Re: How to convert Graphics image to Bitmap? - C# Discussion Boards

How to convert Graphics image to Bitmap?

5-Apr-09 19:42

Why would you use an ArrayList ? That's only there for legacy code. Does it not have a Sort method ( I can't remember ).

Christian Graus

Driven to the arms of OSX by Vista.

"I am new to programming world. I have been learning c# for about past four weeks. I am quite acquainted with the fundamentals of c#. Now I have to work on a project which converts given flat files to XML using the XML serialization method" - SK64 ( but the forums have stuff like this posted every day )

Re: Sort an array list

Tom Deketelaere5-Apr-09 22:47

Tom Deketelaere

5-Apr-09 22:47

Christian Graus wrote:
Does it not have a Sort method

Yes it does (how well it works I don't know, never use arraylists)

Re: Sort an array list

ramz_g8-Apr-09 19:42

ramz_g

8-Apr-09 19:42

Hi,
First u can sort the arraylist using the Sort() method... Then reverse the arraylist using the Reverse() method... Not sure whether this is the best solution, but it is one way of doing it...

Thanks,
ramz_g

FrankeyJames5-Apr-09 14:42

5-Apr-09 14:42

I cna't seem to figure this out and I though I once did this.

I have something like this:

newImage = new Bitmap(path.ToString());
Matrix matrix = new Matrix();
matrix.Rotate(angle);
Graphics g = Graphics.FromImage(newImage);
g.Transform = matrix;
g.Save();

Bitmap newImage2 = new Bitmap(newImage.Width, newImage.Height, g);
Save();
//dispose calls....

An image is created, but it's just completely black. I am wanting to rotate an image at a specified angle, and not use the RotateFlip, which has static values.

Any ideas? Can this Graphics be converted back to a Bitmap?

Christian Graus5-Apr-09 14:44

5-Apr-09 14:44

No, a graphics cannot be 'converted' to a bitmap. newImage is already the image your graphics is drawn on. You don't save the graphics, you save the bitmap.

FrankeyJames5-Apr-09 15:00

5-Apr-09 15:00

That what I was doing originally, but I kept getting expetion "A generic error occurred in GDI+". I'm overwriting the the original image....so maybe I'm doing something wrong and not dispoing of the picture. At any rate, if I save to a different ABS path, then it save the image, but the transform did not appear to have taken effect. I even tried drawing a line, but nothing changes with the picture - it's the same as the orignal.

So, i'm doing something like:

newImage.Save(path);

Should I be doing something different? Is there something I'm not calling on the Graphic object to make it apply to the Bitmap?

Christian Graus5-Apr-09 19:43

5-Apr-09 19:43

Yes, that means .NET already has a lock on the file, you'd need to save to another filename

Xmen Real 5-Apr-09 15:13

Xmen Real

5-Apr-09 15:13

try this

Bitmap newImage2 = new Bitmap(newImage);
Save();

newImage.Save();

Assume Graphics as pencil and Bitmap as paper...Now how you gonna do conversion...

TVMU^P[[IGIOQHG^JSH`A#@`RFJ\c^JPL>;"[,*/|+&WLEZGc`AFXc!L
%^]*IRXD#@GKCQ`R\^SF_WcHbORY87֦ʻ6ϣN8ȤBcRAV\Z^&SU~%CSWQ@#2
W_AD`EPABIKRDFVS)EVLQK)JKQUFK[M`UKs*$GwU#QDXBER@CBN%
R0~53%eYrd8mt^7Z6]iTF+(EWfJ9zaK-iTV.C\y<pjxsg-b$f4ia>

-----------------------------------------------
128 bit encrypted signature, crack if you can

Guffa5-Apr-09 15:23

Guffa

5-Apr-09 15:23

You can't convert a Graphics object to a Bitmap, as it doesn't contain the image. The Graphics object is just used to draw on a canvas, in this case the canvas is a Bitmap object.

You are creating a Graphics object to draw on the original image, but what you want to do is to create it to draw on the new image, then you draw the original image onto the new image.

The transform controls how the drawing is done using the Graphics object, so when you draw the original image using that Graphics object it will be rotated.

Despite everything, the person most likely to be fooling you next is yourself.

FrankeyJames5-Apr-09 17:18

5-Apr-09 17:18

Oh god, stupid me.....

Thanks for the responses everyone. I was going in circles (and sometimes th wrong way) because I thought the graphics was not writing to the original image. In fact it was. The test line i drew wasn't appearing because the coords I gave it were not long enough and my image is so huge that when I went to look at it I never see the line and the picture never rotated. Until I finally seen a red speck.... ;-0

Luc Pattyn5-Apr-09 16:24

Luc Pattyn

5-Apr-09 16:24

Hi,

there are some quirks you have to be aware of:
1. all errors in GDI+ will report "an internal error..."
2. Image.FromFile() locks the file until the image is disposed
BTW: Image.FromStream() does not

Bitmap bm1 = Bitmap.FromFile(filename);    // this locks the file
Bitmap bm2 = new Bitmap(width2, height2);  // the output image
Graphics g = Graphics.FromImage(bm2);      // so we can draw on bm2
g.Transform = matrix...;                   // some transformation
g.DrawImage(bm1);
bm1.Dispose();                             // unlocks the file
bm2.Save(filename, imageFormat);           // save output image to same or other file
g.Dispose();

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FrankeyJames5-Apr-09 17:21

5-Apr-09 17:21

Oh I swear, thank you SOOOO much. I couldn't figure out which object I wasn't dispoing of properly. I knew there was something wrong because if I could create a new bitmap as a new file name it would work, as it wasn't trying to write to the same STILL open file!!

Now on to figuring out to get it to rotate properly given the angle...ehhh.

Thanks for the help everyone!!

Re: Newbies and databases

Luc Pattyn5-Apr-09 18:10

Luc Pattyn

5-Apr-09 18:10

you're welcome.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Newbies and databases

stonebergftw5-Apr-09 14:10

stonebergftw

5-Apr-09 14:10

I'm writing an app to add information to a custom database(which does not exist yet). After that, I will develop an app to work with/view the data.

As a newbie, I'm unaware of exactly what I should be studying to create a database in C#. I've figure out how to create data tables(and datasets) but I'm not sure what to even search for when I'm trying to find code samples or tutorials on how to permanently store the info and every search I do yields stuff with MySQL. Can someone please point me in the right direction?

Christian Graus5-Apr-09 14:18