Hi guys:
I have a problem about the setMouseTracking(). I want to receive the mouseMoveEvent even if no mouse button pressed. As the Qt Document says, I set the mouseTracking property TRUE by setMouseTracking(TRUE),but itdoesn't work.
My app has a MainWindow and a QWidgetStack as the MainWindow's main widget. The WidgetStack contains two widgets. One is QTextEdit, another is QCanvasView. Since I want to deal with the mouseMoveEvent within the QCanvasView, I subclass my own canvasview from QCanvasView. Then in the constructor of my own canvasview I set
the mouseTracking property TRUE. But I'm confused that the contentsMouseMoveEvent() is only called when a mousebutton pressed and moved just as mouseTracking is FALSE.

bellow is my code:
mainwindow.h
Qt Code: 
  1. #include <qdockwindow.h>
  2. #include <qwidgetstack.h>
  3. #include <qtoolbutton.h>
  4. #include <qtextedit.h>
  5. #include <qcanvas.h>
  6. #include "canvasview.h"
  7. class MainWindow: public QMainWindow
  8. {
  9.         Q_OBJECT
  10. public:
  11.         MainWindow(QWidget *parent=0,const char* name = 0);
  12. private slots:
  13.         void switchToolBarMode();
  14.         void switchCentralWidgetMode(int);
  15. private:
  16.         void init();
  17.         QWidgetStack* centralWidgetStack;
  18.         QDockWindow* toolBarDockWindow;
  19.         QWidgetStack* toolBarStack;
  20.         QToolButton* graphicButton;
  21.         QToolButton* quitButton;
  22.         QTextEdit *textEdit;
  23.         CanvasView* canvasView;
  24.         QCanvas*     canvas;
  25.         bool    toolBarMode;
  26. };
  27. #endif
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mainwindow.cpp
Qt Code: 
  1. #include "mainwindow.h"
  2. #include "canvasview.h"
  3. #include <qmainwindow.h>
  4. #include <qapplication.h>
  5. #include <qlayout.h>
  6.  
  7. MainWindow::MainWindow(QWidget* parent, const char* name)
  8.           :QMainWindow(parent,name)
  9. {
  10.         int screenW;
  11.         int screenH;
  12.         screenW = QApplication::desktop()->width();
  13.         screenH = QApplication::desktop()->height();
  14.         this->resize(screenW,screenH);
  15.         toolBarMode = TRUE;
  16.         init();
  17. }
  18.  
  19. void MainWindow::init()
  20. {
  21.         toolBarDockWindow = new QDockWindow(QDockWindow::InDock,this,"toolbardockwindow",0);
  22.         toolBarDockWindow->setOrientation(Qt::Horizontal);
  23.         toolBarDockWindow->setHorizontallyStretchable(TRUE);
  24.         toolBarDockWindow->setVerticallyStretchable(TRUE);
  25.         toolBarDockWindow->setMovingEnabled(FALSE);
  26.         this->moveDockWindow(toolBarDockWindow,Qt::DockBottom);
  27.  
  28.         toolBarStack = new QWidgetStack(toolBarDockWindow);
  29.         toolBarDockWindow->setWidget(toolBarStack);
  30.  
  31. QWidget* editToolBar = new QWidget(toolBarStack);
  32.         QHBoxLayout* editToolBarLayout = new QHBoxLayout(editToolBar,6,6);
  33.         QWidget* graphicToolBar = new QWidget(toolBarStack);
  34.         QHBoxLayout* graphicToolBarLayout = new QHBoxLayout(graphicToolBar,6,6);
  35.         toolBarStack->addWidget(editToolBar,0);
  36.         toolBarStack->addWidget(graphicToolBar,1);
  37.  
  38.         graphicButton = new QToolButton(editToolBar,"graphicutton");
  39.         graphicButton->setUsesTextLabel(TRUE);
  40.         graphicButton->setTextLabel("Graphic",FALSE);
  41.         graphicButton->setFont(QFont("Times",20,QFont::Bold));
  42.         editToolBarLayout->addWidget(graphicButton);
  43.  
