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25 
26 package sun.java2d.pipe;
27 
28 
29 /**
30  * This class defines the API for iterating through the bands
31  * of a region object.
32  */
33 public class RegionIterator {
34     Region region;
35     int curIndex;
36     int numXbands;
37 
RegionIterator(Region r)38     RegionIterator(Region r) {
39         region = r;
40     }
41 
42     /**
43      * Returns a new RegionIterator object representing the same
44      * iteration state as this object to allow multiple iteration
45      * branches from the current position.
46      */
createCopy()47     public RegionIterator createCopy() {
48         RegionIterator r = new RegionIterator(region);
49         r.curIndex = this.curIndex;
50         r.numXbands = this.numXbands;
51         return r;
52     }
53 
54     /**
55      * Copies the iteration state from this RegionIterator object
56      * into another RegionIterator object to allow multiple iteration
57      * branches from the current position.
58      */
copyStateFrom(RegionIterator ri)59     public void copyStateFrom(RegionIterator ri) {
60         if (this.region != ri.region) {
61             throw new InternalError("region mismatch");
62         }
63         this.curIndex = ri.curIndex;
64         this.numXbands = ri.numXbands;
65     }
66 
67     /**
68      * Moves the iteration state to the beginning of the next
69      * Y range in the region returning true if one is found
70      * and recording the low and high Y coordinates of the
71      * range in the array at locations 1 and 3 respectively.
72      */
nextYRange(int[] range)73     public boolean nextYRange(int[] range) {
74         curIndex += numXbands * 2;
75         numXbands = 0;
76         if (curIndex >= region.endIndex) {
77             return false;
78         }
79         range[1] = region.bands[curIndex++];
80         range[3] = region.bands[curIndex++];
81         numXbands = region.bands[curIndex++];
82         return true;
83     }
84 
85     /**
86      * Moves the iteration state to the beginning of the next
87      * X band in the current Y range returning true if one is
88      * found and recording the low and high X coordinates of
89      * the range in the array at locations 0 and 2 respectively.
90      */
nextXBand(int[] range)91     public boolean nextXBand(int[] range) {
92         if (numXbands <= 0) {
93             return false;
94         }
95         numXbands--;
96         range[0] = region.bands[curIndex++];
97         range[2] = region.bands[curIndex++];
98         return true;
99     }
100 }
101