{
internal static class ImageHelper
{
public static Bitmap CloneBitmap(Image source)
{
if (source == null)
return null;
Bitmap image = new Bitmap(source.Width, source.Height);
image.SetResolution(source.HorizontalResolution, source.VerticalResolution);
using (Graphics g = Graphics.FromImage(image))
{
g.DrawImageUnscaled(source, , );
}
return image;
// this can throw OutOfMemory when creating a grayscale image from a cloned bitmap
// return source.Clone() as Bitmap;
}
public static void Save(Image image, Stream stream)
{
Save(image, stream, ImageFormat.Png);
}
public static void Save(Image image, string fileName, ImageFormat format)
{
using (FileStream stream = new FileStream(fileName, FileMode.Create))
{
Save(image, stream, format);
}
}
public static void Save(Image image, Stream stream, ImageFormat format)
{
if (image == null)
return;
if (image is Bitmap)
image.Save(stream, format);
else if (image is Metafile)
{
Metafile emf = null;
using (Bitmap bmp = new Bitmap(, ))
using (Graphics g = Graphics.FromImage(bmp))
{
IntPtr hdc = g.GetHdc();
emf = new Metafile(stream, hdc);
g.ReleaseHdc(hdc);
}
using (Graphics g = Graphics.FromImage(emf))
{
g.DrawImage(image, , );
}
}
}
public static byte[] Load(string fileName)
{
if (!String.IsNullOrEmpty(fileName))
return File.ReadAllBytes(fileName);
return null;
}
public static Image Load(byte[] bytes)
{
if (bytes != null && bytes.Length > )
{
try
{
return new ImageConverter().ConvertFrom(bytes) as Image;
}
catch
{
Bitmap errorBmp = new Bitmap(, );
using (Graphics g = Graphics.FromImage(errorBmp))
{
g.DrawLine(Pens.Red, , , , );
g.DrawLine(Pens.Red, , , , );
}
return errorBmp;
}
}
return null;
}
public static byte[] LoadURL(string url)
{
if (!String.IsNullOrEmpty(url))
{
using (WebClient web = new WebClient())
{
return web.DownloadData(url);
}
}
return null;
}
public static Bitmap GetTransparentBitmap(Image source, float transparency)
{
if (source == null)
return null;
ColorMatrix colorMatrix = new ColorMatrix();
colorMatrix.Matrix33 = - transparency;
ImageAttributes imageAttributes = new ImageAttributes();
imageAttributes.SetColorMatrix(
colorMatrix,
ColorMatrixFlag.Default,
ColorAdjustType.Bitmap);
int width = source.Width;
int height = source.Height;
Bitmap image = new Bitmap(width, height);
image.SetResolution(source.HorizontalResolution, source.VerticalResolution);
using (Graphics g = Graphics.FromImage(image))
{
g.Clear(Color.Transparent);
g.DrawImage(
source,
new Rectangle(, , width, height),
, , width, height,
GraphicsUnit.Pixel,
imageAttributes);
}
return image;
}
public static Bitmap GetGrayscaleBitmap(Image source)
{
Bitmap grayscaleBitmap = new Bitmap(source.Width, source.Height, source.PixelFormat);
// Red should be converted to (R*.299)+(G*.587)+(B*.114)
// Green should be converted to (R*.299)+(G*.587)+(B*.114)
// Blue should be converted to (R*.299)+(G*.587)+(B*.114)
// Alpha should stay the same.
ColorMatrix grayscaleMatrix = new ColorMatrix(new float[][]{
new float[] {0.299f, 0.299f, 0.299f, , },
new float[] {0.587f, 0.587f, 0.587f, , },
new float[] {0.114f, 0.114f, 0.114f, , },
new float[] { , , , , },
new float[] { , , , , }});
ImageAttributes attributes = new ImageAttributes();
attributes.SetColorMatrix(grayscaleMatrix);
// Use a Graphics object from the new image
using (Graphics graphics = Graphics.FromImage(grayscaleBitmap))
{
// Draw the original image using the ImageAttributes we created
graphics.DrawImage(source,
new Rectangle(, , grayscaleBitmap.Width, grayscaleBitmap.Height),
, , grayscaleBitmap.Width, grayscaleBitmap.Height,
GraphicsUnit.Pixel, attributes);
}
return grayscaleBitmap;
}
}
}来自：https://github.com/FastReports/FastReport