Bigger cursors needed

> This sounds good to me. About the 128x128 restriction: Don't. If  
> platforms do not support a particular size, then just fail the  
> primitive and leave it to the image to sort out the problem. There  
> is no reason to make such artificial restrictions these days.
>
> Cheers,
>   - Andreas
>
> Bert Freudenberg wrote:
>> Hi folks,
>> for the OLPC XO with its 200 dpi screen we really need larger  
>> cursors than are currently supported in the VM.
>> AFAIK, all major systems now support arbitrary 32 bit RGBA bitmaps  
>> as cursors.
>> I'd suggest to simply extend primitiveBeCursor to allow 32 bit  
>> forms. An older VM would fail the primitive so action could be  
>> taken on the image side. The primitive would then call a new  
>> function, say
>>     ioSetCursorRGBA(cursorBitsIndex, width, height, offsetX, offsetY)
>> IMHO, we don't really need to support other depths than 32, so we  
>> do not have to give that as parameter to ioSetCursorRGBA().
>> Not sure if we want to restrict cursor size to, say 128x128. What  
>> do the platforms support?
>> - Bert -

> On Mar 4, 2007, at 13:18 , Bert Freudenberg wrote:
>
>> On Mar 3, 2007, at 22:31 , John M McIntosh wrote:
>>
>>> 10.2 has a restriction of 16x16, but that is lifted in 10.3
>>> I'll need to convert to the new NSCursor model. so will do that  
>>> soon in  3.8.16 mac carbon vm.
>>>
>>> If you can point to a image that enables the large cursor  
>>> functionality so I can do testing that would be good.
>>
>> Well, I can't test it without a real implementation. But this  
>> should work if the primitive works:
>>
>> | form cursor |
>> form := Cursor normal asCursorForm as8BitColorForm.
>> form replaceColor: Color white with: (Color green alpha: 0.25).
>> form replaceColor: Color black with: (Color blue alpha: 0.5).
>> form := form asFormOfDepth: 32.
>> form := form magnify: (0@0 extent: 9@16) by: 3.
>> cursor := Cursor extent: form extent depth: 32.
>> form displayOn: cursor at: 0@0 rule: Form blend. "pre-multiply alpha"
>> form asMorph openInHand.
>> cursor show
>>
>> The cursor rendering should match the morph (provided your world  
>> is set to 32 bpp). In particular, the green border should not  
>> appear grayish, if it is, your system does not use pre-multiplied  
>> alpha. We can still change the spec if this is the case.
>
> Err, forgot the offset. Also, much more configurable. Special! Only  
> today! Choose your own source, scale, and colors! ;-)
>
> | source scale colors form cursor |
> source := Cursor read.
> scale := 3.
> colors := {Color blue alpha: 0.5. Color green alpha: 0.25}.
> form := source asCursorForm as8BitColorForm.
> form replaceColor: Color black with: colors first.
> form replaceColor: Color white with: colors second.
> form := form asFormOfDepth: 32.
> form := form magnify: (source innerPixelRectFor: 0 orNot: false)  
> by: scale.
> form asMorph openInHand.
> cursor := Cursor extent: form extent depth: 32.
> form displayOn: cursor at: 0@0 rule: Form blend. "pre-multiply alpha"
> cursor offset: (source offset - 0.5 * scale min: 0@0 max: cursor  
> extent negated) asIntegerPoint.
> cursor show
>
> For testing the offset, "Cursor crossHair" might work best.

> Hi Ian,
>
> I implemented ioSetCursorARGB() on X11 using the XRender extension,  
> see attachment. It's a stand-alone test program that uses  
> ioSetCursorARGB() to show a nicely colored cursor. This is not  
> hooked up to the new primitive yet - can you do this soonish or  
> should I work on a more complete patch?
>
> - Bert -
>
> On Mar 4, 2007, at 16:54 , Bert Freudenberg wrote:
>
>> On Mar 4, 2007, at 13:18 , Bert Freudenberg wrote:
>> | source scale colors form cursor |
>> source := Cursor read.
>> scale := 3.
>> colors := {Color blue alpha: 0.5. Color green alpha: 0.25}.
>> form := source asCursorForm as8BitColorForm.
>> form replaceColor: Color black with: colors first.
>> form replaceColor: Color white with: colors second.
>> form := form asFormOfDepth: 32.
>> form := form magnify: (source innerPixelRectFor: 0 orNot: false)  
>> by: scale.
>> "form asMorph openInHand."
>> cursor := Cursor extent: form extent depth: 32.
>> form displayOn: cursor at: 0@0 rule: Form blend. "pre-multiply alpha"
>> cursor offset: (source offset - 0.5 * scale min: 0@0 max: cursor  
>> extent negated) asIntegerPoint.
>> cursor show
>>
>> For testing the offset, "Cursor crossHair" might work best.