JPG Size - C# Discussion Boards

5-Dec-03 22:09

In the Win 32 API you can find a function called InvertRgn it takes a hdc and region to invert the colors of that region on the hdc so if any body knows a function in the GDI+ which can do the same job could you tell about it ?

Regs'

Mhmoud Rawas
------------
Software Eng.

Alex Korchemniy6-Dec-03 7:53

Alex Korchemniy

6-Dec-03 7:53

Search "InvertRgn win32" in google takes you to this codeproject page : http://www.codeproject.com/gdi/rgnguide.asp

mhmoud rawas6-Dec-03 8:40

6-Dec-03 8:40

Dear AK ,
My Q was about the GDI+ not the GDI i know all that functions in GDI but what i need is a similar functions in GDI+

Mhmoud Rawas
------------
Software Eng.

J. Dunlap6-Dec-03 9:42

J. Dunlap

6-Dec-03 9:42

Create an infinite region and use the Region.Xor or Complement method to combine it with the original region. This effectively inverts it.

"Don't judge each day by the harvest you reap, but by the seeds you plant." -- Robert Louis Stevenson

FLUID UI Toolkit | FloodFill in C# & GDI+

mhmoud rawas6-Dec-03 18:00

6-Dec-03 18:00

Dear jadunlap,
be careful i am speaking about inverting the colors of a region not invetrintg the region Mad | :mad:

Mhmoud Rawas
------------
Software Eng.

J. Dunlap7-Dec-03 14:56

J. Dunlap

7-Dec-03 14:56

Use a ColorMatrix to transform the colors to negative, and set the Graphics object's clipping region to the region to be inverted.

//assumes that b is the Bitmap to be inverted.
ImageAttributes ia = new ImageAttributes();
ColorMatrix cm=new ColorMatrix();
cm.Matrix00=
cm.Matrix11=
cm.Matrix22=-1;
ia.SetColorMatrix(cm);
 
GraphicsPath path=new GraphicsPath();
path.AddEllipse(new Rectangle(20,20,200,200));
Region rgn=new Region(path);
e.Graphics.SetClip(rgn,CombineMode.Replace);
 
e.Graphics.DrawImage(b,
            new Rectangle(0, 0, b.Width, b.Height)
            , 0, 0, b.Width, b.Height, GraphicsUnit.Pixel, ia);

"Have a heart that never hardens, a temper that never tires, a touch that never hurts." -- Charles Dickens

FLUID UI Toolkit | FloodFill in C# & GDI+

JPG Size

mhmoud rawas5-Dec-03 22:07

5-Dec-03 22:07

Dear All ,

Any body knows how to calculate a JPG file size without saving it to the hard disk cuz i would like to allocate a stream for it to pass it to an XML file

Regs'

Mhmoud Rawas
------------
Software Eng.

Heath Stewart6-Dec-03 4:57

6-Dec-03 4:57

Not without performing the algorithm that would run on it, which you could to to an in-memory stream (MemoryStream) to determine the size.

BUT...

You can't save a binary stream to XML. You can use a number of different encodings but by far the most popular is base64. You don't need to know how big it'll be anyway, because you just perform the encoding and set the value on an XML element (or attribute, but data that large isn't really fit for attributes).

The XmlTextWriter class makes it easy to accomplish this using the XmlTextWriter.WriteBase64 method. The XmlTextReader.ReadBase64 does the opposite, of course.

Remember, though, that you don't need to allocate space in an XML file (unless you're doing some weird pre-empted packing routine). It's just a text file and like all text files will grow or shrink (within disk capacity) to accomodate the contents.

-----BEGIN GEEK CODE BLOCK-----
Version: 3.21
GCS/G/MU d- s: a- C++++ UL@ P++(+++) L+(--) E--- W+++ N++ o+ K? w++++ O- M(+) V? PS-- PE Y++ PGP++ t++@ 5 X+++ R+@ tv+ b(-)>b++ DI++++ D+ G e++>+++ h---* r+++ y+++
-----END GEEK CODE BLOCK-----

Anonymous6-Dec-03 6:23

Anonymous

6-Dec-03 6:23

Dear Heath,
First of all thanks for your replay but i think i did not rech my information to you, as i have seen the best way to pass an dynamic image to the crystal report is using the dataset which is in the last form is XML so you have to write it into the the dataset classes and for that you have to use the memory stream and when you like to write to the memory stream you have to allocate an enugh memory space for that bitmap then you write it to the stream so in my test project i have used the max size which can be callulated by size = width * height * 3 + 100 this size is for the normal bitmap not JPG and when i wrote to the stream i found that about 1/3 from the stream is still empty so if you know a way to mesure the size of that bitmap before allocating the memory stream could you help me in this mater

Regards

Heath Stewart6-Dec-03 6:44

6-Dec-03 6:44

Actually, I already gave you a clue in my first paragraph: MemoryStream. Save the Bitmap as a JPEG to a MemoryStream and determine the length by checking the Length property. Also, you don't need to preallocate space in a MemoryStream if you use the right constructor.

