Java example source code file (Renderer.java)
The Renderer.java Java example source code
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* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
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package sun.java2d.pisces;
import sun.awt.geom.PathConsumer2D;
final class Renderer implements PathConsumer2D {
private class ScanlineIterator {
private int[] crossings;
// crossing bounds. The bounds are not necessarily tight (the scan line
// at minY, for example, might have no crossings). The x bounds will
// be accumulated as crossings are computed.
private final int maxY;
private int nextY;
// indices into the segment pointer lists. They indicate the "active"
// sublist in the segment lists (the portion of the list that contains
// all the segments that cross the next scan line).
private int edgeCount;
private int[] edgePtrs;
private static final int INIT_CROSSINGS_SIZE = 10;
// Preconditions: Only subpixel scanlines in the range
// (start <= subpixel_y <= end) will be evaluated. No
// edge may have a valid (i.e. inside the supplied clip)
// crossing that would be generated outside that range.
private ScanlineIterator(int start, int end) {
crossings = new int[INIT_CROSSINGS_SIZE];
edgePtrs = new int[INIT_CROSSINGS_SIZE];
nextY = start;
maxY = end;
edgeCount = 0;
}
private int next() {
int cury = nextY++;
int bucket = cury - boundsMinY;
int count = this.edgeCount;
int ptrs[] = this.edgePtrs;
int bucketcount = edgeBucketCounts[bucket];
if ((bucketcount & 0x1) != 0) {
int newCount = 0;
for (int i = 0; i < count; i++) {
int ecur = ptrs[i];
if (edges[ecur+YMAX] > cury) {
ptrs[newCount++] = ecur;
}
}
count = newCount;
}
ptrs = Helpers.widenArray(ptrs, count, bucketcount >> 1);
for (int ecur = edgeBuckets[bucket]; ecur != NULL; ecur = (int)edges[ecur+NEXT]) {
ptrs[count++] = ecur;
// REMIND: Adjust start Y if necessary
}
this.edgePtrs = ptrs;
this.edgeCount = count;
// if ((count & 0x1) != 0) {
// System.out.println("ODD NUMBER OF EDGES!!!!");
// }
int xings[] = this.crossings;
if (xings.length < count) {
this.crossings = xings = new int[ptrs.length];
}
for (int i = 0; i < count; i++) {
int ecur = ptrs[i];
float curx = edges[ecur+CURX];
int cross = ((int) curx) << 1;
edges[ecur+CURX] = curx + edges[ecur+SLOPE];
if (edges[ecur+OR] > 0) {
cross |= 1;
}
int j = i;
while (--j >= 0) {
int jcross = xings[j];
if (jcross <= cross) {
break;
}
xings[j+1] = jcross;
ptrs[j+1] = ptrs[j];
}
xings[j+1] = cross;
ptrs[j+1] = ecur;
}
return count;
}
private boolean hasNext() {
return nextY < maxY;
}
private int curY() {
return nextY - 1;
}
}
//////////////////////////////////////////////////////////////////////////////
// EDGE LIST
//////////////////////////////////////////////////////////////////////////////
// TODO(maybe): very tempting to use fixed point here. A lot of opportunities
// for shifts and just removing certain operations altogether.
// common to all types of input path segments.
private static final int YMAX = 0;
private static final int CURX = 1;
// NEXT and OR are meant to be indices into "int" fields, but arrays must
// be homogenous, so every field is a float. However floats can represent
// exactly up to 26 bit ints, so we're ok.
private static final int OR = 2;
private static final int SLOPE = 3;
private static final int NEXT = 4;
private float edgeMinY = Float.POSITIVE_INFINITY;
private float edgeMaxY = Float.NEGATIVE_INFINITY;
private float edgeMinX = Float.POSITIVE_INFINITY;
private float edgeMaxX = Float.NEGATIVE_INFINITY;
private static final int SIZEOF_EDGE = 5;
// don't just set NULL to -1, because we want NULL+NEXT to be negative.
private static final int NULL = -SIZEOF_EDGE;
private float[] edges = null;
private static final int INIT_NUM_EDGES = 8;
private int[] edgeBuckets = null;
private int[] edgeBucketCounts = null; // 2*newedges + (1 if pruning needed)
private int numEdges;
private static final float DEC_BND = 20f;
private static final float INC_BND = 8f;
// each bucket is a linked list. this method adds eptr to the
// start of the "bucket"th linked list.
private void addEdgeToBucket(final int eptr, final int bucket) {
edges[eptr+NEXT] = edgeBuckets[bucket];
edgeBuckets[bucket] = eptr;
edgeBucketCounts[bucket] += 2;
}
// Flattens using adaptive forward differencing. This only carries out
// one iteration of the AFD loop. All it does is update AFD variables (i.e.
