圖像可以顯示在很多物件上，這裡我挑選一個常用案例是顯示在畫布canvas上，首先定義一個tk.Canvas物件:

self.drawingpadcanvas = tk.Canvas(drawingpadPanel, background = 'white')

定義Canvas物件的拉把

	drawingpad_sbarV = Scrollbar(drawingpadPanel, orient=tk.VERTICAL)
	drawingpad_sbarH = Scrollbar(drawingpadPanel, orient=tk.HORIZONTAL)
	drawingpad_sbarV.config(command=self.drawingpadcanvas.yview)
	drawingpad_sbarH.config(command=self.drawingpadcanvas.xview)
	self.drawingpadcanvas.config(yscrollcommand=drawingpad_sbarV.set)
	self.drawingpadcanvas.config(xscrollcommand=drawingpad_sbarH.set)
	drawingpad_sbarV.pack(side=tk.RIGHT, fill=tk.Y)
	drawingpad_sbarH.pack(side=tk.BOTTOM, fill=tk.X)

打包Canvas物件的位置

self.drawingpadcanvas.pack(side=tk.TOP, expand=tk.NO)

做一個色彩選擇功能的圖形介面，繼續上篇的Canvas功能，接下來可以增添其他功能，有了畫布就想要有調色盤的功能，當from PIL import ImageColor時﹐，可以開啟調色盤工具，這邊我做了一個簡單的調色盤按鈕，我設定設按鈕的背景顏色

self.Color1Button = tk.Button(ColorPanel, 
                              text = "Color 1",
                              font=('Courier', 7), 
                              command = self.askcolor1)
self.Color1Button.grid(row = 0, column = 0, sticky = tk.E+tk.W)

askcolor()傳回的是HTML格式的色彩，儲存在self.color1[1]上，只要button物件重新config自己的bg設定值，顏色便會回饋在button上

def askcolor1(self, event = None):
      self.color1 = askcolor()
      self.Color1Button.configure(bg=self.color1[1])

此外還想設定線條的粗細，所以做了設定線條粗細的工具

linewidth = ( 1, 2, 3, 4, 5)

tk.Label(self.MarkSettingPanel, 
         text = "Line size",
         font=('Courier', 7)).grid(row = 0, column = 4, sticky = tk.E+tk.W) 

self.linesizespinbox = tk.Spinbox(self.MarkSettingPanel, 
                                    values = linewidth, 
                                    width = 3)
self.linesizespinbox.grid(row = 0, column = 5, sticky = tk.E+tk.W)

平常程式內部運用顏色設定是有很大機會是使用tuple格式(R, G, B)，所以這邊我再加一個HTML轉換RGB tuple函式

def HTMLColorToRGB(self,colorstring):
    colorstring = colorstring.strip()
    if colorstring[0] == '#': colorstring = colorstring[1:]
    if len(colorstring) != 6:
        raise(ValueError, "input #%s is not in #RRGGBB format" % colorstring)
    r, g, b = colorstring[:2], colorstring[2:4], colorstring[4:]
    r, g, b = [int(n, 16) for n in (r, g, b)]
    return (r, g, b)

這樣本篇基本的調色盤作法重點就完成了。

紀錄按下滑鼠左鍵事件，prev為之前發生事件，event為現在發生事件

def mouse_press(self, event):
    global prev
    prev = event

測試事件發生紀錄資料

  print('type: {}'.format(event.type))
  print('widget: {}'.format(event.widget))
  print('num: {}'.format(event.num))
  print('x: {}'.format(event.x))
  print('y: {}'.format(event.y))
  print('x: {}'.format(event.x_root))
  print('y: {}'.format(event.y_root))

滑鼠拖移時繪製線條

def draw(self, event):
    global prev
    self.drawingpadcanvas.create_line(prev.x, prev.y, 
                                      event.x, event.y, 
                                      width = (self.linesizespinbox.get()), 
                                               fill = self.color1[1])
    prev = event