composition.cpp Example File

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#include "composition.h"
#include <QBoxLayout>
#include <QRadioButton>
#include <QTimer>
#include <QDateTime>
#include <QSlider>
#include <QMouseEvent>
#include <qmath.h>
#if QT_CONFIG(opengl)
#include <QOpenGLFunctions>
#include <QOpenGLWindow>
#endif
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 QT_CONFIG(opengl)
    QPushButton *enableOpenGLButton = new QPushButton(mainGroup);
    enableOpenGLButton->setText(tr("Use OpenGL"));
    enableOpenGLButton->setCheckable(true);
    enableOpenGLButton->setChecked(view->usesOpenGL());
#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 QT_CONFIG(opengl)
    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 QT_CONFIG(opengl)
    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);
#if QT_CONFIG(opengl)
    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 QT_CONFIG(opengl)
    if (usesOpenGL() && glWindow()->isValid()) {
        if (!m_blitter.isCreated())
            m_blitter.create();
        int new_pbuf_size = m_pbuffer_size;
        while (size().width() > new_pbuf_size || size().height() > new_pbuf_size)
            new_pbuf_size *= 2;
        while (size().width() < new_pbuf_size/2 && size().height() < new_pbuf_size/2)
            new_pbuf_size /= 2;
        if (!m_fbo || new_pbuf_size != m_pbuffer_size) {
            m_fbo.reset(new QFboPaintDevice(QSize(new_pbuf_size, new_pbuf_size), false, false));
            m_pbuffer_size = new_pbuf_size;
        }
        if (size() != m_previous_size) {
            m_previous_size = size();
            QPainter p(m_fbo.data());
            p.setCompositionMode(QPainter::CompositionMode_Source);
            p.fillRect(QRect(QPoint(0, 0), size()), Qt::transparent);
            p.setCompositionMode(QPainter::CompositionMode_SourceOver);
            drawBase(p);
            p.end();
            m_base_tex = m_fbo->takeTexture();
        }
        painter->beginNativePainting();
        {
            QPainter p(m_fbo.data());
            p.beginNativePainting();
            m_blitter.bind();
            const QRect targetRect(QPoint(0, 0), m_fbo->size());
            const QMatrix4x4 target = QOpenGLTextureBlitter::targetTransform(targetRect, QRect(QPoint(0, 0), m_fbo->size()));
            m_blitter.blit(m_base_tex, target, QOpenGLTextureBlitter::OriginBottomLeft);
            m_blitter.release();
            p.endNativePainting();
            drawSource(p);
            p.end();
            m_compositing_tex = m_fbo->takeTexture();
        }
        painter->endNativePainting();
        painter->beginNativePainting();
        auto *funcs = QOpenGLContext::currentContext()->functions();
        funcs->glEnable(GL_BLEND);
        funcs->glBlendEquation(GL_FUNC_ADD);
        funcs->glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
        m_blitter.bind();
        const QRect targetRect(QPoint(0, 0), m_fbo->size());
        const QMatrix4x4 target = QOpenGLTextureBlitter::targetTransform(targetRect, QRect(QPoint(0, 0), size()));
        m_blitter.blit(m_compositing_tex, target, QOpenGLTextureBlitter::OriginBottomLeft);
        m_blitter.release();
        painter->endNativePainting();
    } 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.sizeInBytes());
        {
            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 QT_CONFIG(opengl)
    if (usesOpenGL()) {
        update();
        return;
    }
#endif
    update(oldRect | newRect);
}