gradients.cpp Example File

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  #include "gradients.h"
  #include "hoverpoints.h"

  #include <algorithm>

  ShadeWidget::ShadeWidget(ShadeType type, QWidget *parent)
      : QWidget(parent), m_shade_type(type), m_alpha_gradient(QLinearGradient(0, 0, 0, 0))
  {

      // Checkers background
      if (m_shade_type == ARGBShade) {
          QPixmap pm(20, 20);
          QPainter pmp(&pm);
          pmp.fillRect(0, 0, 10, 10, Qt::lightGray);
          pmp.fillRect(10, 10, 10, 10, Qt::lightGray);
          pmp.fillRect(0, 10, 10, 10, Qt::darkGray);
          pmp.fillRect(10, 0, 10, 10, Qt::darkGray);
          pmp.end();
          QPalette pal = palette();
          pal.setBrush(backgroundRole(), QBrush(pm));
          setAutoFillBackground(true);
          setPalette(pal);

      } else {
          setAttribute(Qt::WA_NoBackground);
      }

      QPolygonF points;
      points << QPointF(0, sizeHint().height())
             << QPointF(sizeHint().width(), 0);

      m_hoverPoints = new HoverPoints(this, HoverPoints::CircleShape);
  //     m_hoverPoints->setConnectionType(HoverPoints::LineConnection);
      m_hoverPoints->setPoints(points);
      m_hoverPoints->setPointLock(0, HoverPoints::LockToLeft);
      m_hoverPoints->setPointLock(1, HoverPoints::LockToRight);
      m_hoverPoints->setSortType(HoverPoints::XSort);

      setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);

      connect(m_hoverPoints, &HoverPoints::pointsChanged,
              this, &ShadeWidget::colorsChanged);
  }

  QPolygonF ShadeWidget::points() const
  {
      return m_hoverPoints->points();
  }

  uint ShadeWidget::colorAt(int x)
  {
      generateShade();

      QPolygonF pts = m_hoverPoints->points();
      for (int i=1; i < pts.size(); ++i) {
          if (pts.at(i-1).x() <= x && pts.at(i).x() >= x) {
              QLineF l(pts.at(i-1), pts.at(i));
              l.setLength(l.length() * ((x - l.x1()) / l.dx()));
              return m_shade.pixel(qRound(qMin(l.x2(), (qreal(m_shade.width() - 1)))),
                                   qRound(qMin(l.y2(), qreal(m_shade.height() - 1))));
          }
      }
      return 0;
  }

  void ShadeWidget::setGradientStops(const QGradientStops &stops)
  {
      if (m_shade_type == ARGBShade) {
          m_alpha_gradient = QLinearGradient(0, 0, width(), 0);

          for (int i=0; i<stops.size(); ++i) {
              QColor c = stops.at(i).second;
              m_alpha_gradient.setColorAt(stops.at(i).first, QColor(c.red(), c.green(), c.blue()));
          }

          m_shade = QImage();
          generateShade();
          update();
      }
  }

  void ShadeWidget::paintEvent(QPaintEvent *)
  {
      generateShade();

      QPainter p(this);
      p.drawImage(0, 0, m_shade);

      p.setPen(QColor(146, 146, 146));
      p.drawRect(0, 0, width() - 1, height() - 1);
  }

  void ShadeWidget::generateShade()
  {
      if (m_shade.isNull() || m_shade.size() != size()) {

          if (m_shade_type == ARGBShade) {
              m_shade = QImage(size(), QImage::Format_ARGB32_Premultiplied);
              m_shade.fill(0);

              QPainter p(&m_shade);
              p.fillRect(rect(), m_alpha_gradient);

              p.setCompositionMode(QPainter::CompositionMode_DestinationIn);
              QLinearGradient fade(0, 0, 0, height());
              fade.setColorAt(0, QColor(0, 0, 0, 255));
              fade.setColorAt(1, QColor(0, 0, 0, 0));
              p.fillRect(rect(), fade);

