worldsave.cpp

/*
   Copyright (c) 2013, Sean Kasun
   All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright notice, this
 list of conditions and the following disclaimer.

 * Redistributions in binary form must reproduce the above copyright notice,
 this list of conditions and the following disclaimer in the documentation
 and/or other materials provided with the distribution.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 Saves the world to PNG.  It doesn't use stock PNG code because
 the resulting image might be too large to fit into RAM.  Therefore,
 it uses a custom PNG generator that will handle *huge* worlds, but
 make less-than-optimal PNGs.
 */

#include "worldsave.h"
#include "mapview.h"
#include <zlib.h>

WorldSave::WorldSave(QString filename,MapView *map)
{
	this->filename=filename;
	this->map=map;
}
WorldSave::~WorldSave()
{
}

static inline void w32(char *p,quint32 v)
{
	*p++=v>>24;
	*p++=(v>>16)&0xff;
	*p++=(v>>8)&0xff;
	*p++=v&0xff;
}

static void writeChunk(QFile &f,const char *tag,const char *data,int len)
{
	char dword[4];
	w32(dword,len);
	f.write(dword,4);
	f.write(tag,4);
	if (len!=0)
		f.write(data,len);
	quint32 crc=crc32(0,Z_NULL,0);
	crc=crc32(crc,(const Bytef *)tag,4);
	if (len!=0)
		crc=crc32(crc,(const Bytef *)data,len);
	w32(dword,crc);
	f.write(dword,4);
}

void WorldSave::run()
{
	emit progress(tr("Calculating world bounds"),0.0);
	QString path=map->getWorldPath();

	int top,left,right,bottom;
	findBounds(path,&top,&left,&bottom,&right);

	int width=(right+1-left)*16;
	int height=(bottom+1-top)*16;

	QFile png(filename);
	png.open(QIODevice::WriteOnly);

	//output PNG signature
	const char *sig="\x89PNG\x0d\x0a\x1a\x0a";
	png.write(sig,8);
	//output PNG header
	const char *ihdrdata="\x00\x00\x00\x00" //width
			"\x00\x00\x00\x00" //height
			"\x08" //bit depth
			"\x06" //color type (rgba)
			"\x00" //compresion method (deflate)
			"\x00" //filter method (standard)
			"\x00"; //interlace method (none)
	char ihdr[13];
	memcpy(ihdr,ihdrdata,13);
	w32(ihdr,width);
	w32(ihdr+4,height);
	writeChunk(png,"IHDR",ihdr,13);

	int insize=width*16*4+16;
	int outsize=insize*2;

	uchar *scanlines=new uchar[insize];
	for (int i=0;i<16;i++) //set scanline filters to off
		scanlines[i*(width*4+1)]=0;

	uchar *compressed=new uchar[outsize];
	z_stream strm;
	strm.zalloc=Z_NULL;
	strm.zfree=Z_NULL;
	strm.opaque=Z_NULL;
	deflateInit2(&strm,6,Z_DEFLATED,15,8,Z_DEFAULT_STRATEGY);

	double maximum=(bottom+1-top)*(right+1-left);
	double step=0.0;
	for (int z=top;z<=bottom;z++)
	{
		for (int x=left;x<=right;x++,step+=1.0)
		{
			emit progress(tr("Rendering world"),step/maximum);
			int rx=x>>5;
			int rz=z>>5;
			QFile f(path+"/region/r."+QString::number(rx)+"."+QString::number(rz)+".mca");
			if (!f.open(QIODevice::ReadOnly))
			{
				blankChunk(scanlines,width*4+1,x-left);
				continue;
			}
			uchar *header=f.map(0,4096);
			int offset=4*((x&31)+(z&31)*32);
			int coffset=(header[offset]<<16)|(header[offset+1]<<8)|header[offset+2];
			int numSectors=header[offset+3];
			f.unmap(header);
			if (coffset==0) //no chunk here
				blankChunk(scanlines,width*4+1,x-left);
			else
			{
				uchar *raw=f.map(coffset*4096,numSectors*4096);
				NBT nbt(raw);
				Chunk *chunk=new Chunk();
				chunk->load(nbt);
				f.unmap(raw);
				drawChunk(scanlines,width*4+1,x-left,chunk);
				delete chunk;
			}
			f.close();
		}
		//write out scanlines to disk
		strm.avail_in=insize;
		strm.next_in=scanlines;
		do {
			strm.avail_out=outsize;
			strm.next_out=compressed;
			deflate(&strm,(z==bottom)?Z_FINISH:Z_NO_FLUSH);
			writeChunk(png,"IDAT",(const char *)compressed,outsize-strm.avail_out);
		} while (strm.avail_out==0);
	}
	deflateEnd(&strm);
	delete [] scanlines;
	delete [] compressed;

	writeChunk(png,"IEND",NULL,0);
	png.close();
	emit finished();
}


typedef struct {
	int x,z;
} ChunkPos;

