SpanIterator.java

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package sun.java2d.pipe;

/**
 * This interface defines a general method for iterating through the
 * rectangular "spans" that represent the interior of a filled path.
 * <p>
 * There can be many kinds of span iterators used in the rendering
 * pipeline, the most basic being an iterator that scan converts a
 * path defined by any PathIterator, or an nested iterator which
 * intersects another iterator's spans with a clip region.
 * Other iterators can be created for scan converting some of the
 * primitive shapes more explicitly for speed or quality.
 *
 * @author Jim Graham
 */
public interface SpanIterator {
    /**
     * This method returns the bounding box of the spans that the
     * iterator will be returning.
     * The array must be of length at least 4 and upon return, it
     * will be filled with the values:
     * <pre>
     *     {PathMinX, PathMinY, PathMaxX, PathMaxY}.
     * </pre>
     */
    public void getPathBox(int[] pathbox);

    /**
     * This method constrains the spans returned by nextSpan() to the
     * rectangle whose bounds are given.
     */
    public void intersectClipBox(int lox, int loy, int hix, int hiy);

    /**
     * This method returns the next span in the shape being iterated.
     * The array must be of length at least 4 and upon return, it
     * will be filled with the values:
     * <pre>
     *     {SpanMinX, SpanMinY, SpanMaxX, SpanMaxY}.
     * </pre>
     */
    public boolean nextSpan(int[] spanbox);

    /**
     * This method tells the iterator that it may skip all spans
     * whose Y range is completely above the indicated Y coordinate.
     * This method is used to provide feedback from the caller when
     * clipping prevents the display of any data in a given Y range.
     * Typically it will only be called when this iterator has returned
     * a span whose MaxY coordinate is less than the indicated Y and
     * the calling mechanism wants to avoid unnecessary iteration work.
     * While this request could technically be ignored (i.e. a NOP),
     * doing so could potentially cause the caller to make this callback
     * for each span that is being skipped.
     */
    public void skipDownTo(int y);

    /**
     * This method returns a native pointer to a function block that
     * can be used by a native method to perform the same iteration
     * cycle that the above methods provide while avoiding upcalls to
     * the Java object.
     * The definition of the structure whose pointer is returned by
     * this method is defined in:
     * <pre>
     *     src/share/native/sun/java2d/pipe/SpanIterator.h
     * </pre>
     */
    public long getNativeIterator();
}