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Let's get started by, as usual, importing the relevant library. Tkinter, like the

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turtle module, is already pre-installed with every installation of Python.

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As long as you've got Python running,

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then you should be able to simply import Tkinter as the module

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and then you'll be able to use all of the classes and properties and methods

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inside. So for example,

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we could start off by creating a new window,

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and this is sort of equivalent to the screens that we've been working with

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in turtle . So in order to do this,

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we have to dig into the Tkinter module and then find a class called Tk.

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And then once we initialize a new object from that class,

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then we have ourselves a window. But if I run this as it is,

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you'll see absolutely nothing happen

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and it will just go straight away to exit code zero.

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And the reason for this is because we need a way of keeping the window on the

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screen. What Tkinter has done here is it's gone ahead,

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created the window, sees that there's no more instructions

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and then it basically ended the program. Now,

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what we want instead is to sort of have a while loop that basically just keeps

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on running, so something like a while true. And inside this while loop,

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it holds onto this window and keeps on listening to see if there's anything else

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that the user is going to do to interact with that window so that it can

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respond when that happens.

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So this loop is included inside Tkinter

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and all you have to do is get your window to simply call the main loop.

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This main loop is the thing that will keep the window on screen like this.

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So now here is our window and here's the line of code that keeps it on the screen and

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listens for what the user will do to interact with it. For example,

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click on a button or type something.

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Now this line of code always has to be at the very end of your program and all

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the rest of the things that you're going to write

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go in between creating the window and getting the window to run.

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The next thing we can do is we can change the title of that program.

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And we've done this before using turtle.

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We just call the title method and we give a string as the input.

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So 'My first GUI program',

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and now if I rerun my code,

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then you can see that this is what's showing up at the very top bar of my

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program. Now,

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other things that we might want to change with the window is the sizing of it.

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So there is a default size and there's also a way of changing the size.

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And we can do that by tapping into a method called a minimum size.

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The window is going to scale to include all of the components that you put

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inside. If you put a hundred buttons inside,

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it's going to make the window massive.

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But if you don't have a lot of things in the window,

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then you might want to define a minimum size so that you can specify that, by

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default, I want my width to be, let's say, I don't know,

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500 and the height to be 300,

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unless the user wants to resize the window,

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or there's a lot of components that makes the window a lot bigger.

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So when we run our code

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now you can see this is a 500-pixel by 300-pixel window that we've just created

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with our own custom title.

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In addition to creating windows,

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we can, of course, create some components to put inside the window.

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So I want to show you firstly

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how you would create a label. Just as our window was created from the tkinker

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module and it's the Tk class that was used,

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there's also a class inside Tkinter called

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a label. So that we initialize a label class,

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and we can save that to a variable called

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my_label or anything else for that matter.

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Now this label has quite a few things that we can change about it.

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It might not be obvious from the documentation or from the prompt that PyCharm

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gives us,

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but we can, in fact, change a property called text so we can change what is

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displayed inside the label. Let's just write some text called 'I am a label'

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Unfortunately, that's actually not enough to get the label to display.

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So when I run my program as it is, you don't actually see a label anywhere

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on the screen. When we're working with Tkinter

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what we have to do is we first have to create a component like a

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label.

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And then we have to specify how that component is going to be laid out on the

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screen before it will show up.

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And one of the easiest ways of laying out any component is just to get hold of

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that component and then call the method called pack.

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And this is going to place it into the screen and it's going to automatically

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center it on the screen. So now

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if I run the code with this modification,

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you can see our label is now finally showing up and it's packed so that it's in

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the center of the program.

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Now there's other properties that we can modify about our label.

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So we could initialize our label with a piece of text,

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but we can also specify a font. The font is again,

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going to be a tuple,

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and that tuple is first going to take the name of the font,

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so let's say I want to use Arial,

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and then it's going to take the size of the font.

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So let's make it a little bit bigger, maybe a 24 size font. And finally,

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it's going to take whether, if it's bold or italic or, um,

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let's just set it to bold. And now if I run my code again,

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you can see I've now got a Arial font, size 24

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and it's bold.

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You can also change this to italic or you can simply just ignore it and leave

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out that last item and it will just give you a regular piece of text.

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But none of this would show up unless you have this line of code where you

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actually use the packer to pack our label onto the screen. Now

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in the course resources,

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I've linked to the Tkinter documentation on the Python docs and they talk

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about the packer in a lot more detail.

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It's basically a geometry management system.

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It's just a simple way to lay out the components that you're building.

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And this packer has a number of options. So if we scroll down,

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you can see that we can change the expand to a boolean, so true or false.

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And that tells it whether if it should expand to take up the entire space or

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stay as small as it can be. Alternatively,

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you have things like side which changes

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which side should it be packed to, on the left, right, top, or bottom?

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So we know that currently our label is bang in the middle,

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but if I change the side to equal left,

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now when I run the code,

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you can see it's now been packed to the left of the screen.

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And if I say bottom,

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then it's going to go to the bottom and right and top. All of those will work.

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And if I change expand to true,

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you can see it's now trying to take up the entire height and width of the

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available screen size. Now,

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when you're writing this pack function here,

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as soon as I type pack and I open up my parentheses,

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normally we're used to a whole bunch of properties being listed in here for us,

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and we can specify each one and pick and choose basically.

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But in this case, this is all that we see.

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So what's going on here? Compare this to when we used our turtle module and I'm

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going to build a turtle Tim turtle.turtle.

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And then I say, tim.write. Look at how,

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when I opened up the parentheses here, you can see there's the argument

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which is the Object that's going to be written, and then whether

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if the writing should be moved to the bottom corner,

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which direction it should be aligned,

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what's the font and all of the available inputs that we can give to this write

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function. Now compare that to our pack function here.

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This, you'll notice, is really different. Now,

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if you actually look in the documentation for pack,

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you can see it actually has a number of things that we can change; before,

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expand, fill, in, side, and all of these things

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which are modifiable and do various things.

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But how is it that it doesn't seem to exist as one of the arguments that we can

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use? The secret lies in this last part here,

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the **kw. And in the next lesson,

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we're going to talk about some more advanced features of Python arguments.

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And we're going to look at how we can provide default argument values,

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how we can define unlimited positional arguments and unlimited keyword arguments.

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To understand this better, head over to the next lesson

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and we'll do a deep dive on Python arguments.