QtPainter Error Paint device returned engine ==0, type 3 ,Painter not active

Question

I'm trying to paint some points of my image and I don't know why it doesn't work. I have defined a QImage and I want to modify some points. ``` QImage *cou= new QImage(height,largeur,QImage::Format_Mono); cou->fill(1); QPainter *fig=new QPainter (cou); for (i=0;i<size_;i++) { fig-> drawPoint(floor(propa[i]),nbmax[i]); } ``` When I execute the code I obtain ``` QPainter::begin: Paint device returned engine == 0, type: 3 ``` and in the following lines: ``` QPainter::drawPoints: Painter not active ```

Accepted Answer

```
QPainter::begin: Paint device returned engine == 0, type: 3
```

The error means that the image you're trying to paint is a null image. Use `isNull` on `cou`to check this. The cause of image being null may be the wrong `height` and `largeur` params when the image is constructed, or you're out of memory

QtPainter Error Paint device returned engine ==0, type 3 ,Painter not active

Solution

Problem