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| ''' | |
| Example of canvas with that can be scrolled with mouse and | |
| dragged around with middle mouse of the button. | |
| Written and tested using Python 3.4 on Ubuntu x64 14.04 | |
| ''' | |
| from tkinter import * | |
| class MyCanvas(Canvas): | |
| def __init__(self, parent=None, img=None, *parms, **kparms): | |
| Canvas.__init__(self, parent, *parms, **kparms) | |
| self._width = 1000; | |
| self._height = 1000; | |
| self._starting_drag_position = () | |
| self.config(width = self._width, height=self._height, bg='green') | |
| self._draw_some_example_objects() | |
| self._add_scrollbars() | |
| self._addMouseBindings() | |
| self.pack(fill=BOTH, expand=YES) | |
| def _add_scrollbars(self): | |
| self.sbarV = Scrollbar(self.master, orient=VERTICAL) | |
| self.sbarH = Scrollbar(self.master, orient=HORIZONTAL) | |
| self.sbarV.config(command=self.yview) | |
| self.sbarH.config(command=self.xview) | |
| self.config(yscrollcommand=self.sbarV.set) | |
| self.config(xscrollcommand=self.sbarH.set) | |
| self.sbarV.pack(side=RIGHT, fill=Y) | |
| self.sbarH.pack(side=BOTTOM, fill=X) | |
| def _addMouseBindings(self): | |
| # mouse wheel scroll | |
| self.bind('<4>', lambda event : self.yview('scroll', -1, 'units')) | |
| self.bind('<5>', lambda event : self.yview('scroll', 1, 'units')) | |
| # dragging canvas with mouse middle button | |
| self.bind("<Button-2>", self.__start_scroll) | |
| self.bind("<B2-Motion>", self.__update_scroll) | |
| self.bind("<ButtonRelease-2>", self.__stop_scroll) | |
| def __start_scroll(self, event): | |
| # set the scrolling increment. | |
| # value of 0 is unlimited and very fast | |
| # set it to 1,2,3 or whatever to make it slower | |
| self.config(yscrollincrement=3) | |
| self.config(xscrollincrement=3) | |
| self._starting_drag_position = (event.x, event.y) | |
| self.config(cursor="fleur") | |
| def __update_scroll(self, event): | |
| deltaX = event.x - self._starting_drag_position[0] | |
| deltaY = event.y - self._starting_drag_position[1] | |
| self.xview('scroll', deltaX, 'units') | |
| self.yview('scroll', deltaY, 'units') | |
| self._starting_drag_position = (event.x, event.y) | |
| def __stop_scroll(self, event): | |
| # set scrolling speed back to 0, so that mouse scrolling | |
| # works as expected. | |
| self.config(xscrollincrement=0) | |
| self.config(yscrollincrement=0) | |
| self.config(cursor="") | |
| def _draw_some_example_objects(self): | |
| colors = dict(outline="black") | |
| self.config(scrollregion=(0,0, self._width, self._height)) | |
| self.create_rectangle(30, 10, 120, 120, fill="red", **colors) | |
| self.create_rectangle(330, 410, 420, 460, fill="blue", **colors) | |
| self.create_rectangle(830, 810, 920, 960, fill="yellow", **colors) | |
| self.create_rectangle(830, 210, 990, 500, fill="cyan", **colors) | |
| self.create_rectangle(130, 810, 290, 999, fill="gray", **colors) | |
| class MyGUI(Tk): | |
| def __init__(self, *args, **kwargs): | |
| Tk.__init__(self, *args, **kwargs) | |
| self.title("Drag canvas with mouse") | |
| self.geometry("500x500") | |
| self._addWidgets() | |
| def _addWidgets(self): | |
| my_canvas = MyCanvas(self) | |
| if __name__ == '__main__': | |
| MyGUI().mainloop() | |
