Quantizer.​Quantize and BitMaps

I need to quantize more than one bitmap (i.e., create one Gif from several Bitmaps), and am not sure how to do this. Notice below, there should only be one Bitmap argument passed to the Quantizer.Quantize(Bitmap) method.

Example:

OctreeQuantizer Quantizer = new OctreeQuantizer(255,;

using (Bitmap QuantizedBitmap = Quantizer.Quantize(Bitmap))

{

     Response.BufferOutput = true;

     l_QuantizedBitmap.Save(Response.OutputStream, ImageFormat.Gif);

}

In essence, this would be what I need:

Quantizer.Quantize(Bitmap + <br /> + Bitmap + <br /> + Bitmap)

Extra notes: I have an aspx page with an image control and am setting its image.ImageURL to another aspx that is creating the bmp's and quantizing it into a .gif; however, only one image is returned or rendered; thus, the need to combine bmp's prior to quantizing.

Ex:

imgBar.ImageUrl = string.Format("~/ScoreDistGraph.aspx?DemographicType={0}");

Thank you for any guidance you may be able to provide!

this only has to do with the end of your work but...

look at using an image handler in place of an aspx page.

really you can do one of two things with .net:

1) use the .ashx to return the image data

2) make up an extension like .demo  and have requests for *.demo call your handler.

that way for example your page can have a normal looking image tag that just ends with an odd filename.

/Graphs/Demo/PIC0901.demo

where the folder is fake and the filename is fake

but your site sends the right mime-type and data stream

example PIC____.demo

numbers are the key to what you generate per request.

How do you expect the quantizer to put the bitmaps together? on top of each other? side by side? vertical? in a grid? this is completely out of the scope of what the quantizer is doing.. you need to firstly put the bitmaps together by your own logic, and pass the composed bitmap to the quantizer..

So this makes me ask, do you want help on how you should compose bitmaps together? if so, what are your requirements? in a grid? in a line? what orientation? should they be scaled to fit the same constraints?

stevo_ said:

How do you expect the quantizer to put the bitmaps together? on top of each other? side by side? vertical? in a grid? this is completely out of the scope of what the quantizer is doing.. you need to firstly put the bitmaps together by your own logic, and pass the composed bitmap to the quantizer..

So this makes me ask, do you want help on how you should compose bitmaps together? if so, what are your requirements? in a grid? in a line? what orientation? should they be scaled to fit the same constraints?

I need a single bitmap that has images that are stacked vertically. I am creating the same size bitmap image each time, but am unable to compose several bitmap images into on bitmap prior to quantizing. Thanks.

For example:

[Bitmap]

Image1

Image2

Image3

Image4

[End Bitmap]

Quantizer.Quantize(Bitmap);

Turns out it's rather simple:

Have two images: image0 & image 1.

Size newSize = new Size(480, 400);

Bitmap newImage = new Bitmap(newSize.Width, newSize.Height);

Graphics g = Graphics.FromImage(newImage);

g.DrawImage(image0, 0, 0);

g.DrawImage(image1, 0, 440);

g.Flush();

g.Save();

g.Dispose();

Quantizer.Quantize(newImage);

I'm also using an ashx. Thanks figuerres.

Caching can wreak havoc on adding more than one image image at a time to the output stream and what is rendered!

context.Response.Cache.SetCacheability(HttpCacheability.NoCache);

TradingSmiles said:

Caching can wreak havoc on adding more than one image image at a time to the output stream and what is rendered!

 

context.Response.Cache.SetCacheability(HttpCacheability.NoCache);

Yeah that can bite you in a few cases.

also as i recall there are places in your response to set the last modify date and create date of the object.

I think the browser makes a call to get a header to determine if the content is new on the server, if the local cache copy is the same date as the server then it uses the local copy.

so if the modify date is always "Now" then the client will keep fetching the image.

or if you can know that the data has not changed you can let the cache header allow the client to cashe and use modify date to ballance how often you have to re-build your output.

for example if the user is asking for the 2008 year graph then let that be casheable and set a date on it.

then that one graph will not be re-generated for that user on page hits all the time.

but when the data is subject to chnage you can setup a window of time so that you only re-draw that graph like every 5 or 10 minutes per user. let them get a chashed copy for all page hits for x minutes.

that may make this much more scalable for more users and page hits.

if you are planning to have more than a few users that hit this site.

check that out so you can keep the cpu use down to a reasonable level if you may have lots of users.