Copy the KDE 3.5 branch to branches/trinity for new KDE 3.5 features.

BUG:215923


git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/kdeartwork@1054174 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

1 files changed, 881 insertions, 0 deletions

diff --git a/kscreensaver/kdesavers/pendulum.cpp b/kscreensaver/kdesavers/pendulum.cpp
new file mode 100644
index 00000000..801b74dd
--- /dev/null
+++ b/kscreensaver/kdesavers/pendulum.cpp
@@ -0,0 +1,881 @@
+//============================================================================
+//
+// KPendulum screen saver for KDE
+//
+// The screen saver displays a physically realistic simulation of a two-part
+// pendulum.
+//
+// Developed by Georg Drenkhahn, georg-d@users.sourceforge.net
+//
+// $Id$
+//
+/*
+ * Copyright (C) 2004 Georg Drenkhahn
+ *
+ * KRotation is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation.
+ *
+ * KRotation is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place, Suite 330, Boston, MA 02110-1301 USA
+ */
+//============================================================================
+
+// std. C++ headers
+#include <cstdlib>
+
+// Qt headers
+#include <qlineedit.h>
+#include <qspinbox.h>
+#include <qvalidator.h>
+#include <qcolordialog.h>
+#include <qpushbutton.h>
+#include <qtooltip.h>
+// KDE headers
+#include <klocale.h>
+#include <kconfig.h>
+#include <kdebug.h>
+#include <kmessagebox.h>
+
+#include "sspreviewarea.h"
+
+// pendulum.moc includes pendulum.h
+#include "pendulum.moc"
+
+#define KPENDULUM_VERSION "1.1"
+
+// libkscreensaver interface
+extern "C"
+{
+   /// application name for libkscreensaver interface
+   KDE_EXPORT const char *kss_applicationName = "kpendulum.kss";
+   /// application description for libkscreensaver interface
+   KDE_EXPORT const char *kss_description = I18N_NOOP("Simulation of\
+ a two-part pendulum");
+   /// application version for libkscreensaver interface
+   KDE_EXPORT const char *kss_version = KPENDULUM_VERSION;
+
+   /// function to create screen saver object
+   KDE_EXPORT KScreenSaver* kss_create(WId id)
+   {
+      return new KPendulumSaver(id);
+   }
+
+   /// function to create setup dialog for screen saver
+   KDE_EXPORT QDialog* kss_setup()
+   {
+      return new KPendulumSetup();
+   }
+}
+
+//-----------------------------------------------------------------------------
+// PendulumOdeSolver
+//-----------------------------------------------------------------------------
+
+PendulumOdeSolver::PendulumOdeSolver(
+   const double &_t,
+   const double &_dt,
+   std::valarray<double> &_y,
+   const double &_eps,
+   const double &_m1,
+   const double &_m2,
+   const double &_l1,
+   const double &_l2,
+   const double &_g)
+   : RkOdeSolver<double>(_t,_y,_dt,_eps),
+     A(1.0/(_m2*_l1*_l1)),
+     B1(_m2*_l1*_l2),           // constants for faster numeric calculation
+     B(1.0/B1),                 // derived from m1,m2,l1,l2,g
+     C((_m1+_m2)/(_m2*_m2*_l2*_l2)),
+     D(_g*(_m1+_m2)*_l1),
+     E(_g*_m2*_l2),
+     M((_m1+_m2)/_m2)
+{
+}
+
+std::valarray<double> PendulumOdeSolver::f(
+   const double &x,
+   const std::valarray<double> &y) const
+{
+   (void)x; // unused
+
+   const double& q1 = y[0];
+   const double& q2 = y[1];
+   const double& p1 = y[2];
+   const double& p2 = y[3];
+
+   const double cosDq = std::cos(q1-q2);
+   const double iden  = 1.0/(M - cosDq*cosDq); // invers denominator
