Qt 5.6 | Qt Widgets | Composition Modes | composition.cpp Example File

Qt 5.6.2 Reference Documentation

# composition.cpp Example File

painting/composition/composition.cpp

      /****************************************************************************
      **
      ** Copyright (C) 2015 The Qt Company Ltd.
      ** Contact: http://www.qt.io/licensing/
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      ** This file is part of the demonstration applications of the Qt Toolkit.
      **
      ** $QT_BEGIN_LICENSE:LGPL21$
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      ** Alternatively, this file may be used under the terms of the GNU Lesser
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      ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
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      #include "composition.h"
      #include <QBoxLayout>
      #include <QRadioButton>
      #include <QTimer>
      #include <QDateTime>
      #include <QSlider>
      #include <QMouseEvent>
      #include <qmath.h>

      const int animationInterval = 15; // update every 16 ms = ~60FPS

      CompositionWidget::CompositionWidget(QWidget *parent)
          : QWidget(parent)
      {
          CompositionRenderer *view = new CompositionRenderer(this);

          QGroupBox *mainGroup = new QGroupBox(parent);
          mainGroup->setTitle(tr("Composition Modes"));

          QGroupBox *modesGroup = new QGroupBox(mainGroup);
          modesGroup->setTitle(tr("Mode"));

          rbClear = new QRadioButton(tr("Clear"), modesGroup);
          connect(rbClear, SIGNAL(clicked()), view, SLOT(setClearMode()));
          rbSource = new QRadioButton(tr("Source"), modesGroup);
          connect(rbSource, SIGNAL(clicked()), view, SLOT(setSourceMode()));
          rbDest = new QRadioButton(tr("Destination"), modesGroup);
          connect(rbDest, SIGNAL(clicked()), view, SLOT(setDestMode()));
          rbSourceOver = new QRadioButton(tr("Source Over"), modesGroup);
          connect(rbSourceOver, SIGNAL(clicked()), view, SLOT(setSourceOverMode()));
          rbDestOver = new QRadioButton(tr("Destination Over"), modesGroup);
          connect(rbDestOver, SIGNAL(clicked()), view, SLOT(setDestOverMode()));
          rbSourceIn = new QRadioButton(tr("Source In"), modesGroup);
          connect(rbSourceIn, SIGNAL(clicked()), view, SLOT(setSourceInMode()));
          rbDestIn = new QRadioButton(tr("Dest In"), modesGroup);
          connect(rbDestIn, SIGNAL(clicked()), view, SLOT(setDestInMode()));
          rbSourceOut = new QRadioButton(tr("Source Out"), modesGroup);
          connect(rbSourceOut, SIGNAL(clicked()), view, SLOT(setSourceOutMode()));
          rbDestOut = new QRadioButton(tr("Dest Out"), modesGroup);
          connect(rbDestOut, SIGNAL(clicked()), view, SLOT(setDestOutMode()));
          rbSourceAtop = new QRadioButton(tr("Source Atop"), modesGroup);
          connect(rbSourceAtop, SIGNAL(clicked()), view, SLOT(setSourceAtopMode()));
          rbDestAtop = new QRadioButton(tr("Dest Atop"), modesGroup);
          connect(rbDestAtop, SIGNAL(clicked()), view, SLOT(setDestAtopMode()));
          rbXor = new QRadioButton(tr("Xor"), modesGroup);
          connect(rbXor, SIGNAL(clicked()), view, SLOT(setXorMode()));

          rbPlus = new QRadioButton(tr("Plus"), modesGroup);
          connect(rbPlus, SIGNAL(clicked()), view, SLOT(setPlusMode()));
          rbMultiply = new QRadioButton(tr("Multiply"), modesGroup);
          connect(rbMultiply, SIGNAL(clicked()), view, SLOT(setMultiplyMode()));
          rbScreen = new QRadioButton(tr("Screen"), modesGroup);
          connect(rbScreen, SIGNAL(clicked()), view, SLOT(setScreenMode()));
          rbOverlay = new QRadioButton(tr("Overlay"), modesGroup);
          connect(rbOverlay, SIGNAL(clicked()), view, SLOT(setOverlayMode()));
          rbDarken = new QRadioButton(tr("Darken"), modesGroup);
          connect(rbDarken, SIGNAL(clicked()), view, SLOT(setDarkenMode()));
          rbLighten = new QRadioButton(tr("Lighten"), modesGroup);
          connect(rbLighten, SIGNAL(clicked()), view, SLOT(setLightenMode()));
          rbColorDodge = new QRadioButton(tr("Color Dodge"), modesGroup);
          connect(rbColorDodge, SIGNAL(clicked()), view, SLOT(setColorDodgeMode()));
          rbColorBurn = new QRadioButton(tr("Color Burn"), modesGroup);
          connect(rbColorBurn, SIGNAL(clicked()), view, SLOT(setColorBurnMode()));
          rbHardLight = new QRadioButton(tr("Hard Light"), modesGroup);
          connect(rbHardLight, SIGNAL(clicked()), view, SLOT(setHardLightMode()));
          rbSoftLight = new QRadioButton(tr("Soft Light"), modesGroup);
          connect(rbSoftLight, SIGNAL(clicked()), view, SLOT(setSoftLightMode()));
          rbDifference = new QRadioButton(tr("Difference"), modesGroup);
          connect(rbDifference, SIGNAL(clicked()), view, SLOT(setDifferenceMode()));
          rbExclusion = new QRadioButton(tr("Exclusion"), modesGroup);
          connect(rbExclusion, SIGNAL(clicked()), view, SLOT(setExclusionMode()));

