Details
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Bug
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Resolution: Unresolved
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P2: Important
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None
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5.12.0
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None
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iMac, macOS, Qt 5.12.0
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macOS
Description
Unless the 2D context lineJoin is set certain drawing operations where the line drawing steps back on itself e.g. changes direction 180 degrees does not draw properly and the result appears to be incorrect and the incorrect drawing seems to scale with line width.
Test code...
import QtQuick 2.12 import QtQuick.Window 2.12 import QtQuick.Controls 2.2 Window { visible: true width: 640 height: 480 title: qsTr("QML Pencil Line Bug") //////////////////////////////////////////////////////////////////////////// Text { x: 0 y: 0 width: 200 height: 20 font.pixelSize: 15 text: "Does not set strokeStyle" } Canvas { id: canvasDoesnt x:0 y:20 width: 200 height: 200 property int lineWidth: sliderLineWidth.value onPaint: { var c = getContext('2d') c.fillStyle = Qt.rgba(1,1,1,1) c.fillRect(0,0,width,height) c.fillStyle = Qt.rgba(1,0,0,1) c.strokeStyle = '#088' c.lineWidth = lineWidth c.beginPath() c.moveTo(100,100); c.lineTo(100,105); c.lineTo(100,110); c.lineTo(100,105); c.stroke() } } //////////////////////////////////////////////////////////////////////////// Text { x: 200 y: 0 width: 200 height: 20 font.pixelSize: 15 text: "Does set strokeStyle" } Canvas { id: canvasDoes x: 200 y: 20 width: 200 height: 200 property int lineWidth: sliderLineWidth.value onPaint: { var c = getContext('2d') c.fillStyle = Qt.rgba(1,1,1,1) c.fillRect(0,0,width,height) c.fillStyle = Qt.rgba(1,0,0,1) c.strokeStyle = '#088' c.lineWidth = lineWidth // i believe this is the default value c.lineJoin = 'miter' c.beginPath() c.moveTo(100,100); c.lineTo(100,105); c.lineTo(100,110); c.lineTo(100,105); c.stroke() } } //////////////////////////////////////////////////////////////////////////// Slider { id: sliderLineWidth x: 0 y: 220 height: 30 width: 400 from: 1 to: 30 value: 10 orientation: Qt.Horizontal onValueChanged: { canvasDoesnt.requestPaint() canvasDoes.requestPaint() } } }
