How to redirecting "stdout" to a Label widget?
The reason you are not seeing the text set is that it is set correctly for a split second and then immediately set to blank. This is because print is sending a newline to stdout after the print statements. Here is a modified version that appends to the Label rather than overwrite it for every print statement.
class StdoutRedirector(IORedirector): def write(self,str): self.TEXT_INFO.config(text=self.TEXT_INFO.cget('text') + str)
I made a class which copies stdout write calls to a tkinter widget be it a Label or a Text. Works for me on Python3.3.1/WindowsXp.:
import sysclass StdoutToWidget: ''' Retrieves sys.stdout and show write calls also in a tkinter widget. It accepts widgets which have a "text" config and defines their width and height in characters. It also accepts Text widgets. Use stop() to stop retrieving. You can manage output height by using the keyword argument. By default the class tries to get widget\'s height configuration and use that. If that fails it sets self.height to None which you can also do manually. In this case the output will not be trimmed. However if you do not manage your widget, it can grow vertically hard by getting more and more inputs. ''' # Inspired by Jesse Harris and Stathis # http://stackoverflow.com/a/10846997/2334951 # http://stackoverflow.com/q/14710529/2334951 # TODO: horizontal wrapping # make it a widget decorator (if possible) # height management for Text widget mode def __init__(self, widget, height='default', width='default'): self._content = [] self.defstdout = sys.stdout self.widget = widget if height == 'default': try: self.height = widget.cget('height') except: self.height = None else: self.height = height if width == 'default': try: self.width = widget.cget('width') except: self.width = None else: self.width = width def flush(self): ''' Frame sys.stdout's flush method. ''' self.defstdout.flush() def write(self, string, end=None): ''' Frame sys.stdout's write method. This method puts the input strings to the widget. ''' if string is not None: self.defstdout.write(string) try: last_line_last_char = self._content[-1][-1] except IndexError: last_line_last_char = '\n' else: if last_line_last_char == '\n': self._content[-1] = self._content[-1][:-1] if last_line_last_char != '\n' and string.startswith('\r'): self._content[-1] = string[1:] elif last_line_last_char != '\n': self._content[-1] += string elif last_line_last_char == '\n' and string.startswith('\r'): self._content.append(string[1:]) else: self._content.append(string) if hasattr(self.widget, 'insert') and hasattr(self.widget, 'see'): self._write_to_textwidget() else: self._write_to_regularwidget(end) def _write_to_regularwidget(self, end): if self.height is None: self.widget.config(text='\n'.join(self.content)) else: if not end: content = '\n'.join(self.content[-self.height:]) else: content = '\n'.join(self.content[-self.height+end:end]) self.widget.config(text=content) def _write_to_textwidget(self): self.widget.insert('end', '\n'.join(self.content)) self.widget.see('end') def start(self): ''' Starts retrieving. ''' sys.stdout = self def stop(self): ''' Stops retrieving. ''' sys.stdout = self.defstdout @property def content(self): c = [] for li in self._content: c.extend(li.split('\n')) if not self.width: return c else: result = [] for li in c: while len(li) > self.width: result.append(li[:self.width]) li = li[self.width:] result.append(li) return result @content.setter def content(self, string): self._content = string.split('\n') @property def errors(self): return self.defstdout.errors @property def encoding(self): return self.defstdout.encoding
EDIT1: I received a downvote, so here is the updated one. I use this in a Label widget and print() functions appear smoothly in my widget. Moreover as an extra feature if I pass None to the write call and let's say -1 as end argument, then it won't show last line (careful with indexing). I use this because I attached a slider to the widget. I will publish a demo soon.