty:starty + step;          } if (Event->key () = = Qt::key_home)//starting point {StartX = 0;        Starty = 0; } if (Event->key () = = Qt::key_end)//End point {StartX = Width-image.width ();        Starty = Height-image.height ();  }} Drawpix (); This->update ();}  void PaintEvent (qpaintevent *); void KeyEvent::p aintevent (qpaintevent *) {qpainter painter;  Painter.begin (this);   Painter.drawpixmap (qpoint (0, 0), *pix); Draw the image into space and show Painter.end ();} Keyevent::~keyevent () {}

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"QT5 Development and examples" 32, the implementation of keyboard monitoring operation