Android Code Snippet [B4X]Index ScrollTo Heights in BBCodeView - Marked Sections & Words Occurrences

A recent Forum thread inspired this snippet.

There is a on-the-fly search method created by @T201016

In my snippet, indexing is done once (in the attached example about 500 msec)
The example has under 200 lines of code (incl. the sample text).

1. Insert invisible markers between sections and measure height to each marker.
2. Index words by marker height.

Use the code in any way you like.

#Region Shared Files
#CustomBuildAction: folders ready, %WINDIR%\System32\Robocopy.exe,"..\..\Shared Files" "..\Files"
'Ctrl + click to sync files: ide://run?file=%WINDIR%\System32\Robocopy.exe&args=..\..\Shared+Files&args=..\Files&FilesSync=True
#End Region

'Ctrl + click to export as zip: ide://run?File=%B4X%\Zipper.jar&

Sub Class_Globals
    Private Root As B4XView
    Private xui As XUI
    Private BBCodeView1 As BBCodeView
    Private TextEngine1 As BCTextEngine
    Private markerHeights As B4XOrderedMap
    Private wordPositions As Map
    Private minWordLength As Int = 4
    Private BBCVClr As String
    Private ScrollToYOffset As Float = 50dip
    Private actionLabel As Label
    Private wordHighlighted As Boolean
End Sub

Public Sub Initialize
    markerHeights.Put("", 0)   'create default top position
    wordPositions.Initialize   'each word will have a list of heights
End Sub

Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Root.Color = xui.Color_RGB(220, 220, 220)
    Dim BBCVPanel As B4XView = xui.CreatePanel("")
    Root.AddView(BBCVPanel, 50dip, 50dip, Root.Width - 100dip, Root.Height - 100dip)
    Dim actionLabel As Label: actionLabel.Initialize("")
    Dim NotePanel As B4XView = actionLabel
    NotePanel.TextSize = 22
    NotePanel.TextColor = xui.Color_Blue
    NotePanel.SetTextAlignment("CENTER", "CENTER")
    Root.AddView(NotePanel, 50dip, Root.Height - 45dip, Root.Width - 100dip, 40dip)

    BBCodeView1.TextEngine = TextEngine1
    Dim margin As Int = 25dip
    Dim margins As B4XRect: margins.Initialize(margin, margin, margin, margin)
    BBCodeView1.Padding = margins
    BBCodeView1.mBase.Visible = False
    Dim markTime As Long =
    BBCVClr = IntToHex(BBCodeView1.mBase.Color)
    BBCodeView1.Text = getBBCVText            'although not visible this creates all the marks

' for each mark compute height of substring to mark  
    For Each mrkName As String In markerHeights.keys
        BBCodeView1.Text = getBBCVText.SubString2(0, getBBCVText.IndexOf(mrkName))
        Dim h As Int = BBCodeView1.Paragraph.Height / TextEngine1.mScale + BBCodeView1.Padding.Top + BBCodeView1.Padding.Bottom
        markerHeights.Put(mrkName, h)
    BBCodeView1.Text = getBBCVText

    BBCodeView1.mBase.Visible = True        'finally make it visible

    Log(DateTime.Now - markTime)        '467 msec
    showAction("Initial Scroll = Top")
    scrollToWord("Alice", 2)        'go to section with 2nd occurrence of Alice
    showAction($"scrollToWord("Alice", 2)"$)
    scrollToMarker(5)   'scroll to mark 3 = paragraph 3  (as an example)
End Sub

Private Sub showAction(s As String)
    actionLabel.Text = s
End Sub

Private Sub scrollToTop
    If wordHighlighted Then
        BBCodeView1.Text = getBBCVText
        wordHighlighted = False
    End If = 0
End Sub

Private Sub scrollToWord(wrd As String, occurrence As Int)
    Dim heights As List = wordPositions.Get(wrd.ToLowerCase)
    Dim ar() As Object = heights.Get(occurrence - 1)
    Dim h As Int = ar(0)
    BBCodeView1.Text = getBBCVText.Replace(ar(1), $"[url=${ar(1)}][b]${ar(1)}[/b][/url]"$) = h - ScrollToYOffset    'provide a little headroom
    wordHighlighted = True
End Sub

Private Sub scrollToMarker(index As Int)  'ignore
    If wordHighlighted Then
        BBCodeView1.Text = getBBCVText
        wordHighlighted = False
    End If
    Dim h As Int = markerHeights.Get($"~${index}~"$) = h - ScrollToYOffset    'provide a little headroom
End Sub

Private Sub scrollToLastMarker
    If wordHighlighted Then
        BBCodeView1.Text = getBBCVText
        wordHighlighted = False
    End If
    Dim h As Int = markerHeights.Values.Get(markerHeights.Size - 1) = h - ScrollToYOffset    'provide a little headroom
End Sub

Private Sub mark(index As Int) As String
    Dim name As String = $"~${index}~"$
    If markerHeights.ContainsKey(name)  = False Then    'make sure not do it again during height measurements
        markerHeights.Put(name, -1)
    End If
    Return $"[Color=${BBCVClr}]~${index}~[/Color]"$            'make mark invisible - set color to background
End Sub

