Newbie tip: Declaring and Managing Linked MovieClip Instances in Parent Classes

Suppose that we have two MovieClip-based classes called MegaNode and SimpleNode. We have created both of them by drawing two vector shapes on the scene and converting them to those Movieclip-based classes. For some reason, we want to call the instance of the shape that's inside - mainShape, therefore we convert it to a MovieClip, and call the instance mainShape.

Now, since on many occasions the MovieClip class is too general for our purposes, we define a SuperNode class, which extends MC, and servers as the parent for both M

egaNode and SimpleNode. We need to be able to manipulate the mainShape instance, so we instantiate it in the SuperNode class:

public var mainShape:MovieClip;

if we simply do that, the compiler will throw the following error: "1152: A conflict exists with inherited definition SuperNode.mainShape in namespace public."

The reason for that is that by default, all instances of linked MovieClips, such as mainShape, are automatically declared by default at runtime. In order to make sure that we don't get into that error again, we need to go to the ActionScript s

ettings, and uncheck the "Automatically declare stage instances" checkbox. With that done, the above mentioned code will work, and we'll be able to manipulate the mainShape instance from the SuperNode class

NOTE: Make sure that instances like mainShape are always declared as public

stage.width, stage.stageWidth, and loaderInfo.width

For any new Flasher comes the time of dealing with the stage and its properties. It is probably confusing for newcomers to distinguish between stage.width and stage.stageWidth, therefore this post. (the same logic follows for stage.height and stage.stageHeight)

stage.width is defined by the distance between the smallest and the largest x coordinate that its children reach at any certain point in time. If we imagine the stage as a balloon, the further we inflate it, the bigger the distance between its walls gets. Therefore, if you have tried to determine the width/height of the stage using the stage.width/stage.height properties, before anything has been put on the stage, the output must have always been 0.

stage.stageWidth, on the other hand, defines the width of the entire Flash window.

NOTE: Normally, one would assume that if the stage's scale mode is set to StageScaleMode.NO_SCALE, the stage.stageWidth will remain constant, no matter how much we resize the Flash window. Well, no .... stage.stageWidth changes all the time, regardless of what the documentation says.

If you want to get the value of the stage width, as defined in the project settings, or the SWF metadata, you should use loaderInfo.width