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#include "window.h"
#include "compositor.h"

#include <QPainter>
#include <QMatrix4x4>
#include <QOpenGLFunctions>
#include <QOpenGLTexture>
#include <QRandomGenerator>

Window::Window()
{
}

void Window::setCompositor(Compositor *comp) {
    m_compositor = comp;
}

void Window::initializeGL()
{
    m_textureBlitter.create();
}

static QPoint sillyrandom(int seed, QSize screenSize, QSize surfaceSize)
{
    QRandomGenerator rand(seed);
    int xrange = qMax(screenSize.width() - surfaceSize.width(), 200);
    int yrange = qMax(screenSize.height() - surfaceSize.height(), 200);
    return QPoint(rand.bounded(xrange), rand.bounded(yrange));
}

void Window::paintGL()
{
    m_compositor->startRender();

    QOpenGLFunctions *functions = context()->functions();
    functions->glClearColor(.4f, .7f, .1f, 0.5f);
    functions->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    GLenum currentTarget = GL_TEXTURE_2D;
    m_textureBlitter.bind(currentTarget);
    functions->glEnable(GL_BLEND);
    functions->glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

    Q_FOREACH (View *view, m_compositor->views()) {
        auto texture = view->getTexture();
        if (!texture)
            continue;
        if (texture->target() != currentTarget) {
            currentTarget = texture->target();
            m_textureBlitter.bind(currentTarget);
        }
        GLuint textureId = texture->textureId();
        QWaylandSurface *surface = view->surface();
        if (surface && surface->hasContent()) {
            QSize s = surface->size();
            QPointF pos = sillyrandom(view->iviId(), size(), s);
            QRectF surfaceGeometry(pos, s);
            QOpenGLTextureBlitter::Origin surfaceOrigin =
                    view->currentBuffer().origin() == QWaylandSurface::OriginTopLeft
                    ? QOpenGLTextureBlitter::OriginTopLeft
                    : QOpenGLTextureBlitter::OriginBottomLeft;
            QMatrix4x4 targetTransform = QOpenGLTextureBlitter::targetTransform(surfaceGeometry, QRect(QPoint(), size()));
            m_textureBlitter.blit(textureId, targetTransform, surfaceOrigin);
        }
    }
    m_textureBlitter.release();
    m_compositor->endRender();
}
