生成gif或png透明图片的问题，百分酬谢

Question

下面是我的代码不知道错在哪里，就是实现不了。
Bitmap fromImage=new Bitmap("c:\1.gif");
fromImage.MakeTransparent();Bitmap bitmap = new Bitmap(width,height);
Graphics graphic = Graphics.FromImage(bitmap);graphic.DrawImage(fromImage,new Rectangle(0,0, 100, 100), new Rectangle(200,200,100, 100), GraphicsUnit.Pixel);
Image saveImage = Image.FromHbitmap(bitmap.GetHbitmap());
saveImage.Save("c:\2.gif",ImageFormat.Gif);

Answer 1

Bitmap fromImage=new Bitmap("d:\\1.jpg");
           fromImage.MakeTransparent();           Bitmap bitmap = new Bitmap(fromImage.Width, fromImage.Height);
            Graphics graphic = Graphics.FromImage(bitmap);            graphic.DrawImage(fromImage, new Rectangle(0, 0, fromImage.Width, fromImage.Height), new Rectangle(0, 0, fromImage.Width, fromImage.Height), GraphicsUnit.Pixel);
            //Image saveImage = Image.FromHbitmap(bitmap.GetHbitmap());
           bitmap.Save("d:\\2.jpg");

Answer 2

Bitmap 这个类型，应该是有背景的。
换其他类型试试看

Answer 3

将背景色透明
fromImage.MakeTransparent(backcolor);

Answer 4

Bitmap fromImage=new Bitmap("c:\1.gif");
fromImage.MakeTransparent();Bitmap bitmap = new Bitmap(width,height);
Graphics graphic = Graphics.FromImage(bitmap);
／／这里加句
／／bitmap.clear()或者是graphic.clear();有点不大记得了／／graphic.DrawImage(fromImage,new Rectangle(0,0, 100, 100), new Rectangle(200,200,100, 100), GraphicsUnit.Pixel);
Image saveImage = Image.FromHbitmap(bitmap.GetHbitmap());
saveImage.Save("c:\2.gif",ImageFormat.Gif);

Answer 5

还是不行啊，哪位大侠救我
graphic.Clear(Color.Transparent);
graphic.Clear(Color.White);
graphic.Clear(Color.Black);
都试过了再就是cvman()似乎正确一点就是下面这句好象不应该要
Image saveImage = Image.FromHbitmap(bitmap.GetHbitmap());
但透明背景还是没有出来。

Answer 6

试试， 
Bitmap fromImage = new Bitmap("d:\\1.jpg");
            fromImage.MakeTransparent();            Bitmap bitmap = new Bitmap(fromImage.Width, fromImage.Height);
            Graphics graphic = Graphics.FromImage(bitmap);            graphic.DrawImage(fromImage, new Rectangle(0, 0, fromImage.Width, fromImage.Height), new Rectangle(0, 0, fromImage.Width, fromImage.Height), GraphicsUnit.Pixel);
            //Image saveImage = Image.FromHbitmap(bitmap.GetHbitmap());
            bitmap.MakeTransparent();
            bitmap.Save("d:\\2.jpg");

Answer 7

Bitmap fromImage = new Bitmap("d:\\1.jpg");
            fromImage.MakeTransparent();            Bitmap bitmap = new Bitmap(fromImage.Width, fromImage.Height);
            Graphics graphic = Graphics.FromImage(bitmap);            graphic.DrawImage(fromImage, new Rectangle(0, 0, fromImage.Width, fromImage.Height), new Rectangle(0, 0, fromImage.Width, fromImage.Height), GraphicsUnit.Pixel);
            //Image saveImage = Image.FromHbitmap(bitmap.GetHbitmap());
            bitmap.MakeTransparent();
            this.pictureBox1.Image = bitmap;//可以看到已经可以了
            bitmap.Save("d:\\2.jpg");

Answer 8

现在改成这样了，可还是不行啊Bitmap fromImage=new Bitmap("c:\1.gif");
fromImage.MakeTransparent();Bitmap bitmap = new Bitmap(width,height);
Graphics graphic = Graphics.FromImage(bitmap);graphic.DrawImage(fromImage,new Rectangle(0,0, 100, 100), new Rectangle(200,200,100, 100), GraphicsUnit.Pixel);
bitmap.MakeTransparent();
bitmap.Save("c:\2.gif",ImageFormat.Gif);

Answer 9

private void Form1_Load(object sender, System.EventArgs e)
{
Bitmap b=new Bitmap("..\\..\\test.bmp");
b.MakeTransparent(Color.Blue);
this.pictureBox1.Image=b; 
}