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11.6: Colored Shapes

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    43727

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    \(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)

    A shape may be colored in various ways. Node shapes understand the message fillColor:, textColor:, borderColor:. Line shapes understand color:. Let’s color the visualization of the collection hierarchy:

    view shape rectangle
    size: 10;
    borderColor: [ :cls | ('*Array*' match: cls name)
                            ifTrue: [ Color blue ]
                            ifFalse: [ Color black ] ];
    fillColor: [ :cls | cls hasAbstractMethods ifTrue: [ Color lightGray ] ifFalse: [ Color white]
        ].
view nodes: Collection withAllSubclasses.
view edgesFrom: #superclass.
view treeLayout.

    The produced visualization is given in Figure \(\PageIndex{1}\). It easily help identify abstract classes that are not named as “Array” and the ones that are abstract without an abstract method.

    Tree hierarchy with abstract classes labeled.
    Figure \(\PageIndex{1}\): Abstract classes are in gray and classes with the word "Abstract" in their name are blue.

    Similar as with height: and width:, messages to define color either take a symbol, a block or a constant value as argument. The argument is evaluated against the domain object represented by the graphical element (a double dispatch sends the message moValue: to the argument). The use of ifTrue:ifFalse: is not really practicable. Utilities methods are provided for that purpose to easily pick a color from a particular condition. The definition of the shape can simply be:

    view shape rectangle
    size: 10;
    if: [ :cls | ('*Array*' match: cls name) ] borderColor: Color blue;
    if: [ :cls | cls hasAbstractMethods ] fillColor: Color lightGray;
...

    The method hasAbstractMethods is defined on Behavior and Metaclass in Pharo. By sending the hasAbstractMethods to a class return a boolean value telling us whether the class is abstract or not. We recall that an abstract class in Smalltalk is a class that defines or inherits at least one abstract method (i.e., which contains self subclassResponsibility).

    This page titled 11.6: Colored Shapes was last modified on Mon, 26 Jul 2021 15:16:48 GMT and is shared under a CC BY-SA 3.0 license and was authored, remixed, and/or curated by Alexandre Bergel, Damien Cassou, Stéphane Ducasse, Jannik Laval (Square Bracket Associates) via source content that was edited to the style and standards of the LibreTexts platform.