+   const double dq1dt = (A*p1 - B*cosDq*p2)*iden;
+   const double dq2dt = (C*p2 - B*cosDq*p1)*iden;
+
+   std::valarray<double> ypr(y.size());
+   ypr[0] = dq1dt;
+   ypr[1] = dq2dt;
+
+   const double K = B1 * dq1dt*dq2dt * std::sin(q1-q2);
+   ypr[2] = -K - D * std::sin(q1);
+   ypr[3] =  K - E * std::sin(q2);
+
+   return ypr;
+}
+
+//-----------------------------------------------------------------------------
+// Rotation: screen saver widget
+//-----------------------------------------------------------------------------
+
+PendulumGLWidget::PendulumGLWidget(QWidget* parent, const char* name)
+   : QGLWidget(parent, name),
+     eyeR(30),                  // eye coordinates (polar)
+     eyeTheta(M_PI*0.45),
+     eyePhi(0),
+     lightR(eyeR),              // light coordinates (polar)
+     lightTheta(M_PI*0.25),
+     lightPhi(M_PI*0.25),
+     quadM1(gluNewQuadric()),
+     m_barColor(KPendulumSaver::barColorDefault),
+     m_m1Color(KPendulumSaver::m1ColorDefault),
+     m_m2Color(KPendulumSaver::m2ColorDefault)
+{
+}
+
+PendulumGLWidget::~PendulumGLWidget(void)
+{
+   gluDeleteQuadric(quadM1);
+}
+
+void PendulumGLWidget::setEyePhi(double phi)
+{
+   eyePhi = phi;
+   while (eyePhi < 0)      eyePhi += 2.*M_PI;
+   while (eyePhi > 2*M_PI) eyePhi -= 2.*M_PI;
+
+   // get the view port
+   static GLint vp[4];
+   glGetIntegerv(GL_VIEWPORT, vp);
+   // calc new perspective, a resize event is simulated here
+   resizeGL(static_cast<int>(vp[2]), static_cast<int>(vp[3]));
+}
+
+void PendulumGLWidget::setAngles(const double& q1, const double& q2)
+{
+   ang1 = static_cast<GLfloat>(q1*180./M_PI);
+   ang2 = static_cast<GLfloat>(q2*180./M_PI);
+}
+
+void PendulumGLWidget::setMasses(const double& m1, const double& m2)
+{
+   sqrtm1 = static_cast<GLfloat>(sqrt(m1));
+   sqrtm2 = static_cast<GLfloat>(sqrt(m2));
+}
+
+void PendulumGLWidget::setLengths(const double& _l1, const double& _l2)
+{
+   l1 = static_cast<GLfloat>(_l1);
+   l2 = static_cast<GLfloat>(_l2);
+}
+
+void PendulumGLWidget::setBarColor(const QColor& c)
+{
+   if (c.isValid())
+   {
+      m_barColor = c;
+   }
+}
+
+void PendulumGLWidget::setM1Color(const QColor& c)
+{
+   if (c.isValid())
+   {
+      m_m1Color = c;
+   }
+}
+void PendulumGLWidget::setM2Color(const QColor& c)
+{
+   if (c.isValid())
+   {
+      m_m2Color = c;
+   }
+}
+
+/* --------- protected methods ----------- */
+
+void PendulumGLWidget::initializeGL(void)
+{
+   qglClearColor(QColor(black)); // set color to clear the background
+
+   glClearDepth(1);             // depth buffer setup
+   glEnable(GL_DEPTH_TEST);     // depth testing
+   glDepthFunc(GL_LEQUAL);      // type of depth test
+
+   glShadeModel(GL_SMOOTH);     // smooth color shading in poygons
+
+   // nice perspective calculation
+   glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
+
+   // set up the light
+   glEnable(GL_LIGHTING);
+   glEnable(GL_LIGHT0);
+   glEnable(GL_LIGHT1);
+
+   glMatrixMode(GL_MODELVIEW);           // select modelview matrix
+   glLoadIdentity();
+   // set positon of light0
+   GLfloat lightPos[4]=
+      {lightR * sin(lightTheta) * sin(lightPhi),
+       lightR * sin(lightTheta) * cos(lightPhi),
+       lightR * cos(lightTheta),
+       0};
+   glLightfv(GL_LIGHT0, GL_POSITION, lightPos);
+   // set positon of light1
+   lightPos[0] = lightR * sin(lightTheta) * sin(lightPhi+M_PI);
+   lightPos[1] = lightR * sin(lightTheta) * cos(lightPhi+M_PI);
