65 lines
2.0 KiB
Java
65 lines
2.0 KiB
Java
package ar.com.hjg.pngj;
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/**
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* Set of {@link IImageLine} elements.
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* <p>
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* This is actually a "virtual" set, it can be implemented in several ways; for
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* example
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* <ul>
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* <li>Cursor-like: stores only one line, which is implicitly moved when
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* requested</li>
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* <li>All lines: all lines stored as an array of <tt>IImageLine</tt></li>
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* <li>
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* Subset of lines: eg, only first 3 lines, or odd numbered lines. Or a band of
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* neighbours lines that is moved like a
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* cursor.</li>
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* The ImageLine that PngReader returns is hosted by a IImageLineSet (this
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* abstraction allows the implementation to deal
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* with interlaced images cleanly) but the library user does not normally needs
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* to know that (or rely on that), except
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* for the {@link PngReader#readRows()} method.
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* </ul>
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*/
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public interface IImageLineSet<T extends IImageLine> {
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/**
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* Asks for imageline corresponding to row <tt>n</tt> in the original image
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* (zero based). This can trigger side
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* effects in this object (eg, advance a cursor, set current row number...)
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* In some scenarios, this should be consider
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* as alias to (pseudocode) <tt>positionAtLine(n); getCurrentLine();</tt>
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* <p>
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* Throws exception if not available. The caller is supposed to know what
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* he/she is doing
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**/
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public IImageLine getImageLine(int n);
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/**
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* Like {@link #getImageLine(int)} but uses the raw numbering inside the
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* LineSet This makes little sense for a cursor
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*
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* @param n
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* Should normally go from 0 to {@link #size()}
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* @return
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*/
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public IImageLine getImageLineRawNum(int n);
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/**
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* Returns true if the set contain row <tt>n</tt> (in the original
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* image,zero based) currently allocated.
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* <p>
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* If it's a single-cursor, this should return true only if it's positioned
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* there. (notice that hasImageLine(n) can
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* return false, but getImageLine(n) can be ok)
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*
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**/
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public boolean hasImageLine(int n);
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/**
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* Internal size of allocated rows This is informational, it should rarely
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* be important for the caller.
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**/
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public int size();
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}
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