[OpenJDK 2D-Dev] JDK9: RFR: 8039342: Fix raw and unchecked warnings in sun.awt.*

[Jim Graham]

Given how vectors of curves are constructed, either they are the output 
of a previous operation, in which case you need enough curves/edges to 
enclose an area and the count must be 0 or >=2, or they are the result 
of ingesting a Shape.  Looking at the code that ingests a Shape in 
Area.pathToCurves, I thought I could find ways of getting it to generate 
just a single path segment, but there was always some logic that 
eventually prevented it from getting to pruneEdges.

For instance, an empty path ends up with no segments because it only 
gets a single "insertLine(0,0,0,0)" after the PathIterator loop and 
insertLine() itself prunes out that segment and ends up with an empty 
Vector before the path is validated (via NZOp.calculate() or 
EOop.calculate()).

If you just have a moveTo, it tries to insertLine(0,0,0,0) to close off 
the old path which doesn't insert anything, then it inserts an Order0 
moveto point, then it ends with closing off the final path with another 
insertLine(0,0,0,0) which ends up getting ignored.  This gives you a 
Vector of 1 Curve, but it is an Order0 and so it gets pruned out by the 
addEdges() method before that list ever gets to pruneEdges.

If you have moveTo+something else like a lineto, then you get:
moveto - insertLine(0,0,0,0), ignored - insertMove(x1,y1), adds an Order0
lineto - insertLine(x1,y1,x2,y2), adds a line segment
post-pathiterator - insertline(x2,y2,x1,y1), adds a line segment
This ends up with 2 curves in the edges list which does not trigger the 
bad code, but both get eliminated during the cleanup and normalization 
and the resulting Area object has an empty vector.  But, for our 
purposes, we got to pruneEdges with 2 edges.

Finally, I even went so far as to create a bogus shape that skipped 
having a moveto and just had a lineto (I had to implement Shape 
directly) and even that ended up with a line segment out, and then a 
closing line segment back which had >=2 segments.

So, it appears that either an ingested shape will have at least 2 
non-empty, non-Order0 segments, or it will have none.

So, that code is "just in case the laws of physics change" code and it 
was buggy, but was provably-ish never callable.  I imagine that these 
generics mechanisms would have been a god-send, though, back when I was 
actually writing and debugging all of this...

			...jim

On 4/7/14 1:46 PM, Henry Jen wrote:
> Hi,
>
> Please review the webrev cleans up raw and unchecked warnings in sun.awt,
>
> http://cr.openjdk.java.net/~henryjen/jdk9/8039342/0/webrev/
>
> The following changes in AreaOp::pruneEdges() is particular worth
> attention, when numedges < 2, two different type are mixed up in the
> past with use of rawtypes; However, I think it could only work if the
> Vector is empty?
>
> Cheers,
> Henry
>
>
>> @@ -193,16 +193,20 @@
>>              }
>>              return 1;
>>          }
>>      };
>>
>> -    private Vector pruneEdges(Vector edges) {
>> +    private Vector<Curve> pruneEdges(Vector<Edge> edges) {
>>          int numedges = edges.size();
>>          if (numedges < 2) {
>> -            return edges;
>> +            Vector<Curve> rt = new Vector<>();
>> +            for (Edge edge: edges) {
>> +                rt.add(edge.getCurve());
>>          }
>> -        Edge[] edgelist = (Edge[]) edges.toArray(new Edge[numedges]);
>> +            return rt;
>> +        }
>> +        Edge[] edgelist = edges.toArray(new Edge[numedges]);
>>          Arrays.sort(edgelist, YXTopComparator);
>>          if (false) {
>>              System.out.println("pruning: ");
>>              for (int i = 0; i < numedges; i++) {
>>                  System.out.println("edgelist["+i+"] = "+edgelist[i]);
>