+   glLightfv(GL_LIGHT1, GL_POSITION, lightPos);
+
+   // only for lights #>0
+   GLfloat spec[]={1,1,1,1};
+   glLightfv(GL_LIGHT1, GL_SPECULAR, spec);
+   glLightfv(GL_LIGHT1, GL_DIFFUSE, spec);
+
+   // enable setting the material colour by glColor()
+   glEnable(GL_COLOR_MATERIAL);
+
+   GLfloat emi[4] = {.13, .13, .13, 1};
+   glMaterialfv(GL_FRONT, GL_EMISSION, emi);
+}
+
+void PendulumGLWidget::paintGL(void)
+{
+   // clear color and depth buffer
+   glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
+
+   glMatrixMode(GL_MODELVIEW);           // select modelview matrix
+
+   glLoadIdentity();
+
+   static const GLfloat width     = 2.0;
+   static const GLfloat masswidth = 1.0;
+   static const int noOfSlices    = 20;
+
+   // top axis, left (x>0)
+   glTranslatef(0.5*width, 0, 0);
+   glRotatef(90, 0, 1, 0);
+   qglColor(m_barColor);
+   gluCylinder(quadM1, 0.2, 0.2, 5, 10, 1);
+   gluSphere(quadM1, 0.2, 10, 10);
+   // top axis, right
+   glLoadIdentity();
+   glTranslatef(-0.5*width, 0, 0);
+   glRotatef(-90, 0, 1, 0);
+   gluCylinder(quadM1, 0.2, 0.2, 5, 10, 1);
+   gluSphere(quadM1, 0.2, 10, 10);
+   // 1. part, left
+   glLoadIdentity();
+   glRotatef(ang1, 1, 0, 0);
+   glPushMatrix();
+   glTranslatef(0.5*width, 0, -l1);
+   gluCylinder(quadM1, 0.2, 0.2, l1, 10, 1);
+   glPopMatrix();
+
+   // 1. part, right
+   glPushMatrix();
+   glTranslatef(-0.5*width, 0, -l1);
+   gluCylinder(quadM1, 0.2, 0.2, l1, 10, 1);
+   // 1. part, bottom
+   glRotatef(90, 0, 1, 0);
+   gluSphere(quadM1, 0.2, 10, 10); // bottom corner 1
+   gluCylinder(quadM1, 0.2, 0.2, width, 10, 1); // connection
+   glTranslatef(0, 0, 0.5*(width-masswidth));
+   qglColor(m_m1Color);
+   gluCylinder(quadM1, sqrtm1, sqrtm1, masswidth, noOfSlices, 1); // mass 1
+   gluQuadricOrientation(quadM1, GLU_INSIDE);
+   gluDisk(quadM1, 0, sqrtm1, noOfSlices,1); // bottom of mass
+   gluQuadricOrientation(quadM1, GLU_OUTSIDE);
+   glTranslatef(0, 0, masswidth);
+   gluDisk(quadM1, 0, sqrtm1, noOfSlices,1); // top of mass
+
+   glTranslatef(0, 0, 0.5*(width-masswidth));
+   qglColor(m_barColor);
+   gluSphere(quadM1, 0.2, 10, 10); // bottom corner 2
+   glPopMatrix();
+
+   // 2. pendulum bar
+   glLoadIdentity();
+   glTranslatef(0, l1*std::sin(ang1*M_PI/180.), -l1*std::cos(ang1*M_PI/180.));
+   glRotatef(ang2, 1, 0, 0);
+   glTranslatef(0, 0, -l2);
+   qglColor(m_barColor);
+   gluCylinder(quadM1, 0.2, 0.2, l2, 10, 1);
+
+   // mass 2
+   glRotatef(90, 0, 1, 0);
+   glTranslatef(0, 0, -0.5*masswidth);
+   qglColor(m_m2Color);
+   gluCylinder(quadM1, sqrtm2, sqrtm2, masswidth, noOfSlices, 1);
+   gluQuadricOrientation(quadM1, GLU_INSIDE);
+   gluDisk(quadM1, 0, sqrtm2, noOfSlices,1); // bottom of mass
+   gluQuadricOrientation(quadM1, GLU_OUTSIDE);
+   glTranslatef(0, 0, masswidth);
+   gluDisk(quadM1, 0, sqrtm2, noOfSlices,1); // top of mass
+
+   glFlush();
+}
+
+void PendulumGLWidget::resizeGL(int w, int h)
+{
+   // Prevent a divide by zero
+   if (h == 0) h = 1;
+
+   // set the new view port
+   glViewport(0, 0, static_cast<GLint>(w), static_cast<GLint>(h));
+
+   // set up projection matrix
+   glMatrixMode(GL_PROJECTION);
+   glLoadIdentity();
+   // Perspective view
+   gluPerspective(40.0f,
+                  static_cast<GLdouble>(w)/static_cast<GLdouble>(h),
+                  1.0, 100.0f);
+
+   // Viewing transformation, position for better view
