From 5b9ce5d1298f5dffd986b422857cd1624693cabd Mon Sep 17 00:00:00 2001
From: Allan Sandfeld Jensen <allan.jensen@qt.io>
Date: Fri, 15 Dec 2023 13:29:56 +0100
Subject: Simplify QTransform mapping

The generic map can handle projective including the clip, so remove
the unneeded specialized paths. The only remaining projective codepath
is for painter paths which can include curves.

Change-Id: I78fb86c9fe8ce8f126861ccad08c5b29f98c6b05
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
---
 src/gui/painting/qtransform.cpp | 53 ++++-------------------------------------
 1 file changed, 4 insertions(+), 49 deletions(-)

(limited to 'src/gui/painting')

diff --git a/src/gui/painting/qtransform.cpp b/src/gui/painting/qtransform.cpp
index fbb335479a..df57d2c190 100644
--- a/src/gui/painting/qtransform.cpp
+++ b/src/gui/painting/qtransform.cpp
@@ -54,7 +54,7 @@ static void nanWarning(const char *func)
             if (t == TxProject) {                                       \
                 qreal w = (m_matrix[0][2] * FX_ + m_matrix[1][2] * FY_ + m_matrix[2][2]);              \
                 if (w < qreal(Q_NEAR_CLIP)) w = qreal(Q_NEAR_CLIP);     \
-                w = 1./w;                                               \
+                w = qreal(1.)/w;                                        \
                 nx *= w;                                                \
                 ny *= w;                                                \
             }                                                           \
@@ -1256,28 +1256,6 @@ QLineF QTransform::map(const QLineF &l) const
     return QLineF(x1, y1, x2, y2);
 }
 
-static QPolygonF mapProjective(const QTransform &transform, const QPolygonF &poly)
-{
-    if (poly.size() == 0)
-        return poly;
-
-    if (poly.size() == 1)
-        return QPolygonF() << transform.map(poly.at(0));
-
-    QPainterPath path;
-    path.addPolygon(poly);
-
-    path = transform.map(path);
-
-    QPolygonF result;
-    const int elementCount = path.elementCount();
-    result.reserve(elementCount);
-    for (int i = 0; i < elementCount; ++i)
-        result << path.elementAt(i);
-    return result;
-}
-
-
 /*!
     \fn QPolygonF operator *(const QPolygonF &polygon, const QTransform &matrix)
     \since 4.3
@@ -1311,9 +1289,6 @@ QPolygonF QTransform::map(const QPolygonF &a) const
     if (t <= TxTranslate)
         return a.translated(m_matrix[2][0], m_matrix[2][1]);
 
-    if (t >= QTransform::TxProject)
-        return mapProjective(*this, a);
-
     int size = a.size();
     int i;
     QPolygonF p(size);
@@ -1341,9 +1316,6 @@ QPolygon QTransform::map(const QPolygon &a) const
     if (t <= TxTranslate)
         return a.translated(qRound(m_matrix[2][0]), qRound(m_matrix[2][1]));
 
-    if (t >= QTransform::TxProject)
-        return mapProjective(*this, QPolygonF(a)).toPolygon();
-
     int size = a.size();
     int i;
     QPolygon p(size);
@@ -1774,14 +1746,6 @@ void QTransform::setMatrix(qreal m11, qreal m12, qreal m13,
     m_dirty = TxProject;
 }
 
-static inline bool needsPerspectiveClipping(const QRectF &rect, const QTransform &transform)
-{
-    const qreal wx = qMin(transform.m13() * rect.left(), transform.m13() * rect.right());
-    const qreal wy = qMin(transform.m23() * rect.top(), transform.m23() * rect.bottom());
-
-    return wx + wy + transform.m33() < Q_NEAR_CLIP;
-}
-
 QRect QTransform::mapRect(const QRect &rect) const
 {
     TransformationType t = inline_type();
@@ -1802,8 +1766,7 @@ QRect QTransform::mapRect(const QRect &rect) const
             y -= h;
         }
         return QRect(x, y, w, h);
-    } else if (t < TxProject || !needsPerspectiveClipping(rect, *this)) {
-        // see mapToPolygon for explanations of the algorithm.
+    } else {
         qreal x = 0, y = 0;
         MAP(rect.left(), rect.top(), x, y);
         qreal xmin = x;
@@ -1825,11 +1788,7 @@ QRect QTransform::mapRect(const QRect &rect) const
         ymin = qMin(ymin, y);
         xmax = qMax(xmax, x);
         ymax = qMax(ymax, y);
-        return QRect(qRound(xmin), qRound(ymin), qRound(xmax)-qRound(xmin), qRound(ymax)-qRound(ymin));
-    } else {
-        QPainterPath path;
-        path.addRect(rect);
-        return map(path).boundingRect().toRect();
+        return QRectF(xmin, ymin, xmax-xmin, ymax-ymin).toRect();
     }
 }
 
@@ -1872,7 +1831,7 @@ QRectF QTransform::mapRect(const QRectF &rect) const
             y -= h;
         }
         return QRectF(x, y, w, h);
-    } else if (t < TxProject || !needsPerspectiveClipping(rect, *this)) {
+    } else {
         qreal x = 0, y = 0;
         MAP(rect.x(), rect.y(), x, y);
         qreal xmin = x;
@@ -1895,10 +1854,6 @@ QRectF QTransform::mapRect(const QRectF &rect) const
         xmax = qMax(xmax, x);
         ymax = qMax(ymax, y);
         return QRectF(xmin, ymin, xmax-xmin, ymax - ymin);
-    } else {
-        QPainterPath path;
-        path.addRect(rect);
-        return map(path).boundingRect();
     }
 }
 
-- 
cgit v1.2.3