Anything I could do to speed up BitBlt?

[Dude1]

Hey, I missed you all . Yeh, anyways, like the title sais, what can I do? I've heard of using "DoubleBuffering" instead on AutoRedraw, not quite sure what that is all about. Will loading my pictures from harddrive help speed things up, instead of having them all on the form?

Thanks.

[Machaira]

Double-buffering allows you to draw everything to an off-screen location then draw that buffer to the screen. It eliminates flickering and graphics being visible drawn to the screen. Is that the problem you're having? Why do you need to speed it up? What framerate are you getting currently?

[Dude1]

No, my graphics don't flicker or anything, I get an amazing 13 frames per second. It's just that I have 766Mhz and If i slow down my computer to say 400Mhz, you could see how slow the graphics become. Not everybody has fast computers yet. Just want to optimize my code as much as possible.

[Sastraxi]

How many things are you blitting/what size/how are you loading?

[Dude1]

I blit a character, then I have a big background picture larger then the screen, and then use StretchBlt to make it scroll when the character moves. The Background is not big in size about 200KB, it's a jpg. I store all my pictures in pictureboxes on the form, so I don't load anything.

[Amithran]

From what I've read, stretchbitblt is slower. Why are you using it? BitBlt is all you need for scrolling an image, probly fastest too.

[Sastraxi]

I think you should try not to use stretchblit... Just blit the bg with BitBlt and see what performance you get

[Sastraxi]

Darn, I was beaten by about 2 seconds

[Amithran]

well, if you hurry, you could probly be the first to reply to my Matrix code with commentary.

[Dude1]

But If I use BitBlt, where would I blit my bg too? If I blit it to the form it flickers.

Before I had this:

StretchBlt hdc, 0, 0, 2000, 1300, PB.hdc, OfsetX, OfsetY, 2000, 1300, vbSrcCopy

Now I have this:

BitBlt Me.hdc, OfsetX, OfsetY, 2000, 1300, Picture5.hdc, 0, 0, vbMergePaint
BitBlt Me.hdc, OfsetX, OfsetY, 2000, 1300, PB.hdc, 0, 0, vbSrcAnd

and it is slow

[Zaei]

BitBlt hdc, ...

Z.

[Amithran]

create a new picture control (called backBuffer, and bitBlt everything to backBuffer.
Then at the end of the loop, bitBlt backBuffer to me.hdc (or what ever your primary hdc is)

set backBuffer.visible = false so it don't get seen.

[Dude1]

Ok I have :

BitBlt Backbuffer.hdc, -OfsetX, -OfsetY, 2000, 1300, Picture5.hdc, 0, 0, vbMergePaint
BitBlt Backbuffer.hdc, -OfsetX, -OfsetY, 2000, 1300, PB.hdc, 0, 0, vbSrcAnd

the ofset is negative so the bg scrolls against the character, not with.

Now I blit the backbuffer to me:

'BitBlt Me.hdc, -OfsetX, -OfsetY, 2000, 1300, Picture5.hdc, 0, 0, vbMergePaint
BitBlt Me.hdc, -OfsetX, -OfsetY, 2000, 1300, Backbuffer.hdc, 0, 0, vbSrcAnd

but what do I use for the backbuffer mask? If I use picture5, same as bg, the game is slow.

Thanks again.