window.cpp Example File
painting/painterpaths/window.cpp

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 #include <QtGui>

 #include <math.h>

 #include "renderarea.h"
 #include "window.h"

 const float Pi = 3.14159f;

 Window::Window()
 {
     QPainterPath rectPath;
     rectPath.moveTo(20.0, 30.0);
     rectPath.lineTo(80.0, 30.0);
     rectPath.lineTo(80.0, 70.0);
     rectPath.lineTo(20.0, 70.0);
     rectPath.closeSubpath();

     QPainterPath roundRectPath;
     roundRectPath.moveTo(80.0, 35.0);
     roundRectPath.arcTo(70.0, 30.0, 10.0, 10.0, 0.0, 90.0);
     roundRectPath.lineTo(25.0, 30.0);
     roundRectPath.arcTo(20.0, 30.0, 10.0, 10.0, 90.0, 90.0);
     roundRectPath.lineTo(20.0, 65.0);
     roundRectPath.arcTo(20.0, 60.0, 10.0, 10.0, 180.0, 90.0);
     roundRectPath.lineTo(75.0, 70.0);
     roundRectPath.arcTo(70.0, 60.0, 10.0, 10.0, 270.0, 90.0);
     roundRectPath.closeSubpath();

     QPainterPath ellipsePath;
     ellipsePath.moveTo(80.0, 50.0);
     ellipsePath.arcTo(20.0, 30.0, 60.0, 40.0, 0.0, 360.0);

     QPainterPath piePath;
     piePath.moveTo(50.0, 50.0);
     piePath.arcTo(20.0, 30.0, 60.0, 40.0, 60.0, 240.0);
     piePath.closeSubpath();

     QPainterPath polygonPath;
     polygonPath.moveTo(10.0, 80.0);
     polygonPath.lineTo(20.0, 10.0);
     polygonPath.lineTo(80.0, 30.0);
     polygonPath.lineTo(90.0, 70.0);
     polygonPath.closeSubpath();

     QPainterPath groupPath;
     groupPath.moveTo(60.0, 40.0);
     groupPath.arcTo(20.0, 20.0, 40.0, 40.0, 0.0, 360.0);
     groupPath.moveTo(40.0, 40.0);
     groupPath.lineTo(40.0, 80.0);
     groupPath.lineTo(80.0, 80.0);
     groupPath.lineTo(80.0, 40.0);
     groupPath.closeSubpath();

     QPainterPath textPath;
     QFont timesFont("Times", 50);
     timesFont.setStyleStrategy(QFont::ForceOutline);
     textPath.addText(10, 70, timesFont, tr("Qt"));

     QPainterPath bezierPath;
     bezierPath.moveTo(20, 30);
     bezierPath.cubicTo(80, 0, 50, 50, 80, 80);

     QPainterPath starPath;
     starPath.moveTo(90, 50);
     for (int i = 1; i < 5; ++i) {
         starPath.lineTo(50 + 40 * cos(0.8 * i * Pi),
                         50 + 40 * sin(0.8 * i * Pi));
     }
     starPath.closeSubpath();

     renderAreas[0] = new RenderArea(rectPath);
     renderAreas[1] = new RenderArea(roundRectPath);
     renderAreas[2] = new RenderArea(ellipsePath);
     renderAreas[3] = new RenderArea(piePath);
     renderAreas[4] = new RenderArea(polygonPath);
     renderAreas[5] = new RenderArea(groupPath);
     renderAreas[6] = new RenderArea(textPath);
     renderAreas[7] = new RenderArea(bezierPath);
     renderAreas[8] = new RenderArea(starPath);
     Q_ASSERT(NumRenderAreas == 9);

     fillRuleComboBox = new QComboBox;
     fillRuleComboBox->addItem(tr("Odd Even"), Qt::OddEvenFill);
     fillRuleComboBox->addItem(tr("Winding"), Qt::WindingFill);

     fillRuleLabel = new QLabel(tr("Fill &Rule:"));
     fillRuleLabel->setBuddy(fillRuleComboBox);

     fillColor1ComboBox = new QComboBox;
     populateWithColors(fillColor1ComboBox);
     fillColor1ComboBox->setCurrentIndex(
             fillColor1ComboBox->findText("mediumslateblue"));

     fillColor2ComboBox = new QComboBox;
     populateWithColors(fillColor2ComboBox);
     fillColor2ComboBox->setCurrentIndex(
             fillColor2ComboBox->findText("cornsilk"));

     fillGradientLabel = new QLabel(tr("&Fill Gradient:"));
     fillGradientLabel->setBuddy(fillColor1ComboBox);

