src/contextview/graphicsitemfader.cpp

   1 /***************************************************************************
   2  *   Copyright (c) 2007  Nikolaj Hald Nielsen <nhnFreespirit@gmail.com>    *
   3  *                                                                         *
   4  *   This program is free software; you can redistribute it and/or modify  *
   5  *   it under the terms of the GNU General Public License as published by  *
   6  *   the Free Software Foundation; either version 2 of the License, or     *
   7  *   (at your option) any later version.                                   *
   8  *                                                                         *
   9  *   This program is distributed in the hope that it will be useful,       *
  10  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  11  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  12  *   GNU General Public License for more details.                          *
  13  *                                                                         *
  14  *   You should have received a copy of the GNU General Public License     *
  15  *   along with this program; if not, write to the                         *
  16  *   Free Software Foundation, Inc.,                                       *
  17  *   51 Franklin Street, Fifth Floor, Boston, MA  02111-1307, USA.          *
  18  ***************************************************************************/
  19
  20 #include "graphicsitemfader.h"
  21
  22 #include "debug.h"
  23
  24 #include <QPen>
  25
  26 using namespace Context;
  27
  28
  29 GraphicsItemFader::GraphicsItemFader( QGraphicsItem * item, QGraphicsItem * parent )
  30     : QObject()
  31     , QGraphicsItem( parent )
  32     , m_startAlpha( 0 )
  33     , m_targetAlpha( 255 )
  34     , m_fps ( 30 )
  35     , m_duration( 5000 )
  36 {
  37     m_contentItem = item;
  38     m_itemPreviousParent = m_contentItem->parentItem();
  39     m_contentItem->setParentItem( this );
  40     m_contentItem->setZValue( 1 );
  41     m_contentItem->setPos( 1, 1 );
  42
  43     m_shadeRectItem = new QGraphicsRectItem( this );
  44
  45     m_width = m_contentItem->boundingRect().width() + 2;
  46     m_height = m_contentItem->boundingRect().height() + 2;
  47
  48     m_shadeRectItem->setRect( 0, 0, m_width, m_height );
  49     m_shadeRectItem->setPos( 0, 0 ); // needs a slight offset to cover frames on m_contentItem
  50     m_shadeRectItem->setPen( Qt::NoPen );
  51     m_shadeRectItem->setZValue ( 2 );
  52
  53     m_fadeColor = QColor ( 255, 255, 255, 0 );
  54     m_shadeRectItem->setBrush( QBrush ( m_fadeColor ) );
  55
  56     m_timeLine = new QTimeLine( m_duration, this );
  57     connect( m_timeLine, SIGNAL( frameChanged( int ) ), this, SLOT( fadeSlot( int ) ) );
  58     connect( m_timeLine, SIGNAL( finished() ), this, SLOT( fadeFinished() ) );
  59 }
  60
  61 GraphicsItemFader::~GraphicsItemFader()
  62 {
  63     m_timeLine->stop();
  64     fadeSlot( m_animationSteps );
  65     m_contentItem->setParentItem( m_itemPreviousParent );
  66 }
  67
  68 void GraphicsItemFader::setStartAlpha(int alpha)
  69 {
  70     m_startAlpha = alpha;
  71     m_fadeColor.setAlpha( m_startAlpha );
  72     m_shadeRectItem->setBrush( QBrush ( m_fadeColor ) );
  73 }
  74
  75 void GraphicsItemFader::setTargetAlpha(int alpha)
  76 {
  77     m_targetAlpha = alpha;
  78 }
  79
  80 void GraphicsItemFader::setDuration(int ms)
  81 {
  82     m_duration = ms;
  83 }
  84
  85 void GraphicsItemFader::setFPS(int fps)
  86 {
  87     m_fps = fps;
  88 }
  89
  90 QRectF Context::GraphicsItemFader::boundingRect() const
  91 {
  92     return QRect( x(), y(), m_width, m_height );
  93 }
  94
  95
  96 void GraphicsItemFader::setFadeColor(const QColor & color)
  97 {
  98     m_fadeColor = color;
  99     m_fadeColor.setAlpha( m_startAlpha );
 100     m_shadeRectItem->setBrush( QBrush ( m_fadeColor ) );
 101 }
 102
 103 void GraphicsItemFader::fadeSlot(int step)
 104 {
 105     int newAlpha = m_startAlpha + ( step * m_alphaStep );
 106     m_fadeColor.setAlpha( newAlpha );
 107     m_shadeRectItem->setBrush( QBrush ( m_fadeColor ) );
 108
 109     if ( newAlpha == m_targetAlpha )
 110         emit( animationComplete() );
 111
 112     debug() << "fading, new alpha = " << newAlpha <<  endl;
 113 }
 114
 115 void GraphicsItemFader::fadeFinished()
 116 {
 117     DEBUG_BLOCK
 118     emit( animationComplete() );
 119 }
 120
 121 void GraphicsItemFader::startFading()
 122 {
 123     if( m_timeLine->state() != QTimeLine::NotRunning )
 124         m_timeLine->stop();
 125     //total number of animation steps;
 126     m_animationSteps = m_fps * ( ( float ) m_duration / 1000.0 );
 127
 128     //how much should alpha change each step
 129     m_alphaStep = ( ( float ) ( m_targetAlpha - m_startAlpha ) ) / ( float ) m_animationSteps;
 130
 131     debug() << "Start fading, animationSteps = " << m_animationSteps << " over " << m_duration << " mseconds, alphaStep = " <<  m_alphaStep << endl;
 132
 133     m_timeLine->setDuration( m_duration );
 134     m_timeLine->setFrameRange( 0, m_animationSteps );
 135     m_timeLine->start();
 136 }
 137
 138 void GraphicsItemFader::paint(QPainter * painter, const QStyleOptionGraphicsItem * option, QWidget * widget)
 139 {
 140     Q_UNUSED( painter );
 141     Q_UNUSED( option );
 142     Q_UNUSED( widget );
 143 }
 144
 145 #include "graphicsitemfader.moc"