在C＃中怎么动态生成背景透明的GIF文件，还要在上面写字？在线等。。。。。。。。。分不够再加！

[aniuping]

因为我想把生成的GIF文件放在一个有图片背景的TD中，如果生成的GIF文件不透明的话，将会把背景图片覆盖了

[灰太狼]

gif的背景是自己制作的，不是C#可以控制的，你可以用photoshop來制作，或者上網下載透明的gif圖片。如果單純隻想做透明gif的話，可以使用Animagic GIF 32bit，不必用photoshop。

[aniuping]

string filePath = Server.MapPath(".")+"\\Gif\\" + fileName;
if (File.Exists(filePath))
{
//如果文件存在，则直接显示出来
Bitmap bitmap = new Bitmap(filePath);
Response.ContentType = "image/gif";
bitmap.Save(Response.OutputStream,ImageFormat.Gif);
bitmap.Dispose();
}
else
{
objBitmap = new Bitmap(1,1);
g = Graphics.FromImage(objBitmap);
SizeF stringSize = g.MeasureString(showText, stringFont);
int nSpace = (showText.Length-1) * fontSpace;
int nWidth = nSpace+(int)stringSize.Width;
int nHeight = (int)stringSize.Height;
g.Dispose();
objBitmap.Dispose();

objBitmap = new Bitmap(nWidth,nHeight);
g = Graphics.FromImage(objBitmap);
Color color = Color.FromArgb(255,Color.Transparent); //背景透明
g.FillRectangle(new SolidBrush(color), new Rectangle(0,0,nWidth,nHeight));

g.TextRenderingHint = TextRenderingHint.AntiAlias; //提高字符显示质量

int fontLength = showText.Length;
int j=0; //配合定位每个字的位置
//对数组中的每个字进行循环输出
for (int i=0; i<showText.Length; i++)
{
g.DrawString(showText.Substring(i,1), stringFont, new SolidBrush(fontColor), new PointF(j, 0), stringFormat); //画字
j = j + fontSpace + (int)stringSize.Width / showText.Length;

}

//将objGraphics对象保存到指定的stream对象，并输出到客户端
objBitmap.Save(Response.OutputStream, ImageFormat.Gif);
//将objBitmap保存到系统目录下
objBitmap.Save(filePath,ImageFormat.Gif);
}

可是这样生成的GIF却不是透明的

[copine]

用gdi+,不过我没做过，看看这篇
http://www.cnblogs.com/caca/archive/2006/06/24/434825.html

[aniuping]

高手哪去了，怎么没有人遇到这样的问题吗？
<table>
　<tr>
　　<td background="D:\\bottom.jpg">
　　　<img src="http://localhost/Picture/Picture.aspx?　fontName=&fontSize=20&fontSpace=10&showText=&red=0&green=0&blue=0"></img>
　　</td>
　</tr>
</table>

这样做是为了动态添加图片上的文字，Picture.aspx的功能就是生成一个含有文字的透明GIF

[aniuping]

孟老大，进来看看吧！

[pol000]

帮楼主顶~~

[greennetboy]

http://www.cnblogs.com/jillzhang/archive/2006/10/17/530919.html

[aniuping]

谢谢大家的宝贵意见，可问题还是没有解决，着急中。。。。。

[viena]

Imports System.Runtime.InteropServices
Imports System
Imports System.IO
Imports System.Drawing
Imports System.Drawing.Imaging
Imports System.Drawing.Drawing2D



Public Class transparentGif : Inherits System.Web.UI.Page



Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load



Dim pic As New System.Drawing.Bitmap(200, 200, PixelFormat.Format24bppRgb)



'''draw image
Dim blackpen As New Pen(Color.Black, 3)
Dim redpen As New Pen(Color.Red, 4)
Dim silverpen As New Pen(ColorTranslator.FromHtml("#CCCCCC"), 10)
Dim fBrush As SolidBrush = New SolidBrush(ColorTranslator.FromHtml("#0000FF"))
Dim g As Graphics = Graphics.FromImage(pic)



g.Clear(Color.White) ' blank the image
g.DrawLine(silverpen, 7, 80, 110, 80)
g.SmoothingMode = SmoothingMode.AntiAlias ' antialias objects
g.DrawString("TEST", New Font("verdana", 24, FontStyle.Bold), fBrush, New PointF(10, 50))
g.DrawEllipse(blackpen, 5, 5, 110, 110)
g.DrawEllipse(redpen, 1, 1, 118, 118)



'''save new image
pic = recolorGif(pic)



' set the content type
Response.ContentType = "image/gif"



' send the image to the viewer
pic.Save(Response.OutputStream, ImageFormat.Gif)



' tidy up
pic.Dispose()