     fillToLabel = new QLabel(tr("to"));
     fillToLabel->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);

     penWidthSpinBox = new QSpinBox;
     penWidthSpinBox->setRange(0, 20);

     penWidthLabel = new QLabel(tr("&Pen Width:"));
     penWidthLabel->setBuddy(penWidthSpinBox);

     penColorComboBox = new QComboBox;
     populateWithColors(penColorComboBox);
     penColorComboBox->setCurrentIndex(
             penColorComboBox->findText("darkslateblue"));

     penColorLabel = new QLabel(tr("Pen &Color:"));
     penColorLabel->setBuddy(penColorComboBox);

     rotationAngleSpinBox = new QSpinBox;
     rotationAngleSpinBox->setRange(0, 359);
     rotationAngleSpinBox->setWrapping(true);
     rotationAngleSpinBox->setSuffix("\xB0");

     rotationAngleLabel = new QLabel(tr("&Rotation Angle:"));
     rotationAngleLabel->setBuddy(rotationAngleSpinBox);

     connect(fillRuleComboBox, SIGNAL(activated(int)),
             this, SLOT(fillRuleChanged()));
     connect(fillColor1ComboBox, SIGNAL(activated(int)),
             this, SLOT(fillGradientChanged()));
     connect(fillColor2ComboBox, SIGNAL(activated(int)),
             this, SLOT(fillGradientChanged()));
     connect(penColorComboBox, SIGNAL(activated(int)),
             this, SLOT(penColorChanged()));

     for (int i = 0; i < NumRenderAreas; ++i) {
         connect(penWidthSpinBox, SIGNAL(valueChanged(int)),
                 renderAreas[i], SLOT(setPenWidth(int)));
         connect(rotationAngleSpinBox, SIGNAL(valueChanged(int)),
                 renderAreas[i], SLOT(setRotationAngle(int)));
     }

     QGridLayout *topLayout = new QGridLayout;
     for (int i = 0; i < NumRenderAreas; ++i)
         topLayout->addWidget(renderAreas[i], i / 3, i % 3);

     QGridLayout *mainLayout = new QGridLayout;
     mainLayout->addLayout(topLayout, 0, 0, 1, 4);
     mainLayout->addWidget(fillRuleLabel, 1, 0);
     mainLayout->addWidget(fillRuleComboBox, 1, 1, 1, 3);
     mainLayout->addWidget(fillGradientLabel, 2, 0);
     mainLayout->addWidget(fillColor1ComboBox, 2, 1);
     mainLayout->addWidget(fillToLabel, 2, 2);
     mainLayout->addWidget(fillColor2ComboBox, 2, 3);
     mainLayout->addWidget(penWidthLabel, 3, 0);
     mainLayout->addWidget(penWidthSpinBox, 3, 1, 1, 3);
     mainLayout->addWidget(penColorLabel, 4, 0);
     mainLayout->addWidget(penColorComboBox, 4, 1, 1, 3);
     mainLayout->addWidget(rotationAngleLabel, 5, 0);
     mainLayout->addWidget(rotationAngleSpinBox, 5, 1, 1, 3);
     setLayout(mainLayout);

     fillRuleChanged();
     fillGradientChanged();
     penColorChanged();
     penWidthSpinBox->setValue(2);

     setWindowTitle(tr("Painter Paths"));
 }

 void Window::fillRuleChanged()
 {
     Qt::FillRule rule = (Qt::FillRule)currentItemData(fillRuleComboBox).toInt();

     for (int i = 0; i < NumRenderAreas; ++i)
         renderAreas[i]->setFillRule(rule);
 }

 void Window::fillGradientChanged()
 {
     QColor color1 = qvariant_cast<QColor>(currentItemData(fillColor1ComboBox));
     QColor color2 = qvariant_cast<QColor>(currentItemData(fillColor2ComboBox));

     for (int i = 0; i < NumRenderAreas; ++i)
         renderAreas[i]->setFillGradient(color1, color2);
 }

 void Window::penColorChanged()
 {
     QColor color = qvariant_cast<QColor>(currentItemData(penColorComboBox));

     for (int i = 0; i < NumRenderAreas; ++i)
         renderAreas[i]->setPenColor(color);
 }

 void Window::populateWithColors(QComboBox *comboBox)
 {
     QStringList colorNames = QColor::colorNames();
     foreach (QString name, colorNames)
         comboBox->addItem(name, QColor(name));
 }

 QVariant Window::currentItemData(QComboBox *comboBox)
 {
     return comboBox->itemData(comboBox->currentIndex());
 }