// X0, Y0, D*[X|Y], COUNT; not variables used for computing scanline crossings).
private void quadBreakIntoLinesAndAdd(float x0, float y0,
final Curve c,
final float x2, final float y2)
{
final float QUAD_DEC_BND = 32;
final int countlg = 4;
int count = 1 << countlg;
int countsq = count * count;
float maxDD = Math.max(c.dbx / countsq, c.dby / countsq);
while (maxDD > QUAD_DEC_BND) {
maxDD /= 4;
count <<= 1;
}
countsq = count * count;
final float ddx = c.dbx / countsq;
final float ddy = c.dby / countsq;
float dx = c.bx / countsq + c.cx / count;
float dy = c.by / countsq + c.cy / count;
while (count-- > 1) {
float x1 = x0 + dx;
dx += ddx;
float y1 = y0 + dy;
dy += ddy;
addLine(x0, y0, x1, y1);
x0 = x1;
y0 = y1;
}
addLine(x0, y0, x2, y2);
}
// x0, y0 and x3,y3 are the endpoints of the curve. We could compute these
// using c.xat(0),c.yat(0) and c.xat(1),c.yat(1), but this might introduce
// numerical errors, and our callers already have the exact values.
// Another alternative would be to pass all the control points, and call c.set
// here, but then too many numbers are passed around.
private void curveBreakIntoLinesAndAdd(float x0, float y0,
final Curve c,
final float x3, final float y3)
{
final int countlg = 3;
int count = 1 << countlg;
// the dx and dy refer to forward differencing variables, not the last
// coefficients of the "points" polynomial
float dddx, dddy, ddx, ddy, dx, dy;
dddx = 2f * c.dax / (1 << (3 * countlg));
dddy = 2f * c.day / (1 << (3 * countlg));
ddx = dddx + c.dbx / (1 << (2 * countlg));
ddy = dddy + c.dby / (1 << (2 * countlg));
dx = c.ax / (1 << (3 * countlg)) + c.bx / (1 << (2 * countlg)) + c.cx / (1 << countlg);
dy = c.ay / (1 << (3 * countlg)) + c.by / (1 << (2 * countlg)) + c.cy / (1 << countlg);
// we use x0, y0 to walk the line
float x1 = x0, y1 = y0;
while (count > 0) {
while (Math.abs(ddx) > DEC_BND || Math.abs(ddy) > DEC_BND) {
dddx /= 8;
dddy /= 8;
ddx = ddx/4 - dddx;
ddy = ddy/4 - dddy;
dx = (dx - ddx) / 2;
dy = (dy - ddy) / 2;
count <<= 1;
}
// can only do this on even "count" values, because we must divide count by 2
while (count % 2 == 0 && Math.abs(dx) <= INC_BND && Math.abs(dy) <= INC_BND) {
dx = 2 * dx + ddx;
dy = 2 * dy + ddy;
ddx = 4 * (ddx + dddx);
ddy = 4 * (ddy + dddy);
dddx = 8 * dddx;
dddy = 8 * dddy;
count >>= 1;
}
count--;
if (count > 0) {
x1 += dx;
dx += ddx;
ddx += dddx;
y1 += dy;
dy += ddy;
ddy += dddy;
} else {
x1 = x3;
y1 = y3;
}
addLine(x0, y0, x1, y1);
x0 = x1;
y0 = y1;
}
}
private void addLine(float x1, float y1, float x2, float y2) {
float or = 1; // orientation of the line. 1 if y increases, 0 otherwise.
if (y2 < y1) {
or = y2; // no need to declare a temp variable. We have or.
