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package jogamp.opengl.util.pngj;
import java.util.Arrays;
/**
* Lightweight wrapper for an image scanline, used for read and write.
* <p>
* This object can be (usually it is) reused while iterating over the image lines.
* <p>
* See <code>scanline</code> field, to understand the format.
*/
public class ImageLine {
public final ImageInfo imgInfo;
/**
* tracks the current row number (from 0 to rows-1)
*/
private int rown = 0;
/**
* The 'scanline' is an array of integers, corresponds to an image line (row).
* <p>
* Except for 'packed' formats (gray/indexed with 1-2-4 bitdepth) each int is a "sample" (one for channel), (0-255
* or 0-65535) in the respective PNG sequence sequence : (R G B R G B...) or (R G B A R G B A...) or (g g g ...) or
* ( i i i) (palette index)
* <p>
* For bitdepth 1/2/4 , each element is a PACKED byte! To get an unpacked copy, see <code>tf_pack()</code> and its
* inverse <code>tf_unpack()</code>
* <p>
* To convert a indexed line to RGB balues, see <code>ImageLineHelper.tf_palIdx2RGB()</code> (can't do the reverse)
*/
public final int[] scanline; // see explanation above!!
protected FilterType filterUsed; // informational ; only filled by the reader
public final int channels; // copied from imgInfo, more handy
public final int bitDepth; // copied from imgInfo, more handy
public ImageLine(ImageInfo imgInfo) {
this.imgInfo = imgInfo;
channels = imgInfo.channels;
scanline = new int[imgInfo.samplesPerRowP];
this.bitDepth = imgInfo.bitDepth;
}
/** This row number inside the image (0 is top) */
public int getRown() {
return rown;
}
/** Increments row number */
public void incRown() {
this.rown++;
}
/** Sets row number */
public void setRown(int n) {
this.rown = n;
}
/** Sets scanline, making copy from passed array */
public void setScanLine(int[] b) {
System.arraycopy(b, 0, scanline, 0, scanline.length);
}
/**
* Returns a copy from scanline, in byte array.
*
* You can (OPTIONALLY) pass an preallocated array to use.
**/
public int[] getScanLineCopy(int[] b) {
if (b == null || b.length < scanline.length)
b = new int[scanline.length];
System.arraycopy(scanline, 0, b, 0, scanline.length);
return b;
}
/**
* Unpacks scanline (for bitdepth 1-2-4) into buffer.
* <p>
* You can (OPTIONALLY) pass an preallocated array to use.
* <p>
* If scale==TRUE scales the value (just a bit shift).
*/
public int[] tf_unpack(int[] buf, boolean scale) {
int len = scanline.length;
if (bitDepth == 1)
len *= 8;
else if (bitDepth == 2)
len *= 4;
else if (bitDepth == 4)
len *= 2;
if (buf == null)
buf = new int[len];
if (bitDepth >= 8)
System.arraycopy(scanline, 0, buf, 0, scanline.length);
else {
int mask, offset, v;
int mask0 = getMaskForPackedFormats();
int offset0 = 8 - bitDepth;
mask = mask0;
offset = offset0;
for (int i = 0, j = 0; i < len; i++) {
v = (scanline[j] & mask) >> offset;
if (scale)
v <<= offset0;
buf[i] = v;
mask = mask >> bitDepth;
offset -= bitDepth;
if (mask == 0) { // new byte in source
mask = mask0;
offset = offset0;
j++;
}
}
}
return buf;
}
/**
* Packs scanline (for bitdepth 1-2-4) from buffer.
* <p>
* If scale==TRUE scales the value (just a bit shift).
*/
public void tf_pack(int[] buf, boolean scale) { // writes scanline
int len = scanline.length;
if (bitDepth == 1)
len *= 8;
else if (bitDepth == 2)
len *= 4;
else if (bitDepth == 4)
len *= 2;
if (bitDepth >= 8)
System.arraycopy(buf, 0, scanline, 0, scanline.length);
else {
int offset0 = 8 - bitDepth;
int mask0 = getMaskForPackedFormats() >> offset0;
int offset, v;
offset = offset0;
Arrays.fill(scanline, 0);
for (int i = 0, j = 0; i < len; i++) {
v = buf[i];
if (scale)
v >>= offset0;
v = (v & mask0) << offset;
scanline[j] |= v;
offset -= bitDepth;
if (offset < 0) { // new byte in scanline
offset = offset0;
j++;
}
}
}
}
private int getMaskForPackedFormats() { // Utility function for pacj/unpack
if (bitDepth == 1)
return 0x80;
if (bitDepth == 2)
return 0xc0;
if (bitDepth == 4)
return 0xf0;
throw new RuntimeException("?");
}
public FilterType getFilterUsed() {
return filterUsed;
}
/**
* Basic info
*/
public String toString() {
return "row=" + rown + " cols=" + imgInfo.cols + " bpc=" + imgInfo.bitDepth + " size=" + scanline.length;
}
}
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