* prevent having to allocate a bit pixel array in the first place, but we would need a
* line-by-line iterator on the sample grid, which is currently not the case.
*/
int[][] rgba = new int[rows][cols * channels];
ByteArrayOutputStream baos = new ByteArrayOutputStream();
PngWriter pw = new PngWriter(baos, imgInfo);
pw.getMetadata().setText(PngChunkTextVar.KEY_Software, "OTPA");
pw.getMetadata().setText(PngChunkTextVar.KEY_Creation_Time, new Date().toString());
pw.getMetadata().setText(PngChunkTextVar.KEY_Description, "Sample grid bitmap");
String gridCornerStr = String.format(Locale.US, "%.8f,%.8f", sampleGrid.getCenter().y
+ sampleGrid.getYMin() * sampleGrid.getCellSize().y, sampleGrid.getCenter().x
+ sampleGrid.getXMin() * sampleGrid.getCellSize().x);
String gridCellSzStr = String.format(Locale.US, "%.12f,%.12f", sampleGrid.getCellSize().y,
sampleGrid.getCellSize().x);
String offRoadDistStr = String.format(Locale.US, "%f",
sampleGridRenderer.getOffRoadDistanceMeters(precisionMeters));
PngChunkTEXT gridCornerChunk = new PngChunkTEXT(imgInfo);
gridCornerChunk.setKeyVal(OTPA_GRID_CORNER, gridCornerStr);
pw.getChunksList().queue(gridCornerChunk);
PngChunkTEXT gridCellSzChunk = new PngChunkTEXT(imgInfo);
gridCellSzChunk.setKeyVal(OTPA_GRID_CELL_SIZE, gridCellSzStr);
pw.getChunksList().queue(gridCellSzChunk);
PngChunkTEXT offRoadDistChunk = new PngChunkTEXT(imgInfo);
offRoadDistChunk.setKeyVal(OTPA_OFFROAD_DIST, offRoadDistStr);
pw.getChunksList().queue(offRoadDistChunk);
double unit;
switch (zDataType) {
case TIME:
unit = 1.0; // 1:1sec, max 18h
break;
case BOARDINGS:
unit = 1000.0; // 1:0.001 boarding, max 65.5
break;
case WALK_DISTANCE:
unit = 10.0; // 1:0.1m, max 6.55km
break;
default:
throw new IllegalArgumentException("Unsupported Z DataType.");
}
for (ZSamplePoint<WTWD> p : sampleGrid) {
WTWD z = p.getZ();
int row = p.getY() - sampleGrid.getYMin();
int col = p.getX() - sampleGrid.getXMin();
double zz;
switch (zDataType) {
case TIME:
zz = z.wTime / z.w;
break;
case BOARDINGS:
zz = z.wBoardings / z.w;
break;
case WALK_DISTANCE:
zz = z.wWalkDist / z.w;
break;
default:
throw new IllegalArgumentException("Unsupported Z DataType.");
}
int iz;
if (Double.isInfinite(zz)) {
iz = 65535;
} else {
iz = ImageLineHelper.clampTo_0_65535((int) Math.round(zz * unit));
if (iz == 65535)
iz = 65534; // Clamp
}
// d is expressed as a percentage of grid size, max 255%.
// Sometimes d will be bigger than 2.55 x grid size,
// but this should not be too much important as we are off-bounds.
int id = ImageLineHelper.clampTo_0_255((int) Math.round(z.d / precisionMeters * 100));
int offset = col * channels;
rgba[row][offset + 0] = (iz & 0xFF); // z low 8 bits
rgba[row][offset + 1] = (iz >> 8); // z high 8 bits
rgba[row][offset + 2] = id; // d
/*
* Keep the alpha channel at 255, otherwise the RGB channel will be downsampled on some
* rendering clients (namely, JS canvas).
*/
rgba[row][offset + 3] = 255;
}
for (int row = 0; row < rgba.length; row++) {
ImageLineInt iline = new ImageLineInt(imgInfo, rgba[row]);
pw.writeRow(iline, row);
}
pw.end();
// Disallow caching on client side
CacheControl cc = new CacheControl();
cc.setNoCache(true);
// Also put the meta-data in the HTML header (easier to read from JS)