当我在画布中绘制一个矩形时,我知道它的坐标,绝对(canvasx(),canvasy())和相对(我已经通过的那些)。 然后,我可以使用canvas scan_mark()和scan_dragto()方法移动画布。 我怎样才能返回到原始位置(在这些scan_mark()/ scan_dragto()调用中的一个或多个之前)以重新定位用户甚至可能丢失位置的矩形? 是否有任何重置视图命令/方法?我如何跟踪已经发生的变化?
答案 0 :(得分:2)
我见过的Tkinter文档似乎没有提到这一点,但可以调用底层的Tk Canvas xview / yview方法,不带参数来获取当前滚动位置(实际上,作为两个元素的元组,第二个对你没有任何用处)。因此,以下内容应该有效(未经测试):
保存位置:
origX = yourcanvas.xview()[0]
origY = yourcanvas.yview()[0]
恢复位置:
yourcanvas.xview_moveto(origX)
yourcanvas.yview_moveto(origY)
答案 1 :(得分:0)
正如之前的评论@jasonharper,他的建议有效。对于可能遇到同样问题的其他人,我附上了一个工作示例,即使它没有得到很好的清洗而感到骄傲,它可能会让你看到放大和缩小的方式,查看拖动和重置是否可行。
import tkinter as tk
import tkinter.ttk as ttk
class GriddedMazeCanvas(tk.Canvas):
def almost_centered(self, cols, rows):
width = int(self['width'])
height = int(self['height'])
cell_dim = self.settings['cell_dim']
rows = rows % height
cols = cols % width
w = cols * cell_dim
h = rows * cell_dim
if self.zoom < 0:
raise ValueError('zoom is negative:', self.zoom)
zoom = self.zoom // 2 + 1
if self.drawn() and 1 != zoom:
w *= zoom
h *= zoom
h_shift = (width - w) // 2
v_shift = (height - h) // 2
return [h_shift, v_shift,
h_shift + w, v_shift + h]
def __init__(self, *args, **kwargs):
if 'settings' not in kwargs:
raise ValueError("'settings' not passed.")
settings = kwargs['settings']
del kwargs['settings']
super().__init__(*args, **kwargs)
self.config(highlightthickness=0)
self.settings = settings
self.bind_events()
def draw_maze(self, cols, rows):
self.cols = cols
self.rows = rows
if self.not_drawn():
self.cells = {}
self.cell_dim = self.settings['cell_dim']
self.border_thickness = self.settings['border_thickness']
self.zoom = 0
self.delete(tk.ALL)
maze, coords = self._draw_maze(cols, rows, fix=False)
lines = self._draw_grid(coords)
return maze, lines
def _draw_maze(self, cols, rows, fix=True):
data = self.settings
to_max = data['to_max']
border_thickness = data['border_thickness']
poligon_color = data['poligon_color']
poligon_border_color = data['poligon_border_color']
coords = self.almost_centered(cols, rows)
if fix:
# Fix for the disappearing NW borders
if to_max == cols:
coords[0] += 1
if to_max == rows:
coords[1] += 1
maze = self.create_rectangle(*coords,
fill=poligon_color,
outline=poligon_border_color,
width=border_thickness,
tag='maze')
return maze, coords
def _draw_grid(self, coords):
data = self.settings
poligon_border_color = data['poligon_border_color']
cell_dim = data['cell_dim']
if coords is None:
if self.not_drawn():
raise ValueError('The maze is still uninitialized.')
x1, y1, x2, y2 = self.almost_centered(self.cols, self.rows)
else:
x1, y1, x2, y2 = coords
if self.drawn() and 0 != self.zoom:
if self.zoom < 0:
self.zoom = 0
print('no zooming at negative values.')
else:
zoom = self.zoom // 2 + 1
cell_dim *= zoom
lines = []
for i, x in enumerate(range(x1, x2, cell_dim)):
line = self.create_line(x, y1, x, y2,
fill=poligon_border_color,
tags=('grid', 'grid_hl_{}'.format(i)))
lines.append(line)
for i, y in enumerate(range(y1, y2, cell_dim)):
line = self.create_line(x1, y, x2, y,
fill=poligon_border_color,
tags=('grid', 'grid_vl_{}'.format(i)))
lines.append(line)
return lines
def drawn(self):
return hasattr(self, 'cells')
def not_drawn(self):
return not self.drawn()
def bind_events(self):
self.bind('<Button-4>', self.onZoomIn)
self.bind('<Button-5>', self.onZoomOut)
self.bind('<ButtonPress-1>', self.onScrollStart)
self.bind('<B1-Motion>', self.onScrollMove)
self.tag_bind('maze', '<ButtonPress-3>', self.onMouseRight)
def onScrollStart(self, event):
print(event.x, event.y, self.canvasx(event.x), self.canvasy(event.y))
self.scan_mark(event.x, event.y)
def onMouseRight(self, event):
col, row = self.get_pos(event)
print('zoom, col, row:', self.zoom, col, row)
def onScrollMove(self, event):
delta = event.x, event.y
self.scan_dragto(*delta, gain=1)
def onZoomIn(self, event):
if self.not_drawn():
return
max_zoom = 16
self.zoom += 2
if self.zoom > max_zoom:
print("Can't go beyond", max_zoom)
self.zoom = max_zoom
return
print('Zooming in.', event.num, event.x, event.y, self.zoom)
self.draw_maze(self.cols, self.rows)
def onZoomOut(self, event):
if self.not_drawn():
return
self.zoom -= 2
if self.zoom < 0:
print("Can't go below zero.")
self.zoom = 0
return
print('Zooming out.', event.num, event.x, event.y, self.zoom)
self.draw_maze(self.cols, self.rows)
def get_pos(self, event):
x, y = event.x, event.y
cols, rows = self.cols, self.rows
cell_dim, zoom = self.cell_dim, self.zoom
x1, y1, x2, y2 = self.almost_centered(cols, rows)
if not (x1 <= x <= x2 and y1 <= y <= y2):
print('Here we are out of bounds.')
return None, None
scale = (zoom // 2 + 1) * cell_dim
col = (x - x1) // scale
row = (y - y1) // scale
return col, row
class CanvasButton(ttk.Button):
def freeze_origin(self):
if not hasattr(self, 'origin'):
canvas = self.canvas
self.origin = canvas.xview()[0], canvas.yview()[0]
def reset(self):
canvas = self.canvas
x, y = self.origin
canvas.yview_moveto(x)
canvas.xview_moveto(y)
def __init__(self, *args, **kwargs):
if not 'canvas' in kwargs:
raise ValueError("'canvas' not passed.")
canvas = kwargs['canvas']
del kwargs['canvas']
super().__init__(*args, **kwargs)
self.config(command=self.reset)
self.canvas = canvas
root = tk.Tk()
settings = {'cell_dim': 3,
'to_max': 200,
'border_thickness': 1,
'poligon_color': '#F7F37E',
'poligon_border_color': '#AC5D33'}
frame = ttk.Frame(root)
canvas = GriddedMazeCanvas(frame,
settings=settings,
width=640,
height=480)
button = CanvasButton(frame, text='Reset', canvas=canvas)
button.freeze_origin()
canvas.draw_maze(20, 10)
canvas.grid(row=0, column=0, sticky=tk.NSEW)
button.grid(row=1, column=0, sticky=tk.EW)
frame.rowconfigure(0, weight=1)
frame.grid()
root.mainloop()
在最新的Ubuntu 16.10上使用Python 3.4进行测试 (事件:MouseLeft,Mouseright,MouseWheel,ButtonPress) HTH