y2 = y1;
y1 = or;
or = x2;
x2 = x1;
x1 = or;
or = 0;
}
final int firstCrossing = Math.max((int)Math.ceil(y1), boundsMinY);
final int lastCrossing = Math.min((int)Math.ceil(y2), boundsMaxY);
if (firstCrossing >= lastCrossing) {
return;
}
if (y1 < edgeMinY) { edgeMinY = y1; }
if (y2 > edgeMaxY) { edgeMaxY = y2; }
final float slope = (x2 - x1) / (y2 - y1);
if (slope > 0) { // <==> x1 < x2
if (x1 < edgeMinX) { edgeMinX = x1; }
if (x2 > edgeMaxX) { edgeMaxX = x2; }
} else {
if (x2 < edgeMinX) { edgeMinX = x2; }
if (x1 > edgeMaxX) { edgeMaxX = x1; }
}
final int ptr = numEdges * SIZEOF_EDGE;
edges = Helpers.widenArray(edges, ptr, SIZEOF_EDGE);
numEdges++;
edges[ptr+OR] = or;
edges[ptr+CURX] = x1 + (firstCrossing - y1) * slope;
edges[ptr+SLOPE] = slope;
edges[ptr+YMAX] = lastCrossing;
final int bucketIdx = firstCrossing - boundsMinY;
addEdgeToBucket(ptr, bucketIdx);
edgeBucketCounts[lastCrossing - boundsMinY] |= 1;
}
// END EDGE LIST
//////////////////////////////////////////////////////////////////////////////
public static final int WIND_EVEN_ODD = 0;
public static final int WIND_NON_ZERO = 1;
// Antialiasing
final private int SUBPIXEL_LG_POSITIONS_X;
final private int SUBPIXEL_LG_POSITIONS_Y;
final private int SUBPIXEL_POSITIONS_X;
final private int SUBPIXEL_POSITIONS_Y;
final private int SUBPIXEL_MASK_X;
final private int SUBPIXEL_MASK_Y;
final int MAX_AA_ALPHA;
// Cache to store RLE-encoded coverage mask of the current primitive
PiscesCache cache;
// Bounds of the drawing region, at subpixel precision.
private final int boundsMinX, boundsMinY, boundsMaxX, boundsMaxY;
// Current winding rule
private final int windingRule;
// Current drawing position, i.e., final point of last segment
private float x0, y0;
// Position of most recent 'moveTo' command
private float pix_sx0, pix_sy0;
public Renderer(int subpixelLgPositionsX, int subpixelLgPositionsY,
int pix_boundsX, int pix_boundsY,
int pix_boundsWidth, int pix_boundsHeight,
int windingRule)
{
this.SUBPIXEL_LG_POSITIONS_X = subpixelLgPositionsX;
this.SUBPIXEL_LG_POSITIONS_Y = subpixelLgPositionsY;
this.SUBPIXEL_MASK_X = (1 << (SUBPIXEL_LG_POSITIONS_X)) - 1;
this.SUBPIXEL_MASK_Y = (1 << (SUBPIXEL_LG_POSITIONS_Y)) - 1;
this.SUBPIXEL_POSITIONS_X = 1 << (SUBPIXEL_LG_POSITIONS_X);
this.SUBPIXEL_POSITIONS_Y = 1 << (SUBPIXEL_LG_POSITIONS_Y);
this.MAX_AA_ALPHA = (SUBPIXEL_POSITIONS_X * SUBPIXEL_POSITIONS_Y);
this.windingRule = windingRule;
this.boundsMinX = pix_boundsX * SUBPIXEL_POSITIONS_X;
this.boundsMinY = pix_boundsY * SUBPIXEL_POSITIONS_Y;
this.boundsMaxX = (pix_boundsX + pix_boundsWidth) * SUBPIXEL_POSITIONS_X;
this.boundsMaxY = (pix_boundsY + pix_boundsHeight) * SUBPIXEL_POSITIONS_Y;
edges = new float[INIT_NUM_EDGES * SIZEOF_EDGE];
numEdges = 0;
edgeBuckets = new int[boundsMaxY - boundsMinY];
java.util.Arrays.fill(edgeBuckets, NULL);
edgeBucketCounts = new int[edgeBuckets.length + 1];
}
private float tosubpixx(float pix_x) {
