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How to make QTableView to adjust the height of it's horizontal header automatically in PyQt?

  • The thing is I have long sting for header, typically from 4 characters to somewhere 100 characters but the header is dynamic.

    I found that we can make the header wrap using default alignments as Qt.AlignCenter | Qt.Alignment(Qt.TextWordWrap), however it does not make the horizontal height auto adjust based on the contents, I have some initial widths for each of the column. Is there a way to make the header heights auto adjustable whenever a column is resized?

  • Lifetime Qt Champion

    Hi and welcome to devnet,

    100 chars for a header ? That seems a bit excessive. Can you explain your use case ?

  • Hi @SGaist , thanks for the welcome and sorry for late response, I didn't know that I have received some response regarding my post, you can consider following code that I wrote for PySide2 for my use case.

    from PySide2.QtCore import *
    from PySide2.QtWidgets import *
    class HeaderView(QHeaderView):
        def __init__(self, parent):
            super(HeaderView, self).__init__(Qt.Horizontal, parent)
                "QHeaderView::section{background-color: #ffffff; "
                "font-weight: bold; "
                "padding-left: 2px; "
                "color: #3467ba; "
                "border:0px; "
                "border-left: 1px solid #ababab; "
                "border-bottom: 1px solid gray;}")
            sizePol = QSizePolicy()
    class TableView(QTableView):
        def __init__(self, parent=None):
            super(TableView, self).__init__(parent)
            model = DataModel(self)
            self._headerView = HeaderView(self)
        def resizeColumns(self, idx, oldSize, newSize):
            minHeight =(round(max(self._headerView.sectionSizeFromContents(i).width()/(self._headerView.sectionSize(i))
                            for i in range(self.model().columnCount())))
    class DataModel(QAbstractTableModel):
        def __init__(self, parent):
            super(DataModel, self).__init__(parent)
            #Setting some static data
            self._data = [['Dummy-01-0001', 'M', '41.01026694045174', 'NOT HISPANIC OR LATINO', 'Albumin (g/L)', 'N'] for _ in range(5)]+\
                         [['Dummy-01-0001', 'F', '41.01026694045174', 'HISPANIC OR LATINO', 'Chloride (mmol/L)', 'Y'] for _ in range(5)]
            self._header = ['Unique Subject Identifier (USUBJID)', 'Sex (SEX)', 'Age (AGE)', 'Ethnicity (ETHNIC)', 'Parameter (PARAM)', 'Analysis Reference Range Indicator (ANRIND)']
        def rowCount(self, parent=None):
            return len(self._data)
        def columnCount(self, parent=None):
            return len(self._header)
        def data(self, index, role=Qt.DisplayRole):
            if index.isValid() and role==Qt.DisplayRole:
                return str(self._data[index.row()][index.column()])
        def headerData(self, section, orientation:Qt.Horizontal = Qt.Horizontal, role=Qt.DisplayRole):
            if orientation == Qt.Horizontal:
                if role == Qt.DisplayRole:
                    return self._header[section]
                # elif role == Qt.TextAlignmentRole and section==0:
                #     return Qt.AlignLeft|Qt.Alignment(Qt.TextWordWrap)
        def flags(self, index):
            if index.isValid():
                return Qt.ItemIsEnabled | Qt.ItemIsSelectable
    if __name__ == "__main__":
        import sys
        app = QApplication()
        widg = TableView()

    It has some sample data, as you can see, the header for the sample data is a large string, so I can not show them in a Single line, I need to split it to multiple lines which self.setDefaultAlignment(Qt.AlignCenter|Qt.Alignment(Qt.TextWordWrap) is already doing for me, but the problem is, the header height doesn't change with respect to wrapping of the text in the header. I tried connecting resizeSection signal of headerView to a function where I'm doing some estimation of the required height, and then trying to set the minimum height to this estimated height every time user resizes the width of the header column, but I'm not sure if this is the right way to implement what I'm trying to do, also, since it is manual estimation, it is often going to fail when the header string has some too short or too large words. Wrapping is fine for me, the way string splits up on empty space , I just want the height to be increasing and decreasing accordingly.

    I asked this question on stackoverflow as well QTableView with auto-adjusting height for the header, but to me, it seems that, there isn't much community support for PyQt/PySide on stackoverflow.

  • @SGaist Hi SGiast, you seem to appear online, I'd be very grateful if you help me out, and point me to the right direction.

  • Lifetime Qt Champion

    One thing which is not good in your model is that you never call the base class implementation of the methods you override for the cases you do not handle. This means that you do not let the standard flow happen.

    I don't have a machine at hand right now, I'll test this later.

  • @SGaist I tried to take out the code from the actual project to be used as sample, so I might have forgot to implement calling the base classes for the overridden method for the cases that I'm not handling, anyways, please let me know when you are done with the testing, Thank you for your response! I'll be looking forward to hearing from you.

  • Lifetime Qt Champion

    Here is a simple implementation that gets you what you want.

    Note that you can nuke your resizeColumns parts completely.

    class HeaderView(QHeaderView):
        def __init__(self, parent=None):
            super().__init__(Qt.Horizontal, parent=parent)
                "QHeaderView::section{background-color: #ffffff; "
                "font-weight: bold; "
                "padding-left: 2px; "
                "color: #3467ba; "
                "border:0px; "
                "border-left: 1px solid #ababab; "
                "border-bottom: 1px solid gray;}"
            self.setDefaultAlignment(Qt.AlignCenter | Qt.Alignment(Qt.TextWordWrap))
        def sectionSizeFromContents(self, logicalIndex):
            text = self.model().headerData(logicalIndex, self.orientation(), Qt.DisplayRole)
            alignment = self.defaultAlignment()
            metrics = QFontMetrics(self.fontMetrics())
            rect = metrics.boundingRect(QRect(), alignment, text)
            return rect.size()

    On a side note TableView is really not needed here. In fine, you only "configure" it, so there's no need to subclass it.

  • @SGaist Thanks for your response, Yes, I don't need to subclass QTableView, but I need to use the same table at multiple places that is why I sub-classed it. This function sectionSizeFromContents that you overwrote is able to provide the bounding rectangle but it is always constant even if the width of the header section is resized, which is understandable because it is taking only the text and alignment into account and trying to estimate the bounding rectangle for it, and I think it is useful to define some minimum width.
    What I want is to increase/decrease the height of the header whenever the width of a header section is changed; each section will have their own width, but the height needs to be the maximum of the heights required by the sections.
    i.e. for example, let's say there are 5 columns with widths: 60, 100, 80, 75, 90, and height required as: 30,40,50,30,30, then the height of the header needs to be 50 i.e. maximum among 30,40,50,30,30.
    Now let's say user resized a section (2nd section for example) from 100 to 160, then required height for this section will obviously decrease since width for this section increased, let's say required height changed from 50 to 35, then the required heights are 30,40,35,30,30, and maximum of it is 40, so the new height for the header will be 40.

  • Lifetime Qt Champion

    What about getting the size of the other sections to create the reference size ?

  • @SGaist At a time, the user is able to resize only a single column since the resizing is going to happen through mouse, so anytime a column width is resized, the minimum required height for the resized column needs to be calculated, and it should be checked against the minimum height required for all other columns, and whichever is the maximum value, that becomes the current new height of the header.

  • This post is deleted!

  • @SGaist Can you please help me with this? You seem to be the only hope I have.

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