Changes between Version 10 and Version 11 of squeak_faq_new

Timestamp:

03/25/2015 10:58:12 AM (9 years ago)

Author:

daniel.kurzynski

Comment:

--

squeak_faq_new

@@ -29 +29 @@
 * [https://www.hpi.uni-potsdam.de/hirschfeld/trac/SqueakCommunityProjects/wiki/squeak_screencasts Squeak Screencasts]
 
+== Smallcode Syntax ==
+
+=== How do I leave a method without returning a value, e.g. early return? ===
+In !Smalltalk `^` behaves similar to return in other languages. If a method in !Smalltalk should return nothing, typically you return `self`. You should avoid to return `nil`.
+
+=== How do I break inside a loop? ===
+A way to do so is to put the loop into its own method and to add another return. However, you should consider the collection protocol. Usually, there already is a method, that solves your problem. Possible methods could be: `#detect:ifFound:ifNone:` or `#detect:thenDo:ifNone:`.
+
+=== Are there abstract classes in !Smalltalk and how should I name them? ===
+In !Smalltalk a class is abstract when a method is implemented with "self subclassResponsibility". However, you can still create objects of this class, but this method cannot be called. A typically idom is to extend the name with the word "Abstract". Examples in the image are: AbstracEvent, AbstractFont, or AbstractSound.
+
+== Idoms and Patterns ==
+=== How to I access class variables or methods? Via classname or self class? ===
+
+
 == I/O ==
 
 == Graphic (Morphic) ==
 
+=== How do I repeat an image in the background? ===
+An image can be repeated in the Backround using an !InfiniteMorph as a morph's fillstyle:
+{{{
+aForm := Form fromFileNamed: 'picture.png'.
+anInfiniteForm := InfiniteForm with: aForm.
+Morph new
+    extent: 500@500;
+    fillStyle: anInfiniteForm;
+    openInHand.
+}}}
+
+=== How do I react on deleting morphs using halos? ===
+If a morph is delted using the X in the halo menu, `Morph>>dismissViaHalo`, `Morph>>dismissMorph`, `Morph>>delete` are called. If your morph is a subclass of Morph, you can overwrite one of these. Do not forget to call the super implementation. 
+
+=== How do I prevent a Morph from stepping directly after opening? ===
+
+`Morph>>wantsStep` can be overwritten returning false. As a result the morph will not start stepping immediately. Neverthelesse, you can start stepping with `Morph>>startStepping` later on. 
+
+
+=== How do I implement a parallax scrolling for background images? ===
+
+=== How do I change the size of an image independent from the aspect ratio? ===
+A Form can be scaled using `Form>>#magnify:by:smoothing:`. The scale factor can either by a single value or a point to define the scale factor for both height and width.
+The following examples shows how to change the size to 100@50 independent from the original aspect ratio:
+{{{
+MenuIcons helpIcon in: [:form |
+    (form
+        magnify: form boundingBox
+        by: (100@50) / form extent
+        smoothing: 1) asMorph openInHand].
+}}} 
+
+=== How do I insert morphs in the background?===
+
+Instead of using `addMorph:` you can use the following methods to influence the z-level of morphs:
+`#addMorph`, `addMorphFront:`, `#addMorph:behind:`, and `#addMorph:inFrontOf:`.
+
 === How do I rotate a morph? ===
 
-To rotate a morph you can create a !TransformationMorph around your morph and change the angle using: !TransformationMorph>>angle:
+To rotate a morph you can create a !TransformationMorph around your morph and change the angle using: `TransformationMorph>>angle:`
 
 {{{
@@ -45 +97 @@
 }}}
 
-If you want to rotate a local Resource only once at the beginning, you can create a From and rotate it using From>>rotateBy:
+If you want to rotate a local Resource only once at the beginning, you can create a From and rotate it using `From>>rotateBy:`
 You can rotate it later on by creating another rotated copy and exchanging the from of the !ImageMorph. However, this is inperformant if used often.
 
@@ -60 +112 @@
 == Image Concept ==
 
+== Squeak ==
+
+=== How do I change the author initials? ===
+For future code changes you can change your author initials via menu as shown in the picture below.
+
 == Seaside ==