Android Code Snippet CSBuilder with leading margin

Discussion in 'Code Snippets' started by Erel, Mar 9, 2018.

  1. Erel

    Erel Administrator Staff Member Licensed User

    Sub Activity_Create(FirstTime As Boolean)
    Dim cs As CSBuilder
    CallSub3(Me, "AddLeadingMarginSpan", cs, Array As Int(0dip30dip))
    "1) First do text text text, text text text text text text text").PopAll
    CallSub3(Me, "AddLeadingMarginSpan", cs, Array As Int(0dip30dip))
    CRLF).Append("2) Second do text text text, text text text text text text text").PopAll
       Label1.Text = cs
    End Sub

    Sub AddLeadingMarginSpan(cs As Object, FirstAndRest() As Int)
    Dim span As JavaObject
    ""Array(FirstAndRest(0), FirstAndRest(1)))
    Dim jo As JavaObject = cs
    End Sub

    You must use CallSub to call AddLeadingMarginSpan due to the way CSBuilder is implemented. The Sleep(0) is required if you want to call it from Activity_Create as otherwise the CallSub will be ignored (the activity is considered paused at that point).

    The two numbers passed to AddLeadingMarginSpan are the first line margin and the other lines margin.
    Note that in this example I've added two spans. One for each point.
  2. fredo

    fredo Well-Known Member Licensed User

    Thanks for the snippet! It is very useful for structured text output.

    Oh, and this was an eyeopener, since I wasn't aware of:
    My ignorance regarding
    might be the cause for some quirky effects I had once in a while over the last years...
    Claudio Oliveira likes this.
  3. Erel

    Erel Administrator Staff Member Licensed User

    Experts tip:

    Why is CallSub required here?
    CSBuilder is implemented as an object wrapper. It inherits from AbsObjectWrapper<SpannableStringBuilder>.

    We need to call the wrapper 'open' method.
    If we try to get a reference to cs directly:
    Dim jo As JavaObject = cs
    Dim o As Object = cs
    Log(GetType(o)) 'SpannableStringBuilder
    It will return the wrapped SpannableStringBuilder. In most cases we are interested in the wrapped object, however in this specific case we need the wrapper itself.
    The only way to get a reference to the wrapper itself is by calling a method with CallSub where the parameter type is Object:
    Sub AddLeadingMarginSpan(cs As Object, FirstAndRest() As Int)
    Now cs points to the wrapper.
    Log(GetType(c)) 'CSBuilder
    Claudio Oliveira likes this.
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