package ar.com.hjg.pngj.chunks;
import java.io.ByteArrayInputStream;
import ar.com.hjg.pngj.ImageInfo;
import ar.com.hjg.pngj.PngHelperInternal;
import ar.com.hjg.pngj.PngjException;
import ar.com.hjg.pngj.PngjInputException;
/**
* IHDR chunk.
* <p>
* see http://www.w3.org/TR/PNG/#11IHDR
* <p>
* This is a special critical Chunk.
*/
public class PngChunkIHDR extends PngChunkSingle {
public final static String ID = ChunkHelper.IHDR;
private int cols;
private int rows;
private int bitspc;
private int colormodel;
private int compmeth;
private int filmeth;
private int interlaced;
// http://www.w3.org/TR/PNG/#11IHDR
//
public PngChunkIHDR(ImageInfo info) { // argument is normally null here, not used
super(ID, info);
}
@Override
public ChunkOrderingConstraint getOrderingConstraint() {
return ChunkOrderingConstraint.NA;
}
@Override
public ChunkRaw createRawChunk() {
ChunkRaw c = new ChunkRaw(13, ChunkHelper.b_IHDR, true);
int offset = 0;
PngHelperInternal.writeInt4tobytes(cols, c.data, offset);
offset += 4;
PngHelperInternal.writeInt4tobytes(rows, c.data, offset);
offset += 4;
c.data[offset++] = (byte) bitspc;
c.data[offset++] = (byte) colormodel;
c.data[offset++] = (byte) compmeth;
c.data[offset++] = (byte) filmeth;
c.data[offset++] = (byte) interlaced;
return c;
}
@Override
public void parseFromRaw(ChunkRaw c) {
if (c.len != 13)
throw new PngjException("Bad IDHR len " + c.len);
ByteArrayInputStream st = c.getAsByteStream();
cols = PngHelperInternal.readInt4(st);
rows = PngHelperInternal.readInt4(st);
// bit depth: number of bits per channel
bitspc = PngHelperInternal.readByte(st);
colormodel = PngHelperInternal.readByte(st);
compmeth = PngHelperInternal.readByte(st);
filmeth = PngHelperInternal.readByte(st);
interlaced = PngHelperInternal.readByte(st);
}
public int getCols() {
return cols;
}
public void setCols(int cols) {
this.cols = cols;
}
public int getRows() {
return rows;
}
public void setRows(int rows) {
this.rows = rows;
}
public int getBitspc() {
return bitspc;
}
public void setBitspc(int bitspc) {
this.bitspc = bitspc;
}
public int getColormodel() {
return colormodel;
}
public void setColormodel(int colormodel) {
this.colormodel = colormodel;
}
public int getCompmeth() {
return compmeth;
}
public void setCompmeth(int compmeth) {
this.compmeth = compmeth;
}
public int getFilmeth() {
return filmeth;
}
public void setFilmeth(int filmeth) {
this.filmeth = filmeth;
}
public int getInterlaced() {
return interlaced;
}
public void setInterlaced(int interlaced) {
this.interlaced = interlaced;
}
public boolean isInterlaced() {
return getInterlaced() == 1;
}
/** throws PngInputException if unexpected values */
public ImageInfo createImageInfo() {
check();
boolean alpha = (getColormodel() & 0x04) != 0;
boolean palette = (getColormodel() & 0x01) != 0;
boolean grayscale = (getColormodel() == 0 || getColormodel() == 4);
// creates ImgInfo and imgLine, and allocates buffers
return new ImageInfo(getCols(), getRows(), getBitspc(), alpha, grayscale, palette);
}
public void check() {
if (cols < 1 || rows < 1 || compmeth != 0 || filmeth != 0)
throw new PngjInputException("bad IHDR: col/row/compmethod/filmethod invalid");
if (bitspc != 1 && bitspc != 2 && bitspc != 4 && bitspc != 8 && bitspc != 16)
throw new PngjInputException("bad IHDR: bitdepth invalid");
if (interlaced < 0 || interlaced > 1)
throw new PngjInputException("bad IHDR: interlace invalid");
switch (colormodel) {
case 0:
break;
case 3:
if (bitspc == 16)
throw new PngjInputException("bad IHDR: bitdepth invalid");
break;
case 2:
case 4:
case 6:
if (bitspc != 8 && bitspc != 16)
throw new PngjInputException("bad IHDR: bitdepth invalid");
break;
default:
throw new PngjInputException("bad IHDR: invalid colormodel");
}
}
}