import java.awt.*;

public class MyGridLayout implements LayoutManager {

	/* I can't make this a subclass of java.awt.GridLayout (as I originally
	intended) because I have to have access to the fields of GridLayout, which are
	declared accessible only inside the same package. Therefore I would have to
	put this class into package java.awt, which causes a bunch of
	SecurityExceptions when trying to use it.

	Differences to java.awt.GridLayout:
	o makes hgaps and vgaps not only between the components, but also at the borders
	o can make hgaps and vgaps proportional to total width/height */

	int hgap;
	int vgap;
	int rows;
	int cols;
	float relhgap;
	float relvgap;

	public MyGridLayout(int rows, int cols, int hgap, int vgap) {
		if ((rows == 0) && (cols == 0)) {
			throw new IllegalArgumentException("rows and cols cannot both be zero");
		}
		this.rows = rows;
		this.cols = cols;
		this.hgap = hgap;
		this.vgap = vgap;
		this.relhgap = 0;
		this.relvgap = 0;
	}

	public MyGridLayout(int rows, int cols, float relhgap, float relvgap, int minhgap, int minvgap) {
		this.rows = rows;
		this.cols = cols;
		this.hgap = minhgap;
		this.vgap = minvgap;
		this.relhgap = relhgap;
		this.relvgap = relvgap;
	}
	
	public MyGridLayout(int rows, int cols, float relhgap, float relvgap) {
		this(rows, cols, relhgap, relvgap, 0, 0);
	}
	
	public MyGridLayout() {
		this(1, 0, 0, 0);
	}
	
	public MyGridLayout(int rows, int cols) {
		this(rows, cols, 0, 0);
	}
	
	public int getRows() {
		return rows;
	}
	
	public void setRows(int rows) {
		if ((rows == 0) && (this.cols == 0)) {
			throw new IllegalArgumentException("rows and cols cannot both be zero");
		}
		this.rows = rows;
	}
	
	public int getColumns() {
		return cols;
	}
	
	public void setColumns(int cols) {
		if ((cols == 0) && (this.rows == 0)) {
			throw new IllegalArgumentException("rows and cols cannot both be zero");
		}
		this.cols = cols;
	}
	
	public int getHgap() {
		return hgap;
	}
	
	public float getRelHgap() {
		return relhgap;
	}
	
	public void setHgap(int hgap) {
		this.hgap = hgap;
	}
	
	public void setHgap(float relhgap) {
		this.relhgap = relhgap;
	}
	
	public int getVgap() {
		return vgap;
	}
	
	public float getRelVgap() {
		return relvgap;
	}
	
	public void setVgap(int vgap) {
		this.vgap = vgap;
	}
	
	public void setVgap(float relvgap) {
		this.relvgap = relvgap;
	}
	
	public void addLayoutComponent(String name, Component comp) {
	}
	
	public void removeLayoutComponent(Component comp) {
	}
	
	public Dimension preferredLayoutSize(Container parent) {
		Insets insets = parent.getInsets();
		int ncomponents = parent.getComponentCount();
		int nrows = rows;
		int ncols = cols;

		if (nrows > 0) {
			ncols = (ncomponents + nrows - 1) / nrows;
		} else {
			nrows = (ncomponents + ncols - 1) / ncols;
		}
		int w = 0;
		int h = 0;
		for (int i = 0 ; i < ncomponents ; i++) {
			Component comp = parent.getComponent(i);
			Dimension d = comp.getPreferredSize();
			if (w < d.width) {
				w = d.width;
			}
			if (h < d.height) {
				h = d.height;
			}
		}
		int hgap = this.hgap;
		int vgap = this.vgap;
		if (relhgap != 0) hgap = Math.round(relhgap*ncols*w/(1-relhgap*(ncols+1)));
		if (relvgap != 0) vgap = Math.round(relvgap*nrows*h/(1-relvgap*(nrows+1)));
		return new Dimension(insets.left + insets.right + ncols*w + (ncols+1)*hgap, insets.top + insets.bottom + nrows*h + (nrows+1)*vgap);
	}
	
	public Dimension minimumLayoutSize(Container parent) {
		Insets insets = parent.getInsets();
		int ncomponents = parent.getComponentCount();
		int nrows = rows;
		int ncols = cols;

		if (nrows > 0) {
			ncols = (ncomponents + nrows - 1) / nrows;
		} else {
			nrows = (ncomponents + ncols - 1) / ncols;
		}
		int w = 0;
		int h = 0;
		for (int i = 0 ; i < ncomponents ; i++) {
			Component comp = parent.getComponent(i);
			Dimension d = comp.getMinimumSize();
			if (w < d.width) {
				w = d.width;
			}
			if (h < d.height) {
				h = d.height;
			}
		}
		int hgap = this.hgap;
		int vgap = this.vgap;
		if (relhgap != 0) hgap = Math.round(relhgap*ncols*w/(1-relhgap*(ncols+1)));
		if (relvgap != 0) vgap = Math.round(relvgap*nrows*h/(1-relvgap*(nrows+1)));
		return new Dimension(insets.left + insets.right + ncols*w + (ncols+1)*hgap, insets.top + insets.bottom + nrows*h + (nrows+1)*vgap);
	}
	
	public void layoutContainer(Container parent) {
		Insets insets = parent.getInsets();
		int ncomponents = parent.getComponentCount();
		int nrows = rows;
		int ncols = cols;

		if (ncomponents == 0) {
			return;
		}
		if (nrows > 0) {
			ncols = (ncomponents + nrows - 1) / nrows;
		} else {
			nrows = (ncomponents + ncols - 1) / ncols;
		}
		int w = parent.getSize().width - (insets.left + insets.right);
		int h = parent.getSize().height - (insets.top + insets.bottom);
		int minhgap = hgap;
		int hgap = Math.round(relhgap*w);
		if (hgap < minhgap) hgap = minhgap;
		int minvgap = vgap;
		int vgap = Math.round(relvgap*h);
		if (vgap < minvgap) vgap = minvgap;
		w = (w - (ncols + 1) * hgap) / ncols;
		h = (h - (nrows + 1) * vgap) / nrows;

		for (int c = 0, x = insets.left + hgap ; c < ncols ; c++, x += w + hgap) {
			for (int r = 0, y = insets.top + vgap ; r < nrows ; r++, y += h + vgap) {
				int i = r * ncols + c;
				if (i < ncomponents) {
					parent.getComponent(i).setBounds(x, y, w, h);
				}
			}
		}
	}
	
	public String toString() {
		return getClass().getName() + "[hgap=" + hgap + ",vgap=" + vgap + ",relhgap=" + relhgap + ",relvgap=" + relvgap + ",rows=" + rows + ",cols=" + cols + "]";
	}
	
}