c#批量给图片添加水印,
想做一个小工具!批量给图片加上自己的透明图片水印和透明文字,求教.
已经创建了一个带透明的png图片作为水印.如何合并到背景图片上.?
求给代码和思路.谢谢 c# 图片 bitmap graphics
[解决办法]
原来写的wpf的打水印的 楼主可以借鉴下
public class WatermarkHelper
{
string _waterImgPath;
BitmapSource _waterPic;
string _prefix = null;
// constructors
public WatermarkHelper(string waterImgFilePath, string prefix = null)
{
this._waterImgPath = waterImgFilePath;
this._waterPic = new BitmapImage(new Uri(this._waterImgPath));
if (prefix == null)
prefix = "";
this._prefix = prefix;
// this._result = false;
}
// public members
public void AddWatermark_SaveToDir(string inputFilePath, string outputDir)
{
if (!Directory.Exists(outputDir))
Directory.CreateDirectory(outputDir);
string output_filepath = Path.Combine(
outputDir,
string.Format("{0}{1}", this._prefix, Path.GetFileName(inputFilePath))
); // <-- use Path.Combine to prevent potential problems
// process
Process(inputFilePath, output_filepath);
}
public void AddWatermark_SaveToFile(string inputFilePath, string output_filepath) // <-- you see what i mean when i say 'flexibility'
{
// create directory if it doesn't exist yet
string output_dir = Path.GetDirectoryName(output_filepath);
if (!Directory.Exists(output_dir))
Directory.CreateDirectory(output_dir);
// process
Process(inputFilePath, output_filepath);
}
// internal logic
bool Process(string input_filepath, string output_filepath) // <-- let upper logic determine the output filename, these will provide flexibility
{
// load source image
// BitmapSource bitmap = new BitmapImage(new Uri(input_filepath));
BitmapImage bitmap = new BitmapImage();
bitmap.BeginInit();
bitmap.UriSource = new Uri(input_filepath);
bitmap.CacheOption = BitmapCacheOption.OnLoad;
bitmap.EndInit();
// create render bitmap
var rtbitmap = new RenderTargetBitmap(bitmap.PixelWidth,
bitmap.PixelHeight,
bitmap.DpiX,
bitmap.DpiY,
PixelFormats.Default);
// draw watermark
var drawingVisual = new DrawingVisual();
using (var dc = drawingVisual.RenderOpen())
{
// draw source image
dc.DrawImage(bitmap, new Rect(0, 0, bitmap.Width, bitmap.Height));
// determine the render size of the watermark
double hs = bitmap.Height * 0.3 / this._waterPic.Height;
double ws = bitmap.Width * 0.3 / this._waterPic.Width;
double scale = hs > ws ? ws : hs;
if (bitmap.Height / bitmap.Width > 5)
{
scale = bitmap.Width * 0.8 / this._waterPic.Width;
}
else if (bitmap.Width / bitmap.Height > 5)
{
scale = bitmap.Height * 0.8 / this._waterPic.Height;
}
double Wstart = bitmap.Width - this._waterPic.Width * scale - 20 < 0 ? 0 : bitmap.Width - this._waterPic.Width * scale - 20;
double Hstart = bitmap.Height - this._waterPic.Height * scale;
// draw water make
dc.DrawImage(this._waterPic, new Rect(Wstart, Hstart, this._waterPic.Width * scale, this._waterPic.Height * scale));
}
rtbitmap.Render(drawingVisual);
var bitmapEncoder = new PngBitmapEncoder();
bitmapEncoder.Frames.Add(BitmapFrame.Create(rtbitmap));
// save image
if (File.Exists(output_filepath))
File.Delete(output_filepath);
using (FileStream file = new FileStream(output_filepath, FileMode.Create))
bitmapEncoder.Save(file);
// return
return true;
}
}
#region 图片加上水印的操作
/// <summary>
/// 向图片上写文字再输出
/// </summary>
/// <param name="img"></param>
/// <param name="text"></param>
/// <returns></returns>
public static Image WriteString(Image img, string text)
{
Bitmap bmap = new Bitmap(img);
Graphics g = Graphics.FromImage(bmap);
Font font = new Font("楷体", 15);
PointF pf = new PointF();//((float)(img.Width/2-2.5),img.Height/2-2.5);
pf.X = 0;
pf.Y = 0;
g.DrawString(text, font, Brushes.Gold, pf);
g.Dispose();
return bmap;
}
/// <summary>
/// 将图片加载水印图片
/// </summary>
/// <param name="markImg"></param>
/// <param name="fromImg"></param>
/// <returns></returns>
public static Image WriteImg(Image markImg, Image fromImg)
{
Bitmap b = new Bitmap(fromImg);
Graphics g = Graphics.FromImage(b);
g.DrawImage(markImg, 0, 0, markImg.Width, markImg.Height);
g.Dispose();
return b;
}
#endregion
