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POQt: view added to layout not updating, but will update when not in layout
 

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  1. POQt: view added to layout not updating, but will update when not in layout
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    <p>A widget called Tachometer will update accordingly when a signal is sent from its corresponding model, but it will not respond at all when I add the widget to a layout. What might account for this? Without showing the internals of the model or the view (which would be exhaustive), I will attempt to point out where it is not working:</p> <pre><code>void MainWindow::setupWidgets() { QHBoxLayout *horiz1 = new QHBoxLayout(); QHBoxLayout *horiz2 = new QHBoxLayout(); odometer = new Odometer(ui-&gt;dashFrame); fuelGauge = new FuelGauge(ui-&gt;dashFrame); tripometer = new Tripometer(ui-&gt;dashFrame); tachometer = new Tachometer(ui-&gt;dashFrame); temperatureGauge = new TemperatureGauge(ui-&gt;dashFrame); oilPressureGauge = new OilPressureGauge(); QVBoxLayout *vertOPG = new QVBoxLayout(); if ( oilPressureGauge-&gt;getTitle() != "" ) { QLabel *OPGLabel = new QLabel(oilPressureGauge-&gt;getTitle()); vertOPG-&gt;addWidget(OPGLabel); } vertOPG-&gt;addWidget(oilPressureGauge); speedometer = new Speedometer(ui-&gt;dashFrame); horiz1-&gt;addWidget(tachometer); horiz1-&gt;addWidget(speedometer); horiz2-&gt;addWidget(fuelGauge); horiz2-&gt;addWidget(temperatureGauge); horiz2-&gt;addLayout(vertOPG); horiz2-&gt;addWidget(tripometer); horiz2-&gt;addWidget(odometer); // will NOT update when added to layout QVBoxLayout *vert1 = new QVBoxLayout(ui-&gt;dashFrame); vert1-&gt;addLayout(horiz1); vert1-&gt;addLayout(horiz2); this-&gt;ui-&gt;dashFrame-&gt;setLayout(vert1); } </code></pre> <p>I am perplexed that the other Widgets will update as expected, but not the object named tachometer. As I said before, if I don't add it to the layout, e.g.</p> <pre><code>// ... tachometer = new Tachometer(ui-&gt;dashFrame); // ... </code></pre> <p>it appears to work just fine. Furthermore, by debugging on the console I see that the RPM value for the tachometer is being sent to the appropriate slot that updates the view for the tachometer (I just noticed the tachometer finally responded to the update, but it isn't updating after every timeout as it should). It seems like some latency issues are clearly involved here. If anyone might have an idea as to why this might be, I would greatly appreciate some clarification.</p>
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    1. PTQuestion
    1. USSaulo Silva
    1. USdtg
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      1. POQt: view added to layout not updating, but will update when not in layout
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    1. COHow do you display new data in `Tachometer`? I mean, how do you draw it?
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      1. POQt: view added to layout not updating, but will update when not in layout
      1. USPavel Strakhov
    2. COTachometer is displayed similar to an analog clock. I use the same widget display for both the Tach and the Speedometer, but use the strategy pattern to draw different values on the surface depending on what widget it is. The view is fed a value after every millisecond... As I mentioned before it only seems to not update when I add the widget to a layout (but the others seem to perform fine).
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      1. POQt: view added to layout not updating, but will update when not in layout
      1. USdtg
    3. COWhich slots in this widget are related to the problem? What do they do? How and where are they connected to signals? How paintEvent is implemented? Is paintEvent executed properly? Is paintEvent working with up-to-date data? Try to repaint() widgets forcely at every update.
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      1. POQt: view added to layout not updating, but will update when not in layout
      1. USPavel Strakhov
 

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