+   // Theta is polar angle 0<Theta<Pi
+   gluLookAt(
+      eyeR * sin(eyeTheta) * sin(eyePhi),
+      eyeR * sin(eyeTheta) * cos(eyePhi),
+      eyeR * cos(eyeTheta),
+      0,0,0,
+      0,0,1);
+}
+
+//-----------------------------------------------------------------------------
+// KPendulumSaver: screen saver class
+//-----------------------------------------------------------------------------
+
+KPendulumSaver::KPendulumSaver(WId id) :
+   KScreenSaver(id),
+   solver(0),
+   m_massRatio(massRatioDefault),
+   m_lengthRatio(lengthRatioDefault),
+   m_g(gDefault),
+   m_E(EDefault),
+   m_persChangeInterval(persChangeIntervalDefault)
+{
+   setEraseColor(black);
+   erase();                     // erase area
+   glArea = new PendulumGLWidget(this); // create gl widget
+   glArea->setEyePhi(eyePhiDefault);
+
+   readSettings();              // read global settings into pars
+   initData();                  // init solver and glArea with read settings
+
+   embed(glArea);               // embed gl widget and resize it
+   glArea->show();              // show gl widget
+
+   // set up and start cyclic timer
+   timer = new QTimer(this);
+   timer->start(deltaT, TRUE);
+   connect(timer, SIGNAL(timeout()), this, SLOT(doTimeStep()));
+}
+
+KPendulumSaver::~KPendulumSaver()
+{
+   // time, rotation are automatically deleted with parent KPendulumSaver
+   delete solver;
+}
+
+
+void KPendulumSaver::readSettings()
+{
+   // read configuration settings from config file
+   KConfig *config = KGlobal::config();
+   config->setGroup("Settings");
+
+   // internal saver parameters are set to stored values or left at their
+   // default values if stored values are out of range
+   setMassRatio(
+      config->readDoubleNumEntry(
+         "mass ratio",
+         KPendulumSaver::massRatioDefault));
+   setLengthRatio(
+      config->readDoubleNumEntry(
+         "length ratio",
+         KPendulumSaver::lengthRatioDefault));
+   setG(
+      config->readDoubleNumEntry(
+         "g",
+         KPendulumSaver::gDefault));
+   setE(
+      config->readDoubleNumEntry(
+         "E",
+         KPendulumSaver::EDefault));
+   setPersChangeInterval(
+      config->readUnsignedNumEntry(
+         "perspective change interval",
+         KPendulumSaver::persChangeIntervalDefault));
+
+   // set the colours
+   setBarColor(config->readColorEntry("bar color", &barColorDefault));
+   setM1Color( config->readColorEntry("m1 color",  &m1ColorDefault));
+   setM2Color( config->readColorEntry("m2 color",  &m2ColorDefault));
+}
+
+void KPendulumSaver::initData()
+{
+   const double m1plusm2 = 2;   // m1+m2
+   const double m2 = m_massRatio * m1plusm2;
+   const double m1 = m1plusm2 - m2;
+   glArea->setMasses(m1, m2);
+   glArea->setAngles(0, 0);
+
+   const double l1plusl2 = 9;   // l1+l2
+   const double l2 = m_lengthRatio * l1plusl2;
+   const double l1 = l1plusl2 - l2;
+   glArea->setLengths(l1, l2);
+
+   // kinetic energy of m2 and m1
+   const double kin_energy = m_E * m_g * (l1*m1 + (m1+m2)*(l1+l2));
+   // angular velocity for 1. and 2. pendulum
+   const double qp = sqrt(2.*kin_energy/((m1+m2)*l1*l1 + m2*l2*l2 + m2*l1*l2));
+
+   // assemble initial y for solver
+   std::valarray<double> y(4);
+   y[0] = 0;                    // q1
+   y[1] = 0;                    // q2
+   y[2] = (m1+m2)*l1*l1*qp + 0.5*m2*l1*l2*qp; // p1
+   y[3] = m2*l2*l2*qp + 0.5*m2*l1*l2*qp; // p2
+
+   // delete old solver