          QGroupBox *circleColorGroup = new QGroupBox(mainGroup);
          circleColorGroup->setTitle(tr("Circle color"));
          QSlider *circleColorSlider = new QSlider(Qt::Horizontal, circleColorGroup);
          circleColorSlider->setRange(0, 359);
          circleColorSlider->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
          connect(circleColorSlider, SIGNAL(valueChanged(int)), view, SLOT(setCircleColor(int)));

          QGroupBox *circleAlphaGroup = new QGroupBox(mainGroup);
          circleAlphaGroup->setTitle(tr("Circle alpha"));
          QSlider *circleAlphaSlider = new QSlider(Qt::Horizontal, circleAlphaGroup);
          circleAlphaSlider->setRange(0, 255);
          circleAlphaSlider->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
          connect(circleAlphaSlider, SIGNAL(valueChanged(int)), view, SLOT(setCircleAlpha(int)));

          QPushButton *showSourceButton = new QPushButton(mainGroup);
          showSourceButton->setText(tr("Show Source"));
      #if defined(USE_OPENGL) && !defined(QT_OPENGL_ES)
          QPushButton *enableOpenGLButton = new QPushButton(mainGroup);
          enableOpenGLButton->setText(tr("Use OpenGL"));
          enableOpenGLButton->setCheckable(true);
          enableOpenGLButton->setChecked(view->usesOpenGL());

          if (!QGLFormat::hasOpenGL() || !QGLPixelBuffer::hasOpenGLPbuffers())
              enableOpenGLButton->hide();
      #endif
          QPushButton *whatsThisButton = new QPushButton(mainGroup);
          whatsThisButton->setText(tr("What's This?"));
          whatsThisButton->setCheckable(true);

          QPushButton *animateButton = new QPushButton(mainGroup);
          animateButton->setText(tr("Animated"));
          animateButton->setCheckable(true);
          animateButton->setChecked(true);

          QHBoxLayout *viewLayout = new QHBoxLayout(this);
          viewLayout->addWidget(view);
          viewLayout->addWidget(mainGroup);

          QVBoxLayout *mainGroupLayout = new QVBoxLayout(mainGroup);
          mainGroupLayout->addWidget(circleColorGroup);
          mainGroupLayout->addWidget(circleAlphaGroup);
          mainGroupLayout->addWidget(modesGroup);
          mainGroupLayout->addStretch();
          mainGroupLayout->addWidget(animateButton);
          mainGroupLayout->addWidget(whatsThisButton);
          mainGroupLayout->addWidget(showSourceButton);
      #if defined(USE_OPENGL) && !defined(QT_OPENGL_ES)
          mainGroupLayout->addWidget(enableOpenGLButton);
      #endif

          QGridLayout *modesLayout = new QGridLayout(modesGroup);
          modesLayout->addWidget(rbClear, 0, 0);
          modesLayout->addWidget(rbSource, 1, 0);
          modesLayout->addWidget(rbDest, 2, 0);
          modesLayout->addWidget(rbSourceOver, 3, 0);
          modesLayout->addWidget(rbDestOver, 4, 0);
          modesLayout->addWidget(rbSourceIn, 5, 0);
          modesLayout->addWidget(rbDestIn, 6, 0);
          modesLayout->addWidget(rbSourceOut, 7, 0);
          modesLayout->addWidget(rbDestOut, 8, 0);
          modesLayout->addWidget(rbSourceAtop, 9, 0);
          modesLayout->addWidget(rbDestAtop, 10, 0);
          modesLayout->addWidget(rbXor, 11, 0);

