/*   頂点変形 ImageFilter  Ver 0.00   */
/*                                    */
/*                                    */
/*   by Atsushi              98/5/7   */


package net.antun.lib.awt.image;

import java.awt.Dimension;
import java.awt.image.ColorModel;


public class TransformationImageFilter extends SinglepassImageFilter
{
	/*   ---   Field   ---   */

	private int width,height;

	private int px0,py0,px1,py1,px2,py2,px3,py3;
	private int ox,oy;

	private int ax,ay,bx,by,cx,cy,dx,dy;

	/*   ---   Constructor   ---   */

	public TransformationImageFilter(int px0,int py0,int px1,int py1,
	                                 int px2,int py2,int px3,int py3)
	{
		this.px0=px0;this.py0=py0;
		this.px1=px1;this.py1=py1;
		this.px2=px2;this.py2=py2;
		this.px3=px3;this.py3=py3;
		
		ax=px0            ;ay=py0            ;
		bx=px1-px0        ;by=py1-py0        ;
		cx=px2-px0        ;cy=py2-py0        ;
		dx=px3-px1-px2+px0;dy=py3-py1-py2+py0;
	}

	/*   ---   フィルタリング   ---   */

	public void setDimensions(int width,int height)
	{
		int maxWidth,maxHeight;
	
		super.setDimensions(width,height);
		
		maxWidth =Math.max(Math.max(px0,px1),Math.max(px2,px3));
		maxHeight=Math.max(Math.max(py0,py1),Math.max(py2,py3));
		ox=-Math.min(Math.min(px0,px1),Math.min(px2,px3));
		oy=-Math.min(Math.min(py0,py1),Math.min(py2,py3));
		this.width =ox+maxWidth;
		this.height=oy+maxHeight;
		
		consumer.setDimensions(this.width,this.height);
	}

	protected void filterImage()
	{
		int xx,yy,p[];
		double a,b,c,u,v,nx,ny;
	
		p=new int[width];
		for (int y=0;y<=height-1;y++)
		{
			for (int x=0;x<=width-1;x++)
			{
				// x-ox=ax+bx*xx+cx*yy+dx*xx*yy
				// y-oy=ay+by*xx+cy*yy+dy*xx*yy
				a=dy*bx-dx*by;
				b=cy*bx+dy*ax-cx*by-dx*ay-dy*(x-ox)+dx*(y-oy);
				c=cy*ax-cx*ay-cy*(x-ox)+cx*(y-oy);
				if (a==0)
				{
					u=(-c)/b;
					v=(-c)/b;
				}
				else
				{
					u=(-b-Math.sqrt(b*b-4.0*a*c))/(2.0*a);
					v=(-b+Math.sqrt(b*b-4.0*a*c))/(2.0*a);
				}
				if (cx+dx*v==0.0 && cy+dy*v==0.0)
				{
					nx=u;
					if (cy+dy*u==0.0)
					{
						ny=((x-ox)-ax-bx*u)/(cx+dx*u);
					}
					else
					{
						ny=((y-oy)-ay-by*u)/(cy+dy*u);
					}
				}
				else
				{
					nx=v;
					if (cy+dy*v==0.0)
					{
						ny=((x-ox)-ax-bx*v)/(cx+dx*v);
					}
					else
					{
						ny=((y-oy)-ay-by*v)/(cy+dy*v);
					}
				}
				if (Double.isNaN(nx) || Double.isNaN(ny))
				{
					xx=-1;
					yy=-1;
				}
				else
				{
					xx=(int)(originalSize.width *nx);
					yy=(int)(originalSize.height*ny);
				}
				if (0<=xx && xx<=originalSize.width -1 &&
				    0<=yy && yy<=originalSize.height-1)
				{
					p[x]=original[xx+yy*originalSize.width];
				}
				else
				{
					p[x]=0;
				}
			}
			consumer.setPixels(0,y,width,1,defaultRGB,p,0,width);
		}
	}

	public void setHints(int hint)
	{
		consumer.setHints(TOPDOWNLEFTRIGHT | COMPLETESCANLINES |
		                  SINGLEPASS | (hint & SINGLEFRAME));
	}

	/*   ---   文字列化   ---   */

	public String toString()
	{
		StringBuffer param=new StringBuffer();
	
		param.append("point=");
		param.append("("+px0+","+py0+"),");
		param.append("("+px1+","+py1+"),");
		param.append("("+px2+","+py2+"),");
		param.append("("+px3+","+py3+")");
		return getClass().getName()+"["+param+"]";
	}
}