+   if (solver!=0) delete solver;
+   // init new solver
+   solver = new PendulumOdeSolver(
+      0.0,                      // t
+      0.01,                     // first dt step size estimation
+      y,
+      1e-5,                     // eps
+      m1,
+      m2,
+      l1,
+      l2,
+      m_g);
+}
+
+
+void KPendulumSaver::setBarColor(const QColor& c)
+{
+   glArea->setBarColor(c);
+}
+QColor KPendulumSaver::barColor(void) const
+{
+   return glArea->barColor();
+}
+
+const QColor KPendulumSaver::barColorDefault(255, 255, 127);
+
+void KPendulumSaver::setM1Color(const QColor& c)
+{
+   glArea->setM1Color(c);
+}
+QColor KPendulumSaver::m1Color(void) const
+{
+   return glArea->m1Color();
+}
+
+const QColor KPendulumSaver::m1ColorDefault(170,   0, 127);
+
+void KPendulumSaver::setM2Color(const QColor& c)
+{
+   glArea->setM2Color(c);
+}
+QColor KPendulumSaver::m2Color(void) const
+{
+   return glArea->m2Color();
+}
+
+const QColor KPendulumSaver::m2ColorDefault( 85, 170, 127);
+
+
+void KPendulumSaver::setMassRatio(const double& massRatio)
+{
+   // range check is not neccessary in normal operation because validators check
+   // the values at input.  But the validators do not check for corrupted
+   // settings read from disk.
+   if (massRatio >= massRatioLimitLower
+       && massRatio <= massRatioLimitUpper
+       && m_massRatio != massRatio)
+   {
+      m_massRatio = massRatio;
+      if (timer!=0)
+      {
+         initData();
+      }
+   }
+}
+
+const double KPendulumSaver::massRatioLimitLower = 0.01;
+const double KPendulumSaver::massRatioLimitUpper = 0.99;
+const double KPendulumSaver::massRatioDefault    = 0.5;
+
+void KPendulumSaver::setLengthRatio(const double& lengthRatio)
+{
+   if (lengthRatio >= lengthRatioLimitLower
+       && lengthRatio <= lengthRatioLimitUpper
+       && m_lengthRatio != lengthRatio)
+   {
+      m_lengthRatio = lengthRatio;
+      if (timer!=0)
+      {
+         initData();
+      }
+   }
+}
+
+const double KPendulumSaver::lengthRatioLimitLower = 0.01;
+const double KPendulumSaver::lengthRatioLimitUpper = 0.99;
+const double KPendulumSaver::lengthRatioDefault    = 0.5;
+
+void KPendulumSaver::setG(const double& g)
+{
+   if (g >= gLimitLower
+       && g <= gLimitUpper
+       && m_g != g)
+   {
+      m_g = g;
+      if (timer!=0)
+      {
+         initData();
+      }
+   }
+}
+
+const double KPendulumSaver::gLimitLower = 0.1;
+const double KPendulumSaver::gLimitUpper = 300.0;
+const double KPendulumSaver::gDefault    = 40.0;
+
+void KPendulumSaver::setE(const double& E)
+{
+   if (E >= ELimitLower
+       && E <= ELimitUpper
+       && m_E != E)
+   {
+      m_E = E;
+      if (timer!=0)
+      {
+         initData();
+      }
+   }
+}
+
+const double KPendulumSaver::ELimitLower = 0.0;
+const double KPendulumSaver::ELimitUpper = 5.0;
+const double KPendulumSaver::EDefault    = 1.2;
+
+void KPendulumSaver::setPersChangeInterval(
+   const unsigned int& persChangeInterval)
+{
+   if (persChangeInterval >= persChangeIntervalLimitLower
+       && persChangeInterval <= persChangeIntervalLimitUpper
+       && m_persChangeInterval != persChangeInterval)
+   {
+      m_persChangeInterval = persChangeInterval;
+      // do not restart simulation here
+   }
+}
+
+const double KPendulumSaver::eyePhiDefault = 0.25*M_PI;
+
+
+void KPendulumSaver::doTimeStep()
+{
+   /* time (in seconds) of perspective change.
