Out of curiosity, I implemented a QQuickPaintedItem-based PathMask type. The result looks like this:
[image: Path_Mask.png]
The code is:
pathmask.h
#ifndef PATHMASK_H
#define PATHMASK_H
#include <QObject>
#include <QQuickItem>
#include <QQuickPaintedItem>
#include <QPainter>
#include <QPainterPath>
class PathMask : public QQuickPaintedItem
{
Q_OBJECT
public:
explicit PathMask(QQuickItem *parent = Q_NULLPTR);
~PathMask();
virtual void paint(QPainter *painter);
Q_INVOKABLE void beginPath();
Q_INVOKABLE void moveTo(qreal x, qreal y);
Q_INVOKABLE void lineTo(qreal x, qreal y);
Q_INVOKABLE void closePath();
private:
QPainterPath *m_path{Q_NULLPTR};
};
#endif // PATHMASK_H
pathmask.cpp
#include "pathmask.h"
#include <QPainterPath>
#include <QtMath>
PathMask::PathMask(QQuickItem *parent) :
QQuickPaintedItem(parent)
{
}
PathMask::~PathMask()
{
delete m_path;
}
void PathMask::paint(QPainter *painter)
{
if (m_path) {
painter->setRenderHint(QPainter::Antialiasing);
painter->setBrush( QBrush(QColor("black")) );
painter->drawPath( *m_path );
}
}
void PathMask::beginPath()
{
delete m_path;
m_path = new QPainterPath;
update();
}
void PathMask::moveTo(qreal x, qreal y)
{
Q_ASSERT(m_path);
m_path->moveTo(x,y);
}
void PathMask::lineTo(qreal x, qreal y)
{
Q_ASSERT(m_path);
m_path->lineTo(x, y);
}
void PathMask::closePath()
{
Q_ASSERT(m_path);
m_path->closeSubpath();
update();
}
main.qml
import QtQuick 2.5
import QtQuick.Controls 2.0
import QtQuick.Controls.Material 2.0
import QtGraphicalEffects 1.0
import io.qt.forum 1.0
ApplicationWindow {
title: "PathMask Demo"
visible: true
width: 400
height: 400
color: "black"
Image {
id: src
anchors.fill: parent
visible: false
source: "file:///home/patrick/Downloads/f22.jpg"
}
PathMask {
id: mask
anchors.fill: parent
visible: false
}
Component.onCompleted: {
mask.beginPath()
mask.moveTo(360, 200);
var Pi = 3.141592653589793238463;
for (var i = 1; i < 5; ++i) {
mask.lineTo(200 + 160 * Math.cos(0.8 * i * Pi),
200 + 160 * Math.sin(0.8 * i * Pi));
}
mask.closePath();
}
OpacityMask {
anchors.fill: src
source: src
maskSource: mask
}
}
