InkCollector Signiture Made Easy

左手的ㄟ右手 2022-08-19 14:14 138阅读 0赞

转自：http://www.codeproject.com/Articles/105570/InkCollector-Signiture-Made-Easy

The following article is useful when trying to import Ink into a database. I have tried to keep it as simple as possible.

![Example.png][]

I've successfully used this in my Access database that holds about 500 signatures; the average signature size is about 1500 characters. The largest one on record is 2853 and the smallest one on record is 1139. To store this in a Microsoft Access Database, you will need to save it in a memo field as the maximum number of characters in a Text field is 255.

## Using the Code ##

First add the reference for `Microsoft.Ink`to your VB Project, next create a group box on your form. Before your form class, add `Imports Microsoft.Ink` so that a `InkCollector` control can be created. First, define the `InkCollector`control. Then, create the control from your form load `sub`and give it the handle of your group box.

Your code should then look something like this:

Imports Microsoft.Ink 'Required for InkCollector
    
    Public Class frmMain
    
        Dim Sig_InkCollector As InkCollector 'The InkCollector
    
        Private Sub frmMain_Load(ByVal sender As Object, ByVal e As System.EventArgs) _
    	Handles Me.Load
            Sig_InkCollector = New InkCollector(GroupBox1.Handle)
            Sig_InkCollector.Enabled = True
            Sig_InkCollector.AutoRedraw = True
        End Sub
    End Class

I have just completed adding a function that converts the `base64 string` to an image so that it can be attached to a RTF, HTML or printed easily.

#### To Clear the Signiture ####

Specify call the `clear sub`from the `Signiture`module, then specify the `InkCollector`and the `GroupBox`which contains the `InkCollector`control.

Signiture.Clear(Sig_InkCollector, GroupBox1)

**To Set the Signiture**

To load a `signiture Base64 string` into the `inkCollector`, call the following `Sub`, specify the `InkCollector`and the `GroupBox` which contains the `InkCollector`control, then the `Base64 String`.

Signiture.SetBase64(Sig_InkCollector, GroupBox1, TextBox1.Text)

#### To Get the Signiture ####

To read the `Signiture`from the `InkCollector`, call the following function and specify the `InkCollector`. The `Base64 String` will be returned.

Textbox1.Text = Signiture.GetBase64(Sig_InkCollector)

#### To Convert Base64 to Image ####

To convert a stored `Base64InkSerializedFormat String` to an `Image`, so that the `signiture`can be displayed in a report.

PictureBox1.Image = Signiture.Base64toImage(TextBox1.Text)

## Source ##

Imports Microsoft.Ink 'Required for InkPicture
    Imports System.Text 'Required by UTF8Encoding
    Imports System.IO 'Required by MemoryStream
    ''' <summary>
    ''' Signiture Made Easy Module
    ''' Created by Marco van der Merwe (22 September 2010)
    ''' </summary>
    Module Signiture
    ''' <summary>
    ''' Returns String in Format(PersistenceFormat = Base64InkSerializedFormat)
    ''' </summary>
    ''' <param name="InkCollector"></param>
    ''' <returns> String Format(PersistenceFormat = Base64InkSerializedFormat)</returns>
    ''' <remarks></remarks>
    Function GetBase64(ByVal InkCollector As InkCollector) As String
    Dim utf8 As UTF8Encoding = New UTF8Encoding()
    InkCollector.Enabled = False
    Return utf8.GetString(InkCollector.Ink.Save_
    	(PersistenceFormat.Base64InkSerializedFormat, CompressionMode.Maximum))
    InkCollector.Enabled = True
    End Function
    ''' <summary>
    ''' Sets the Base 64 Ink from String
    ''' </summary>
    ''' <param name="InkCollector"></param>
    ''' <param name="GroupBox"></param>
    ''' <param name="Base64"></param>
    ''' <remarks></remarks>
    Sub SetBase64(ByVal InkCollector As InkCollector, _
    	ByVal GroupBox As GroupBox, ByVal Base64 As String)
    Dim loadedInk As Ink = New Ink()
    Dim utf8 As UTF8Encoding = New UTF8Encoding()
    InkCollector.Enabled = False
    InkCollector.Ink.DeleteStrokes() ' Clear all strokes
    loadedInk.Load(utf8.GetBytes(Base64))
    InkCollector.Ink = loadedInk
    InkCollector.Enabled = True
    GroupBox.Invalidate()
    End Sub
    ''' <summary>
    ''' Clear Signiture
    ''' </summary>
    ''' <param name="InkCollector"></param>
    ''' <param name="GroupBox"></param>
    ''' <remarks></remarks>
    Sub Clear(ByVal InkCollector As InkCollector, ByVal GroupBox As GroupBox)
    InkCollector.Enabled = False ' Disable InkPicture to clear
    InkCollector.Ink.DeleteStrokes() ' Clear all strokes
    GroupBox.Invalidate() ' Redraw frame
    InkCollector.Enabled = True ' Reenale InkPicture for entry
    End Sub
     
    ''' <summary>
    ''' Converts String Format(PersistenceFormat = Base64InkSerializedFormat) 
    ''' to System.Drawing.Image
    ''' </summary>
    ''' <param name="Base64"></param>
    ''' <returns>System.Drawing.Image</returns>
    ''' <remarks></remarks>
    Function Base64toImage(ByVal Base64 As String) As System.Drawing.Image
    Dim utf8 As UTF8Encoding = New UTF8Encoding()
    Dim imgSig As System.Drawing.Image
    Dim tmploadedInk As Ink = New Ink()
    Dim strGIF As String
    Dim imageBytes() As Byte
    Dim MS As MemoryStream
    'Load the Base64 String in Format(PersistenceFormat = Base64InkSerializedFormat) as ink
    tmploadedInk.Load(utf8.GetBytes(Base64))
    'Convert the ink to Base64 String in format 
    '(PersistenceFormat.Gif, CompressionMode.Maximum)
    strGIF = Convert.ToBase64String(tmploadedInk.Save_
    	(PersistenceFormat.Gif, CompressionMode.Maximum))
    'Convert Base64 String to Byte Array
    imageBytes = Convert.FromBase64String(strGIF)
    MS = New MemoryStream(imageBytes, 0, imageBytes.Length)
    ' Convert byte[] to Image
    MS.Write(imageBytes, 0, imageBytes.Length)
    imgSig = Image.FromStream(MS, True)
    Return imgSig
    End Function
    End Module

## Points of Interest ##

I’ve tried everything with `InkPicture`for about 3 weeks and had no results, until I started using `InkCollector`. I had many unexplained errors and very little help with `InkPicture`, this is far easier to use.

I know the Access Database gets quite large, but at least these signitures are secured by a password and my data is at least stored in the same database.

## History ##

*  Added Image Support, to convert `Base64InkSerializedFormat string` to `Image`

[Example.png]: /images/20220731/e6dbe92be40e45fa88f68c52c1caabbb.png