          } else {
              m_shade = QImage(size(), QImage::Format_RGB32);
              QLinearGradient shade(0, 0, 0, height());
              shade.setColorAt(1, Qt::black);

              if (m_shade_type == RedShade)
                  shade.setColorAt(0, Qt::red);
              else if (m_shade_type == GreenShade)
                  shade.setColorAt(0, Qt::green);
              else
                  shade.setColorAt(0, Qt::blue);

              QPainter p(&m_shade);
              p.fillRect(rect(), shade);
          }
      }
  }

  GradientEditor::GradientEditor(QWidget *parent)
      : QWidget(parent)
  {
      QVBoxLayout *vbox = new QVBoxLayout(this);
      vbox->setSpacing(1);
      vbox->setMargin(1);

      m_red_shade = new ShadeWidget(ShadeWidget::RedShade, this);
      m_green_shade = new ShadeWidget(ShadeWidget::GreenShade, this);
      m_blue_shade = new ShadeWidget(ShadeWidget::BlueShade, this);
      m_alpha_shade = new ShadeWidget(ShadeWidget::ARGBShade, this);

      vbox->addWidget(m_red_shade);
      vbox->addWidget(m_green_shade);
      vbox->addWidget(m_blue_shade);
      vbox->addWidget(m_alpha_shade);

      connect(m_red_shade, &ShadeWidget::colorsChanged,
              this, &GradientEditor::pointsUpdated);
      connect(m_green_shade, &ShadeWidget::colorsChanged,
             this, &GradientEditor::pointsUpdated);
      connect(m_blue_shade, &ShadeWidget::colorsChanged,
              this, &GradientEditor::pointsUpdated);
      connect(m_alpha_shade, &ShadeWidget::colorsChanged,
              this, &GradientEditor::pointsUpdated);
  }

  inline static bool x_less_than(const QPointF &p1, const QPointF &p2)
  {
      return p1.x() < p2.x();
  }

  void GradientEditor::pointsUpdated()
  {
      qreal w = m_alpha_shade->width();

      QGradientStops stops;

      QPolygonF points;

      points += m_red_shade->points();
      points += m_green_shade->points();
      points += m_blue_shade->points();
      points += m_alpha_shade->points();

      std::sort(points.begin(), points.end(), x_less_than);

      for (int i = 0; i < points.size(); ++i) {
          qreal x = int(points.at(i).x());
          if (i + 1 < points.size() && x == points.at(i + 1).x())
              continue;
          QColor color((0x00ff0000 & m_red_shade->colorAt(int(x))) >> 16,
                       (0x0000ff00 & m_green_shade->colorAt(int(x))) >> 8,
                       (0x000000ff & m_blue_shade->colorAt(int(x))),
                       (0xff000000 & m_alpha_shade->colorAt(int(x))) >> 24);

          if (x / w > 1)
              return;

          stops << QGradientStop(x / w, color);
      }

      m_alpha_shade->setGradientStops(stops);

      emit gradientStopsChanged(stops);
  }

  static void set_shade_points(const QPolygonF &points, ShadeWidget *shade)
  {
      shade->hoverPoints()->setPoints(points);
      shade->hoverPoints()->setPointLock(0, HoverPoints::LockToLeft);
      shade->hoverPoints()->setPointLock(points.size() - 1, HoverPoints::LockToRight);
      shade->update();
  }

  void GradientEditor::setGradientStops(const QGradientStops &stops)
  {
      QPolygonF pts_red, pts_green, pts_blue, pts_alpha;

      qreal h_red = m_red_shade->height();
      qreal h_green = m_green_shade->height();
      qreal h_blue = m_blue_shade->height();
      qreal h_alpha = m_alpha_shade->height();

      for (int i = 0; i < stops.size(); ++i) {
          qreal pos = stops.at(i).first;
          QRgb color = stops.at(i).second.rgba();
          pts_red << QPointF(pos * m_red_shade->width(), h_red - qRed(color) * h_red / 255);
          pts_green << QPointF(pos * m_green_shade->width(), h_green - qGreen(color) * h_green / 255);
          pts_blue << QPointF(pos * m_blue_shade->width(), h_blue - qBlue(color) * h_blue / 255);
          pts_alpha << QPointF(pos * m_alpha_shade->width(), h_alpha - qAlpha(color) * h_alpha / 255);
      }

      set_shade_points(pts_red, m_red_shade);
      set_shade_points(pts_green, m_green_shade);
      set_shade_points(pts_blue, m_blue_shade);
      set_shade_points(pts_alpha, m_alpha_shade);

