/*
Copyright 2003-2012 Dmitry Barashev, GanttProject Team

This file is part of GanttProject, an opensource project management tool.

GanttProject is free software: you can redistribute it and/or modify 
it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

GanttProject is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GanttProject.  If not, see <http://www.gnu.org/licenses/>.
 */
package biz.ganttproject.core.chart.render;

import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.font.FontRenderContext;
import java.awt.font.TextLayout;
import java.awt.geom.Rectangle2D;

import biz.ganttproject.core.chart.canvas.TextMetrics;

/**
 * Contains methods to calculate the text length
 * 
 * @author bard
 */
public class TextLengthCalculatorImpl implements TextMetrics {
  private Graphics2D myGraphics;

  private State myState;

  public TextLengthCalculatorImpl(Graphics2D g) {
    setGraphics(g);
  }

  public void setGraphics(Graphics2D g) {
    myGraphics = g;
    myState = null;
  }

  /** @return the length of text for the given g */
  public static int getTextLength(Graphics2D g, String text) {
    if (text.length() == 0) {
      return 0;
    }
    FontRenderContext frc = g.getFontRenderContext();
    Font font = g.getFont();
    TextLayout layout = new TextLayout(text, font, frc);
    Rectangle2D bounds = layout.getBounds();
    return (int) bounds.getWidth() + 1;
  }

  public int getTextHeight(Font f, String s) {
    Font existing = myGraphics.getFont();
    myGraphics.setFont(f);
    int result = getTextHeight(s);
    myGraphics.setFont(existing);
    return result;
  }

  @Override
  public int getTextHeight(String text) {
    return (int) myGraphics.getFontMetrics().getLineMetrics(text, myGraphics).getHeight();
  }

  @Override
  public int getTextLength(String text) {
    return getTextLength(myGraphics, text);
  }

  @Override
  public Object getState() {
    if (myState == null) {
      myState = new State(myGraphics.getFontRenderContext(), myGraphics.getFont());
    }
    return myState;
  }

  /** Internally used class containing unique variable for the current state */
  private static class State {
    // Internal values determining the uniqueness of the state
    FontRenderContext context;
    Font font;

    State(FontRenderContext context, Font font) {
      this.context = context;
      this.font = font;
      assert context != null;
      assert font != null;
    }

    @Override
    public boolean equals(Object o) {
      State rvalue = (State) o;
      if (rvalue == null) {
        return false;
      }
      return rvalue.context.equals(this.context) && rvalue.font.equals(this.font);
    }

    @Override
    public int hashCode() {
      return font.hashCode();
    }
  }
}