[Tutor] saving Tkinter canvas as jpg

[eryksun]

On Sun, Dec 8, 2013 at 8:49 PM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>
> https://pypi.python.org/pypi/Pillow/ is a fork of PIL.  I've never used it
> myself but here's hoping!!!

ImageGrab has built-in support for Microsoft Windows only:

https://github.com/python-imaging/Pillow/blob/2.2.1/PIL/ImageGrab.py#L29
https://github.com/python-imaging/Pillow/blob/2.2.1/_imaging.c#L3365
https://github.com/python-imaging/Pillow/blob/2.2.1/display.c#L313

A Tk canvas supports saving to a PostScript file, if that suffices
(i.e. if you can render PostScript as an image):

    canvas.postscript(file='filename.ps', colormode='color')

http://www.tcl.tk/man/tcl8.5/TkCmd/canvas.htm#M51

OS X includes a screencapture utility that you could call with the
subprocess module:

http://ss64.com/osx/screencapture.html

This answer on Stack Overflow uses the OS X CoreGraphics API:

http://stackoverflow.com/a/13026264/205580
http://pythonhosted.org/pyobjc/apinotes/Quartz.html

Or you could switch to a GUI toolkit with better support for saving
images, such as Qt:

https://qt-project.org/doc/qt-4.8/qpixmap.html
https://qt-project.org/doc/qt-4.8/qpainter.html

Here's a really basic example using PyQt4. Clicking on the "Capture"
button paints the widget to a pixmap that's then saved to "spam.png"
and the desktop to "screenshot.jpg" with 95% quality.

    import sys
    from PyQt4 import QtCore, QtGui

    class Spam(QtGui.QWidget):
        def __init__(self):
            super(Spam, self).__init__()
            self.setGeometry(100, 100, 300, 225)
            self.setWindowTitle("Spam")
            self.btncap = QtGui.QPushButton("Capture", self)
            self.btncap.clicked.connect(self.capture)
            self.show()

        def paintEvent(self, event):
            p = QtGui.QPainter(self)
            p.setFont(QtGui.QFont("Times", 20))
            flags = QtCore.Qt.AlignBottom | QtCore.Qt.AlignRight
            p.drawText(event.rect(), flags, "Spam")

        def capture(self):
            wid = app.desktop().winId()
            QtGui.QPixmap.grabWidget(self).save(
                "spam.png", "png")
            QtGui.QPixmap.grabWindow(wid).save(
                "screenshot.jpg", "jpg", 95)


    if __name__ == "__main__":
        app = QtGui.QApplication(sys.argv)
        spam = Spam()
        sys.exit(app.exec_())