What is a Bitmap's memory layout?

\Frank\

On the Internet there are many descriptions of the memory layout for a DIB.

But none that I can find for a Bitmap.

Is that because a Bitmap's layout depends on a related device.

If that's the case, is a clipboard's Bitmap layout always related to the
screen?

Thanx

Aug 17 '07 #1

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4445

Ignacio Machin \( .NET/ C# MVP \)

Hi,

A bitmap is just that, a map of bits

Each pixel is represented by a given number of bytes (Depending of the
resolution) and they are row after row.

Is that enuogh?

""Frank"" <Fr***@a-znet.comwrote in message
news:ew******** ******@TK2MSFTN GP02.phx.gbl...

On the Internet there are many descriptions of the memory layout for a
DIB.

But none that I can find for a Bitmap.

Is that because a Bitmap's layout depends on a related device.

If that's the case, is a clipboard's Bitmap layout always related to the
screen?

Thanx

Aug 17 '07 #2

=?ISO-8859-1?Q?G=F6ran_Andersson?=

"Frank" wrote:

On the Internet there are many descriptions of the memory layout for a DIB.

But none that I can find for a Bitmap.

Do you mean the System.Drawing. Bitmap class?

If so, use the LockBits method to access the image data. It provides you
with a BitmapData object that contains the information you need to
access the data. You don't have to bother about details of the memory
layout, like if it's stored top-down or bottom-up.

Is that because a Bitmap's layout depends on a related device.

What related device? The layout depends on the pixel format of the bitmap.

If that's the case, is a clipboard's Bitmap layout always related to the
screen?

Why would it be? Any program can place a Bitmap in the clipboard, so the
format would be decided by the program.

--
Göran Andersson
_____
http://www.guffa.com

Aug 17 '07 #3

\Frank\

I meant the Windows Bitmap
I did find the description of how to save a Windows GDI Bitmap on a file and
it's the same as that for saving a DIB.

But often I see on the Clipboard "Bitmap" as well as "DIB Bitmap"
There is also CF_Bitmap and CF_DIB

Are they really saved the same on a file?

What is the difference between what is retrieved from a Bitmap (CF_Bitmap)
and a DIB(CF_DIB) from the clipboard?
Thanx
Added "pointed to by HBITMAP"

>On the Internet there are many descriptions of the memory layout for a
DIB.
But none that I can find for a Bitmap pointed to by HBITMAP
Is that because a Bitmap's layout depends on a related device.
If that's the case, is a clipboard's Bitmap layout always related to the
screen?

Aug 17 '07 #4

\Frank\

I meant the Windows Bitmap
I did find the discription of how to save a Windows GDI Bitmap on a file and
it's the same as that for saving a DIB.

But often I see on the Clipboard "Bitmap" as well as "DIB Bitmap"
There is also CF_Bitmap and CF_DIB

Are they really saved the same on a file?

What is the difference between what is retrieved from a Bitmap (CF_Bitmap)
and a DIB(CF_DIB) from the clipboard?
Thanx

Aug 17 '07 #5

=?ISO-8859-1?Q?G=F6ran_Andersson?=

"Frank" wrote:

I meant the Windows Bitmap

There are several different ways of representing a bitmap, both in
memory and as files.

I did find the description of how to save a Windows GDI Bitmap on a file and
it's the same as that for saving a DIB.

That's not surprising. A GDI Bitmap can't be saved as a useful format,
so you save a GDI Bitmap in DIB format.

But often I see on the Clipboard "Bitmap" as well as "DIB Bitmap"
There is also CF_Bitmap and CF_DIB

The clipboard format values all start with CF_, so "Bitmap" and "DIB
Bitmap" are only descriptions of the formats.

MSDN: Clipboard Formats:
http://msdn2.microsoft.com/en-us/library/ms649013.aspx

Are they really saved the same on a file?

What is the difference between what is retrieved from a Bitmap (CF_Bitmap)
and a DIB(CF_DIB) from the clipboard?

CF_BITMAP is a handle to a bitmap object. CF_DIB is a DIB bitmap object.
You can retrieve any of those as either of those, as the system can
convert between them.

--
Göran Andersson
_____
http://www.guffa.com

Aug 18 '07 #6

\Frank\

CF_BITMAP is a handle to a bitmap object.

I'm having trouble phrasing my question because of lack of background.

But given the above handle, assuming I can use it to get an object from the
clipboard. what is that object like?

Is it a DDB that is oriented to the screen?

Or something else?

Thanks for staying with me on this

Aug 18 '07 #7

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