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  1. Qt
  2. QTBUG-65073

Canvas render issues when size is smaller than 64x64

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    • Icon: Bug Bug
    • Resolution: Unresolved
    • Icon: P2: Important P2: Important
    • None
    • 5.9.2
    • Quick: Core Declarative QML
    • None
    • Windows 10 / 8.1 x64 with Qt 5.9.2

      Hi,

      we found that if the width or height of a Canvas component is smaller than 64 (magic number?), then things we painted will get scaled.

      This issue only occurs when renderStrategy is set to Canvas.Cooperative and renderTarget is set to Canvas.FramebufferObject.

      Here's a minimum example to reproduce this issue:

      import QtQuick 2.6
import QtQuick.Window 2.2

Window {
    visible: true
    width: 32
    height: 32

    Canvas {
        anchors.fill: parent

        renderStrategy: Canvas.Cooperative
        renderTarget: Canvas.FramebufferObject

        onPaint: {
            var ctx = getContext("2d");
            ctx.fillRect(0, 0, width, height);
        }
    }
}

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            qt.team.quick.subscriptions Qt Quick and Widgets Team
            gpbeta Joshua GPBeta
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              Created:
              Updated:

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