  }

  GradientWidget::GradientWidget(QWidget *parent)
      : QWidget(parent)
  {
      setWindowTitle(tr("Gradients"));

      m_renderer = new GradientRenderer(this);

      QGroupBox *mainGroup = new QGroupBox(this);
      mainGroup->setTitle(tr("Gradients"));

      QGroupBox *editorGroup = new QGroupBox(mainGroup);
      editorGroup->setTitle(tr("Color Editor"));
      m_editor = new GradientEditor(editorGroup);

      QGroupBox *typeGroup = new QGroupBox(mainGroup);
      typeGroup->setTitle(tr("Gradient Type"));
      m_linearButton = new QRadioButton(tr("Linear Gradient"), typeGroup);
      m_radialButton = new QRadioButton(tr("Radial Gradient"), typeGroup);
      m_conicalButton = new QRadioButton(tr("Conical Gradient"), typeGroup);

      QGroupBox *spreadGroup = new QGroupBox(mainGroup);
      spreadGroup->setTitle(tr("Spread Method"));
      m_padSpreadButton = new QRadioButton(tr("Pad Spread"), spreadGroup);
      m_reflectSpreadButton = new QRadioButton(tr("Reflect Spread"), spreadGroup);
      m_repeatSpreadButton = new QRadioButton(tr("Repeat Spread"), spreadGroup);

      QGroupBox *defaultsGroup = new QGroupBox(mainGroup);
      defaultsGroup->setTitle(tr("Defaults"));
      QPushButton *default1Button = new QPushButton(tr("1"), defaultsGroup);
      QPushButton *default2Button = new QPushButton(tr("2"), defaultsGroup);
      QPushButton *default3Button = new QPushButton(tr("3"), defaultsGroup);
      QPushButton *default4Button = new QPushButton(tr("Reset"), editorGroup);

      QPushButton *showSourceButton = new QPushButton(mainGroup);
      showSourceButton->setText(tr("Show Source"));
  #ifdef QT_OPENGL_SUPPORT
      QPushButton *enableOpenGLButton = new QPushButton(mainGroup);
      enableOpenGLButton->setText(tr("Use OpenGL"));
      enableOpenGLButton->setCheckable(true);
      enableOpenGLButton->setChecked(m_renderer->usesOpenGL());
      if (!QGLFormat::hasOpenGL())
          enableOpenGLButton->hide();
  #endif
      QPushButton *whatsThisButton = new QPushButton(mainGroup);
      whatsThisButton->setText(tr("What's This?"));
      whatsThisButton->setCheckable(true);

      // Layouts
      QHBoxLayout *mainLayout = new QHBoxLayout(this);
      mainLayout->addWidget(m_renderer);
      mainLayout->addWidget(mainGroup);

      mainGroup->setFixedWidth(180);
      QVBoxLayout *mainGroupLayout = new QVBoxLayout(mainGroup);
      mainGroupLayout->addWidget(editorGroup);
      mainGroupLayout->addWidget(typeGroup);
      mainGroupLayout->addWidget(spreadGroup);
      mainGroupLayout->addWidget(defaultsGroup);
      mainGroupLayout->addStretch(1);
      mainGroupLayout->addWidget(showSourceButton);
  #ifdef QT_OPENGL_SUPPORT
      mainGroupLayout->addWidget(enableOpenGLButton);
  #endif
      mainGroupLayout->addWidget(whatsThisButton);

      QVBoxLayout *editorGroupLayout = new QVBoxLayout(editorGroup);
      editorGroupLayout->addWidget(m_editor);

      QVBoxLayout *typeGroupLayout = new QVBoxLayout(typeGroup);
      typeGroupLayout->addWidget(m_linearButton);
      typeGroupLayout->addWidget(m_radialButton);
      typeGroupLayout->addWidget(m_conicalButton);

