Im working with Tkinter currently and im trying to make an draggable canvas image, the code i've "made"/edited from another stack overflow question, the second one to be particular. There code works for me when im using tk.Frame()
, but it gives an error for Canvas.create_image()
. So i edited it a little but now it seems to to be moving the image at all when i drag it
My code:
from tkinter import *
import pyautogui
x,y=pyautogui.size()
tk = Tk()
c = Canvas(tk, width=x, height=y)
c.place(x=-2,y=-3)
img = ImageTk.PhotoImage(PIL.Image.open(r"Data\backgrounds\background.jpg"))
c.create_image(0, 0, image=img, anchor=NW)
def command6():
print("command6")
def make_draggable(widget,btn="<Button-1>",motion="<B1-Motion>"):
def __draggable__(widget):
c.tag_bind(btn,btn,on_drag_start)
c.tag_bind(motion,motion,on_drag_motion)
def on_drag_start(event):
widget = event.widget
widget._drag_start_x = event.x
widget._drag_start_y = event.y
def on_drag_motion(event):
widget = event.widget
x = widget.winfo_x() - widget._drag_start_x event.x
y = widget.winfo_y() - widget._drag_start_y event.y
widget.move(widget,x, y)
__draggable__(widget)
APP_6 = r'apps\File.png'
APP_6 = PIL.Image.open(APP_6)
APP_6 = APP_6.resize((48,48),PIL.Image.ANTIALIAS)
APP_6 = ImageTk.PhotoImage(APP_6)
image_6 = ImageTk.PhotoImage(PIL.Image.open(r"apps\File.png"))
image_id_6 = c.create_image(48,48, image=APP_6)
c.move(image_id_6, 1,y-735)
c.tag_bind(image_id_6, '<Button-1>',command6)
make_draggable(image_id_6)
tk.mainloop()
this gives no errors or any unwanted output in the console.
CodePudding user response:
There are few issues inside make_draggable()
function:
- first argument of
.tag_bind()
is the item ID of a canvas item. For your case, it iswidget
argument ofmake_draggable()
. So the following lines:
c.tag_bind(btn,btn,on_drag_start)
c.tag_bind(motion,motion,on_drag_motion)
should be changed to
c.tag_bind(widget, btn, on_drag_start)
c.tag_bind(widget, motion, on_drag_motion)
Same apply to c.move(...)
inside on_drag_motion()
- the logic/calculation on moving the canvas item is wrong
Below is the modified make_draggable()
function:
def make_draggable(widget, btn="<Button-1>", motion="<B1-Motion>"):
def __draggable__(widget):
c.tag_bind(widget, btn, on_drag_start)
c.tag_bind(widget, motion, on_drag_motion)
c._item_id = widget # save the item ID for later use
def on_drag_start(event):
widget = event.widget
# get the top-left coordinates of the selected item
x, y, *_ = widget.bbox(widget._item_id)
# save the offset of current mouse position from the top-left coordinates
widget._dx = event.x - x
widget._dy = event.y - y
def on_drag_motion(event):
widget = event.widget
# calculate the top-left coordinates of the item that the item to be moved to
x = event.x - widget._dx
y = event.y - widget._dy
# move the item using moveto() instead of move()
widget.moveto(widget._item_id, x, y)
__draggable__(widget)
As the above logic applies only on the item of the last call of make_draggable()
. It is better to use class instead of function:
class make_draggable():
def __init__(self, item_id, btn="<Button-1>", motion="<B1-Motion>"):
self.item_id = item_id
c.tag_bind(item_id, btn, self.on_drag_start, add=True)
c.tag_bind(item_id, motion, self.on_drag_motion, add=True)
def on_drag_start(self, event):
x, y, *_ = event.widget.bbox(self.item_id)
self.dx, self.dy = event.x-x, event.y-y
def on_drag_motion(self, event):
event.widget.moveto(self.item_id, event.x-self.dx, event.y-self.dy)