//helper functions for the findBounds function

static bool outside(int side,ChunkPos &edge,ChunkPos &p)
{
	switch (side)
	{
	case 0: //top
		return edge.z>p.z;
	case 1: //left
		return edge.x>p.x;
	case 2: //bottom
		return edge.z<p.z;
	default: //right
		return edge.x<p.x;
	}
}
static bool onside(int side,ChunkPos &edge,ChunkPos &p)
{
	switch (side)
	{
	case 0: //top or bottom
	case 2:
		return edge.z==p.z;
	default: //left or right
		return edge.x==p.x;
	}
}


/*
 This routine loops through all the region filenames and constructs a list
 of regions that lie along the edges of the map.  Then it loops through
 those region headers and finds the furthest chunks.  The end result is
 the boundary chunks for the entire world.

 Because we only check at the chunk level, there could be up to 15 pixels
 of padding around the edge of the final image.  However, if we just
 went by regions, there could be 511 pixels of padding.
 */
void WorldSave::findBounds(QString path, int *top, int *left, int *bottom, int *right)
{
	QStringList filters;
	filters<<"*.mca";

	QDirIterator it(path+"/region",filters);
	QList<ChunkPos> edges[4];
	ChunkPos cur;
	bool hasOne=false;

	//loop through all region files and find the extremes
	while (it.hasNext())
	{
		QString fn=it.next();
		int pos=fn.length()-5;
		ushort c;
		//figure out the x/z of the region
		for (int i=0;i<2;i++)
		{
			int p=0;
			int scale=1;
			while (pos>0 && (c=fn.at(pos).unicode())!='.')
			{
				if (c=='-')
					p=-p;
				else
					p+=(c-'0')*scale;
				pos--;
				scale*=10;
			}
			pos--;
			if (i==0) cur.z=p;
			else cur.x=p;
		}
		if (!hasOne)
		{
			for (int e=0;e<4;e++)
				edges[e].append(cur);
			hasOne=true;
		}
		for (int e=0;e<4;e++)
			if (outside(e,edges[e].front(),cur))
			{
				edges[e].clear();
				edges[e].append(cur);
			}
			else if (onside(e,edges[e].front(),cur))
				edges[e].append(cur);
	}
	//find image bounds
	int minz=32,maxz=0,minx=32,maxx=0;
	for (int e=0;e<4;e++)
	{
		for (int i=0;i<edges[e].length();i++)
		{
			QFile f(path+"/region/r."+
					QString::number(edges[e].at(i).x)+
					"."+QString::number(edges[e].at(i).z)+".mca");
			f.open(QIODevice::ReadOnly);
			uchar *header=f.map(0,4096);
			//loop through all chunk headers.
			for (int offset=0;offset<4096;offset+=4)
			{
				int coffset=(header[offset]<<16)|(header[offset+1]<<8)|header[offset+2];
				if (coffset!=0)
				{
					switch (e)
					{
					case 0: //smallest Z
						if (minz>offset/128) minz=offset/128;
						break;
					case 1: //smallest X
						if (minx>(offset&127)/4) minx=(offset&127)/4;
						break;
					case 2: //largest Z
						if (maxz<offset/128) maxz=offset/128;
						break;
					case 3: //largest X
						if (maxx<(offset&127)/4) maxx=(offset&127)/4;
						break;
					}
				}
			}
			f.unmap(header);
			f.close();
		}
	}
	*top=(edges[0].front().z*32)+minz;
	*left=(edges[1].front().x*32)+minx;
	*bottom=(edges[2].front().z*32)+maxz;
	*right=(edges[3].front().x*32)+maxx;
}

// sets chunk to transparent
void WorldSave::blankChunk(uchar *scanlines, int stride, int x)
{
	int offset=x*16*4+1;
	for (int y=0;y<16;y++,offset+=stride)
		memset(scanlines+offset,0,16*4);
}
void WorldSave::drawChunk(uchar *scanlines, int stride, int x, Chunk *chunk)
{
	//render chunk with current settings
	map->renderChunk(chunk);
	//we can't memcpy each scanline because it's in BGRA format.
	int offset=x*16*4+1;
	int ioffset=0;
	for (int y=0;y<16;y++,offset+=stride)
	{
		int xofs=offset;
		for (int x=0;x<16;x++,xofs+=4)
		{
			scanlines[xofs+2]=chunk->image[ioffset++];
			scanlines[xofs+1]=chunk->image[ioffset++];
			scanlines[xofs+0]=chunk->image[ioffset++];
			scanlines[xofs+3]=chunk->image[ioffset++];
		}
	}
}