Using BBitmap::SetBits

[Dan Pidcock]

Anybody still here??

I have some problems with using SetBits. I thought that the following
is the way to do it:
uint8 pixel[3]; // is ushort also 8 bits??
pixel[0] = 255; // red?
pixel[1] = 0; // green?
pixel[2] = 255; // blue?
// data length offset mode
bitmap->SetBits(pixel, 3, 100, B_RGB32)

I expected this to set the pixel to a magenta colour but it doesn't.
Changing the colours I can't yet work out what is going on and the
BeBook doesn't really explain this. I guess I have misunderstood the
byte to colour mapping?

Oh yes I intend to use Bits() in the long run but though it would be
easier to first get it working with SetBits().

Thanks,

Dan

[Jøhnny Fävòrítê (it means "genetic antagonism")]

Post by Dan Pidcock
Anybody still here??

just me, marco, and the spammers, i think. ask a tcp/ip question, that
would determine if donn cave is still reading.

Post by Dan Pidcock
I have some problems with using SetBits. I thought that the following
uint8 pixel[3]; // is ushort also 8 bits??
pixel[0] = 255; // red?
pixel[1] = 0; // green?
pixel[2] = 255; // blue?
// data length offset mode
bitmap->SetBits(pixel, 3, 100, B_RGB32)
I expected this to set the pixel to a magenta colour but it doesn't.

have a closer look at the BBitmap documentation, it answers your
question handily. you've got the RGB components in the wrong order.

[Dan Pidcock]

The problem was I was using ushort instead of uint8.
I thought I had tried uint8 too but obviously not.

Dan

Post by Dan Pidcock
Anybody still here??
I have some problems with using SetBits. I thought that the following
uint8 pixel[3]; // is ushort also 8 bits??
pixel[0] = 255; // red?
pixel[1] = 0; // green?
pixel[2] = 255; // blue?
// data length offset mode
bitmap->SetBits(pixel, 3, 100, B_RGB32)
I expected this to set the pixel to a magenta colour but it doesn't.
Changing the colours I can't yet work out what is going on and the
BeBook doesn't really explain this. I guess I have misunderstood the
byte to colour mapping?
Oh yes I intend to use Bits() in the long run but though it would be
easier to first get it working with SetBits().
Thanks,
Dan

[revol]

***@hotmail.com (Dan Pidcock) writes:

Yeah ushort is 2 bytes.
Btw, unless you really need high throughput the prefered method
to draw on a BBitmap is to attach a BView to it, and draw on
that BView. That will hold you from internal format changes and
endianness issues.
Btw, drawing a 1 pixel point on BView can be done by drawing
a 1x1 rect, as in:
theview->FillRect(BRect(x,y,x,y));

François.

Post by Dan Pidcock
The problem was I was using ushort instead of uint8.
I thought I had tried uint8 too but obviously not.
Dan

Post by Dan Pidcock
Anybody still here??
I have some problems with using SetBits. I thought that the following
uint8 pixel[3]; // is ushort also 8 bits??
pixel[0] = 255; // red?
pixel[1] = 0; // green?
pixel[2] = 255; // blue?
// data length offset mode
bitmap->SetBits(pixel, 3, 100, B_RGB32)
I expected this to set the pixel to a magenta colour but it doesn't.
Changing the colours I can't yet work out what is going on and the
BeBook doesn't really explain this. I guess I have misunderstood the
byte to colour mapping?
Oh yes I intend to use Bits() in the long run but though it would be
easier to first get it working with SetBits().
Thanks,
Dan