return pix_x * SUBPIXEL_POSITIONS_X;
}
private float tosubpixy(float pix_y) {
return pix_y * SUBPIXEL_POSITIONS_Y;
}
public void moveTo(float pix_x0, float pix_y0) {
closePath();
this.pix_sx0 = pix_x0;
this.pix_sy0 = pix_y0;
this.y0 = tosubpixy(pix_y0);
this.x0 = tosubpixx(pix_x0);
}
public void lineTo(float pix_x1, float pix_y1) {
float x1 = tosubpixx(pix_x1);
float y1 = tosubpixy(pix_y1);
addLine(x0, y0, x1, y1);
x0 = x1;
y0 = y1;
}
private Curve c = new Curve();
@Override public void curveTo(float x1, float y1,
float x2, float y2,
float x3, float y3)
{
final float xe = tosubpixx(x3);
final float ye = tosubpixy(y3);
c.set(x0, y0, tosubpixx(x1), tosubpixy(y1), tosubpixx(x2), tosubpixy(y2), xe, ye);
curveBreakIntoLinesAndAdd(x0, y0, c, xe, ye);
x0 = xe;
y0 = ye;
}
@Override public void quadTo(float x1, float y1, float x2, float y2) {
final float xe = tosubpixx(x2);
final float ye = tosubpixy(y2);
c.set(x0, y0, tosubpixx(x1), tosubpixy(y1), xe, ye);
quadBreakIntoLinesAndAdd(x0, y0, c, xe, ye);
x0 = xe;
y0 = ye;
}
public void closePath() {
// lineTo expects its input in pixel coordinates.
lineTo(pix_sx0, pix_sy0);
}
public void pathDone() {
closePath();
}
@Override
public long getNativeConsumer() {
throw new InternalError("Renderer does not use a native consumer.");
}
private void _endRendering(final int pix_bboxx0, final int pix_bboxx1,
int ymin, int ymax)
{
// Mask to determine the relevant bit of the crossing sum
// 0x1 if EVEN_ODD, all bits if NON_ZERO
int mask = (windingRule == WIND_EVEN_ODD) ? 0x1 : ~0x0;
// add 2 to better deal with the last pixel in a pixel row.
int width = pix_bboxx1 - pix_bboxx0;
int[] alpha = new int[width+2];
int bboxx0 = pix_bboxx0 << SUBPIXEL_LG_POSITIONS_X;
int bboxx1 = pix_bboxx1 << SUBPIXEL_LG_POSITIONS_X;
// Now we iterate through the scanlines. We must tell emitRow the coord
// of the first non-transparent pixel, so we must keep accumulators for
// the first and last pixels of the section of the current pixel row
// that we will emit.
// We also need to accumulate pix_bbox*, but the iterator does it
// for us. We will just get the values from it once this loop is done
int pix_maxX = Integer.MIN_VALUE;
int pix_minX = Integer.MAX_VALUE;
int y = boundsMinY; // needs to be declared here so we emit the last row properly.
ScanlineIterator it = this.new ScanlineIterator(ymin, ymax);
for ( ; it.hasNext(); ) {
int numCrossings = it.next();
int[] crossings = it.crossings;
y = it.curY();
if (numCrossings > 0) {
int lowx = crossings[0] >> 1;
int highx = crossings[numCrossings - 1] >> 1;
int x0 = Math.max(lowx, bboxx0);
int x1 = Math.min(highx, bboxx1);
pix_minX = Math.min(pix_minX, x0 >> SUBPIXEL_LG_POSITIONS_X);
pix_maxX = Math.max(pix_maxX, x1 >> SUBPIXEL_LG_POSITIONS_X);
}
int sum = 0;
int prev = bboxx0;
for (int i = 0; i < numCrossings; i++) {
int curxo = crossings[i];
int curx = curxo >> 1;
// to turn {0, 1} into {-1, 1}, multiply by 2 and subtract 1.
