Solved Picture
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I simplified the code a bit.
The first function takes an image, the coordinates of the top left corner and the size of the rectangle (4x4 in your case) and tells you what is the dominant primary colour there
The second one takes an image, the coordinates of the top left corner and the size of the rectangle (4x4 in your case) and fills that rectangle with the colour in the argument
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@Payx
Hi, i added some comments. Its basically the same as what you tried , just broken up into good functions to produce clean code.// this function , you give the image and the start and size of the current rect you are processing QColor dominantColour(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(); x < maxBottom; ++x) { 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; } // this function can fill an rect with a color. So its used with dominantColour to actually replace the colors void fillSection(QImage& image, const QPoint& topLeft, const QSize& rectSize, const QColor& colour) { // 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()); // go over all pixels in the rect for(int x = topLeft.x(); x < maxRight; ++x) { for(int y = topLeft.y(); x < maxBottom; ++x) { image.setPixelColor(x, y, colour); // replace color } } }
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Thanks for your help,
I got one error
undefined reference to 'MainWindow::dominantColor()'
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thats wasnt a simple letter that occured an error,
undefined reference to 'MainWindow::dominantColour()'
undefined reference to ''MainWindow::fillSection()' -
Because they are not part of MainWindow. Take a look again a the function signature.
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Here my window.h
private slots: void on_push_clicked(); QColor dominantColour(); void fillSection(); void on_push2_clicked();
You said my function is not part of MainWindow, so i try to add MainWindow::
void MainWindow::fillSection(QImage& pixi, const QPoint& topLeft, const QSize& rectSize, const QColor& colour) {
and its said prototype for void Main...... does not match any in class 'MainWindow'
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Note: neither
dominantColour
norfillSection
make sense in the slots category. -
its said prototype for void Main...... does not match any in class 'MainWindow'
They don't match, the compiler's correct.
class MainWindow { // ... void fillSection(); // ... };
in the header has different prototype from :
void MainWindow::fillSection(QImage& pixi, const QPoint& topLeft, const QSize& rectSize, const QColor& colour) { // ...
in the source file. They must match, it's a requirement of the language.
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So where am i suppose to declare my functions ?
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@Payx Again:
void fillSection()
is NOT the same as
void fillSection(QImage& pixi, const QPoint& topLeft, const QSize& rectSize, const QColor& colour)
So, either change void fillSection() to void fillSection(QImage& pixi, const QPoint& topLeft, const QSize& rectSize, const QColor& colour), or other way around. This is really basic C++.
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Hi,
- Function arguments must match otherwise u will get error.
- Declare your functions in Header File, provide the definition in source file.
- Use slots only when u want to get the values when signal is emitted providing the connect(); . Otherwise declare in any one of below specifiers.
- add function in either of the access specifier depending upon your need
private:
void fillSection();public:
void fillSection();protected:
void fillSection();The arguments which provided in declaration should match with the definition along with data type.
Thanks,
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Thanks both of you, it works !
The problem i think is that i don't understand english very well, that's my problem.So if i understood well,
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); }
I check what the code do, if i'm right i have to define the
rectSize.height()
and rectSize.width()and last question
when i havefor(int x = topLeft.x(); x < maxRight; ++x) { for(int y = topLeft.y(); x < maxBottom; ++x) {
in the second line, it's not 'y' the variable who change?
and
const int maxRight = qMin(pixi.width(), topLeft.x() + rectSize.width()); for(int x = topLeft.x(); x < maxRight; ++x) {
if we define rectSize (4*4) the for will go from 0 to 4 only no ? we need to change the rectsize at the end of the for no ?
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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
in the second line, it's not 'y' the variable who change?
yes, I corrected it but @mrjj was faster and copied the code before I could amend it
the for will go from 0 to 4 only no ?
no, it will go from 0 to 3, 4 pixels
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no, it will go from 0 to 3, 4 pixels
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 ?
this makes no sense
When i want to call a function i have to write :
fillSection();
but as i said i got an error.
so i change to fillSection(QImage& pixi, const QPoint& topLeft, const QSize& rectSize, const QColor& colour);
why this makes no sense?
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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?
why this makes no sense?
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@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
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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
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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)
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@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 }