[iOS] Why empty QOpenGLWidget update/repaint() uses about 20%-50% cpu?

[vitaliynet]

Hello
I am new and just touch a the framework.

Now in the QT I see the same thing but load is about 20%-50%.
On iPhone 10 - 15-20% cpu load
On iPad 13 inch Pro - 30-50% cpu load.

Yes it's better with -O3. About 28-34% but wait.. it's just empty screen. Perhaps I'm doing something wrong? Or not called something before the initialisation? And the difference between repaint() and update() I not noticed at all. I want about 6-7% cpu, like the native iOS's setNeedDisplay() does it. But not sure what to do. Thanks.

This is my code. BTW, about 6-8% uses mouseMoveEvent when I move the finger.


Moreover, energy use is HIGH in the Xcode profiler avr: 83.4% GPU. It's really strange. I never saw this in any project. Always just: Low.

Thank you!

#include "mainwidget.h"
 
MainWidget::MainWidget(QOpenGLWidget *parent) : QOpenGLWidget(parent)
{
 
}
 
MainWidget::~MainWidget() {
 
}
 
 
void MainWidget::resizeEvent(QResizeEvent *e) {
    QOpenGLWidget::resizeEvent(e);
}
 
 
void MainWidget::mouseMoveEvent(QMouseEvent *e) {
    update();
}
 
void MainWidget::paintGL()
{
 
}

#include "mainwidget.h"

MainWidget::MainWidget(QOpenGLWidget *parent) : QOpenGLWidget(parent)
{
    
}

MainWidget::~MainWidget() {

}


void MainWidget::resizeEvent(QResizeEvent *e) {
    QOpenGLWidget::resizeEvent(e);
}


void MainWidget::mouseMoveEvent(QMouseEvent *e) {
    update();
}

void MainWidget::paintGL()
{
    
}

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