如何在使用python的kivy中掩蓋圖像？

Question

我想用特定的蒙版來掩蓋圖像，但我似乎無法找到方法。

我讀過的文檔，發現這個https://kivy.org/docs/api-kivy.graphics.stencil_instructions.html#這看起來很有希望，但例如僅在kivy語言（我不我的項目中使用）

我還發現這https://groups.google.com/forum/#!topic/kivy-users/-XXe3F2JoSc但第一個例子是有點混亂，第二個使用StencilView這似乎是一個不同的事情

因此，一個普遍的例子是appretiated

的代碼部分：

#some code... 

    picture_mask = Image(source = "Assets/picture_frame_mask.png", size_hint = (0, 0), 
             size = (200, 200), 
             pos = (50,100)) 
    #Now what ? 

    player_picture = Image(source = "Assets/player.png", size_hint = (0, 0), 
          allow_stretch = True, keep_ratio = False, 
          size = (200, 200), 
          pos = (50,100)) 
    self.add_widget(player_picture) 

    #rest of code... 

Answer 1

鐵托已經在郵件列表中回答了它，但我會多描述一下。要在畫布內部放置圖像，您可以準確使用Rectangle()，source。但在這裏配備了一個適當大小的問題，所以無論是寫入圖像的完整大小，或像size=[640/5.0,480/5.0]或者只是640/5（我用py2.7）

如何使用模板文檔中描述的那樣，在Python它非常相似。您使用with canvas:，其中畫布是您小部件的畫布，因此self.canvas。對你而言有趣的是mask()功能，我在這裏評論了幾件事情，以便讓你清楚。

要理解面具實際做了什麼，可以將面具想象成一張帶有洞的紙。你只能看到洞裏有什麼。

from kivy.graphics import * 
#^^^^^^ all imports you need for that to work + App()/runTouchApp() 

from kivy.app import App 
from kivy.uix.widget import Widget 
from kivy.core.window import Window 
from kivy.uix.button import Button 
from kivy.uix.boxlayout import BoxLayout 

class Root(Widget): 
    def __init__(self, **kw): 
     super(Root, self).__init__() 
     with self.canvas: 
      Color(1,0,0,0.5) 
      Rectangle(pos=self.pos, size=Window.size) 

     bx=BoxLayout(width=Window.width) 
     but1=Button(text="mask it!") 
     but1.bind(on_release=self.mask) 
     but2=Button(text="clear it!") 
     but2.bind(on_release=self.clear) 

     bx.add_widget(but1) 
     bx.add_widget(but2) 
     self.add_widget(bx) 
     #after few hundred lines of code you'll hate to type even ".add_" 
     #binding on_release and other is a way more shorter 
     #learn kv, have less troubles :) 

    def mask(self, *args): 
     with self.canvas: 
      #you have to "push" the stencil instructions 
      #imagine StencilPush and StencilPop as { and } 
      StencilPush() 

      #set mask 
      Rectangle(pos=[self.pos[0],self.pos[1]+200], size=[100,100]) 

      #use mask 
      StencilUse() 

      #draw something and mask will be placed on it 
      #Color(1,1,1) for full color, otherwise it tints image 
      Color(0,1,0) 
      Rectangle(source='<your picture>',\ 
      pos=[0,0], size=[Window.width-200,Window.height-200]) 

      #disable Stencil or mask will take effect on everything 
      #until StencilPop() 
      StencilPop() 

      #here it doesn't take effect 
      Color(0,1,1) 
      Rectangle(pos=[self.pos[0]+200,self.pos[1]+200],\ 
      size=[Window.width-200,Window.height-200]) 

      #However here, when StencilPop() and StencilUse() 
      #are again, mask is still in the memory 
      StencilPush() 
      StencilUse() 

      #mask is applied... and draws nothing 
      #because it's not in the mask's area 
      Color(1,1,0) 
      Rectangle(pos=[self.pos[0]+200,self.pos[1]+200],\ 
      size=[Window.width-200,Window.height-200]) 

      #I think UnUse() is optional 
      StencilUnUse() 

      #and of course Pop() it 
      StencilPop() 

    def clear(self, *args): 
     self.canvas.clear() 
     self.__init__() 

class My(App): 
    def build(self): 
     return Root() 

My().run()