+    * - t<0: no change yet
+    * - t=0: change starts
+    * - 0<t<moving time: change takes place
+    * - t=moving time: end of the change */
+   static double persChangeTime = -5;
+
+   // integrate a step ahead
+   solver->integrate(0.001*deltaT);
+
+   // read new y from solver
+   const std::valarray<double> y = solver->Y();
+
+   // tell glArea the new coordinates/angles of the pendulum
+   glArea->setAngles(y[0], y[1]);
+
+   // handle perspective change
+   persChangeTime += 0.001*deltaT;
+   if (persChangeTime > 0)
+   {
+      // phi value at the start of a perspective change
+      static double eyePhi0     = eyePhiDefault;
+      // phi value at the end of a perspective change
+      static double eyePhi1     = 0.75*M_PI;
+      static double deltaEyePhi = eyePhi1-eyePhi0;
+
+      // movement acceleration/deceleration
+      const double a = 3;
+      // duration of the change period
+      const double movingTime = 2.*sqrt(fabs(deltaEyePhi)/a);
+
+      // new current phi of eye
+      double eyePhi = persChangeTime < 0.5*movingTime ?
+         // accelerating phase
+         eyePhi0 + (deltaEyePhi>0?1:-1)
+         * 0.5*a*persChangeTime*persChangeTime:
+         // decellerating phase
+         eyePhi1 - (deltaEyePhi>0?1:-1)
+         * 0.5*a*(movingTime-persChangeTime)*(movingTime-persChangeTime);
+
+      if (persChangeTime>movingTime)
+      {  // perspective change has finished
+         // set new time till next change
+         persChangeTime = -double(m_persChangeInterval);
+         eyePhi0 = eyePhi = eyePhi1;
+         // find new phi value with angleLimit < phi < Pi-angleLimit or
+         // Pi+angleLimit < phi < 2*Pi-angleLimit
+         const double angleLimit = M_PI*0.2;
+         for (eyePhi1 = 0;
+              eyePhi1<angleLimit
+                 || (eyePhi1<M_PI+angleLimit && eyePhi1>M_PI-angleLimit)
+                 || eyePhi1>2*M_PI-angleLimit;
+              eyePhi1 = double(rand())/RAND_MAX * 2*M_PI)
+         {}
+         // new delta phi for next change
+         deltaEyePhi = eyePhi1 - eyePhi0;
+         // find shortest perspective change
+         if (deltaEyePhi < -M_PI) deltaEyePhi += 2*M_PI;
+      }
+
+      glArea->setEyePhi(eyePhi); // set new perspective
+   }
+
+   glArea->updateGL();          // repaint scenery
+   timer->start(deltaT, TRUE);  // restart timer
+}
+
+// public slot of KPendulumSaver, forward resize event to public slot of glArea
+// to allow the resizing of the gl area withing the setup dialog
+void KPendulumSaver::resizeGlArea(QResizeEvent* e)
+{
+   glArea->resize(e->size());
+}
+
+//-----------------------------------------------------------------------------
+// KPendulumSetup: dialog to setup screen saver parameters
+//-----------------------------------------------------------------------------
+
+KPendulumSetup::KPendulumSetup(QWidget* parent, const char* name)
+   : KPendulumSetupUi(parent, name),
+     // create saver and give it the WinID of the preview area
+     saver(new KPendulumSaver(preview->winId()))
+{
+   // the dialog should block, no other control center input should be possible
+   // until the dialog is closed
+   setModal(TRUE);
+
+   // create input validators
+   mEdit->setValidator(new QDoubleValidator(
