protected virtual bool IsSameDstImage(ImageResize other)
{
if (other != null)
{
return (Width == other.Width
&& Height == other.Height
&& UsePercentages == other.UsePercentages
&& PreserveAspectRatio == other.PreserveAspectRatio);
}
return false;
}
public virtual Image GetThumbnail()
{
// Flag whether a new image is required
bool recalculate = false;
double new_width = Width;
double new_height = Height;
// Is there a cached source image available? If not,
// load the image if a filename was specified; otherwise
// use the image in the Image property
if (!IsSameSrcImage(m_cache))
{
if (m_image_path.Length > 0)
{
// Load via stream rather than Image.FromFile to release the file
// handle immediately
if (m_src_image != null)
m_src_image.Dispose();
// Wrap the FileStream in a "using" directive, to ensure the handle
// gets closed when the object goes out of scope
using (Stream stream = new FileStream(m_image_path, FileMode.Open))
m_src_image = Image.FromStream(stream);
recalculate = true;
}
}
// Check whether the required destination image properties have
// changed
if (!IsSameDstImage(m_cache))
{
// Yes, so we need to recalculate.
// If you opted to specify width and height as percentages of the original
// image's width and height, compute these now
if (UsePercentages)
{
if (Width != 0)
{
new_width = (double)m_src_image.Width * Width / 100;
if (PreserveAspectRatio)
{
new_height = new_width * m_src_image.Height / (double)m_src_image.Width;
}
}
if (Height != 0)
{
new_height = (double)m_src_image.Height * Height / 100;
if (PreserveAspectRatio)
{
new_width = new_height * m_src_image.Width / (double)m_src_image.Height;
}
}
}
else
{
// If you specified an aspect ratio and absolute width or height, then calculate this
// now; if you accidentally specified both a width and height, ignore the
// PreserveAspectRatio flag
if (PreserveAspectRatio)
{
if (Width != 0 && Height == 0)
{
new_height = (Width / (double)m_src_image.Width) * m_src_image.Height;
}
else if (Height != 0 && Width == 0)
{
new_width = (Height / (double)m_src_image.Height) * m_src_image.Width;
}
}
}
recalculate = true;
}
if (recalculate)
{
// Calculate the new image
if (m_dst_image != null)
{
m_dst_image.Dispose();
m_graphics.Dispose();
}
Bitmap bitmap = new Bitmap((int)new_width, (int)new_height, m_src_image.PixelFormat);
m_graphics = Graphics.FromImage(bitmap);
m_graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
m_graphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
m_graphics.DrawImage(m_src_image, 0, 0, bitmap.Width, bitmap.Height);
m_dst_image = bitmap;
// Cache the image and its associated settings
m_cache = this.MemberwiseClone() as ImageResize;
}
return m_dst_image;
}
protected virtual bool IsSameSrcImage(ImageResize other)
{
if (other != null)
{
return (File == other.File
&& Image == other.Image);
}
return false;
}