Private Sub getBBCVText As String
    Dim s As String = $"
[TextSize=22][b]Chapter I: Down the Rabbit-Hole[/b][/TextSize]
Alice was beginning to get very tired of sitting by her sister on the bank, and of having nothing to do: once or twice she had peeped into the book her sister was reading, but it had no pictures or conversations in it, “and what is the use of a book,” thought Alice “without pictures or conversations?”
So she was considering in her own mind (as well as she could, for the hot day made her feel very sleepy and stupid), whether the pleasure of making a daisy-chain would be worth the trouble of getting up and picking the daisies, when suddenly a White Rabbit with pink eyes ran close by her.
There was nothing so very remarkable in that; nor did Alice think it so very much out of the way to hear the Rabbit say to itself, “Oh dear! Oh dear! I shall be late!” (when she thought it over afterwards, it occurred to her that she ought to have wondered at this, but at the time it all seemed quite natural); but when the Rabbit actually took a watch out of its waistcoat-pocket, and looked at it, and then hurried on, Alice started to her feet, for it flashed across her mind that she had never before seen a rabbit with either a waistcoat-pocket, or a watch to take out of it, and burning with curiosity, she ran across the field after it, and fortunately was just in time to see it pop down a large rabbit-hole under the hedge.
In another moment down went Alice after it, never once considering how in the world she was to get out again.
The rabbit-hole went straight on like a tunnel for some way, and then dipped suddenly down, so suddenly that Alice had not a moment to think about stopping herself before she found herself falling down a very deep well.
Either the well was very deep, or she fell very slowly, for she had plenty of time as she went down to look about her and to wonder what was going to happen next. First, she tried to look down and make out what she was coming to, but it was too dark to see anything; then she looked at the sides of the well, and noticed that they were filled with cupboards and book-shelves; here and there she saw maps and pictures hung upon pegs. She took down a jar from one of the shelves as she passed; it was labelled “ORANGE MARMALADE”, but to her great disappointment it was empty: she did not like to drop the jar for fear of killing somebody underneath, so managed to put it into one of the cupboards as she fell past it.
“Well!” thought Alice to herself, “after such a fall as this, I shall think nothing of tumbling down stairs! How brave they’ll all think me at home! Why, I wouldn’t say anything about it, even if I fell off the top of the house!” (Which was very likely true.)
Down, down, down. Would the fall never come to an end? “I wonder how many miles I’ve fallen by this time?” she said aloud. “I must be getting somewhere near the centre of the earth. Let me see: that would be four thousand miles down, I think—” (for, you see, Alice had learnt several things of this sort in her lessons in the schoolroom, and though this was not a very good opportunity for showing off her knowledge, as there was no one to listen to her, still it was good practice to say it over) “—yes, that’s about the right distance—but then I wonder what Latitude or Longitude I’ve got to?” (Alice had no idea what Latitude was, or Longitude either, but thought they were nice grand words to say.)
Presently she began again. “I wonder if I shall fall right through the earth! How funny it’ll seem to come out among the people that walk with their heads downward! The Antipathies, I think—” (she was rather glad there was no one listening, this time, as it didn’t sound at all the right word) “—but I shall have to ask them what the name of the country is, you know. Please, Ma’am, is this New Zealand or Australia?” (and she tried to curtsey as she spoke—fancy curtseying as you’re falling through the air! Do you think you could manage it?) “And what an ignorant little girl she’ll think me for asking! No, it’ll never do to ask: perhaps I shall see it written up somewhere.”
    Return s.SubString2(s.IndexOf("~~~") + 4, s.LastIndexOf("~~~") - 1)
End Sub

Public Sub IntToHex(Color As Int) As String
    Dim bcx As ByteConverter
    Dim r As Int = Bit.And(0xff, Bit.UnsignedShiftRight(Color, 16))
    Dim g As Int = Bit.And(0xff, Bit.UnsignedShiftRight(Color, 8))
    Dim b As Int = Bit.And(0xff, Bit.UnsignedShiftRight(Color, 0))
    Dim result As String = bcx.HexFromBytes(Array As Byte(r, g, b))
    Return "#" & result.toLowerCase
End Sub

Public Sub indexWords(text As String)
    Dim ignoreChars As String = $"~!@#$%^&*()_+-={}|[]\:";<>?,./“”'""$
    Dim v() As String = Regex.Split(CRLF, text)
    Dim currentMark As String
    For Each s As String In v
        If s.StartsWith($"[Color=${BBCVClr}]~"$) Then
            currentMark = s.SubString2(s.IndexOf("~"), s.LastIndexOf("~") + 1)
            Dim w() As String = Regex.Split(" ", s)
            For Each t As String In w
                t = t.Trim
                If t.Length < minWordLength Then Continue
                Dim sb As StringBuilder: sb.Initialize
                For k = 0 To t.Length - 1
                    Dim c As String = t.CharAt(k)
                    If ignoreChars.Contains(c) = False Then sb.Append(c)
                t = sb.toString
                Dim tlower As String = t.toLowerCase
                Dim h As Int = markerHeights.Get(currentMark)
                If wordPositions.containsKey(tlower) Then
                    Dim heights As List = wordPositions.Get(tlower)
                    Dim heights As List: heights.Initialize
                    wordPositions.Put(tlower, heights)
                End If
                heights.Add(Array(h, t))
        End If
End Sub

Private Sub BBCodeView1_LinkClicked (URL As String)
End Sub



    18.2 KB · Views: 55

Similar Threads