Mig-infocom MiG Calendar Tutorial Manual do Utilizador descarregar pdf (Página 17)

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SVG (Scalable Vector Graphics) format and AShape. SVG is

broader in context but AShape has more flexible layout support and

is more geared towards Java and Java2D. AShape has the ability for

non uniform scaling, a functionality that SVG currently lacks.

There are many concrete classes that implements the AShape

interface. VectorShape, TextShape, ImageShape and

FeatherShape (for blurring) are some of them. It is also very easy

to write your own AShapes if the built in ones don't cover your

particular use case. The AbstractShape implements most of the

boiler plate and all you have to do is extend it and provide the painting

code.

The layout idea behind AShape is that you provide it (actually the

ARootShape) with a reference rectangle and then tell it to paint itself

relative to that rectangle. The AShape itself decides how it should

relate to that rectangle, but it will probably in most cases just cover the

whole of it. Sub shapes of a shape are then placed according to the

bounds that the parent shape actually used. The placement relative to

the Rectangle bounds is normally specified with a PlaceRect, or

rather one of the concrete classes that implement that interface

(AbsRect or AlignRect).

A PlaceRect describes how one Rectangle relates to another

Rectangle, optionally with a reference Dimension (i.e. size). The

PlaceRect handling and a lot of other boiler plate is done in

AbstractShape so you don't have to bother with it normally. That

is also why almost every xxxShape takes a PlaceRect as

argument in its constructor.

The sub shapes can freely relate to its parent's bounds and since the

PlaceRect implementations have a very flexible coordinating

system they can do this in a very advanced and dynamic fashion. It is

for instance quite easy to describe something like: 'use the right 50%

of the parent's bounds but no more than 10 pixels, right justified if

constrained'.

But how does siblings interact? With ShapeLayouts. Every

AShape has a ShapeLayout that actually gives the sub shapes

theirs reference rectangle. If no layout is specified explicitly the

DefaultShapeLayout is used which will layout all sub shapes

with the exact bounds of the parent (on which it is installed). All sibling

will thus get the same reference bounds to used for placing

themselves and there are no sibling cooperation.

RowShapeLayout and DockingShapeLayout are delivered by

default and how they work and are supposed to be used is specified in

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