      QVBoxLayout *spreadGroupLayout = new QVBoxLayout(spreadGroup);
      spreadGroupLayout->addWidget(m_padSpreadButton);
      spreadGroupLayout->addWidget(m_repeatSpreadButton);
      spreadGroupLayout->addWidget(m_reflectSpreadButton);

      QHBoxLayout *defaultsGroupLayout = new QHBoxLayout(defaultsGroup);
      defaultsGroupLayout->addWidget(default1Button);
      defaultsGroupLayout->addWidget(default2Button);
      defaultsGroupLayout->addWidget(default3Button);
      editorGroupLayout->addWidget(default4Button);

      connect(m_editor, &GradientEditor::gradientStopsChanged,
              m_renderer, &GradientRenderer::setGradientStops);
      connect(m_linearButton, &QRadioButton::clicked,
              m_renderer, &GradientRenderer::setLinearGradient);
      connect(m_radialButton, &QRadioButton::clicked,
              m_renderer, &GradientRenderer::setRadialGradient);
      connect(m_conicalButton,&QRadioButton::clicked,
              m_renderer, &GradientRenderer::setConicalGradient);

      connect(m_padSpreadButton, &QRadioButton::clicked,
              m_renderer, &GradientRenderer::setPadSpread);
      connect(m_reflectSpreadButton, &QRadioButton::clicked,
              m_renderer, &GradientRenderer::setReflectSpread);
      connect(m_repeatSpreadButton, &QRadioButton::clicked,
              m_renderer, &GradientRenderer::setRepeatSpread);

      connect(default1Button, &QPushButton::clicked,
              this, &GradientWidget::setDefault1);
      connect(default2Button, &QPushButton::clicked,
              this, &GradientWidget::setDefault2);
      connect(default3Button, &QPushButton::clicked,
              this, &GradientWidget::setDefault3);
      connect(default4Button, &QPushButton::clicked,
              this, &GradientWidget::setDefault4);

      connect(showSourceButton, &QPushButton::clicked,
              m_renderer, &GradientRenderer::showSource);
  #ifdef QT_OPENGL_SUPPORT
      connect(enableOpenGLButton, QOverload<bool>::of(&QPushButton::clicked),
              m_renderer, &ArthurFrame::enableOpenGL);
  #endif

      connect(whatsThisButton, QOverload<bool>::of(&QPushButton::clicked),
              m_renderer, &ArthurFrame::setDescriptionEnabled);
      connect(whatsThisButton, QOverload<bool>::of(&QPushButton::clicked),
              m_renderer->hoverPoints(), &HoverPoints::setDisabled);
      connect(m_renderer, QOverload<bool>::of(&ArthurFrame::descriptionEnabledChanged),
              whatsThisButton, &QPushButton::setChecked);
      connect(m_renderer, QOverload<bool>::of(&ArthurFrame::descriptionEnabledChanged),
              m_renderer->hoverPoints(), &HoverPoints::setDisabled);

      m_renderer->loadSourceFile(":res/gradients/gradients.cpp");
      m_renderer->loadDescription(":res/gradients/gradients.html");

      QTimer::singleShot(50, this, SLOT(setDefault1()));
  }

  void GradientWidget::setDefault(int config)
  {
      QGradientStops stops;
      QPolygonF points;
      switch (config) {
      case 1:
          stops << QGradientStop(0.00, QColor::fromRgba(0));
          stops << QGradientStop(0.04, QColor::fromRgba(0xff131360));
          stops << QGradientStop(0.08, QColor::fromRgba(0xff202ccc));
          stops << QGradientStop(0.42, QColor::fromRgba(0xff93d3f9));
          stops << QGradientStop(0.51, QColor::fromRgba(0xffb3e6ff));
          stops << QGradientStop(0.73, QColor::fromRgba(0xffffffec));
          stops << QGradientStop(0.92, QColor::fromRgba(0xff5353d9));
          stops << QGradientStop(0.96, QColor::fromRgba(0xff262666));
          stops << QGradientStop(1.00, QColor::fromRgba(0));
          m_linearButton->animateClick();
          m_repeatSpreadButton->animateClick();
          break;

