File indexing completed on 2024-05-19 16:34:46

 /*
     SPDX-FileCopyrightText: 2021 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
 
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #include "scene/shadowitem.h"
 #include "deleted.h"
 #include "shadow.h"
 
 namespace KWin
 {
 
 ShadowItem::ShadowItem(Shadow *shadow, Window *window, Scene *scene, Item *parent)
     : Item(scene, parent)
     , m_window(window)
     , m_shadow(shadow)
 {
     connect(window, &Window::windowClosed, this, &ShadowItem::handleWindowClosed);
 
     connect(shadow, &Shadow::offsetChanged, this, &ShadowItem::updateGeometry);
     connect(shadow, &Shadow::rectChanged, this, &ShadowItem::updateGeometry);
     connect(shadow, &Shadow::textureChanged, this, &ShadowItem::handleTextureChanged);
 
     updateGeometry();
     handleTextureChanged();
 }
 
 ShadowItem::~ShadowItem()
 {
 }
 
 Shadow *ShadowItem::shadow() const
 {
     return m_shadow;
 }
 
 void ShadowItem::updateGeometry()
 {
     const QRectF rect = m_shadow->rect() + m_shadow->offset();
 
     setPosition(rect.topLeft());
     setSize(rect.size());
     discardQuads();
 }
 
 void ShadowItem::handleTextureChanged()
 {
     scheduleRepaint(rect());
     discardQuads();
 }
 
 void ShadowItem::handleWindowClosed(Window *original, Deleted *deleted)
 {
     m_window = deleted;
 }
 
 static inline void distributeHorizontally(QRectF &leftRect, QRectF &rightRect)
 {
     if (leftRect.right() > rightRect.left()) {
         const qreal boundedRight = std::min(leftRect.right(), rightRect.right());
         const qreal boundedLeft = std::max(leftRect.left(), rightRect.left());
         const qreal halfOverlap = (boundedRight - boundedLeft) / 2.0;
         leftRect.setRight(boundedRight - halfOverlap);
         rightRect.setLeft(boundedLeft + halfOverlap);
     }
 }
 
 static inline void distributeVertically(QRectF &topRect, QRectF &bottomRect)
 {
     if (topRect.bottom() > bottomRect.top()) {
         const qreal boundedBottom = std::min(topRect.bottom(), bottomRect.bottom());
         const qreal boundedTop = std::max(topRect.top(), bottomRect.top());
         const qreal halfOverlap = (boundedBottom - boundedTop) / 2.0;
         topRect.setBottom(boundedBottom - halfOverlap);
         bottomRect.setTop(boundedTop + halfOverlap);
     }
 }
 
 WindowQuadList ShadowItem::buildQuads() const
 {
     // Do not draw shadows if window width or window height is less than 5 px. 5 is an arbitrary choice.
     if (!m_window->wantsShadowToBeRendered() || m_window->width() < 5 || m_window->height() < 5) {
         return WindowQuadList();
     }
 
     const QSizeF top(m_shadow->elementSize(Shadow::ShadowElementTop));
     const QSizeF topRight(m_shadow->elementSize(Shadow::ShadowElementTopRight));
     const QSizeF right(m_shadow->elementSize(Shadow::ShadowElementRight));
     const QSizeF bottomRight(m_shadow->elementSize(Shadow::ShadowElementBottomRight));
     const QSizeF bottom(m_shadow->elementSize(Shadow::ShadowElementBottom));
     const QSizeF bottomLeft(m_shadow->elementSize(Shadow::ShadowElementBottomLeft));
     const QSizeF left(m_shadow->elementSize(Shadow::ShadowElementLeft));
     const QSizeF topLeft(m_shadow->elementSize(Shadow::ShadowElementTopLeft));
 
     const QMarginsF shadowMargins(
         std::max({topLeft.width(), left.width(), bottomLeft.width()}),
         std::max({topLeft.height(), top.height(), topRight.height()}),
         std::max({topRight.width(), right.width(), bottomRight.width()}),
         std::max({bottomRight.height(), bottom.height(), bottomLeft.height()}));
 
     const QRectF outerRect = rect();
 
     const int width = shadowMargins.left() + std::max(top.width(), bottom.width()) + shadowMargins.right();
     const int height = shadowMargins.top() + std::max(left.height(), right.height()) + shadowMargins.bottom();
 
     QRectF topLeftRect;
     if (!topLeft.isEmpty()) {
         topLeftRect = QRectF(outerRect.topLeft(), topLeft);
     } else {
         topLeftRect = QRectF(outerRect.left() + shadowMargins.left(),
                              outerRect.top() + shadowMargins.top(), 0, 0);
     }
 
