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List:       kde-commits
Subject:    [Calligra] b902835: assistants: fix RulerAssistant for horizontal line
From:       Geoffry Song <goffrie () gmail ! com>
Date:       2010-12-21 21:29:41
Message-ID: 20101221212941.D9AB6A60B9 () git ! kde ! org
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commit b902835511c00d02d7b2e35ca648d7d01d8962a6
branch master
Author: Geoffry Song <goffrie@gmail.com>
Date:   Tue Dec 21 15:15:09 2010 -0500

    assistants: fix RulerAssistant for horizontal lines

diff --git a/krita/plugins/assistants/RulerAssistant/RulerAssistant.cc \
b/krita/plugins/assistants/RulerAssistant/RulerAssistant.cc index da75975..930daab \
                100644
--- a/krita/plugins/assistants/RulerAssistant/RulerAssistant.cc
+++ b/krita/plugins/assistants/RulerAssistant/RulerAssistant.cc
@@ -36,16 +36,17 @@ RulerAssistant::RulerAssistant()
 QPointF RulerAssistant::project(const QPointF& pt) const
 {
     Q_ASSERT(handles().size() == 2);
-    double x1 = handles()[0]->x();
-    double y1 = handles()[0]->y();
-    double x2 = handles()[1]->x();
-    double y2 = handles()[1]->y();
-    double a1 = (y2 - y1) / (x2 - x1);
-    double b1 = y1 - x1 * a1;
-    double a2 = (x2 - x1) / (y1 - y2);
-    double b2 = pt.y() - a2 * pt.x();
-    double xm = (b2 - b1) / (a1 - a2);
-    return QPointF(xm, xm * a1 + b1);
+    const QLineF line(*handles()[0], *handles()[1]);
+    const qreal
+        dx = line.dx(),
+        dy = line.dy(),
+        dx2 = dx * dx,
+        dy2 = dy * dy,
+        invsqrlen = 1.0 / (dx2 + dy2);
+    QPointF r(dx2 * pt.x() + dy2 * line.x1() + dx * dy * (pt.y() - line.y1()),
+            dx2 * line.y1() + dy2 * pt.y() + dx * dy * (pt.x() - line.x1()));
+    r *= invsqrlen;
+    return r;
 }
 
 QPointF RulerAssistant::adjustPosition(const QPointF& pt, const QPointF& \
/*strokeBegin*/)


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