如何透明绘制图像的某些部分 [英] How to draw certain parts of an image transparent

问题描述

我目前正在Vb.net上的一个程序上书写，我需要将图像的某些区域或某些像素设置为透明.我不是要在图像透明中设置相似的颜色，而是要将图像中的特定像素或区域设置为透明.

这是我尝试的代码，但是没有用:

 公共 类 Form1
     Dim 可以绘制 As  布尔值 = 错误
    暗 g  As 图形
    昏暗目标目标 新建位图( 233 ， 209 )

    私有 子 Form1_Load( ByVal 发​​件人目标 对象， ByVal  e 句柄 结束 子

    私有 子 PictureBox1_LostFocus( ByVal 发​​件人目标 对象， ByVal  e  As  System.EventArgs)错误
    结束 子

    私有 子 Picturebox1_MouseDown( ByVal 发​​件人目标 对象， ByVal  e  As  System.Windows.Forms.MouseEventArgs)正确
    结束 子

    私有 子 Picturebox1_MouseMove(> ByVal 发​​件人目标 对象， ByVal  e  As  System.Windows.Forms.MouseEventArgs)如果 canpaint = 真实 然后
            g.FillEllipse(Brushes.Transparent，e.X，e.Y， 4 ， 4 )
            updateimage()
        结束 如果
    结束 子

    私有 子 Picturebox1_MouseUp( ByVal 发​​件人目标 对象， ByVal  e  As  System.Windows.Forms.MouseEventArgs)错误
    结束 子

    私有  Sub  updateimage()
        PictureBox1.Image =目标
    结束 子
结束 类 

解决方案

为了获得所需的结果，您需要使用setpixel方法清除像素.
在这里，我刚刚使用矩形(您将其指定为4x4)清除了像素.

 导入 System.Drawing
公共 类 Form1
     Dim 可以绘制 As  布尔值 = 错误
    暗 g  As 图形
    昏暗目标目标 新建位图( 200 ， 200 )
    暗 b  As 笔刷
    枚举 dmode
        d
        Ë
    结束 枚举
     Dim  m  As  dmode = dmode.d

    私有 子 Form1_KeyDown( ByVal 发​​件人目标 对象， ByVal  e 句柄 选择 案例 e.KeyCode
            案例 Keys.R
                m = dmode.d
                b =笔刷红色
            案例 Keys.G
                m = dmode.d
                b =画笔绿色
            案例 Keys.K
                m = dmode.d
                b =笔刷.黑色
            案例 Keys.T ' 透明度
                m = dmode.e
        结束 选择
    结束 子

    私人 子 Form1_Load( ByVal 发​​件人目标 对象， ByVal  e 句柄 结束 子

    私有 子 PictureBox1_LostFocus( ByVal 发​​件人目标 对象， ByVal  e  As  System.EventArgs)错误
    结束 子

    私有 子 Picturebox1_MouseDown( ByVal 发​​件人目标 对象， ByVal  e  As  System.Windows.Forms.MouseEventArgs)正确
    结束 子

    私有 子 Picturebox1_MouseMove(> ByVal 发​​件人目标 对象， ByVal  e  As  System.Windows.Forms.MouseEventArgs)如果 canpaint = 真实 然后
            如果 m = dmode.d 然后
                g.FillEllipse(b，e.X，e.Y， 4 ， 4 )
            其他
                对于 i  As  整数 = eX 收件人 eX +  4 
                    对于 j  As  整数 = eY 收件人是+  4 
                        target.SetPixel(i，j，Color.Transparent)
                    下一步
                下一步
            结束 如果
            updateimage()
        结束 如果
    结束 子

    私有 子 Picturebox1_MouseUp( ByVal 发​​件人目标 对象， ByVal  e  As  System.Windows.Forms.MouseEventArgs)错误
    结束 子

    私有  Sub  updateimage()
        PictureBox1.Image =目标
    结束 子

结束 类 

I am currently writing on a program in Vb.net where I need certain regions or certain pixels of an image to be set transparent. I am not looking for setting a similar color in an image transparent, but specific pixels or regions in the image to be set transparent.

Here''s the code I tryed, but didn''t work:

Public Class Form1
    Dim canpaint As Boolean = False
    Dim g As Graphics
    Dim target As New Bitmap(233, 209)

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        target = PictureBox1.Image
        g = Graphics.FromImage(target)
    End Sub

    Private Sub PictureBox1_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles PictureBox1.LostFocus
        canpaint = False
    End Sub

    Private Sub Picturebox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
        canpaint = True
    End Sub

    Private Sub Picturebox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
        If canpaint = True Then
            g.FillEllipse(Brushes.Transparent, e.X, e.Y, 4, 4)
            updateimage()
        End If
    End Sub

    Private Sub Picturebox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
        canpaint = False
    End Sub

    Private Sub updateimage()
        PictureBox1.Image = target
    End Sub
End Class

解决方案

Hi Actually painting with Transparant brush will not draw/overwrite any thing.
To get the desired result you need to clear the pixels using the setpixel method.
Here I''ve just cleared the pixels using the rectangle (which you''ve given as 4x4).

Imports System.Drawing
Public Class Form1
    Dim canpaint As Boolean = False
    Dim g As Graphics
    Dim target As New Bitmap(200, 200)
    Dim b As Brush
    Enum dmode
        d
        e
    End Enum
    Dim m As dmode = dmode.d

    Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown
        Select Case e.KeyCode
            Case Keys.R
                m = dmode.d
                b = Brushes.Red
            Case Keys.G
                m = dmode.d
                b = Brushes.Green
            Case Keys.K
                m = dmode.d
                b = Brushes.Black
            Case Keys.T 'for Transparancy
                m = dmode.e
        End Select
    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        PictureBox1.Image = target
        b = Brushes.Black
        g = Graphics.FromImage(target)
    End Sub

    Private Sub PictureBox1_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles PictureBox1.LostFocus
        canpaint = False
    End Sub

    Private Sub Picturebox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
        canpaint = True
    End Sub

    Private Sub Picturebox1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
        If canpaint = True Then
            If m = dmode.d Then
                g.FillEllipse(b, e.X, e.Y, 4, 4)
            Else
                For i As Integer = e.X To e.X + 4
                    For j As Integer = e.Y To e.Y + 4
                        target.SetPixel(i, j, Color.Transparent)
                    Next
                Next
            End If
            updateimage()
        End If
    End Sub

    Private Sub Picturebox1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
        canpaint = False
    End Sub

    Private Sub updateimage()
        PictureBox1.Image = target
    End Sub

End Class

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