透明渐变反射 - VB.NET？

Question

我想知道如何去增加一个上下颠倒梯度反射，与此类似：

我会推论第一反射的位图是颠倒了。然后，在Photoshop中，我会为图像添加一个alpha蒙版，并使用黑色/白色渐变的顶部到底部。

如何在VB.NET中添加alpha遮罩/渐变组合？我似乎无法找到任何功能。

Answer 1

下面是使用Bitmaps

Dim bm_src1 As Bitmap = CType(pb1.Image.Clone, Bitmap) 
Dim bm_out As New Bitmap(bm_src1.Width, bm_src1.Height) 
Using gr As Graphics = Graphics.FromImage(bm_out) 
    'Flip image 
    gr.TranslateTransform(CSng(bm_src1.Width/2), CSng(bm_src1.Height/2)) 
    gr.RotateTransform(180) 
    gr.TranslateTransform(-CSng(bm_src1.Width/2), -CSng(bm_src1.Height/2)) 
    ' Give the images alpha gradients. 
    Dim alpha As Integer 
    For x As Integer = 0 To bm_src1.Width - 1 
    For y As Integer = 0 To bm_src1.Height - 1 
     alpha = (255 * y) \ bm_src1.Height 
     Dim clr As Color = bm_src1.GetPixel(x, y) 
     clr = Color.FromArgb(alpha, clr.R, clr.G, clr.B) 
     bm_src1.SetPixel(x, y, clr) 
    Next 
    Next 
    ' Draw the images onto the result. 
    gr.DrawImage(bm_src1, 0, 0) 
End Using 
' Display the result. 
pbResult.Image = bm_out 'picturebox output