rle.frm

rle静态图片压缩DELPHI代码,可以对DEPHI程序员了解有很大帮助

VERSION 4.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   1815
   ClientLeft      =   2925
   ClientTop       =   2775
   ClientWidth     =   3855
   Height          =   2220
   Left            =   2865
   LinkTopic       =   "Form1"
   ScaleHeight     =   1815
   ScaleWidth      =   3855
   Top             =   2430
   Width           =   3975
   Begin VB.CommandButton Command2 
      Caption         =   "Command2"
      Height          =   495
      Left            =   2520
      TabIndex        =   4
      Top             =   1200
      Width           =   1215
   End
   Begin VB.CommandButton Command1 
      Caption         =   "Command1"
      Height          =   495
      Left            =   120
      TabIndex        =   3
      Top             =   1200
      Width           =   1215
   End
   Begin VB.TextBox Text3 
      Height          =   285
      Left            =   120
      TabIndex        =   2
      Text            =   "Text3"
      Top             =   840
      Width           =   3615
   End
   Begin VB.TextBox Text2 
      Height          =   285
      Left            =   120
      TabIndex        =   1
      Text            =   "Text2"
      Top             =   480
      Width           =   3615
   End
   Begin VB.TextBox Text1 
      Height          =   285
      Left            =   120
      TabIndex        =   0
      Text            =   "Text1"
      Top             =   120
      Width           =   3615
   End
End
Attribute VB_Name = "Form1"
Attribute VB_Creatable = False
Attribute VB_Exposed = False
Function RLEDecode(InputString As String) As String

    Dim RLEString As String
    Dim TextString As String
    Dim x As Integer
    
    For x = 1 To Len(InputString)
        ThisChar = Mid$(InputString, x, 1)
        If ThisChar = "~" Then
            TextString = TextString & String$(Asc(Mid$(InputString, x + 1, 1)), PrevChar)
            x = x + 1
        Else
            TextString = TextString & ThisChar
        End If
        
        PrevChar = ThisChar
    Next x
    
    RLEDecode = TextString

End Function

Function RLEEncode(InputString As String) As String

    Dim LastChar As String
    Dim ThisChar As String
    Dim RLEString As String
    Dim DupeChar As String
    Dim x As Integer
    Dim RepeatCount As Integer
    
    RepeatCount = 0
    For x = 1 To Len(InputString)
        ThisChar = Mid$(InputString, x, 1)
        If LastChar = ThisChar Then
            
            'If there is only 1 repeating (like the e in Cheese)
            'then don't encode
            'because it will take 1 extra byte
            If Mid$(InputString$, x + 1, 1) <> ThisChar And _
                RepeatCount = 0 Then
                RLEString = RLEString & ThisChar
                LastChar = ThisChar
            Else
                RepeatCount = RepeatCount + 1
        
                'We can only encode up to 254 repeats after that
                'we have to start the new sequence again
                If RepeatCount = 254 Then
                    RLEString = RLEString & "~" & Chr$(RepeatCount)
                    RepeatCount = 0
                    LastChar = ""
                End If
            End If
        Else
            If RepeatCount > 0 Then
                RLEString = RLEString & "~" & Chr$(RepeatCount)
                RepeatCount = 0
            End If
    
            RLEString = RLEString & ThisChar
            LastChar = ThisChar
        End If
    Next x
    
    'If the last chars in string are repeats
    If RepeatCount > 0 Then
        RLEString = RLEString & "~" & Chr$(RepeatCount)
        RepeatCount = 0
    End If
    
    RLEEncode = RLEString

End Function

Private Sub Command1_Click()

Dim RLEEncodedString As String
    Dim temp As String
    
    temp = Text1.Text
    
    RLEEncodedString = RLEEncode(temp)
    
    Text2.Text = RLEEncodedString
    
    MsgBox "Encoded Length = " & Str$(Len(RLEEncodedString))

End Sub

Private Sub Command2_Click()

Dim temp As String
    Dim DecodedString As String
    
    temp = Text2.Text
    
    DecodedString = RLEDecode(temp)
    
    Text3.Text = DecodedString
    MsgBox "Decoded length = " & Str$(Len(DecodedString))

End Sub


Private Sub Form_Load()

Me.Caption = "Run Length Encode Example"
Command1.Caption = "RLE Encode"
    Command2.Caption = "RLE Decode"
    
    Text1.Text = "AAAAAAAAAABBBBBBBBBBCCCCC"
    Text2.Text = ""
    Text3.Text = ""
End Sub