examples/painting/concentriccircles/circlewidget.cpp
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     1 /****************************************************************************
       
     2 **
       
     3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
       
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    38 ** $QT_END_LICENSE$
       
    39 **
       
    40 ****************************************************************************/
       
    41 
       
    42 #include <QtGui>
       
    43 
       
    44 #include "circlewidget.h"
       
    45 
       
    46 #include <stdlib.h>
       
    47 
       
    48 //! [0]
       
    49 CircleWidget::CircleWidget(QWidget *parent)
       
    50     : QWidget(parent)
       
    51 {
       
    52     floatBased = false;
       
    53     antialiased = false;
       
    54     frameNo = 0;
       
    55 
       
    56     setBackgroundRole(QPalette::Base);
       
    57     setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
       
    58 }
       
    59 //! [0]
       
    60 
       
    61 //! [1]
       
    62 void CircleWidget::setFloatBased(bool floatBased)
       
    63 {
       
    64     this->floatBased = floatBased;
       
    65     update();
       
    66 }
       
    67 //! [1]
       
    68 
       
    69 //! [2]
       
    70 void CircleWidget::setAntialiased(bool antialiased)
       
    71 {
       
    72     this->antialiased = antialiased;
       
    73     update();
       
    74 }
       
    75 //! [2]
       
    76 
       
    77 //! [3]
       
    78 QSize CircleWidget::minimumSizeHint() const
       
    79 {
       
    80     return QSize(50, 50);
       
    81 }
       
    82 //! [3]
       
    83 
       
    84 //! [4]
       
    85 QSize CircleWidget::sizeHint() const
       
    86 {
       
    87     return QSize(180, 180);
       
    88 }
       
    89 //! [4]
       
    90 
       
    91 //! [5]
       
    92 void CircleWidget::nextAnimationFrame()
       
    93 {
       
    94     ++frameNo;
       
    95     update();
       
    96 }
       
    97 //! [5]
       
    98 
       
    99 //! [6]
       
   100 void CircleWidget::paintEvent(QPaintEvent *)
       
   101 {
       
   102     QPainter painter(this);
       
   103     painter.setRenderHint(QPainter::Antialiasing, antialiased);
       
   104     painter.translate(width() / 2, height() / 2);
       
   105 //! [6]
       
   106 
       
   107 //! [7]
       
   108     for (int diameter = 0; diameter < 256; diameter += 9) {
       
   109         int delta = abs((frameNo % 128) - diameter / 2);
       
   110         int alpha = 255 - (delta * delta) / 4 - diameter;
       
   111 //! [7] //! [8]
       
   112         if (alpha > 0) {
       
   113             painter.setPen(QPen(QColor(0, diameter / 2, 127, alpha), 3));
       
   114 
       
   115             if (floatBased) {
       
   116                 painter.drawEllipse(QRectF(-diameter / 2.0, -diameter / 2.0,
       
   117                                            diameter, diameter));
       
   118             } else {
       
   119                 painter.drawEllipse(QRect(-diameter / 2, -diameter / 2,
       
   120                                           diameter, diameter));
       
   121             }
       
   122         }
       
   123     }
       
   124 }
       
   125 //! [8]