+                          KPendulumSaver::massRatioLimitLower,
+                          KPendulumSaver::massRatioLimitUpper,
+                          5, mEdit));
+   lEdit->setValidator(new QDoubleValidator(
+                          KPendulumSaver::lengthRatioLimitLower,
+                          KPendulumSaver::lengthRatioLimitUpper,
+                          5, lEdit));
+   gEdit->setValidator(new QDoubleValidator(
+                          KPendulumSaver::gLimitLower,
+                          KPendulumSaver::gLimitUpper,
+                          5, gEdit));
+   eEdit->setValidator(new QDoubleValidator(
+                          KPendulumSaver::ELimitLower,
+                          KPendulumSaver::ELimitUpper,
+                          5, eEdit));
+
+   // set input limits for the perspective change interval time
+   persSpinBox->setMinValue(KPendulumSaver::persChangeIntervalLimitLower);
+   persSpinBox->setMaxValue(KPendulumSaver::persChangeIntervalLimitUpper);
+
+   // set tool tips of editable fields
+   QToolTip::add(
+      mEdit,
+      i18n("Ratio of 2nd mass to sum of both masses.\nValid values from %1 to %2.")
+      .arg(KPendulumSaver::massRatioLimitLower, 0, 'f', 2)
+      .arg(KPendulumSaver::massRatioLimitUpper, 0, 'f', 2));
+   QToolTip::add(
+      lEdit,
+      i18n("Ratio of 2nd pendulum part length to the sum of both part lengths.\nValid values from %1 to %2.")
+      .arg(KPendulumSaver::lengthRatioLimitLower, 0, 'f', 2)
+      .arg(KPendulumSaver::lengthRatioLimitUpper, 0, 'f', 2));
+   QToolTip::add(
+      gEdit,
+      i18n("Gravitational constant in arbitrary units.\nValid values from %1 to %2.")
+      .arg(KPendulumSaver::gLimitLower, 0, 'f', 2)
+      .arg(KPendulumSaver::gLimitUpper, 0, 'f', 2));
+   QToolTip::add(
+      eEdit,
+      i18n("Energy in units of the maximum potential energy of the given configuration.\nValid values from %1 to %2.")
+      .arg(KPendulumSaver::ELimitLower, 0, 'f', 2)
+      .arg(KPendulumSaver::ELimitUpper, 0, 'f', 2));
+   QToolTip::add(
+      persSpinBox,
+      i18n("Time in seconds after which a random perspective change occurs.\nValid values from %1 to %2.")
+      .arg(KPendulumSaver::persChangeIntervalLimitLower)
+      .arg(KPendulumSaver::persChangeIntervalLimitUpper));
+
+   // init preview area
+   preview->setBackgroundColor(black);
+   preview->show();    // otherwise saver does not get correct size
+
+   // read settings from saver and update GUI elements with these values, saver
+   // has read settings in its constructor
+
+   // set editable fields with stored values as defaults
+   QString text;
+   text.setNum(saver->massRatio());
+   mEdit->setText(text);
+   text.setNum(saver->lengthRatio());
+   lEdit->setText(text);
+   text.setNum(saver->g());
+   gEdit->setText(text);
+   text.setNum(saver->E());
+   eEdit->setText(text);
+
+   persSpinBox->setValue(saver->persChangeInterval());
+
+   barColorButton->setPaletteBackgroundColor(saver->barColor());
+   m1ColorButton->setPaletteBackgroundColor(saver->m1Color());
+   m2ColorButton->setPaletteBackgroundColor(saver->m2Color());
+
+   // if the preview area is resized it emmits the resized() event which is
+   // caught by the saver.  The embedded GlArea is resized to fit into the
+   // preview area.
