Loading an image to a memory DC

[jsbach]

Hi all,
Currently I'm working on a program that makes an extensive use of bitblt Api function to copy images from one picture box to another.

My questions are:
1. Will the copying be significantly faster if I'll use memory DC for storing the source picture? (by using CreatCompaibleDC and LoadImage Api functions), and
2. I would like to hide the picture files from the user, so is there a way to load the pictures to the memory DC from a picture box rather then in a file?
Any help or a piece of code will be greatly appreciated.

[Crunchy Cat]

1. Yes.
2. Instead of a PictureBox, stuff the image into a resource file (VB
Comes with a resource editor and some built in functions for
loading the resources at run-time). When you compile the
application, the image will be physically part of your .exe (and
not a seperate file on your file system). You code will create
a compatible DC, load the bitmap resource, select the resource
into the DC, and then blit it to some destination DC. There are
gazillions of examples of how to do these things all over the
forum so I recommend using the 'search' functionalities
provided.

[jsbach]

Hi Crunchy Cat,
After I posted this thread I made some tests to see how faster is bitbliting from a memory DC vs picture box. surprisingly, all tests showed that there are not any advantage to memory DC over
picture box when speed is in concern. Apparently in both method the data is being read directly from memory. If you want I'll post the code I used for testing.
As for the other one, I guess it can be worked out this way.
Thanks allot!

[Crunchy Cat]

Hi jsbach, I should have been more specific. The actual blit
operation shouldn't really take any additional time. It's the
control's instantiation and picture loading that takes un-
necessary time. If you had to keep 10 DCs active at any given
time, then 10 memory DCs will be alot less resource draining than
10 picture boxes .

-CC