Scratch

I seem to find making tutorials somewhat fun. Here's another one.
This tutorial is about working in Squeak, the language Scratch is written in.
It starts from Scratch (ha... ha... ha...) and works down to the most intricate pieces of code.

A good place to start if you are thinking of making your own mod!

NOTE:
This tutorial uses the Scratch Source Code as a referral point. If you are using the normal Scratch 1.4, please download the Source from this page and use it instead. I recommend you also copy the SCRATCH.EXE file from the Scratch installation folder along with all the Plugin.dll's to have features such as presentation mode enabled. This tutorial also talks about the Scratch skin. Download the Skin zip folder and unzip it into the source code directory with "ScratchSkin" as a name.

another important note
if you are planning to publish your mod, please read the scratch source code license.
And please be creative, add something other than blocks (as requested by nXIII and annoys many other Squeakers!)

By this point you should have the browser open, that green window where all the coding's done. here's an explanation of it:

on top, there are four panes. from right to left:
1. 'categories'. for organization. dont appear in code
2. 'class names'. learn about these later on (not to be confused with CLASS!)
3. 'message categories'. for organization. don't appear in code
4. 'methods'. individual methods, or functions, belonging to each instance of a class (instance methods) or the class itself (class methods).

on bottom is the code pane. here the code for the selected method is inserted.
the path selected here is the one of the blockSpecs, used later on.
for more info on blockSpecs and how they work, visit the first page of this thread.

Here we go with the tutorial:

The Squeak Syntax

The squeak syntax used in Scratch is very basic:

- initialize methods are ones that are called when a Morph Object is created.

- Morphs are the graphic elements

- There are many 'classes', which are groups of code or separate morphs

- classes have two two types of methods, instance methods and class (static) methods.

- inside the classes (again, not to be confused with 'the class' above) are methods

- methods are the actual code that make the program work.
   they execute code when they are called, and can optionally return a value.
   different methods can call each other by using 'self nameOfMethod' if in
   the same class (in an instance) or 'NameOfClass new nameOfMethod' for
   a separate class.

Common squeak commands - "what's inside that code?"

Understanding and coding squeak commands is not easy without the knowledge of some simple basics; here are a few of the most used ones.

-> Always separate lines of code by a period (or full stop for english)
    That way squeak knows it can move on to the next command

-> true/false statements: this method performs a certain action if the statement
    is true, and a different if the statement is false.

valueYouWantToTest = true ifTrue: [self doThis]
                           ifFalse: [self doThat].

-> reporting a value: you can report a value using the little hat key (shift+six) ( ^ ).
    this is used when creating methods for either Scratch's reporter blocks or methods
    which can be called using if statements. note that the arrow also serves as a script
    stopper, so it can be used before commands too if you want it to be the last one.

-> declaring variables: squeak makes a large use of variables. if a variable is not included
    in the method title and you want to use it in your code, add this to the first line:

 | t1 t2 t3 |

that jut declared (created) three variables - t1, t2, and t3.

-> setting variables: your variables are no use if you can't set them to a value or string.
    to do this, you need to add this code:

t1 _ 'hello'
OR
t1 _ 53

the first one set the variable to the string 'hello', the second to the number 53. make sure you use quotes when typing strings! note: the underscore should appear as an arrow pointing left.

Useful to know when creating a mod or editing scratch

On to Scratch itself now. Ever wondered how the blocks are made? Or where the interface all starts from? This bit here will answer your questions.

-> The blocks are created in ScriptableScratchMorph's (class) blockSpecs (method).
add blockSpecs using this thread. Once you're used to it, you can try your own blocks.

On to the Scratch UI, or user interface. all of the graphics visible in scratch start from ScratchFrameMorph. that's the main graphic element which covers the whole area of the scratch window. You can find it along with all the other elements in Scratch-UI-Panes. From there you can edit a number of things, including:
-> the window title
    under private > updateProjectName, change the names that say 'Scratch'

-> all of the scratch skin, including fonts
    to edit graphic elements of the skin, change them in the ScratchSkin folder and then load them into the skin using

 ScratchFrameMorph readSkinFrom: (FileDirectory default directoryNamed: 'ScratchSkin') ifAbsent: [^ nil]

-> menus
    under 'menu/button actions', find individual menus called editMenu:, helpMenu:
    and so on. to add a simple menu item, use this code:
    menu add: 'some text' action: #chooseWhateverMethodHere.
    to add a separator, use: menu addLine.

-> dialogs
    Dialogs are created using the morph DialogBoxMorph.
    Simple dialogs can me shown with the code DialogBoxMorph inform: 'something'
    If you want to add a title you can use DialogBoxMorph inform: 'contents' title: 'title'
    TBC
_____________

This post is continuosly updated. coming soon: how to show advanced dialog boxes (wierd. i posted it already but seems to have deleted all of my work on it boohooo)

feel free to suggest stuff to add to this post. i am open to suggestions!

Last edited by LS97 (2010-10-12 08:20:52)