AuroraMiddleware/qt5base-lts
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Examples: use std::atan2 for simper angle calculations

Browse Source 
Using std::atan2 gets the right answer directly from dy and dx,
without having to fix up quadrant as we needed to with acos (albeit we
have to negate dy in some cases, to match prior sense of angles).  In
the process, it avoids explicit division, which would be an error when
the line's length is zero.

Change-Id: Ia2923159d38834e08e6f15cbff6766ed419fa804
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
This commit is contained in:
Edward Welbourne 2017-01-11 11:35:25 +01:00
parent 89870a35bd
commit 0b822c2209
5 changed files with 13 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
examples/touch/pinchzoom/mouse.cpp
View File

@ -54,7 +54,7 @@
#include <QPainter>
#include <QStyleOption>
#include <math.h>
#include <cmath>
static const double Pi = 3.14159265358979323846264338327950288419717;
static double TwoPi = 2.0 * Pi;
@ -139,9 +139,7 @@ void Mouse::timerEvent(QTimerEvent *)
//! [5]
QLineF lineToCenter(QPointF(0, 0), mapFromScene(0, 0));
if (lineToCenter.length() > 150) {
qreal angleToCenter = ::acos(lineToCenter.dx() / lineToCenter.length());
if (lineToCenter.dy() < 0)
angleToCenter = TwoPi - angleToCenter;
qreal angleToCenter = std::atan2(lineToCenter.dy(), lineToCenter.dx());
angleToCenter = normalizeAngle((Pi - angleToCenter) + Pi / 2);
if (angleToCenter < Pi && angleToCenter > Pi / 4) {
@ -170,9 +168,7 @@ void Mouse::timerEvent(QTimerEvent *)
continue;
QLineF lineToMouse(QPointF(0, 0), mapFromItem(item, 0, 0));
qreal angleToMouse = ::acos(lineToMouse.dx() / lineToMouse.length());
if (lineToMouse.dy() < 0)
angleToMouse = TwoPi - angleToMouse;
qreal angleToMouse = std::atan2(lineToMouse.dy(), lineToMouse.dx());
angleToMouse = normalizeAngle((Pi - angleToMouse) + Pi / 2);
if (angleToMouse >= 0 && angleToMouse < Pi / 2) {

10
examples/widgets/graphicsview/collidingmice/mouse.cpp
View File

@ -54,7 +54,7 @@
#include <QPainter>
#include <QStyleOption>
#include <math.h>
#include <cmath>
static const double Pi = 3.14159265358979323846264338327950288419717;
static double TwoPi = 2.0 * Pi;
@ -140,9 +140,7 @@ void Mouse::advance(int step)
//! [5]
QLineF lineToCenter(QPointF(0, 0), mapFromScene(0, 0));
if (lineToCenter.length() > 150) {
qreal angleToCenter = ::acos(lineToCenter.dx() / lineToCenter.length());
if (lineToCenter.dy() < 0)
angleToCenter = TwoPi - angleToCenter;
qreal angleToCenter = std::atan2(lineToCenter.dy(), lineToCenter.dx());
angleToCenter = normalizeAngle((Pi - angleToCenter) + Pi / 2);
if (angleToCenter < Pi && angleToCenter > Pi / 4) {
@ -171,9 +169,7 @@ void Mouse::advance(int step)
continue;
QLineF lineToMouse(QPointF(0, 0), mapFromItem(item, 0, 0));
qreal angleToMouse = ::acos(lineToMouse.dx() / lineToMouse.length());
if (lineToMouse.dy() < 0)
angleToMouse = TwoPi - angleToMouse;
qreal angleToMouse = std::atan2(lineToMouse.dy(), lineToMouse.dx());
angleToMouse = normalizeAngle((Pi - angleToMouse) + Pi / 2);
if (angleToMouse >= 0 && angleToMouse < Pi / 2) {

6
examples/widgets/graphicsview/diagramscene/arrow.cpp
View File

@ -51,7 +51,7 @@
#include "arrow.h"
#include <math.h>
#include <cmath>
#include <QPen>
#include <QPainter>
@ -132,9 +132,7 @@ void Arrow::paint(QPainter *painter, const QStyleOptionGraphicsItem *,
setLine(QLineF(intersectPoint, myStartItem->pos()));
//! [5] //! [6]
double angle = ::acos(line().dx() / line().length());
if (line().dy() >= 0)
angle = (Pi * 2) - angle;
double angle = std::atan2(-line().dy(), line().dx());
QPointF arrowP1 = line().p1() + QPointF(sin(angle + Pi / 3) * arrowSize,
cos(angle + Pi / 3) * arrowSize);

7
examples/widgets/graphicsview/elasticnodes/edge.cpp
View File

@ -51,12 +51,11 @@
#include "edge.h"
#include "node.h"
#include <math.h>
#include <cmath>
#include <QPainter>
static const double Pi = 3.14159265358979323846264338327950288419717;
static double TwoPi = 2.0 * Pi;
//! [0]
Edge::Edge(Node *sourceNode, Node *destNode)
@ -139,9 +138,7 @@ void Edge::paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *)
//! [6]
// Draw the arrows
double angle = ::acos(line.dx() / line.length());
if (line.dy() >= 0)
angle = TwoPi - angle;
double angle = std::atan2(-line.dy(), line.dx());
QPointF sourceArrowP1 = sourcePoint + QPointF(sin(angle + Pi / 3) * arrowSize,
cos(angle + Pi / 3) * arrowSize);

6
examples/widgets/itemviews/chart/pieview.cpp
View File

@ -125,9 +125,9 @@ QModelIndex PieView::indexAt(const QPoint &point) const
return QModelIndex();
// Determine the angle of the point.
double angle = (180 / M_PI) * std::acos(cx / d);
if (cy < 0)
angle = 360 - angle;
double angle = (180 / M_PI) * std::atan2(cy, cx);
if (angle < 0)
angle = 360 + angle;
// Find the relevant slice of the pie.
double startAngle = 0.0;