End Sub



Private Function GetColorPalette() As ColorPalette
' Make a new Bitmap object to get its Palette.
Dim bitmap As Bitmap = New Bitmap(1, 1, PixelFormat.Format8bppIndexed)
Dim palette As ColorPalette = bitmap.Palette ' Grab the palette
bitmap.Dispose()
Return palette ' Send the palette back
End Function




Private Function recolorGif(ByVal image As Image) As Bitmap
Dim nColors As Integer = 16



' Make a new 8-BPP indexed bitmap that is the same size as the source image.
Dim Width As Integer = image.Width
Dim Height As Integer = image.Height



Dim bitmap As Bitmap = New Bitmap(Width, Height, PixelFormat.Format8bppIndexed)



' Create a color palette big enough to hold the colors you want.
Dim pal As ColorPalette = GetColorPalette()



' Initialize a new color table with entries
Dim i As Integer



' set palette the lazy way!
' replace with a proper color algorithm
For i = 0 To nColors - 1
pal.Entries(i) = Color.FromArgb(255, 100, 100, 100)
Next



pal.Entries(0) = Color.FromArgb(255, 0, 0, 0)
pal.Entries(1) = Color.FromArgb(255, 255, 0, 0)
pal.Entries(2) = Color.FromArgb(255, 0, 255, 0)
pal.Entries(3) = Color.FromArgb(255, 0, 0, 255)
pal.Entries(4) = Color.FromArgb(255, 204, 204, 204)
pal.Entries(nColors - 1) = Color.FromArgb(0, 255, 255, 255)



'web safe palette use values =
'00 51 102 153 204 255



' Set the palette into the new Bitmap object.
bitmap.Palette = pal



Dim BmpCopy As Bitmap = New Bitmap(Width, Height, PixelFormat.Format32bppArgb)



Dim g As Graphics
g = Graphics.FromImage(BmpCopy)



g.PageUnit = GraphicsUnit.Pixel



' Transfer the Image to the Bitmap.
g.DrawImage(image, 0, 0, Width, Height)



' Force g to release its resources, namely BmpCopy.
g.Dispose()



' Lock a rectangular portion of the bitmap for writing.
Dim bitmapData As BitmapData
Dim rect As Rectangle = New Rectangle(0, 0, Width, Height)



bitmapData = bitmap.LockBits(rect, ImageLockMode.WriteOnly, PixelFormat.Format8bppIndexed)



' Copy the pixels from the source image
Dim pixels As IntPtr = bitmapData.Scan0
Dim bits As Byte() ' the buffer
Dim pBits As Int32



If (bitmapData.Stride > 0) Then
pBits = pixels.ToInt32()
Else
pBits = pixels.ToInt32() + bitmapData.Stride * (Height - 1)
End If



Dim stride As Integer = Math.Abs(bitmapData.Stride)
ReDim bits(Height * stride) ' Allocate the working buffer.



Dim row As Integer
Dim col As Integer



For row = 0 To Height - 1
For col = 0 To Width - 1



Dim pixel As Color
Dim i8BppPixel As Integer = row * stride + col



pixel = BmpCopy.GetPixel(col, row)



Dim colorIndex As Double
If pixel.R = 0 And pixel.G = 0 And pixel.B = 0 Then
colorIndex = 0
ElseIf pixel.R > 100 And pixel.G = 0 And pixel.B = 0 Then
colorIndex = 1
ElseIf pixel.G > 100 And pixel.R = 0 And pixel.B = 0 Then
colorIndex = 2
ElseIf pixel.B > 100 And pixel.R = 0 And pixel.G = 0 Then
colorIndex = 3
ElseIf pixel.B = 204 And pixel.R = 204 And pixel.G = 204 Then
colorIndex = 4
Else
colorIndex = (nColors - 1)
End If



bits(i8BppPixel) = CByte(colorIndex)



Next col
Next row



' Put the image bits definition into the bitmap.
Dim win32 As win32api = New win32api()
win32.CopyArrayTo(pBits, bits, Height * stride)
bitmap.UnlockBits(bitmapData)



Return bitmap



BmpCopy.Dispose()
bitmap.Dispose()



End Function



End Class



Public Class win32api




<DllImport("KERNEL32.DLL", EntryPoint:="RtlMoveMemory", _
SetLastError:=True, CharSet:=CharSet.Auto, _
ExactSpelling:=True, _
CallingConvention:=CallingConvention.StdCall)> _
Public Shared Sub CopyArrayTo(<[In](), MarshalAs(UnmanagedType.I4)> ByVal hpvDest As Int32, <[In](), Out()> ByVal hpvSource() As Byte, ByVal cbCopy As Integer)
' Leave function empty
End Sub



End Class