[haiku-bugs] [Haiku] #10773: Gradient color stop sorting is not stable.
- From: "pulkomandy" <trac@xxxxxxxxxxxx>
- Date: Tue, 22 Apr 2014 08:38:04 -0000
#10773: Gradient color stop sorting is not stable.
--------------------------------+------------------------------
Reporter: pulkomandy | Owner: stippi
Type: bug | Status: new
Priority: normal | Milestone: R1
Component: Kits/Interface Kit | Version: R1/Development
Keywords: | Blocked By:
Blocking: | Has a Patch: 0
Platform: All |
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Consider the following code used to create a stripped pattern using a
BGradient:
{{{
gradient.AddColor(black, 0);
gradient.AddColor(black, 127);
gradient.AddColor(white, 127);
gradient.AddColor(white, 255);
}}}
In ConvertToScreenForDrawing, the gradient stops will be sorted using
BList.Sort. The sorting algorithm is not stable, so the two middle stops
may be swapped. There are two ways to fix this:
* Implement a stable sorting algorithm
(http://en.wikipedia.org/wiki/Category:Stable_sorts)
* Remove the AddColorStop method index parameter and use code similar to
AddColor to find the proper index, or make that method private. This would
allow BGradient to keep the list sorted, and remove the need for sorting
it later. The method is used only in app_server (for reading the gradient
data from app_server link) and when unarchiving a gradient.
What is the preferred solution?
--
Ticket URL: <https://dev.haiku-os.org/ticket/10773>
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