ObtainBestPen()

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mritter0

ObtainBestPen()

Posted on: 2016/10/20 1:20 #1

Just popping in


RedPen=IGraphics->ObtainBestPen(DefaultPubScreen->ViewPort.ColorMap,0xFFFFFFFF,0x00000000,0x00000000,

        OBP_Precision,                            PRECISION_GUI,

        OBP_FailIfBad,                            FALSE,

    TAG_END);

Do I really need to specify the alpha channel? Does it have any benefit to specify it? Will I get a more accurate color with/without it?

thomas

Re: ObtainBestPen()

Posted on: 2016/10/20 7:42 #2

Not too shy to talk

Where do you see an alpha channel? There is no way to specify an alpha channel. There is only red, green, blue, precision and fail if bad.

ChrisH

Re: ObtainBestPen()

Posted on: 2016/10/20 11:31 #3

Home away from home

@mritter0
I think you only have to specify the alpha channel if you are directly specifying the drawing colour for OS4. As thomas says, pen-based colours shouldn't have anything to do with alpha channel.

Author of the PortablE programming language.

mritter0

Re: ObtainBestPen()

Posted on: 2016/10/20 16:45 #4

Just popping in

0xFFFFFFFF is not ARGB?

It's not the same as html/web based colors?

#FFFFFF = 0x00FFFFFF ?

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broadblues

Re: ObtainBestPen()

Posted on: 2016/10/20 18:01 #5

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@mritter0

Quote:

0xFFFFFFFF is not ARGB?

No it's a left justified 32 bit fraction.

from autodocs:

R = red level (32 bit left justified fraction)
G = green level (32 bit left justified fraction)
B = blue level (32 bit left justified fraction)

if your 256 bit colour is r then

R = r + (r<<8) + (r<<16) + (r<<24)

see also the doc for setRGB32 et al

Quote:

It's not the same as html/web based colors?

#FFFFFF = 0x00FFFFFF ?

Be careful not to make mistake either when you need an ARGB colour do not set the A part to 00 set it to FF, else at some future point when alpha support is extended all your graphics wil disappear (applies mainly tro SetRPAttrs()

Blender For OS4.x : Blues : Walker Broad

ChrisH

Re: ObtainBestPen()

Posted on: 2016/10/20 21:31 #6

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@broadblues Quote:

No it's a left justified 32 bit fraction.

from autodocs:

R = red level (32 bit left justified fraction)
G = green level (32 bit left justified fraction)
B = blue level (32 bit left justified fraction)
...
see also the doc for setRGB32 et al

I always found this really baffling. I mean it dates back to AmigaOS 1.x (edit: nope, it's actually 3.0) era: Why would they implement 96 bit (3*32 bit) colour depth - that's overkill even today (24 bits is pretty good, and 30 bits is about as good as it gets on consumer video formats.)

Quote:

Be careful not to make mistake either when you need an ARGB colour do not set the A part to 00 set it to FF, else at some future point when alpha support is extended all your graphics wil disappear (applies mainly tro SetRPAttrs()

Hmmm, I thought alpha-channel support was already widely used in OS4, certainly SetRPAttrs() already uses it. And so does MUI4 iirc.

Edited by ChrisH on 2016/10/20 22:14:26

Author of the PortablE programming language.

broadblues

Re: ObtainBestPen()

Posted on: 2016/10/20 23:38 #7

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@ChrisH

Quote:

always found this really baffling. I mean it dates back to AmigaOS 1.x (edit: nope, it's actually 3.0) era: Why would they implement 96 bit (3*32 bit) colour depth - that's overkill even today (24 bits is pretty good, and 30 bits is about as good as it gets on consumer video formats.)

Honestly I don't know, it could be that using fractional values was more flexible when convert between different colours spaces, or it could just be they were overly optimitic about how long it would be before HDR displays would surface.

A 32 bit fraction also allows aribitray depth. Less than 8 bits as well as more than 8bits by that I mean converting from a 32 bit fraction to a 5bit depth (for a 15/16 screen) is more acurate then converting from an 8bit value.

For the real why you need someone who was "there"

Quote:

Hmmm, I thought alpha-channel support was already widely used in OS4, certainly SetRPAttrs() already uses it. And so does MUI4 iirc.

There is limited support IIUC, some things take the alpha value more things don't.

Blender For OS4.x : Blues : Walker Broad

mritter0

Re: ObtainBestPen()

Posted on: 2016/10/21 0:11 #8

Just popping in

I totally see my poorly asked question. I still had HTML color codes on the brain.

Anyway, I made a little function to make things easier for myself.


int32 GreenPen=ObtainPenHex((STRPTR)"#00FF00");





int32

ObtainPenHex(STRPTR HexValue)

{

    TEXT                            value[5];

    uint32                            r, g, b;



    IUtility->SNPrintf(value,3,"%s",HexValue+1);

    r=strtol(value,NULL,16);



    IUtility->SNPrintf(value,3,"%s",HexValue+3);

    g=strtol(value,NULL,16);



    IUtility->SNPrintf(value,3,"%s",HexValue+5);

    b=strtol(value,NULL,16);



    return(IGraphics->ObtainBestPen(DefaultPubScreen->ViewPort.ColorMap,((r<<24) | (r<<16) | (r<<8) | r),(g<<24) | ((g<<16) | (g<<8) | g),((b<<24) | (b<<16) | (b<<8) | b),

        OBP_Precision,                            PRECISION_GUI,

        OBP_FailIfBad,                            FALSE,

    TAG_END));

}





    IGraphics->ReleasePen(DefaultPubScreen->ViewPort.ColorMap,BluePen);

    BluePen=-1;

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broadblues

Re: ObtainBestPen()

Posted on: 2016/10/21 2:32 #9

Home away from home

ermm

may I suggest simply

htmlcolor = stroul(HexValue + 1,NULL,16);

r = (htmlcolor & 0xFF0000) >> 16;
g = (htmlcolor & 0x00FF00) >> 8;
b = (htmlcolor & 0x0000FF);

rather than all those SNPrintfs ?

maybe with abit of error chacking and format verification for good measure

Blender For OS4.x : Blues : Walker Broad

Gazelle

Re: ObtainBestPen()

Posted on: 2016/10/21 13:28 #10

Just popping in

@mritter0
or even:


int32 GreenPen=ObtainPenHex(0x00FF00);



int32

ObtainPenHex(uint32 htmlColour)

{

    uint32 r, g, b;



    r = ((htmlColour & 0xFF0000) >> 16) * 0x01010101;

    g = ((htmlColour & 0x00FF00) >> 8)  * 0x01010101;

    b = ((htmlColour & 0x0000FF))       * 0x01010101;



    return(IGraphics->ObtainBestPen(DefaultPubScreen->ViewPort.ColorMap, r, g, b,

                                    OBP_Precision, PRECISION_GUI,

                                    OBP_FailIfBad, FALSE,

                                    TAG_END)

    );

}

salass00

Re: ObtainBestPen()

Posted on: 2016/11/15 20:58 #11

Just can't stay away

@mritter0

To make converting from 8-bit to 32-bit RGB components simpler you can define a macro for it like so:

#define RGB8to32(c) ((uint32)(c) * 0x01010101UL)

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