     QRectF topRightRect;
     if (!topRight.isEmpty()) {
         topRightRect = QRectF(outerRect.right() - topRight.width(), outerRect.top(),
                               topRight.width(), topRight.height());
     } else {
         topRightRect = QRectF(outerRect.right() - shadowMargins.right(),
                               outerRect.top() + shadowMargins.top(), 0, 0);
     }
 
     QRectF bottomRightRect;
     if (!bottomRight.isEmpty()) {
         bottomRightRect = QRectF(outerRect.right() - bottomRight.width(),
                                  outerRect.bottom() - bottomRight.height(),
                                  bottomRight.width(), bottomRight.height());
     } else {
         bottomRightRect = QRectF(outerRect.right() - shadowMargins.right(),
                                  outerRect.bottom() - shadowMargins.bottom(), 0, 0);
     }
 
     QRectF bottomLeftRect;
     if (!bottomLeft.isEmpty()) {
         bottomLeftRect = QRectF(outerRect.left(), outerRect.bottom() - bottomLeft.height(),
                                 bottomLeft.width(), bottomLeft.height());
     } else {
         bottomLeftRect = QRectF(outerRect.left() + shadowMargins.left(),
                                 outerRect.bottom() - shadowMargins.bottom(), 0, 0);
     }
 
     // Re-distribute the corner tiles so no one of them is overlapping with others.
     // By doing this, we assume that shadow's corner tiles are symmetric
     // and it is OK to not draw top/right/bottom/left tile between corners.
     // For example, let's say top-left and top-right tiles are overlapping.
     // In that case, the right side of the top-left tile will be shifted to left,
     // the left side of the top-right tile will shifted to right, and the top
     // tile won't be rendered.
     distributeHorizontally(topLeftRect, topRightRect);
     distributeHorizontally(bottomLeftRect, bottomRightRect);
     distributeVertically(topLeftRect, bottomLeftRect);
     distributeVertically(topRightRect, bottomRightRect);
 
     qreal tx1 = 0.0,
           tx2 = 0.0,
           ty1 = 0.0,
           ty2 = 0.0;
 
     WindowQuadList quads;
     quads.reserve(8);
 
     if (topLeftRect.isValid()) {
         tx1 = 0.0;
         ty1 = 0.0;
         tx2 = topLeftRect.width();
         ty2 = topLeftRect.height();
         WindowQuad topLeftQuad;
         topLeftQuad[0] = WindowVertex(topLeftRect.left(), topLeftRect.top(), tx1, ty1);
         topLeftQuad[1] = WindowVertex(topLeftRect.right(), topLeftRect.top(), tx2, ty1);
         topLeftQuad[2] = WindowVertex(topLeftRect.right(), topLeftRect.bottom(), tx2, ty2);
         topLeftQuad[3] = WindowVertex(topLeftRect.left(), topLeftRect.bottom(), tx1, ty2);
         quads.append(topLeftQuad);
     }
 
     if (topRightRect.isValid()) {
         tx1 = width - topRightRect.width();
         ty1 = 0.0;
         tx2 = width;
         ty2 = topRightRect.height();
         WindowQuad topRightQuad;
         topRightQuad[0] = WindowVertex(topRightRect.left(), topRightRect.top(), tx1, ty1);
         topRightQuad[1] = WindowVertex(topRightRect.right(), topRightRect.top(), tx2, ty1);
         topRightQuad[2] = WindowVertex(topRightRect.right(), topRightRect.bottom(), tx2, ty2);
         topRightQuad[3] = WindowVertex(topRightRect.left(), topRightRect.bottom(), tx1, ty2);
         quads.append(topRightQuad);
     }
 
     if (bottomRightRect.isValid()) {
         tx1 = width - bottomRightRect.width();
         tx2 = width;
         ty1 = height - bottomRightRect.height();
         ty2 = height;
         WindowQuad bottomRightQuad;
         bottomRightQuad[0] = WindowVertex(bottomRightRect.left(), bottomRightRect.top(), tx1, ty1);
         bottomRightQuad[1] = WindowVertex(bottomRightRect.right(), bottomRightRect.top(), tx2, ty1);
         bottomRightQuad[2] = WindowVertex(bottomRightRect.right(), bottomRightRect.bottom(), tx2, ty2);
         bottomRightQuad[3] = WindowVertex(bottomRightRect.left(), bottomRightRect.bottom(), tx1, ty2);
         quads.append(bottomRightQuad);
     }
 
     if (bottomLeftRect.isValid()) {
         tx1 = 0.0;
         tx2 = bottomLeftRect.width();
         ty1 = height - bottomLeftRect.height();
         ty2 = height;
         WindowQuad bottomLeftQuad;
         bottomLeftQuad[0] = WindowVertex(bottomLeftRect.left(), bottomLeftRect.top(), tx1, ty1);
         bottomLeftQuad[1] = WindowVertex(bottomLeftRect.right(), bottomLeftRect.top(), tx2, ty1);
         bottomLeftQuad[2] = WindowVertex(bottomLeftRect.right(), bottomLeftRect.bottom(), tx2, ty2);
         bottomLeftQuad[3] = WindowVertex(bottomLeftRect.left(), bottomLeftRect.bottom(), tx1, ty2);
         quads.append(bottomLeftQuad);
     }
 