  44.         QSpacerItem* editToolBarSpacer = new QSpacerItem(0,0,QSizePolicy::Expanding,QSizePolicy::Minimum);
  45.         editToolBarLayout->addItem(editToolBarSpacer);
  46. quitButton = new QToolButton(graphicToolBar,"quitbutton");
  47.         quitButton->setUsesTextLabel(TRUE);
  48.         quitButton->setTextLabel("Return",FALSE);
  49.         quitButton->setFont(QFont("Times",20,QFont::Bold));
  50.         graphicToolBarLayout->addWidget(quitButton);
  51.  
  52.         QSpacerItem* graphicToolBarSpacer = new QSpacerItem(0,0,QSizePolicy::Expanding,QSizePolicy::Minimum);
  53.         graphicToolBarLayout->addItem(graphicToolBarSpacer);
  54.  
  55.         toolBarStack->raiseWidget(0);
  56.  
  57.         connect(graphicButton,SIGNAL(clicked()),this,SLOT(switchToolBarMode()));
  58.         connect(quitButton,SIGNAL(clicked()),this,SLOT(switchToolBarMode()));
  59.  
  60.         //construct the QWidgetStack as the MainWindow's main widget.
  61.         centralWidgetStack = new QWidgetStack(this);
  62.         //add textedit into the QWidgetStack.
  63.         textEdit = new QTextEdit(centralWidgetStack,"textedit");
  64.         textEdit->setTextFormat(Qt::PlainText);
  65.         textEdit->setFocus();
  66.         centralWidgetStack->addWidget(textEdit,0);
  67.         //add canvasView into the QWidgetStack.
  68.         canvas = new QCanvas(this);
  69.         canvasView = new CanvasView(canvas,centralWidgetStack,"canvasview");
  70.         centralWidgetStack->addWidget(canvasView,1);
  71.  
  72.         this->setCentralWidget(centralWidgetStack);
  73.         centralWidgetStack->raiseWidget(0);
  74.            connect(toolBarStack,SIGNAL(aboutToShow(int)),this,SLOT(switchCentralWidgetMode(int)));
  75.  
  76. }
  77. void MainWindow::switchToolBarMode()
  78. {
  79.         if(toolBarMode){
  80.                 toolBarStack->raiseWidget(1);
  81.         }else{
  82.                 toolBarStack->raiseWidget(0);
  83.         }
  84.         toolBarMode = !toolBarMode;
  85.  
  86. }
  87.  
  88. void MainWindow::switchCentralWidgetMode(int i)
  89. {
  90.         centralWidgetStack->raiseWidget(i);
  91. }
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canvasview.h
Qt Code: 
  1. #ifndef CANVASVIEW_H
  2. #define CANVASVIEW_H
  3. #include <qcanvas.h>
  4.  
  5. class CanvasView:public QCanvasView
  6. {
  7. public:
  8.         CanvasView(QCanvas* canvas, QWidget* parent, const char* name);
  9. protected:
  10.         void contentsMouseMoveEvent(QMouseEvent* e);
  11.  
  12. };
  13. #endif
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canvasview.cpp
Qt Code: 
  1. #include "canvasview.h"
  2. #include <qcanvas.h>
  3. #include <qapplication.h>
  4. CanvasView::CanvasView(QCanvas* canvas, QWidget* parent, const char* name)
  5.                 :QCanvasView(canvas,parent,name)
  6. {
  7.         setMouseTracking(TRUE);
  8. }
  9.  
  10. void CanvasView::contentsMouseMoveEvent(QMouseEvent* e)
  11. {
  12.         qWarning("The MouseMoveEvent has been received!");
  13. }
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main.cpp
Qt Code: 
  1. #include <qapplication.h>
  2. #include "mainwindow.h"
  3. #include "canvasview.h"
  4.  
  5. int main(int argc,char* argv[])
  6. {
  7.         QApplication app(argc,argv);
  8.         MainWindow* mainwindow = new MainWindow();
  9.         app.setMainWidget(mainwindow);
  10.         mainwindow->show();
  11.         return app.exec();
  12. }
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