C# 图片处理

按比例调整图片尺寸

#region 按比例调整图片尺寸
public static Bitmap GetThumbnail(Image bmp, int width, int height)
{
    if (width == 0)
    {
        width = height * bmp.Width / bmp.Height;
    }
    if (height == 0)
    {
        height = width * bmp.Height / bmp.Width;
    }
    Image imgSource = bmp;
    Bitmap outBmp = new Bitmap(width, height);
    Graphics g = Graphics.FromImage(outBmp);
    g.Clear(Color.Transparent);
    // 设置画布的描绘质量   
    g.CompositingQuality = CompositingQuality.HighQuality;
    g.SmoothingMode = SmoothingMode.HighQuality;
    g.InterpolationMode = InterpolationMode.HighQualityBicubic;

    g.DrawImage(imgSource, new Rectangle(0, 0, width, height + 1), 0, 0, imgSource.Width, imgSource.Height, GraphicsUnit.Pixel);

    g.Dispose();
    imgSource.Dispose();
    bmp.Dispose();
    return outBmp;
}
#endregion

  

合成图片

/// <summary>
/// 两种图片合并，类似相册，有个背景图，中间贴自己的目标图片        
/// <param name="sourceImg">粘贴的源图片</param>
/// <param name="destImg">粘贴的目标图片</param>
/// <param name="name">合成图片存储路径</param>
/// </summary>
public void CombinImage(string sourceImg, string destImg, string name)
{
    System.Drawing.Image imgBack = System.Drawing.Image.FromFile(sourceImg);     //相框图片 
    System.Drawing.Image img = System.Drawing.Image.FromFile(destImg);        //照片图片

    Bitmap bmp = new Bitmap(imgBack.Width, imgBack.Height);

    Graphics g = Graphics.FromImage(bmp);
    g.Clear(Color.White);
    g.DrawImage(imgBack, 0, 0, imgBack.Width, imgBack.Height);
    //g.FillRectangle(System.Drawing.Brushes.Black, 16, 16, (int)112 + 2, ((int)73 + 2));//相片四周刷一层黑色边框

    //g.DrawImage(img, 照片与相框的左边距, 照片与相框的上边距, 照片宽, 照片高);
    g.DrawImage(img, imgBack.Width / 2 - img.Width / 2 + 0, imgBack.Height / 2 - img.Height / 2 + 0, img.Width, img.Height);
    GC.Collect();

    //保存指定格式图片
    bmp.Save(name, ImageFormat.Png);    
}

 合成前：

合成后：