          modesLayout->addWidget(rbPlus, 0, 1);
          modesLayout->addWidget(rbMultiply, 1, 1);
          modesLayout->addWidget(rbScreen, 2, 1);
          modesLayout->addWidget(rbOverlay, 3, 1);
          modesLayout->addWidget(rbDarken, 4, 1);
          modesLayout->addWidget(rbLighten, 5, 1);
          modesLayout->addWidget(rbColorDodge, 6, 1);
          modesLayout->addWidget(rbColorBurn, 7, 1);
          modesLayout->addWidget(rbHardLight, 8, 1);
          modesLayout->addWidget(rbSoftLight, 9, 1);
          modesLayout->addWidget(rbDifference, 10, 1);
          modesLayout->addWidget(rbExclusion, 11, 1);

          QVBoxLayout *circleColorLayout = new QVBoxLayout(circleColorGroup);
          circleColorLayout->addWidget(circleColorSlider);

          QVBoxLayout *circleAlphaLayout = new QVBoxLayout(circleAlphaGroup);
          circleAlphaLayout->addWidget(circleAlphaSlider);

          view->loadDescription(":res/composition/composition.html");
          view->loadSourceFile(":res/composition/composition.cpp");

          connect(whatsThisButton, SIGNAL(clicked(bool)), view, SLOT(setDescriptionEnabled(bool)));
          connect(view, SIGNAL(descriptionEnabledChanged(bool)), whatsThisButton, SLOT(setChecked(bool)));
          connect(showSourceButton, SIGNAL(clicked()), view, SLOT(showSource()));
      #if defined(USE_OPENGL) && !defined(QT_OPENGL_ES)
          connect(enableOpenGLButton, SIGNAL(clicked(bool)), view, SLOT(enableOpenGL(bool)));
      #endif
          connect(animateButton, SIGNAL(toggled(bool)), view, SLOT(setAnimationEnabled(bool)));

          circleColorSlider->setValue(270);
          circleAlphaSlider->setValue(200);
          rbSourceOut->animateClick();

          setWindowTitle(tr("Composition Modes"));
      }

      void CompositionWidget::nextMode()
      {
          /*
            if (!m_animation_enabled)
            return;
            if (rbClear->isChecked()) rbSource->animateClick();
            if (rbSource->isChecked()) rbDest->animateClick();
            if (rbDest->isChecked()) rbSourceOver->animateClick();
            if (rbSourceOver->isChecked()) rbDestOver->animateClick();
            if (rbDestOver->isChecked()) rbSourceIn->animateClick();
            if (rbSourceIn->isChecked()) rbDestIn->animateClick();
            if (rbDestIn->isChecked()) rbSourceOut->animateClick();
            if (rbSourceOut->isChecked()) rbDestOut->animateClick();
            if (rbDestOut->isChecked()) rbSourceAtop->animateClick();
            if (rbSourceAtop->isChecked()) rbDestAtop->animateClick();
            if (rbDestAtop->isChecked()) rbXor->animateClick();
            if (rbXor->isChecked()) rbClear->animateClick();
          */
      }

      CompositionRenderer::CompositionRenderer(QWidget *parent)
          : ArthurFrame(parent)
      {
          m_animation_enabled = true;
          m_animationTimer = startTimer(animationInterval);
          m_image = QImage(":res/composition/flower.jpg");
          m_image.setAlphaChannel(QImage(":res/composition/flower_alpha.jpg"));
          m_circle_alpha = 127;
          m_circle_hue = 255;
          m_current_object = NoObject;
          m_composition_mode = QPainter::CompositionMode_SourceOut;

          m_circle_pos = QPoint(200, 100);

          setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
      #ifdef USE_OPENGL
          m_pbuffer = 0;
          m_pbuffer_size = 1024;
      #endif
      }

      QRectF rectangle_around(const QPointF &p, const QSizeF &size = QSize(250, 200))
      {
          QRectF rect(p, size);
          rect.translate(-size.width()/2, -size.height()/2);
          return rect;
      }

      void CompositionRenderer::setAnimationEnabled(bool enabled)
      {
          if (m_animation_enabled == enabled)
              return;
          m_animation_enabled = enabled;
          if (enabled) {
              Q_ASSERT(!m_animationTimer);
              m_animationTimer = startTimer(animationInterval);
          } else {
              killTimer(m_animationTimer);
              m_animationTimer = 0;
          }
      }

      void CompositionRenderer::updateCirclePos()
      {
          if (m_current_object != NoObject)
              return;
          QDateTime dt = QDateTime::currentDateTime();
          qreal t = (dt.toTime_t() * 1000 + dt.time().msec()) / 1000.0;

          qreal x = width() / qreal(2) + (qCos(t*8/11) + qSin(-t)) * width() / qreal(4);
          qreal y = height() / qreal(2) + (qSin(t*6/7) + qCos(t * qreal(1.5))) * height() / qreal(4);

          setCirclePos(QLineF(m_circle_pos, QPointF(x, y)).pointAt(0.02));
      }

      void CompositionRenderer::drawBase(QPainter &p)
      {
          p.setPen(Qt::NoPen);

