Interaction with Graphics Also displaying GIFs

Text Output on the graphics window There is a class called Text which will put the message on the graphics window msg = Text(Point(10, 200), “Hello”) msg.draw(win) Will put the word Hello on the graphics window, centered horizontally at the given point. You can use setSize to change the font size, setStyle to change to “bold” or “italic”, and setFace to change the font. You can use setText to change the message displayed. The 2 nd argument to Text must be a String and ONE string!! If you want to output numbers you will have to use typecasting and concatenation

Interaction also implies input! How does the program get input from the user using the graphics window? Using getMouse to let the user indicate a location on the window Using a text Entry to let the user enter text from the keyboard

getMouse() getMouse is a method associated with the GraphWin class, so you call it using a window object, like win. win.getMouse() It does return a value, specifically a Point object, indicating where the user clicked The use we have had for getMouse, to act as a pause at the end of the program, ignores this return value. If you want to save the point for later use, you would store it in a variable User_point = win.getMouse()

Using getMouse() msg = Text(Point(50, 50),”click a point”) msg.draw(win) userPt = win.getMouse() circ = Circle (userPt, 25) circ.draw(win) This will draw a small circle around the point the user clicked. Note that the constructor Point does not have to be called when the argument is already a point! Do not write “circ = Circle(Point(userPt),25)”

How to do text Input from the graphics window You should prompt the user on the graphics window just as you did on the Shell screen when not doing graphics. This needs a Text object Then create an Entry object (which allows the user to type in a box) Arguments: Point for box to center on, integer size of box Put some text into the Entry object (using setText) Use a getMouse to pause until the user clicks (after they type) Use getText to get the user input from the Entry object (will be string) Then process the string input as desired

Using text Entry prompt = Text (Point(150, 200), “Enter a number”) prompt.draw(win) user_input = Entry(Point(150, 150), 5) # box big enough for 5 chars user_input.setText(“ “) # 5 spaces, could also be a default value user_input.draw(win) win.getMouse() # must be there! Or getText will not work number = float(user_input.getText())

How to display a GIF on the graphics window Uses the Image class pic = Image(Point(100, 100), “cat.gif”) Assumes there is a file called cat.gif in the same folder as the source file pic will be an image object which can be drawn on the graphics window centered at the point give pic.draw(win) Many other methods exist to manipulate the image pixel by pixel getPixel, setPixel, save HINT: you have to save your source code (.py) before these methods will work. The interpreter has to have somewhere to look for the gif file