Picture

VRonin

Yes but if my picture is composed by 500 pixels, it will go from 0 to 3 pixels, and thats it, so i have to increase at the end of my "for" no ?

what would you do?

@Payx said in Picture:

why this makes no sense?

www.cplusplus.com/doc/tutorial/functions/

www.cplusplus.com/doc/tutorial/classes/

Payx

@VRonin I got rectSize = 4*4

the function will calculate the color in the rect 44, if my picture is 500500, i have to increase at the end of my "for" the rectSize.

like say that my maxRight isnt

qMin(pixi.width(), topLeft.x() + rectSize.width());

anymore

and it's like qMin(pixi.width(), rectSize.width()+4)

and at the end of my for i will add a line to increase again and again the maxRight

VRonin

those to functions are designed to work on a single 4x4 area, you need to build something around them to make them work over the whole picture

Payx

Thanks for your link obviously what i need.

so i replace : i got

QColor dominantColor(pixi,point,size);

and i define pixi as my image (in mainwindow.h)
and QPoint point(0,0);
and QSize size(4,4); thats correct ?

but i block for the QColor in void fillSection(QImage& image, const QPoint& topLeft, const QSize& rectSize, const QColor& colour)

kshegunov

@VRonin said in Picture:

@Payx said in Picture:

i will have :

void MainWindow::on_push2_clicked()
{
   QColor dominantColor(const QImage& pixi, const QPoint& topLeft, const QSize& rectSize);
   void fillSection(QImage& pixi, const QPoint& topLeft, const QSize& rectSize, const QColor& colour);
}

this makes no sense

It's valid C++, although highly unusual. Consider this:

void userFunction1()
{
    int x;
    testFunc(x);  //< Compile error: undeclared identifier testFunc
}

void userFunction2()
{
    void testFunc(int &);

    int x;
    testFunc(x); //< We are okay
}

void testFunc(int & z)
{
    z = 0;
}

C++ forbids function definitions to appear inside function bodies, but not declarations. On the other hand, class declarations and class definitions are valid inside functions, e.g.:

void terribleToReadFunction()
{
    struct  {
        int memberOfAnonymous() const
        {
            return 0;
        }
    } inst;

    int z = inst.memberOfAnonymous(); //< z is 0
}

Payx

@kshegunov
sorry i lost you

in my

void MainWindow::on_push2_clicked()
{
	QPoint point(0,0);
	QSize size(4,4);
	QColor dominantColor(pixi,point,size);

}

i try this i give what function needed and i declared point and size before

mrjj

@Payx said in Picture:
almost correct.

void MainWindow::on_push2_clicked()
{
QPoint point(0,0);
QSize size(4,4);
QColor domicolor=dominantColor(pixi,point,size); // where does pixi come from? its in .h?

}

kshegunov

@Payx said in Picture:

sorry i lost you

No, it's me who lost you. I was commenting on @VRonin's remark about your code. However, this:

QColor dominantColor(pixi,point,size);

is neither a function call, nor is it a function declaration. The compiler will interpret this as a variable and will throw "unknown conversion from type X to type Y" errors. You should carefully read @VRonin's link on functions - what is a declaration, what is a definition and how to put it all together. Otherwise you are in for a terrible time, Qt or otherwise.

Kind regards.

Payx

I have to declare my function,
say what they do
and call it.

I say in my .cpp what she does :

QColor dominantColor(const QImage& image, const QPoint& topLeft, const QSize& rectSize) {
// calculate start stop values for the rect
	 const int maxRight = qMin(image.width(), topLeft.x() + rectSize.width());
	const int maxBottom = qMin(image.height(), topLeft.y() + rectSize.height());
	QVector<QColor> coloursList; // this is a list of all colors seen!
	for(int x = topLeft.x(); x < maxRight; ++x) {
		for(int y = topLeft.y(); y < maxBottom; ++y) {
			coloursList << image.pixelColor(x, y); // store all colors seen in this Rect
		}
	}

	// these are functions that count (accumulate) how many times RED, GREEN and blue been used ( using the list from before)
	const qint64 sumRed = std::accumulate(coloursList.constBegin(), coloursList.constEnd(), 0, [](qint64 strt,  const QColor & val)->qint64 {return strt + val.red();});
	const qint64 sumGreen = std::accumulate(coloursList.constBegin(), coloursList.constEnd(), 0, [](qint64 strt, const QColor & val)->qint64 {return strt + val.green();});
	const qint64 sumBlue = std::accumulate(coloursList.constBegin(), coloursList.constEnd(), 0, [](qint64 strt, const QColor & val)->qint64 {return strt + val.blue();});
	// now we check out which is most used
	if(sumRed >= sumGreen  && sumRed >= sumBlue)
		return Qt::red;
	if(sumGreen  >= sumBlue)
		return Qt::green;
	return Qt::blue;
}

I call her and i stock the result in a QColor

void MainWindow::on_push2_clicked()
{
	QPoint point(0,0);
	QSize size(4,4);
	QColor domicolor=dominantColor(pixi,point,size);
// pixi is my image declared in .h with QImage pixi;

}

the problem that i dont know where i can declare her. I try every possibilities

VRonin

ok, now we are making progress. you got what the dominant colour is, now you have to paint the rectange

Payx

@VRonin said in Picture:

ok, now we are making progress. you got what the dominant colour is, now you have to paint the rectange

sorry if don't listen to you very well but

it say that my function isnt declared (dominantColor)

VRonin

http://www.cplusplus.com/doc/tutorial/functions/#declarations

Payx

Okay i fixed it

MainWindow::MainWindow(QWidget *parent) :
	QMainWindow(parent),
	ui(new Ui::MainWindow)
{
		ui->setupUi(this);

}
QColor dominantColor(const QImage& image, const QPoint& topLeft, const QSize& rectSize);
void fillSection(QImage& image, const QPoint& topLeft, const QSize& rectSize, const QColor& colour);

MainWindow::~MainWindow()
{
	delete ui;
}

So now with, fillSection, the problem i have is to declare something who correspond to QColor& colour

i check the code again, and i think its colourList no ?

VRonin

sorry if don't listen to you very well but

No worries, I'm explicitly refraining from giving you the exact answer and rather trying to send you on the right path.

i check the code again, and i think its colourList no ?

Nope, colourList will die: http://www.cplusplus.com/doc/tutorial/namespaces/#scopes

Payx

@VRonin said in Picture:

Nope, colourList will die: http://www.cplusplus.com/doc/tutorial/namespaces/#scopes

Ok i got it, we will put the returned color from QColor dominantColor, thats right ?

VRonin

Getting warmer and warmer

Payx

I got :

QColor domicolor=dominantColor(pixi,point,size);

The returned color is "domicolor", so i put domicolor in :

void fillSection(pixi, point, size, domicolor);

VRonin

sooo close!
http://www.cplusplus.com/doc/tutorial/functions/#void

Payx

I call her with just :

fillSection(pixi,point,size,domicolor);

VRonin

@Payx Bingo!