/// <summary>
/// 为图像加上水印（忽略gif格式），直接在原始图像上做处理。
/// </summary>
/// <param name="bitmap">需要处理的图像</param>
/// <param name="context">水印上下文实例</param>
/// <returns>返回是否处理过图像。</returns>
public static bool WaterMark(
Bitmap bitmap, ImageWaterMarkContext context)
{
if (bitmap == null || context == null)
{
return(false);
}
//Gif不加水印的
if (bitmap.RawFormat == ImageFormat.Gif)
{
return(false);
}
float width; //水印宽
float height; //水印高
float x = 0F; //坐标.x
float y = 0F; //坐标.y
Graphics g = Graphics.FromImage(bitmap);
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
Bitmap image = null;
if (context.Image != null)
{
//图像水印
width = context.Image.Width;
height = context.Image.Height;
image = context.Image;
}
else
{
//文本水印
if (context.TextFont == null)
{
context.TextFont = ImageWaterMarkContext.DefaultTextFont;
}
SizeF size = g.MeasureString(context.Text, context.TextFont);
width = size.Width + 10F;
height = size.Height + 6F;
image = new Bitmap((int)width, (int)height);
Graphics g2 = Graphics.FromImage(image);
g2.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g2.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
g2.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
g2.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;
if (context.TextBackColor == null)
{
context.TextBackColor = ImageWaterMarkContext.DefaultTextBackColor;
}
if (context.TextForeColor == null)
{
context.TextForeColor = ImageWaterMarkContext.DefaultTextForeColor;
}
if (context.TextBorderColor == null)
{
context.TextBorderColor = ImageWaterMarkContext.DefaultBorderColor;
}
g2.Clear(context.TextBackColor);
g2.DrawRectangle(new Pen(context.TextBorderColor, 1F), 0F, 0F, width - 2F, height - 2F);
g2.DrawString(context.Text, context.TextFont, new SolidBrush(context.TextForeColor), 3, 3);
g2.Dispose();
g2 = null;
}
//水印超出范围
if (width * 2 >= bitmap.Width || height * 2 >= bitmap.Height)
{
return(false);
}
//推算坐标
switch (context.Location)
{
case ImageWaterMarkLocation.TopLeft:
x = context.Margin.Left;
y = context.Margin.Top;
break;
case ImageWaterMarkLocation.TopCenter:
x = (bitmap.Width - width) / 2; y = context.Margin.Top;
break;
case ImageWaterMarkLocation.TopRight:
x = bitmap.Width - context.Margin.Right - width; y = context.Margin.Top;
break;
case ImageWaterMarkLocation.MiddleLeft:
x = context.Margin.Left; y = (bitmap.Height - height) / 2;
break;
case ImageWaterMarkLocation.MiddleCenter:
x = (bitmap.Width - width) / 2; y = (bitmap.Height - height) / 2;
break;
case ImageWaterMarkLocation.MiddleRight:
x = bitmap.Width - context.Margin.Right - width; y = (bitmap.Height - height) / 2;
break;
case ImageWaterMarkLocation.BottomLeft:
x = context.Margin.Left; y = bitmap.Height - height - context.Margin.Bottom;
break;
case ImageWaterMarkLocation.BottomCenter:
x = (bitmap.Width - width) / 2; y = bitmap.Height - height - context.Margin.Bottom;
break;
case ImageWaterMarkLocation.BottomRight:
x = bitmap.Width - context.Margin.Right - width; y = bitmap.Height - height - context.Margin.Bottom;
break;
}
if (x < 0F || y < 0F)
{
return(false);
}
//图像水印
image.SetResolution(bitmap.HorizontalResolution, bitmap.VerticalResolution);
ImageAttributes imageAttributes = new ImageAttributes();
imageAttributes.SetRemapTable(new ColorMap[] {
new ColorMap()
{
OldColor = Color.FromArgb(255, 0, 255, 0),
NewColor = Color.FromArgb(0, 0, 0, 0),
}
}, ColorAdjustType.Bitmap);
if (context.Opacity < 0F || context.Opacity > 1F)
{
context.Opacity = 0.51F;
}
imageAttributes.SetColorMatrix(new ColorMatrix(new float[][] {
new float[] { 1.0F, 0.0F, 0.0F, 0.0F, 0.0F },
new float[] { 0.0F, 1.0F, 0.0F, 0.0F, 0.0F },
new float[] { 0.0F, 0.0F, 1.0F, 0.0F, 0.0F },
new float[] { 0.0F, 0.0F, 0.0F, context.Opacity, 0.0F },//65透明度
new float[] { 0.0F, 0.0F, 0.0F, 0.0F, 1.0F },
}), ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
g.DrawImage(image, new Rectangle((int)x, (int)y, (int)width, (int)height), 0, 0, width, height, GraphicsUnit.Pixel, imageAttributes);
g.Dispose();
g = null;
if (context.Image == null)
{
image.Dispose();
image = null;
}
return(true);
}
/// <summary>
/// 为图像加上水印（忽略gif格式），直接在原始图像上做处理。
/// </summary>
/// <param name="bitmap">需要处理的图像</param>
/// <param name="context">水印上下文实例</param>
/// <returns>返回是否处理过图像。</returns>
public static bool WaterMark(
this
Bitmap bitmap, ImageWaterMarkContext context)
{
return(ImageWaterMark.WaterMark(bitmap, context));
}