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VB.NET在动态创建的png图像周围绘制两个像素的透明边框?

system.drawing.graphics system.drawing vb.net

Paradox Code · 技术社区 · 9 年前

我对图形编程很陌生,更不用说VB了,所以我在这里遇到了麻烦。我已经完成了基本上所有的代码,我所缺少的就是在图像周围添加几个像素的透明填充/边框,我被卡住了。我环顾四周,但我看到的例子似乎极其复杂,在我看来就像是一个过度的例子(一页又一页的代码)。

任何指导或易于理解的教程/示例都将非常感谢。

附加以下当前代码:

当前代码

Dim img As Image = New Bitmap(100, 100)

Dim Drawing As Graphics = Graphics.FromImage(img)
Dim rand As New Random
Dim bgcolor As Color = Color.FromArgb(rand.Next(64, 196), rand.Next(64, 196), rand.Next(64, 196))

Dim family As FontFamily = Nothing

Dim fontName As String = "Lucida Sans Typewriter"
Dim fontSize As Single = 42

Using fontTester As New Font(fontName, fontSize, FontStyle.Regular, GraphicsUnit.Pixel)
    If fontTester.Name = fontName Then 
        family = New FontFamily("Lucida Sans Typewriter")
    Else
        Try
            Dim privateFonts As New System.Drawing.Text.PrivateFontCollection()
            privateFonts.AddFontFile(HttpContext.Current.Server.MapPath("~/") + "\styles\fonts\LTYPE.ttf")
            Dim font As New System.Drawing.Font(privateFonts.Families(0), 42)
            family = font.FontFamily
        Catch ex As Exception
            family = New FontFamily("Arial")
        End Try
    End If
End Using

Dim FontText As Font = New Font(family, 42, FontStyle.Regular)

Drawing.Clear(bgcolor)
Dim textBrush As Brush = New SolidBrush(Color.White)
Drawing.DrawString(initials, FontText, textBrush, 7, 16)
Drawing.Save()
textBrush.Dispose()
Drawing.Dispose()

2 回复 | 直到 9 年前

Nico Schertler 9 年前

您可以通过将图像清除为透明,然后在每个方向上绘制一个比图像小2像素的背景矩形来完成此操作:

Drawing.Clear(Color.Transparent)
Drawing.FillRectangle(New SolidBrush(bgcolor), 2, 2, 96, 96)
'Draw text ...

mago 9 年前

以下代码是将黑色字体周围的一个像素更改为透明的示例。扩展代码以考虑多个像素应该很容易。如果您的图像不是如示例代码中所示的文本字符串那样的矩形,则此代码可以正常工作。即使将字体颜色设置为黑色,也有一些像素不是纯黑色,它们有一些阴影,因此在我的示例中,我检查红色分量是否为255以说明灰色阴影。

        Dim bmp As New Bitmap(width, height)
        Dim g As Graphics = Graphics.FromImage(bmp)
        Dim rand As New Random
        Dim bgcolor As Color = Color.Red
        g.Clear(bgcolor)
        Dim FontText As Font = New Font("Arial", 42, FontStyle.Regular)

        Dim textBrush As Brush = New SolidBrush(Color.Black)
        g.DrawString("Teste", FontText, textBrush, 7, 16)
        For i As Integer = 0 To Width - 1
            For j As Integer = 0 To Height - 1
               If bmp.GetPixel(i, j).R < 255 Then
                    If (bmp.GetPixel(i - 1, j).R = 255 And bmp.GetPixel(i - 1, j).G = 0 And bmp.GetPixel(i - 1, j).B = 0) Then
                        bmp.SetPixel(i, j, Color.Transparent)
                    End If
                    If (bmp.GetPixel(i + 1, j).R = 255 And bmp.GetPixel(i + 1, j).G = 0 And bmp.GetPixel(i + 1, j).B = 0) Then
                        bmp.SetPixel(i, j, Color.Transparent)
                    End If
                    If (bmp.GetPixel(i, j - 1).R = 255 And bmp.GetPixel(i, j - 1).G = 0 And bmp.GetPixel(i, j - 1).B = 0) Then
                        bmp.SetPixel(i, j, Color.Transparent)
                    End If
                    If (bmp.GetPixel(i, j + 1).R = 255 And bmp.GetPixel(i, j + 1).G = 0 And bmp.GetPixel(i, j + 1).B = 0) Then
                        bmp.SetPixel(i, j, Color.Transparent)
                    End If
                    If (bmp.GetPixel(i + 1, j + 1).R = 255 And bmp.GetPixel(i + 1, j + 1).G = 0 And bmp.GetPixel(i + 1, j + 1).B = 0) Then
                        bmp.SetPixel(i, j, Color.Transparent)
                    End If
                    If (bmp.GetPixel(i - 1, j - 1).R = 255 And bmp.GetPixel(i - 1, j - 1).G = 0 And bmp.GetPixel(i - 1, j - 1).B = 0) Then
                        bmp.SetPixel(i, j, Color.Transparent)
                    End If
                    If (bmp.GetPixel(i + 1, j - 1).R = 255 And bmp.GetPixel(i + 1, j - 1).G = 0 And bmp.GetPixel(i + 1, j - 1).B = 0) Then
                        bmp.SetPixel(i, j, Color.Transparent)
                    End If
                    If (bmp.GetPixel(i - 1, j + 1).R = 255 And bmp.GetPixel(i - 1, j + 1).G = 0 And bmp.GetPixel(i - 1, j + 1).B = 0) Then
                        bmp.SetPixel(i, j, Color.Transparent)
                    End If
                   End If

            Next
        Next

        textBrush.Dispose()
        g.Dispose()

        bmp.Save("TESTE.png", System.Drawing.Imaging.ImageFormat.Png)