int crorientation = ((curxo & 0x1) << 1) - 1;
if ((sum & mask) != 0) {
int x0 = Math.max(prev, bboxx0);
int x1 = Math.min(curx, bboxx1);
if (x0 < x1) {
x0 -= bboxx0; // turn x0, x1 from coords to indeces
x1 -= bboxx0; // in the alpha array.
int pix_x = x0 >> SUBPIXEL_LG_POSITIONS_X;
int pix_xmaxm1 = (x1 - 1) >> SUBPIXEL_LG_POSITIONS_X;
if (pix_x == pix_xmaxm1) {
// Start and end in same pixel
alpha[pix_x] += (x1 - x0);
alpha[pix_x+1] -= (x1 - x0);
} else {
int pix_xmax = x1 >> SUBPIXEL_LG_POSITIONS_X;
alpha[pix_x] += SUBPIXEL_POSITIONS_X - (x0 & SUBPIXEL_MASK_X);
alpha[pix_x+1] += (x0 & SUBPIXEL_MASK_X);
alpha[pix_xmax] -= SUBPIXEL_POSITIONS_X - (x1 & SUBPIXEL_MASK_X);
alpha[pix_xmax+1] -= (x1 & SUBPIXEL_MASK_X);
}
}
}
sum += crorientation;
prev = curx;
}
// even if this last row had no crossings, alpha will be zeroed
// from the last emitRow call. But this doesn't matter because
// maxX < minX, so no row will be emitted to the cache.
if ((y & SUBPIXEL_MASK_Y) == SUBPIXEL_MASK_Y) {
emitRow(alpha, y >> SUBPIXEL_LG_POSITIONS_Y, pix_minX, pix_maxX);
pix_minX = Integer.MAX_VALUE;
pix_maxX = Integer.MIN_VALUE;
}
}
// Emit final row
if (pix_maxX >= pix_minX) {
emitRow(alpha, y >> SUBPIXEL_LG_POSITIONS_Y, pix_minX, pix_maxX);
}
}
public void endRendering() {
int spminX = Math.max((int)Math.ceil(edgeMinX), boundsMinX);
int spmaxX = Math.min((int)Math.ceil(edgeMaxX), boundsMaxX);
int spminY = Math.max((int)Math.ceil(edgeMinY), boundsMinY);
int spmaxY = Math.min((int)Math.ceil(edgeMaxY), boundsMaxY);
int pminX = spminX >> SUBPIXEL_LG_POSITIONS_X;
int pmaxX = (spmaxX + SUBPIXEL_MASK_X) >> SUBPIXEL_LG_POSITIONS_X;
int pminY = spminY >> SUBPIXEL_LG_POSITIONS_Y;
int pmaxY = (spmaxY + SUBPIXEL_MASK_Y) >> SUBPIXEL_LG_POSITIONS_Y;
if (pminX > pmaxX || pminY > pmaxY) {
this.cache = new PiscesCache(boundsMinX >> SUBPIXEL_LG_POSITIONS_X,
boundsMinY >> SUBPIXEL_LG_POSITIONS_Y,
boundsMaxX >> SUBPIXEL_LG_POSITIONS_X,
boundsMaxY >> SUBPIXEL_LG_POSITIONS_Y);
return;
}
this.cache = new PiscesCache(pminX, pminY, pmaxX, pmaxY);
_endRendering(pminX, pmaxX, spminY, spmaxY);
}
public PiscesCache getCache() {
if (cache == null) {
throw new InternalError("cache not yet initialized");
}
return cache;
}
private void emitRow(int[] alphaRow, int pix_y, int pix_from, int pix_to) {
// Copy rowAA data into the cache if one is present
if (cache != null) {
if (pix_to >= pix_from) {
cache.startRow(pix_y, pix_from);
// Perform run-length encoding and store results in the cache
int from = pix_from - cache.bboxX0;
int to = pix_to - cache.bboxX0;
int runLen = 1;
int startVal = alphaRow[from];
for (int i = from + 1; i <= to; i++) {
int nextVal = startVal + alphaRow[i];
if (nextVal == startVal) {
runLen++;
} else {
cache.addRLERun(startVal, runLen);
runLen = 1;
startVal = nextVal;
}
}
cache.addRLERun(startVal, runLen);
}
}
java.util.Arrays.fill(alphaRow, 0);
}
}
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