.Net Graphics: drawing text on a bitmap

I use this code here.

Graphics backgroundGraphics;
backgroundImage = (Bitmap)Image.FromFile(AppDomain.CurrentDomain.BaseDirectory + "\images\Header.jpg");
backgroundGraphics = Graphics.FromImage(backgroundImage);
var font = new Font("Perpetua Titling MT", 24F, FontStyle.Regular);
backgroundGraphics.DrawString(authorname.ToUpper(), font, new SolidBrush(Color.FromArgb(100, 0, 0, 0)), 10, 5);

Now save – or output to the browser:

backgroundImage.Save(context.Response.OutputStream, ImageFormat.Jpeg);

Response.Redirect and 302 and 301 status codes

If you use Response.Redirect to direct users to a new location, you should be aware that it issues a status code of 302, which means that “the resource resides temporarily under a different URI.” If you intend to communicate that the resource has permanently changed locations, you should not use Response.Redirect. This is important for search engines and other crawlers that might need to know the definitive url.

To send a 301 redirect:

Response.Status = "301 Moved Permanently";
Response.StatusCode = 301;
Response.AddHeader("Location", url);
Response.End();

Update: ASP.Net 4.0 ads a Response.RedirectPermanent() method.

Set the admin color scheme for all WordPress users

INSERT INTO wp_usermeta
(
user_id,
meta_key,
meta_value
)
(
SELECT
id,
'admin_color',
'classic'
FROM wp_users
WHERE id  NOT  IN (SELECT user_Id FROM wp_usermeta WHERE meta_key = 'admin_color')
)
 
UPDATE wp_usermeta SET meta_value = 'classic' WHERE meta_key = 'admin_color'

SQL script to migrate from Movable Type to WordPress

While trying to migrate a large blog from Movable Type to WordPress, I found the built-in export and import functionality unable to handle volume of content on the blog or to properly preserve the primary keys needed for permalinks.

With assistance from Alvaro on the MisesDev list, we came up with the following MySql SQL script to import the entries directly from the Movable Type (5.01) database to WordPress (2.9.2). What would take many hours otherwise can be done in a minute or two. This is especially important if you don’t want to lose data during the time it takes to migrate the blog, as the script can be run immediately before the switch. This script also includes additional stuff like IP addresses and url-friendly names.
Continue reading “SQL script to migrate from Movable Type to WordPress” »

Luhn algorithm validation via a CustomValidator control

The Luhn algorithm is a checksum used for credit cards and many other identifying numbers as a basic integrity validation check.  It’s useful for credit card forms because it avoids unneeded transaction attempts when card numbers are mis-typed.
It’s easy to add an account # Luhn checksum validation control to credit card forms in ASP.Net:
  • Add this method to your business logic.
  • Add a <asp:CustomValidator  … /> control with the error message, target control, etc.
  • Add and wire up a void ServerValidation method:
void ServerValidation(object source, ServerValidateEventArgs args) {
// use a RequiredFieldValidator to check for an empty value
 if (txtCardNum.Text == string.Empty) args.IsValid = true;
 args.IsValid = IsCreditCardValid(this.txtCardNum.Text);
}
 
protected override void OnInit(EventArgs e)    {
 base.OnInit(e);
 valLunCode.ServerValidate += ServerValidation;
}
  • (Optional:) For client-side code, use a Javascript version from here.

Correct photo orientation using EXIF data with C#

When processing photos, sometimes you want to re-orient the photo according the orientation recorded by the camera (such as the iPhone’s accelerometer) and stored in the EXIF meta data.  It’s easy to do:

// Rotate the image according to EXIF data
var bmp = new Bitmap(pathToImageFile);
var exif = new EXIFextractor(ref bmp, "n"); // get source from http://www.codeproject.com/KB/graphics/exifextractor.aspx?fid=207371
 
if (exif["Orientation"] != null)
{
RotateFlipType flip = OrientationToFlipType(exif["Orientation"].ToString());
 
if (flip != RotateFlipType.RotateNoneFlipNone) // don't flip of orientation is correct
{
bmp.RotateFlip(flip);
exif.setTag(0x112, "1"); // Optional: reset orientation tag
bmp.Save(pathToImageFile, ImageFormat.Jpeg);
}
 
// Match the orientation code to the correct rotation:
 
private static RotateFlipType OrientationToFlipType(string orientation)
{
switch (int.Parse(orientation))
{
case 1:
return RotateFlipType.RotateNoneFlipNone;
break;
case 2:
return RotateFlipType.RotateNoneFlipX;
break;
case 3:
return RotateFlipType.Rotate180FlipNone;
break;
case 4:
return RotateFlipType.Rotate180FlipX;
break;
case 5:
return RotateFlipType.Rotate90FlipX;
break;
case 6:
return RotateFlipType.Rotate90FlipNone;
break;
case 7:
return RotateFlipType.Rotate270FlipX;
break;
case 8:
return RotateFlipType.Rotate270FlipNone;
break;
default:
return RotateFlipType.RotateNoneFlipNone;
}
}

Maxing out HTTP compression in IIS7

1:  In IIS7 manager, enable dynamic and static compriession.   (This adds <urlCompression doStaticCompression=”true” doDynamicCompression=”true” /> to applicationHost.config)

2: Open C:WindowsSystem32InetsrvConfigapplicationHost.config and go to the httpCompression section. For both dynamicTypes and staticTypes: <mimetype=”*/*” enabled=”true”>

3:   Run appcmd in %systemroot%system32inetsrv
appcmd set config /section:httpCompression /[name=’gzip’].dynamicsCompressionLevel:10
appcmd set config /section:httpCompression /[name=’gzip’].staticCompressionLevel:10

(Set the value to 7,8,or 9 for less CPU usage)

Note: compressing static files prevents them from displaying incrementally while the rest of the file downloads in the background. This may be useful for viewing partially loaded PDF’s, text files, images, etc. It may be appropriate to enable/disable compression per-directory in some cases.

More information on IIS7 HTTP compression.

n. 1: automatic, but with an element of magic. 2: too complex to understand and/or explain