QPainter and 2D Graphics

masayoshi

Does this code work well? I can not compile it. (Qt 5.7.1)
QPainter and 2D Graphics

// 
error: use of undeclared identifier 'engine'; did you mean 'inline'?
    if (engine)
        ^~~~~~
        inline

jsulm

@masayoshi From a quick view on that example engine wasn't declared anywhere. You can simply change it like this:

if (engine)
  painter.begin(engine);
else
  painter.begin(this);

to

  painter.begin(this);

Is it possible to download source code for the examples there?
You should ask authors of the book.

masayoshi

@jsulm said in QPainter and 2D Graphics:

@masayoshi From a quick view on that example engine wasn't declared anywhere. You can simply change it like this:
if (engine)
  painter.begin(engine);
else
  painter.begin(this);
to
  painter.begin(this);
Is it possible to download source code for the examples there?
You should ask authors of the book.

After doing that, I can compile it.
When I save image to SVG, I get the following error.

//your code here
QWidget::paintEngine: Should no longer be called
QPainter::begin: Paint device returned engine == 0, type: 1
QPainter::end: Painter not active, aborted

mrjj

@masayoshi
Can you show the code that saves ?
It seems like you are using a QPainter outside the Paint function which is not supported.

masayoshi

@mrjj said in QPainter and 2D Graphics:

@masayoshi
Can you show the code that saves ?
It seems like you are using a QPainter outside the Paint function which is not supported.

Chapter 3. QPainter and 2D Graphics

I only used this code. I used Qt 5.7

masayoshi

@jsulm said in QPainter and 2D Graphics:

Is it possible to download source code for the examples there?
You should ask authors of the book.

Thank you. I read book carefully. I got source code. It works on my computer.
I will look it up carefully.

// Source code

    if (generator)
        painter.begin(generator);
    else
        painter.begin(this);