composition.cpp Example File

painting/composition/composition.cpp
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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.toMSecsSinceEpoch() / 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);
}

© 2016 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.