+   connect(preview, SIGNAL(resized(QResizeEvent*)),
+           saver,   SLOT(resizeGlArea(QResizeEvent*)));
+}
+
+KPendulumSetup::~KPendulumSetup()
+{
+   delete saver;
+}
+
+// Ok pressed - save settings and exit
+void KPendulumSetup::okButtonClickedSlot()
+{
+   KConfig* config = KGlobal::config();
+   config->setGroup("Settings");
+
+   config->writeEntry("mass ratio",   saver->massRatio());
+   config->writeEntry("length ratio", saver->lengthRatio());
+   config->writeEntry("g",            saver->g());
+   config->writeEntry("E",            saver->E());
+   config->writeEntry("perspective change interval",
+                      saver->persChangeInterval());
+   config->writeEntry("bar color",    saver->barColor());
+   config->writeEntry("m1 color",     saver->m1Color());
+   config->writeEntry("m2 color",     saver->m2Color());
+
+   config->sync();
+   accept();
+}
+
+void KPendulumSetup::aboutButtonClickedSlot()
+{
+   KMessageBox::about(this, i18n("\
+<h3>KPendulum Screen Saver for KDE</h3>\
+<p>Simulation of a two-part pendulum</p>\
+<p>Copyright (c) Georg&nbsp;Drenkhahn 2004</p>\
+<p><tt>georg-d@users.sourceforge.net</tt></p>"));
+}
+
+void KPendulumSetup::mEditLostFocusSlot(void)
+{
+   if (mEdit->hasAcceptableInput())
+   {
+      saver->setMassRatio(mEdit->text().toDouble());
+   }
+   else
+   {  // write current setting back into input field
+      QString text;
+      text.setNum(saver->massRatio());
+      mEdit->setText(text);
+   }
+}
+void KPendulumSetup::lEditLostFocusSlot(void)
+{
+   if (lEdit->hasAcceptableInput())
+   {
+      saver->setLengthRatio(lEdit->text().toDouble());
+   }
+   else
+   {  // write current setting back into input field
+      QString text;
+      text.setNum(saver->lengthRatio());
+      lEdit->setText(text);
+   }
+}
+void KPendulumSetup::gEditLostFocusSlot(void)
+{
+   if (gEdit->hasAcceptableInput())
+   {
+      saver->setG(gEdit->text().toDouble());
+   }
+   else
+   {  // write current setting back into input field
+      QString text;
+      text.setNum(saver->g());
+      gEdit->setText(text);
+   }
+}
+void KPendulumSetup::eEditLostFocusSlot(void)
+{
+   if (eEdit->hasAcceptableInput())
+   {
+      saver->setE(eEdit->text().toDouble());
+   }
+   else
+   {  // write current setting back into input field
+      QString text;
+      text.setNum(saver->E());
+      eEdit->setText(text);
+   }
+}
+void KPendulumSetup::persChangeEnteredSlot(int t)
+{
+   saver->setPersChangeInterval(t);
+}
+
+void KPendulumSetup::barColorButtonClickedSlot(void)
+{
+   QColor color = QColorDialog::getColor(
+      saver->barColor(), this, "bar color dialog");
+   if (color.isValid())
+   {
+      saver->setBarColor(color);
+      barColorButton->setPaletteBackgroundColor(color);
+   }
+}
+void KPendulumSetup::m1ColorButtonClickedSlot(void)
+{
+   QColor color = QColorDialog::getColor(
+      saver->m1Color(), this, "mass 1 color dialog");
+   if (color.isValid())
+   {
+      saver->setM1Color(color);
+      m1ColorButton->setPaletteBackgroundColor(color);
+   }
+}
+void KPendulumSetup::m2ColorButtonClickedSlot(void)
+{
+   QColor color = QColorDialog::getColor(
+      saver->m2Color(), this, "mass 2 color dialog");
+   if (color.isValid())
+   {
+      saver->setM2Color(color);
+      m2ColorButton->setPaletteBackgroundColor(color);
+   }
+}