Increasing Canvas speed

Kamac · Sep 29, 2011

Hi.

I've got problems, since when i changed my technique to Canvas from ImageView, the FPSes dropped pretty much.

All of that is because i have to redraw the whole screen (so i can remove the character to place it on the background again). Maybe i should do it some else way?

kickaha · Sep 29, 2011

Instead of redrawing the whole screen, use ClipPath to limit the redraw region.

Edit to add:

If you have a static background, why not have that as a separate image, and use another canvas to draw your moveable things on.

thedesolatesoul · Sep 29, 2011

You dont have to redraw the whole screen. Look at Erels arkanoid sample.
Instead of Invalidating the whole screen, just invalidate the parts you want to redraw.
And even then look for other leaks...do not keep reloading and redrawing bitmaps.

Kamac · Sep 29, 2011

You dont have to redraw the whole screen. Look at Erels arkanoid sample.
Instead of Invalidating the whole screen, just invalidate the parts you want to redraw.
And even then look for other leaks...do not keep reloading and redrawing bitmaps.

How can i clean a part of the screen

I'll look on Erel's example.

thedesolatesoul · Sep 29, 2011

If you have the background bitmap loaded in memory, you copy that region onto the part you want to clear.
I think Erels example doesnt have a background so maybe he is just painting a black rectangle.

Kamac · Sep 29, 2011

I think Erels example doesnt have a background so maybe he is just painting a black rectangle.

He's using transparent DrawRect :sign0137:

Widget · Sep 29, 2011

Kamac said:
How can i clean a part of the screen

I'll look on Erel's example.

Kamac,
What works for me is to put a transparent panel on top of the bitmap and draw on the transparent panel. To clear the part of the drawing, I draw a transparent rectangle on the transparent panel. Or I can also set the transparent panel's color to transparent to clear the entire transparent panel but this is slower.

This is like drawing on a transparency, and then wiping off the drawings. It works well on zoomed images and panned images too.

Widget

Kamac · Sep 29, 2011

I've actually figured this out.

Incredible how fast is it running now. Waaaay faster than with imageviews

I made it this way:

draw a transparent rect just where the player was to clear him out

draw the background

draw some object

draw the player

Mikie · Sep 29, 2011

Kamac,

Are you trying to use b4a to create games?
I am using Corona. Very fast.

Mikie

thedesolatesoul · Sep 29, 2011

Kamac said:
I've actually figured this out.

Incredible how fast is it running now. Waaaay faster than with imageviews

I made it this way:

draw a transparent rect just where the player was to clear him out

draw the background

draw some object

draw the player

What is the point of drawing a transparent rect initially? (BTW...what IS a transparent rect?)

Increasing Canvas speed

Kamac

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