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Details

Type: Bug
Resolution: Fixed
Priority: P2: Important
Fix Version/s: 6.7.1, 6.8.0 FF
Affects Version/s: 6.6.2, 6.6.3, 6.7.0 RC2
Component/s: Quick: Shapes
Labels:
None

Commits:
1314d046f (dev), efa233bc4 (6.7)

Description

Using the Shape.CurveRenderer as the preferred renderer can cause crashes for certain line geometries when using a dash pattern.

The following QML example reproduces the crash (on Windows)

import QtQuick
import QtQuick.Shapes

Window {
    id: root;
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")   
   
    Shape
    {
        preferredRendererType: Shape.CurveRenderer;        
        ShapePath
        {
            startX: -1.654507349898284;
            startY: 2.5602595487477107
            dashPattern: [2, 2];
            dashOffset: 4;
            strokeWidth: 5.8575662686300545;
            strokeColor: "purple";
            capStyle: ShapePath.FlatCap;
            strokeStyle: ShapePath.DashLine;
            joinStyle: ShapePath.RoundJoin;             
            PathLine
            {
                x: 119.95107002130986;
                y: 81.14499586882086
            }
        }
    }
}

This causes an assertion to be hit in the QQuadPath::dashed method:

...
while (true) {
    bool gotAll = cutter.consume(pattern.at(dashIndex) - offset);
                                            ^^^^^^^^^
    QVector2D nextPoint = cutter.currentCutPoint();
        if (dashIndex & 1)
...

where dashIndex has the value 2, where pattern is a QVarLengthArray of length 2, causing an index out of bounds assertion: n <= size() - pos