You didn't mention before that you weren't saving the XML file to disk. While you can use CDATA sections to write binary data, this is not recommended - especially when you persist XML to disk or for transport. This is where binary encodings like base64 are necessary. If Cyrstal isn't extensible enough to base64 decode an image, then you'll have to keep doing what you're doing.

mhmoud rawas6-Dec-03 7:22

6-Dec-03 7:22

Dear Heath ,
which constructor do you mean i have seen all the memory stream constructors should take the capsity of the stream so could you specify the constructor

Thanks,

Mhmoud Rawas
------------
Software Eng.

mhmoud rawas6-Dec-03 7:24

6-Dec-03 7:24

Opps ..... Sory i have found it if i use the defualt constructor it takes a dynamic stream

Mhmoud Rawas
------------
Software Eng.

mhmoud rawas6-Dec-03 7:17

6-Dec-03 7:17

Sorry the last replay is from me but i was not loged in

Mhmoud Rawas
------------
Software Eng.

File Size over Internet

eggie55-Dec-03 21:06

Re: File Size over Internet

5-Dec-03 21:06

How could I find the size of a picture (http://www.willapa.wednet.edu/images/amigo.jpg)

When every I try to use .Legnth, it tells my Stream dosn't support seeking... or somthing like that.

Any ideas?

Oh, yeah...

and also, I was wondering if it was possible to do a .GetFiles over the internet....

/\ |_ E X E GG

leppie5-Dec-03 21:51

leppie

5-Dec-03 21:51

When using he HTTPWebRequest a header will be returned with some info including length and modified date.

leppie ::AllocCPArticle("Zee blog");
Seen on my Campus BBS: Linux is free...coz no-one wants to pay for it.

Re: File Size over Internet

Heath Stewart6-Dec-03 4:50

Re: File Size over Internet

6-Dec-03 4:50

Right, specifically HttpWebResponse.ContentLength and HttpWebResponse.LastModified.

eggie56-Dec-03 11:20

Identifying the Web Server

6-Dec-03 11:20

This answers my last question too. Thanks.

/\ |_ E X E GG

eggie55-Dec-03 15:07

5-Dec-03 15:07

How would I identify what type of webserver a site is running? (IIS, Apache, Xitami)

Right now, i'm messing around in the System.Net Namespace but not really finding anything.

Can anyone help me out?

/\ |_ E X E GG

eggie55-Dec-03 16:05

5-Dec-03 16:05

ok, i just went though every class I could think of on MSDN. I couldn't find anything that stuck out.

Any ideas?

/\ |_ E X E GG

Heath Stewart6-Dec-03 4:49

6-Dec-03 4:49

Just make a HttpWebRequest and get the HttpWebResponse. The HttpWebResponse.Server property returns a string that identifies the server. This corresponds to the HTTP Server: header.

Here's an example:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://www.codeproject.com");
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Console.WriteLine(response.Server);

eggie56-Dec-03 5:54

6-Dec-03 5:54

hmmm, what do you know... this Heath Stewart character knew the answer to this question.

I'm just curioius, did you sorta know this already. Or did you search for it?

/\ |_ E X E GG

Heath Stewart6-Dec-03 6:36

6-Dec-03 6:36

This - and most solutions I post - I know already. I'm both blessed and cursed with a photographic memory. Smile | :)

Besides, HTTP and HTML (if you call that programming) was one of the first programming things I did besides the dinky little things I did on my C64, so the HTTP Server: header was nothing new.

It's not that I always remember the exact method or property, though. In some cases, I know that a certain class has a certain method or property that takes certain parameters and returns a certain type. As I've said many times in the past, it isn't so much memorizing every signature in the .NET Framework (or anything else for that matter), as it is remember that something exists and roughly where to find it. The important part of research is at least becoming familiar with what's available and having an idea of where to look. So, using your question as an example (if I couldn't remember what the property or method was called), I knew it would be on the HttpWebResponse (since the whole pluggable protocol API is aptly and consistently named - the HttpWeb part - and that the client couldn't know what the server was till it got a response back - thus using Response instead of Request) so I would just jump to that class and look.

eggie56-Dec-03 11:25