Line graph Plot in Qdialog

Meenu

I'm new for QT. I was created Qdialog based application under Ubuntu operating system (like Ubuntu SDK IDE -> File -> New File or Project -> Application -> QT Widget's App -> Base Class : QDialog). Working Good.

I like to plot line graph in this dialog. i have array of data arr[1024]. how can i plot as a line graph?

? Offline

@Meenu Hi, welcome to the Qt forum! Have a look at the LineChart Example.

Meenu

Error QtCharts/QChartView: No such file or directory. Can i install QtChart Separately. I'm using QT Creator 3.5.1 based on QT 5.6.0(GCC 5.3.1 20160413, 32 bit). I was seen this example from Google. but i don't know how to implement. Kindly explain step by step.

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@Meenu It's an add-on module and should be provided by Ubuntu's package manager.

Meenu

how to add manually

? Offline

@Meenu package manager

mrjj

@Meenu
hi
if u only need something really simple. ( ie no zoom etc)
you can also just draw on an image and show in a Label.

alternate text

test project
https://www.dropbox.com/s/qwde8lb0fkjrrh3/mycheapgraph.zip?dl=0

its few lines of code

int GetBarHeight(int MAX) {
return rand() % (MAX - 5) + 5;
}

void MainWindow::on_pushButton_released() {
  int h = ui->label->height();
  int w = ui->label->width();
  QPixmap pix(w, h);
  QPainter paint(&pix);
  pix.fill( Qt::white );
  paint.setPen(QColor(0, 0, 0, 255));
  int y = 0;
  int x = 0;
  int bw = 10; // bar width
  for (int barcount = 0; barcount < 12; ++barcount) {
    paint.setBrush(QColor(255 - x, 34 + x, 255, 255));
    paint.drawRect(x, h - GetBarHeight(h),  bw, h );
    x += bw + 4;
  }
  paint.end();
  ui->label->setPixmap(pix);
}

? Offline

@mrjj Nice color gradient ;-)

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@Meenu This might help you with Ubuntu's package manager: https://help.ubuntu.com/lts/serverguide/apt.html

Meenu

@mrjj
I want to plot line graph. so i changed the code like below

int data[255];
int i = 0;
for (i = 0; i < 255; ++i)  data[i] = i;
for (i = 0; i < 255; ++i)  paint.drawLine(i, data[i], i+1, data[i+1]);

Here How to Set Lable's pixel (0,0) as bottom left corner?
Now, Graph plotting reversely(Top left corner).

mrjj

@Meenu
hi
you can change for painter with
painter.translate();

http://doc.qt.io/qt-5/qpainter.html#translate

its not related to the label at all.
we draw on image and label just show it :)

Meenu

@Wieland Getting Error - chartdataset.cpp:30:36: fatal error: private/chartdataset_p.h: No such file or directory.
I was download qtcharts-opensource-src-5.7.0 and installed successfully, like from download directory.

> qmake
> sudo make

line chart from examples working good. i like to implement this chart in my QDialog.
Now, i came to my code and simply add

#include <QtCharts/QChartView>
#include <QtCharts/QLineSeries>

how can i link QTChart with my *.Pro File.

Meenu

@mrjj Thank you. Its Working.

paint.translate(0,h);
paint.scale(1.0, -1.0);

VRonin

@Meenu said:

so i changed the code like below
for (i = 0; i < 255; ++i)  paint.drawLine(i, data[i], i+1, data[i+1]);

If you cannot see the problem there add #include <array> and change int data[255]; into std::array<int,255> data;

Meenu

@VRonin Its plotting random data. nice.

Meenu

After install QTChart / QWT chart controls, is possible to use these controls in to QDialog box.
How to link with *.PRO File.
QWT link process :

QWT_DIR = /usr/local/qwt-6.1.3
INCLUDEPATH += $$QWT_DIR/include

CONFIG(debug, debug|release):LIBS += -L$$QWT_DIR\lib\ \
-lqwtd5
else:LIBS += -L$$QWT_DIR\lib\ \
-lqwt5

DEFINES += QWT_DLL

is correct?