Re: Rapid gfx display Qs

"senn" <senn@homeplace&.fix> wrote in message news:OVFbVLmuIHA.4376@xxxxxxxxxxxxxxxxxxxxxxx

Thanks for your test running of this particular GDI+
program code. My goal was to se if it ran on Vista.
I suppose you *did* run it on Vista?

Yep. I ran it on Vista and it ran fine.

And you did not se any smash-up with the Startbutton.?

No. Works fine in that area.

If I use a .bmp of size around 1200x700 the time
is around 100 millisec. Apparently around 3 times
as slow as Olafs dxcode. I didn't follow the long
threads in details. But, didn't they load a small
picture and stretched it.

They may have done at one stage, I didn't read all of the code or all of the thread in full, but the image which was used in the various timings tests was a 1280 x 720 pixel jpeg image on disk, which was loaded and converted into a DIB by the Intel jpeg library and then stretched by drawing the DIB into a VB Form or a PictureBox.

I downloaded the Intel .jpg library. Did I read in
one of the treads - it doesn't support collour depts
above of what ?

As far as I know there are no colour depth limitations with the Intel jpg library. It will certainly load a full colour jpeg file into a full colour DIBSection. I haven't delved into the jpeg library in any great depth (pun intended!) and perhaps Olaf will know if there are any such limitations, but I think there are not.

As far as speed is concerned, it is the Intel jpeg library which is responsible for the fast loading and "conversion from jpeg" times, both in Olaf's code and in the results I reported myself using the Intel jpeg wrapper at the vbAccelerator link I posted. The effect of the other things on the overall timing is minimal by comparison. Essentially, loading a large pixel size bmp is slow mostly because of the large amount of data that needs to be dragged from the disk, and the "read from disk" time disk can be speeded up greatly by loading an equivalent jpg image from disk instead of a bmp, simply because a jpg image of the same pixel size has its data greatly compressed and there is therefore very much less data to be read from disk. However, if you are using the VB LoadPicture method or GDI or GDI+ to load the jpg from disk then all of the time you saved by loading a comparatively small amount of data is negated by the fact that those methods (LoadPicture, GDI, GDI+) are slow at decoding and converting the jpg data, so you don't end up winning. However, that's where the Intel jpeg library comes into its own, because the Intel jpeg library decodes and converts jpeg data very much faster than LoadPicture or GDI or GDI+, so you do actually gain a lot in speed by loading a jpg instead of a bmp if you use the Intel jpeg library to load and convert it.

Mike



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