Doubts related with QPainter & QVector

[j0rt4g4]

Well I have 2 questions but I have really no idea of what I can do to solve this.

About QPainter:
in the .h file:

public:
	QVector<int> xpuntos;
	QVector<int> ypuntos;

public:
	QVector<int> xpuntos;
	QVector<int> ypuntos;

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In the cpp:

r,paso, itemax,and i (defined).
 
for(r=0.0;r<=4.0;r+=paso){
			i=0;
			x0=qrand();
			x0/=RAND_MAX;
			while(i<itemax){
			x=r*x0*(1.0-x0);
				//if( (x-x0)<epsilon){
				//	painter.drawPoint((int)(r*450.0/4.0),(int)(0-(x*450)));
				//	break;
				//}
			x0=x;
			i++;
				if(i>250){
					xpuntos.append((int)(r*450.0/4.0));
					ypuntos.append((int)(0-(x*450)));
				}
			}
	}
	for(i=0;i<xpuntos.size();i++){
		painter.drawPoint(xpuntos.at(i),y.puntos.at(i));   //it could no determine type ....
	}

r,paso, itemax,and i (defined).

for(r=0.0;r<=4.0;r+=paso){
			i=0;
			x0=qrand();
			x0/=RAND_MAX;
			while(i<itemax){
			x=r*x0*(1.0-x0);
				//if( (x-x0)<epsilon){
				//	painter.drawPoint((int)(r*450.0/4.0),(int)(0-(x*450)));
				//	break;
				//}
			x0=x;
			i++;
				if(i>250){
					xpuntos.append((int)(r*450.0/4.0));
					ypuntos.append((int)(0-(x*450)));
				}
			}
	}
	for(i=0;i<xpuntos.size();i++){
		painter.drawPoint(xpuntos.at(i),y.puntos.at(i));   //it could no determine type ....
	}

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The error is Qt doesn't recognize the type. why it cant determine type?

About QVector:
in the .h file:

QVector<QPoints> puntos;

QVector<QPoints> puntos;

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In the cpp:
My idea was inserting calculated data
i have 100 points with positions double x, double y.For example:

x=0.0, y=1;
for(i=0;i<itmax;i++){
x+=0.01
y=C*y0*(1.0-y0);
//Now the question... how I could add correctly this values to the QPoints vector?. My idea was:
puntos.append( puntos.setX( (int) x, puntos.setY( (int) y)  );
}

x=0.0, y=1;
for(i=0;i<itmax;i++){
x+=0.01
y=C*y0*(1.0-y0);
//Now the question... how I could add correctly this values to the QPoints vector?. My idea was:
puntos.append( puntos.setX( (int) x, puntos.setY( (int) y)  );
}

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It doesn't worked.... any other idea?

[drhex]

try

QVector<QPoint> puntos;
 
...
 
  puntos.append(QPoint(int(x),int(y)));

QVector<QPoint> puntos;

...

  puntos.append(QPoint(int(x),int(y)));

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as for the unrecognized type, can you post the error mesage you get?

[j0rt4g4]

And to access that "QVector<QPoints>" this will be the way?

for(i=0;i<puntos.size(); i++){
painter.drawPoint(puntos.at(i));
}

for(i=0;i<puntos.size(); i++){
painter.drawPoint(puntos.at(i));
}

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In archive " If I use painter.draw crashes.zip (9.6 KB)" and it doesnt paint in the "widget" ... at all...

and "Unrecogniced type.zip (10.1 k) " reflects my doubt number #1. thanks

[jpn]

And to access that "QVector<QPoints>" this will be the way?

for(i=0;i<puntos.size(); i++){
painter.drawPoint(puntos.at(i));
}

for(i=0;i<puntos.size(); i++){
painter.drawPoint(puntos.at(i));
}

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Yet better using QPainter::drawPoints():

painter.drawPoints(&puntos.at[0], puntos.count());

painter.drawPoints(&puntos.at[0], puntos.count());

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[j0rt4g4]

Yet better using QPainter::drawPoints():

painter.drawPoints(&puntos.at[0], puntos.count());

painter.drawPoints(&puntos.at[0], puntos.count());

