Laying Widgets in QGridLayout - qt

Question

I need to create the QWidget(QtoolButton) in QgridLayout without specifying the indices for row and column. It should automatically get created to next empty cell in the layout according to row and column mentioned.
I was not able to find any method in QgridLayout help.
I tried .addWidget (self, QWidget w), but it add all the QWidget to the index of (0,0) and all the buttons lie over each other.
Thanks in advance.

Answer 1

Let's suppose that you have a QGridLayout with 4 rows and 3 columns and you want to add buttons to it automatically from top to bottom and from left to right. That can easily be achieved if you are able to predict the position of the next button to be added. In our case:
row = number of added buttons / number of columns
column = number of added buttons % number of columns
(other type of filling work similarly). Let's put it in code:
from PyQt4.QtGui import *
class MyMainWindow(QMainWindow):
def __init__(self, parent=None):
super(MyMainWindow, self).__init__(parent)
self.central = QWidget(self)
self.grid = QGridLayout(self.central)
self.rows = 4
self.cols = 3
self.items = self.grid.count()
while(self.items < (self.rows * self.cols)):
self.addButton()
self.setCentralWidget(self.central)
def addButton(self):
# the next free position depends on the number of added items
row = self.items/self.cols
col = self.items % self.cols
# add the button to the next free position
button = QPushButton("%s, %s" % (row, col))
self.grid.addWidget(button, row, col)
# update the number of items
self.items = self.grid.count()
if __name__ == "__main__":
import sys
app = QApplication(sys.argv)
ui = MyMainWindow()
ui.show()
sys.exit(app.exec_())

Answer 2

You can handle the "next empty cell" by calculating rows and columns yourself. For example, you can subclass QGridLayout to implement any "next empty cell" algorithm according to your needs:
class AutoGridLayout(QGridLayout):
def __init__(self):
QGridLayout.__init__(self)
self.column = 0
self.row = 0
def addNextWidget(self, widget):
self.addWidget(widget, self.row, self.column)
self.column = self.column + 1 # Automatically advance to next column
# Setup main widget
app = QApplication(sys.argv)
mainWindow = QMainWindow()
centralWidget = QWidget()
mainWindow.setCentralWidget(centralWidget)
# Add widgets using the AutoGridLayout
layout = AutoGridLayout()
centralWidget.setLayout(layout)
layout.addNextWidget(QPushButton("1", centralWidget))
layout.addNextWidget(QPushButton("2", centralWidget))
layout.addNextWidget(QPushButton("3", centralWidget))
# Show and run the application
mainWindow.show()
app.exec_()
This source shall only show the general idea - you can manage the row and column indices according to your needs. Just implement the necessary logic in the addNextWidget() method by calculating the next desired row/column (in this example, the next column in row 0 is used).

Answer 3

Addition to other answers: If you need just rows with variable number of items, and not an actual grid, then you should use multiple QHBoxLayouts (one for each row) nested in one QVBoxLayout. That will also get you the behaviour you want, new items created on demand, without nasty gaps.