          QLinearGradient rect_gradient(0, 0, 0, height());
          rect_gradient.setColorAt(0, Qt::red);
          rect_gradient.setColorAt(.17, Qt::yellow);
          rect_gradient.setColorAt(.33, Qt::green);
          rect_gradient.setColorAt(.50, Qt::cyan);
          rect_gradient.setColorAt(.66, Qt::blue);
          rect_gradient.setColorAt(.81, Qt::magenta);
          rect_gradient.setColorAt(1, Qt::red);
          p.setBrush(rect_gradient);
          p.drawRect(width() / 2, 0, width() / 2, height());

          QLinearGradient alpha_gradient(0, 0, width(), 0);
          alpha_gradient.setColorAt(0, Qt::white);
          alpha_gradient.setColorAt(0.2, Qt::white);
          alpha_gradient.setColorAt(0.5, Qt::transparent);
          alpha_gradient.setColorAt(0.8, Qt::white);
          alpha_gradient.setColorAt(1, Qt::white);

          p.setCompositionMode(QPainter::CompositionMode_DestinationIn);
          p.setBrush(alpha_gradient);
          p.drawRect(0, 0, width(), height());

          p.setCompositionMode(QPainter::CompositionMode_DestinationOver);

          p.setPen(Qt::NoPen);
          p.setRenderHint(QPainter::SmoothPixmapTransform);
          p.drawImage(rect(), m_image);
      }

      void CompositionRenderer::drawSource(QPainter &p)
      {
          p.setPen(Qt::NoPen);
          p.setRenderHint(QPainter::Antialiasing);
          p.setCompositionMode(m_composition_mode);

          QRectF circle_rect = rectangle_around(m_circle_pos);
          QColor color = QColor::fromHsvF(m_circle_hue / 360.0, 1, 1, m_circle_alpha / 255.0);
          QLinearGradient circle_gradient(circle_rect.topLeft(), circle_rect.bottomRight());
          circle_gradient.setColorAt(0, color.light());
          circle_gradient.setColorAt(0.5, color);
          circle_gradient.setColorAt(1, color.dark());
          p.setBrush(circle_gradient);

          p.drawEllipse(circle_rect);
      }

      void CompositionRenderer::paint(QPainter *painter)
      {
      #if defined(USE_OPENGL) && !defined(QT_OPENGL_ES)
          if (usesOpenGL()) {

              int new_pbuf_size = m_pbuffer_size;
              if (size().width() > m_pbuffer_size || size().height() > m_pbuffer_size)
                  new_pbuf_size *= 2;

              if (size().width() < m_pbuffer_size/2 && size().height() < m_pbuffer_size/2)
                  new_pbuf_size /= 2;

              if (!m_pbuffer || new_pbuf_size != m_pbuffer_size) {
                  if (m_pbuffer) {
                      m_pbuffer->deleteTexture(m_base_tex);
                      m_pbuffer->deleteTexture(m_compositing_tex);
                      delete m_pbuffer;
                  }

                  m_pbuffer = new QGLPixelBuffer(QSize(new_pbuf_size, new_pbuf_size), QGLFormat::defaultFormat(), glWidget());
                  m_pbuffer->makeCurrent();
                  m_base_tex = m_pbuffer->generateDynamicTexture();
                  m_compositing_tex = m_pbuffer->generateDynamicTexture();
                  m_pbuffer_size = new_pbuf_size;
              }

              if (size() != m_previous_size) {
                  m_previous_size = size();
                  QPainter p(m_pbuffer);
                  p.setCompositionMode(QPainter::CompositionMode_Source);
                  p.fillRect(QRect(0, 0, m_pbuffer->width(), m_pbuffer->height()), Qt::transparent);
                  drawBase(p);
                  p.end();
                  m_pbuffer->updateDynamicTexture(m_base_tex);
              }

              qreal x_fraction = width()/float(m_pbuffer->width());
              qreal y_fraction = height()/float(m_pbuffer->height());