     QRectF topRect(QPointF(topLeftRect.right(), outerRect.top()),
                    QPointF(topRightRect.left(), outerRect.top() + top.height()));
 
     QRectF rightRect(QPointF(outerRect.right() - right.width(), topRightRect.bottom()),
                      QPointF(outerRect.right(), bottomRightRect.top()));
 
     QRectF bottomRect(QPointF(bottomLeftRect.right(), outerRect.bottom() - bottom.height()),
                       QPointF(bottomRightRect.left(), outerRect.bottom()));
 
     QRectF leftRect(QPointF(outerRect.left(), topLeftRect.bottom()),
                     QPointF(outerRect.left() + left.width(), bottomLeftRect.top()));
 
     // Re-distribute left/right and top/bottom shadow tiles so they don't
     // overlap when the window is too small. Please notice that we don't
     // fix overlaps between left/top(left/bottom, right/top, and so on)
     // corner tiles because corresponding counter parts won't be valid when
     // the window is too small, which means they won't be rendered.
     distributeHorizontally(leftRect, rightRect);
     distributeVertically(topRect, bottomRect);
 
     if (topRect.isValid()) {
         tx1 = shadowMargins.left();
         ty1 = 0.0;
         tx2 = tx1 + top.width();
         ty2 = topRect.height();
         WindowQuad topQuad;
         topQuad[0] = WindowVertex(topRect.left(), topRect.top(), tx1, ty1);
         topQuad[1] = WindowVertex(topRect.right(), topRect.top(), tx2, ty1);
         topQuad[2] = WindowVertex(topRect.right(), topRect.bottom(), tx2, ty2);
         topQuad[3] = WindowVertex(topRect.left(), topRect.bottom(), tx1, ty2);
         quads.append(topQuad);
     }
 
     if (rightRect.isValid()) {
         tx1 = width - rightRect.width();
         ty1 = shadowMargins.top();
         tx2 = width;
         ty2 = ty1 + right.height();
         WindowQuad rightQuad;
         rightQuad[0] = WindowVertex(rightRect.left(), rightRect.top(), tx1, ty1);
         rightQuad[1] = WindowVertex(rightRect.right(), rightRect.top(), tx2, ty1);
         rightQuad[2] = WindowVertex(rightRect.right(), rightRect.bottom(), tx2, ty2);
         rightQuad[3] = WindowVertex(rightRect.left(), rightRect.bottom(), tx1, ty2);
         quads.append(rightQuad);
     }
 
     if (bottomRect.isValid()) {
         tx1 = shadowMargins.left();
         ty1 = height - bottomRect.height();
         tx2 = tx1 + bottom.width();
         ty2 = height;
         WindowQuad bottomQuad;
         bottomQuad[0] = WindowVertex(bottomRect.left(), bottomRect.top(), tx1, ty1);
         bottomQuad[1] = WindowVertex(bottomRect.right(), bottomRect.top(), tx2, ty1);
         bottomQuad[2] = WindowVertex(bottomRect.right(), bottomRect.bottom(), tx2, ty2);
         bottomQuad[3] = WindowVertex(bottomRect.left(), bottomRect.bottom(), tx1, ty2);
         quads.append(bottomQuad);
     }
 
     if (leftRect.isValid()) {
         tx1 = 0.0;
         ty1 = shadowMargins.top();
         tx2 = leftRect.width();
         ty2 = ty1 + left.height();
         WindowQuad leftQuad;
         leftQuad[0] = WindowVertex(leftRect.left(), leftRect.top(), tx1, ty1);
         leftQuad[1] = WindowVertex(leftRect.right(), leftRect.top(), tx2, ty1);
         leftQuad[2] = WindowVertex(leftRect.right(), leftRect.bottom(), tx2, ty2);
         leftQuad[3] = WindowVertex(leftRect.left(), leftRect.bottom(), tx1, ty2);
         quads.append(leftQuad);
     }
 
     return quads;
 }
 
 } // namespace KWin