How to create a Print Preview Dialog for a method

[JonB]

@LT-K101
And what is canvas, and what do you expect this to do? The docs for QPrintPreviewDialog::paintRequested(QPrinter *printer) tell you

The printer instance supplied is the paint device onto which you should paint the contents of each page, using the QPrinter instance in the same way as you would when printing directly.

[LT-K101]

@JonB I want to call the printReport() in the printpreviewDialog to initiate a QDialog popup for the user to view the pdf created in printReport method and then print.

[JonB]

@LT-K101
Well, your current code does not presently do anything like that....

You are inside a method of an already-created QPrintPreviewDialog, at the paintRequested stage. This is not where or for popping up dialogs, and you don't want some dialog there to view the PDF since you are already inside a previewer.

[jsulm]

@LT-K101 said in How to create a Print Preview Dialog for a method:

Below is the printReport method details.

No wonder there is nothing in preview dialog.
As documentation explains (see @JonB post) you need to use the provided printer to generate the preview...

[LT-K101]

@jsulm Honestly, I'm lost since this is the first time trying to implement this, I was following some examples online which is getting me confused. Please how do I use the provided printer to generate the preview in my case. I know it easy for you and @JonB to do this.Please I need assistance with this. Thanks

[jsulm]

@LT-K101 Did you check https://doc.qt.io/qt-5/qtprintsupport-index.html ?

[JonB]

@LT-K101
Please start by following @jsulm's reference. You can also get help by Googling, say, qprintpreviewdialog paintrequested example. We do not even know what it is that you want to print/print preview....

[LT-K101]

@jsulm Please I did check it but I did not understand it

[jsulm]

@LT-K101 said in How to create a Print Preview Dialog for a method:

but I did not understand it

What exactly?
There is an example:

printer.setOutputFileName("print.ps");
QPainter painter;
painter.begin(&printer);
for (int page = 0; page < numberOfPages; ++page) {
    // Use the painter to draw on the page.
    if (page != lastPage)
        printer.newPage();
 }
painter.end();

[LT-K101]

@JonB It's the C++ syntax that confuses me. Sorry for bothering you.Please below is a report method I want to preview and print. It works perfectly without a Dialog by saving to disk so I wanted to use QPrintPreviewDialog to let user preview the report before printing.

def printReport(self):
    filename, ok = QtWidgets.QFileDialog.getSaveFileName(self, 'Save file', '', 'Pdf files (*.pdf)')  
    if ok:
         # Open local project
         project = valentina.project.connect('./temp.vsp')

         # Make report instance
         report = project.report(name='tempofficials_summary',
                                        dsn='sqlite://C:/Users/PC/Desktop/PROJECT/temp.db',
                                        query="SELECT firstname,surname,email,phone,address,dob, '{}' || image as full_path FROM temp_table WHERE id_no={}".format(
                                            'C:/Users/LTK101/Desktop/PROJECT/img/', id))

        # Print result as PDF
        report.printToDisk(filename)

[jsulm]

@LT-K101 said in How to create a Print Preview Dialog for a method:

I wanted to use QPrintPreviewDialog to let user preview the report before printing.

Then please do what was suggested here. Something like (should not be difficult to translate it to Python):

def reportPreview(self, printer):
    QPainter painter;
    painter.begin(printer);
    for (int page = 0; page < numberOfPages; ++page) {
        // Use the painter to draw on the page.
        // Put here code to draw preview using painter
        if (page != lastPage)
            printer.newPage();
     }
    painter.end();

def printpreviewDialog(self):
    printer = QPrinter(QPrinter.HighResolution)
    previewDialog = QPrintPreviewDialog(printer, self)
    previewDialog.paintRequested.connect(self.reportPreview)
    previewDialog.exec_()

[JonB]

@LT-K101
Noone can answer this without knowing exactly what a valentina.project is. I see it has some printToDisk() method. QPrintPreviewDialog requires a QPrinter. So does a valentina.project offer to print to a QPrinter?

[LT-K101]

@JonB It has printToDisk() which save the report as pdf and printToLocalPrinter() which print to any default printer set as default without a dialog so I was trying to see if I could use QPrintPreviewDialog.

[JonB]

@LT-K101 said in How to create a Print Preview Dialog for a method:

printToLocalPrinter() which print to any default printer

If that accepts a QPrinter it can be sent to a QPrintPreviewDialog. But it does not look like it can? Looks like it does something about the printer internally instead?

If I had been asking for help on whatever a valentina.project is or whatever your "report"/"report writer" is, which provides these print...() calls, I would have supplied a link reference to it, plus however it interacts with Qt. But you would like us to answer without having that. I'm not even sure it integrates with Qt, let alone QPrinter, if it is just some Python thing what Qt integration does it have?

[LT-K101]

@JonB Well the Valentina report is written with Qt I have been able to integrate with PyQt5. The developers have not written a Dialog for the print method yet, when I asked I was told I can use pyQt5 to create a custom Dialog so I was hoping QPrintPreviewDialog will do the magic for me. Below is the image they suggested it could be done using pyqt.

[JonB]

@LT-K101 said in How to create a Print Preview Dialog for a method:

Well the Valentina report is written with Qt I have been able to integrate with PyQt5.

Is it really that hard to provide a link to this thing if you want help with it, after being asked to do so several times? I just don't get why you don't....

A custom dialog to invite the user to print is not the same thing as a QPrintPreviewDialog to allow previewing of the output.

[LT-K101]

@JonB Well even creating a custom Dialog is my headache now.Any assistance please?

[JonB]

@LT-K101
Seriously, in what way? Create a QDialog to ask the user if they want to print, whether to file or physical printer? And/or maybe a QFileDialog to let the user pick a file/location to save to?

Or maybe that inbuilt Windows Print dialog is all user needs anyway, seems to offer print to printer or to file?

[LT-K101]

@JonB said in How to create a Print Preview Dialog for a method:

maybe that inbuilt Windows Print dialog is all user needs anyway, seems to offer print to printer or to file?

Creating the a Dialog to offer print to printer or to file which will connect to my print method is what I need please.

[JonB]

@LT-K101
You write a dialog to ask the user whether they want to print and if they say yes you call printToLocalPrinter() or printToDisk() or similar. I'm not writing that for you, it's a dialog, I have no idea what your issue is. You also already have a printReport() shown earlier which does a getSaveFileName() and calls printToDisk(filename), so I don't know what your problem is.