I am writing a draftsman in QT. When drawing with any color after a single click on LKM, a black dot appears.

Question

If you hold down the LMB and hold the mouse, you get a line, as it should be. This is the project itself: https://vk.com/doc66577607_445871169
This is the code snippet with the drawing itself:

void paintScene::mousePressEvent(QGraphicsSceneMouseEvent *event) { if (event->button() == Qt::LeftButton) { addEllipse(event->scenePos().x() - brushSize, event->scenePos().y() - brushSize, (brushSize*2), (brushSize*2), pen, brush); previousPoint = event->scenePos(); } } void paintScene::mouseMoveEvent(QGraphicsSceneMouseEvent *event) { if (event->buttons() == Qt::LeftButton) { addLine(previousPoint.x(), previousPoint.y(), event->scenePos().x(), event->scenePos().y(), QPen(color,brushSize*2,Qt::SolidLine,Qt::RoundCap)); previousPoint = event->scenePos(); } }

UPD: figured out. In changeColor, I did not set the brush and pen colors. Thank.

Accepted Answer · 2017-05-24T21:53:22

In the addEllipse call addEllipse you use a black pen and / or brush .

Why do you even draw something in mousePressEvent ?

There, the color is set different.

Where exactly? For the line every time you create a new pen with the color color . Do the same in addEllipse , and the dot will be blue:

 addEllipse(event->scenePos().x() - brushSize, event->scenePos().y() - brushSize, (brushSize*2), (brushSize*2), QPen(color,brushSize*2,Qt::SolidLine,Qt::RoundCap), brush);

And where does the paintEvent ? It's about drawing as a reaction to mouse movement.

In the paintScene constructor: puu.sh/w0z0V/62aaed644f.png .
But whichever you set by default and on which you change, the dots are still black

I am writing a draftsman in QT. When drawing with any color after a single click on LKM, a black dot appears.

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