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It can't be just like that. I tried:

for(long int i=0;i<250;i++){
			painter.drawPoints(&puntos.at(i), puntos.count());
			//painter.drawPoint(i,50);	
		}

for(long int i=0;i<250;i++){
			painter.drawPoints(&puntos.at(i), puntos.count());
			//painter.drawPoint(i,50);	
		}

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What I want is to generate pointsF when I click "Generar"
and to paint on the widget called "widget" when I click in Pintar.
But when I click Paint.... and I did this code for drawing on it like this:

QPainter painter(widget);
	painter.setPen(Qt::white);
	QBrush brush(1);
	brush.setColor(QColor::fromRgbF(1,1,1,1));
	painter.setBrush(brush);
	painter.drawRect(0,0,450,450); //draw a white rect

QPainter painter(widget);
	painter.setPen(Qt::white);
	QBrush brush(1);
	brush.setColor(QColor::fromRgbF(1,1,1,1));
	painter.setBrush(brush);
	painter.drawRect(0,0,450,450); //draw a white rect

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It doesn't draw anything.... and how can I see if the slot "Generar" is working Correctly?... :S

I dont know if I have to make it "current()" of something like that to draw on it..
It draws when I use QPainter painter(this) but it draw in the whole windows, and I need it draws in the object called widget.

[jpn]

Why "it can't be like that"? There is no point to call drawPoints() in a loop, because it already takes an ARRAY of points. The whole idea of drawPoints() is the take all the points in a group so that you don't have to call drawPoint() for each and every point.

When it comes to the visible result on the screen, there is no difference between these two:

for(i=0;i<puntos.size(); i++){
    painter.drawPoint(puntos.at(i));
}

for(i=0;i<puntos.size(); i++){
    painter.drawPoint(puntos.at(i));
}

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and

painter.drawPoints(&puntos.at[0], puntos.count());

painter.drawPoints(&puntos.at[0], puntos.count());

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The latter is just more efficient.

[j0rt4g4]

Why "it can't be like that"?

for(i=0;i<puntos.size(); i++){
    painter.drawPoint(puntos.at(i));
}

for(i=0;i<puntos.size(); i++){
    painter.drawPoint(puntos.at(i));
}

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and

painter.drawPoints(&puntos.at[0], puntos.count());

painter.drawPoints(&puntos.at[0], puntos.count());

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The latter is just more efficient.

Thank you for aswering because there is a tiny diference between them...
If you use "[]" or "()" of course there's a diference.
If I use "[]" i got this mistake: Invalid types' <unknown types>[int]' for array suscript.
I got your point and you're rigth is more eficient do it like this:

painter.drawPoints(&puntos.at(0), puntos.count());

painter.drawPoints(&puntos.at(0), puntos.count());

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If but I got the problem If I use:

QPainter painter(this) // it draws in the whole windows
QPainter painter(widget) // it doesn't draws at all

QPainter painter(this) // it draws in the whole windows
QPainter painter(widget) // it doesn't draws at all

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Why is happening this?. I have no clue

[jpn]

If but I got the problem If I use:

QPainter painter(this) // it draws in the whole windows
QPainter painter(widget) // it doesn't draws at all

QPainter painter(this) // it draws in the whole windows
QPainter painter(widget) // it doesn't draws at all

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Why is happening this?. I have no clue

A widget can only paint on itself. It can NOT paint on other widgets. Reimplement the paintEvent() handler of THAT widget you want to paint on.

[j0rt4g4]

mmmm And how I can do that?
I used designer to promote this widget called "widget" so I could create .h file and .cpp file about the "writing area" but I dont know if that what you meant.

[j0rt4g4]

Well I will keep my doubt... And check if in other forum give me an answer... thanks

[jpn]

mmmm And how I can do that?
I used designer to promote this widget called "widget" so I could create .h file and .cpp file about the "writing area" but I dont know if that what you meant.

So put your painting code into that class. Reimplement the paintEvent() function of that class as usual. Don't try to open a painter on that widget in another class.

[jpn]

painter.drawPoint(xpuntos.at(i),y.puntos.at(i));   //it could no determine type ....

painter.drawPoint(xpuntos.at(i),y.puntos.at(i));   //it could no determine type ....

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Notice "y.puntos" vs. "ypuntos". Next time please paste the error message.