      case 2:
          stops << QGradientStop(0.00, QColor::fromRgba(0xffffffff));
          stops << QGradientStop(0.11, QColor::fromRgba(0xfff9ffa0));
          stops << QGradientStop(0.13, QColor::fromRgba(0xfff9ff99));
          stops << QGradientStop(0.14, QColor::fromRgba(0xfff3ff86));
          stops << QGradientStop(0.49, QColor::fromRgba(0xff93b353));
          stops << QGradientStop(0.87, QColor::fromRgba(0xff264619));
          stops << QGradientStop(0.96, QColor::fromRgba(0xff0c1306));
          stops << QGradientStop(1.00, QColor::fromRgba(0));
          m_radialButton->animateClick();
          m_padSpreadButton->animateClick();
          break;

      case 3:
          stops << QGradientStop(0.00, QColor::fromRgba(0));
          stops << QGradientStop(0.10, QColor::fromRgba(0xffe0cc73));
          stops << QGradientStop(0.17, QColor::fromRgba(0xffc6a006));
          stops << QGradientStop(0.46, QColor::fromRgba(0xff600659));
          stops << QGradientStop(0.72, QColor::fromRgba(0xff0680ac));
          stops << QGradientStop(0.92, QColor::fromRgba(0xffb9d9e6));
          stops << QGradientStop(1.00, QColor::fromRgba(0));
          m_conicalButton->animateClick();
          m_padSpreadButton->animateClick();
          break;

      case 4:
          stops << QGradientStop(0.00, QColor::fromRgba(0xff000000));
          stops << QGradientStop(1.00, QColor::fromRgba(0xffffffff));
          break;

      default:
          qWarning("bad default: %d\n", config);
          break;
      }

      QPolygonF pts;
      int h_off = m_renderer->width() / 10;
      int v_off = m_renderer->height() / 8;
      pts << QPointF(m_renderer->width() / 2, m_renderer->height() / 2)
          << QPointF(m_renderer->width() / 2 - h_off, m_renderer->height() / 2 - v_off);

      m_editor->setGradientStops(stops);
      m_renderer->hoverPoints()->setPoints(pts);
      m_renderer->setGradientStops(stops);
  }

  GradientRenderer::GradientRenderer(QWidget *parent)
      : ArthurFrame(parent)
  {
      m_hoverPoints = new HoverPoints(this, HoverPoints::CircleShape);
      m_hoverPoints->setPointSize(QSize(20, 20));
      m_hoverPoints->setConnectionType(HoverPoints::NoConnection);
      m_hoverPoints->setEditable(false);

      QVector<QPointF> points;
      points << QPointF(100, 100) << QPointF(200, 200);
      m_hoverPoints->setPoints(points);

      m_spread = QGradient::PadSpread;
      m_gradientType = Qt::LinearGradientPattern;
  }

  void GradientRenderer::setGradientStops(const QGradientStops &stops)
  {
      m_stops = stops;
      update();
  }

  void GradientRenderer::mousePressEvent(QMouseEvent *)
  {
      setDescriptionEnabled(false);
  }

  void GradientRenderer::paint(QPainter *p)
  {
      QPolygonF pts = m_hoverPoints->points();

      QGradient g;

      if (m_gradientType == Qt::LinearGradientPattern) {
          g = QLinearGradient(pts.at(0), pts.at(1));

      } else if (m_gradientType == Qt::RadialGradientPattern) {
          g = QRadialGradient(pts.at(0), qMin(width(), height()) / 3.0, pts.at(1));

      } else {
          QLineF l(pts.at(0), pts.at(1));
          qreal angle = l.angle(QLineF(0, 0, 1, 0));
          if (l.dy() > 0)
              angle = 360 - angle;
          g = QConicalGradient(pts.at(0), angle);
      }

      for (int i = 0; i < m_stops.size(); ++i)
          g.setColorAt(m_stops.at(i).first, m_stops.at(i).second);

      g.setSpread(m_spread);

      p->setBrush(g);
      p->setPen(Qt::NoPen);

      p->drawRect(rect());

  }