              {
                  QPainter p(m_pbuffer);
                  p.setCompositionMode(QPainter::CompositionMode_Source);
                  p.fillRect(QRect(0, 0, m_pbuffer->width(), m_pbuffer->height()), Qt::transparent);

                  p.save(); // Needed when using the GL1 engine
                  p.beginNativePainting(); // Needed when using the GL2 engine

                  glBindTexture(GL_TEXTURE_2D, m_base_tex);
                  glEnable(GL_TEXTURE_2D);
                  glColor4f(1.,1.,1.,1.);

                  glBegin(GL_QUADS);
                  {
                      glTexCoord2f(0, 1.0);
                      glVertex2f(0, 0);

                      glTexCoord2f(x_fraction, 1.0);
                      glVertex2f(width(), 0);

                      glTexCoord2f(x_fraction, 1.0-y_fraction);
                      glVertex2f(width(), height());

                      glTexCoord2f(0, 1.0-y_fraction);
                      glVertex2f(0, height());
                  }
                  glEnd();

                  glDisable(GL_TEXTURE_2D);

                  p.endNativePainting(); // Needed when using the GL2 engine
                  p.restore(); // Needed when using the GL1 engine

                  drawSource(p);
                  p.end();
                  m_pbuffer->updateDynamicTexture(m_compositing_tex);
              }

              painter->beginNativePainting(); // Needed when using the GL2 engine
              glWidget()->makeCurrent(); // Needed when using the GL1 engine
              glBindTexture(GL_TEXTURE_2D, m_compositing_tex);
              glEnable(GL_TEXTURE_2D);
              glEnable(GL_BLEND);
              glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
              glColor4f(1.,1.,1.,1.);
              glBegin(GL_QUADS);
              {
                  glTexCoord2f(0, 1.0);
                  glVertex2f(0, 0);

                  glTexCoord2f(x_fraction, 1.0);
                  glVertex2f(width(), 0);

                  glTexCoord2f(x_fraction, 1.0-y_fraction);
                  glVertex2f(width(), height());

                  glTexCoord2f(0, 1.0-y_fraction);
                  glVertex2f(0, height());
              }
              glEnd();
              glDisable(GL_TEXTURE_2D);
              painter->endNativePainting(); // Needed when using the GL2 engine
          } else
      #endif
          {
              // using a QImage
              if (m_buffer.size() != size()) {
                  m_buffer = QImage(size(), QImage::Format_ARGB32_Premultiplied);
                  m_base_buffer = QImage(size(), QImage::Format_ARGB32_Premultiplied);

                  m_base_buffer.fill(0);

                  QPainter p(&m_base_buffer);

                  drawBase(p);
              }

              memcpy(m_buffer.bits(), m_base_buffer.bits(), m_buffer.byteCount());

              {
                  QPainter p(&m_buffer);
                  drawSource(p);
              }

              painter->drawImage(0, 0, m_buffer);
          }
      }

      void CompositionRenderer::mousePressEvent(QMouseEvent *e)
      {
          setDescriptionEnabled(false);

          QRectF circle = rectangle_around(m_circle_pos);

          if (circle.contains(e->pos())) {
              m_current_object = Circle;
              m_offset = circle.center() - e->pos();
          } else {
              m_current_object = NoObject;
          }
          if (m_animation_enabled) {
              killTimer(m_animationTimer);
              m_animationTimer = 0;
          }
      }

      void CompositionRenderer::mouseMoveEvent(QMouseEvent *e)
      {
          if (m_current_object == Circle)
              setCirclePos(e->pos() + m_offset);
      }

      void CompositionRenderer::mouseReleaseEvent(QMouseEvent *)
      {
          m_current_object = NoObject;

          if (m_animation_enabled) {
              Q_ASSERT(!m_animationTimer);
              m_animationTimer = startTimer(animationInterval);
          }
      }

      void CompositionRenderer::timerEvent(QTimerEvent *event)
      {
          if (event->timerId() == m_animationTimer)
              updateCirclePos();
      }

      void CompositionRenderer::setCirclePos(const QPointF &pos)
      {
          const QRect oldRect = rectangle_around(m_circle_pos).toAlignedRect();
          m_circle_pos = pos;
          const QRect newRect = rectangle_around(m_circle_pos).toAlignedRect();
      #if defined(USE_OPENGL) && !defined(QT_OPENGL_ES)
          if (usesOpenGL()) {
              update();
              return;
          }
      #endif
          update(oldRect | newRect);
      }