Question

C# Winform设置图片透明度。

Image newImage = Image.FromFile("图片1.jpg");
Graphics g = this.CreateGraphics();
g.DrawImage(newImage, 0, 0);
想设置图片透明度，如何写？

Answer 1

//改变图片的透明度

        private Image ChangeAlpha(Image image)

        {

            Bitmap img = new Bitmap(image);

            using (Bitmap bmp = new Bitmap(img.Width, img.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb))

            {

                using (Graphics g = Graphics.FromImage(bmp))

                {

                    g.DrawImage(img, 0, 0);

                    for (int h = 0; h <= img.Height - 1; h++)

                    {

                        for (int w = 0; w <= img.Width - 1; w++)

                        {

                            Color c = img.GetPixel(w, h);

                            bmp.SetPixel(w, h, Color.FromArgb(200, c.R, c.G, c.B));

                        }

                    }

                    return (Image)bmp.Clone();

                }

            }

        }
调用：
Image image1 = Image.FromFile(Application.StartupPath + @"图片路径");
this.panel1.BackgroundImage = ChangeAlpha(image1);

Answer 2

你可以把这个图片加载到窗体中，然后设置窗体的透明度