/*

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

 */
package org.apache.batik.dom.svg;

import java.awt.geom.Rectangle2D;
import java.awt.geom.Point2D;

/**
 * This class provides the interface for the SVGTextContentElement
 * for the bridge to implement.
 *
 * @author nicolas.socheleau@bitflash.com
 * @version $Id$
 */
public interface SVGTextContent
{
    /**
     * Returns the total number of characters to be
     * rendered within the current element.
     * Includes characters which are included
     * via a &lt;tref&gt; reference.
     *
     * @return Total number of characters.
     */
    int getNumberOfChars();

    /**
     * Returns a tightest rectangle which defines the
     * minimum and maximum X and Y values in the user
     * coordinate system for rendering the glyph(s)
     * that correspond to the specified character.
     * The calculations assume that  all glyphs occupy
     * the full standard glyph cell for the font. If
     * multiple consecutive characters are rendered
     * inseparably (e.g., as a single glyph or a
     * sequence of glyphs), then each of the inseparable
     * characters will return the same extent.
     *
     * @param charnum The index of the character, where the
     *    first character has an index of 0.
     * @return The rectangle which encloses all of
     *    the rendered glyph(s).
     */
    Rectangle2D getExtentOfChar(int charnum );

    /**
     * Returns the current text position before rendering
     * the character in the user coordinate system for
     * rendering the glyph(s) that correspond to the
     * specified character. The current text position has
     * already taken into account the effects of any inter-
     * character adjustments due to properties 'kerning',
     * 'letter-spacing' and 'word-spacing' and adjustments
     * due to attributes x, y, dx and dy. If multiple
     * consecutive characters are rendered inseparably
     * (e.g., as a single glyph or a sequence of glyphs),
     * then each of the inseparable characters will return
     * the start position for the first glyph.
     *
     * @param charnum The index of the character, where the
     *    first character has an index of 0.
     * @return The character's start position.
     */
    Point2D getStartPositionOfChar(int charnum);

    /**
     * Returns the current text position after rendering
     * the character in the user coordinate system for
     * rendering the glyph(s) that correspond to the
     * specified character. This current text position
     * does not take into account the effects of any inter-
     * character adjustments to prepare for the next
     * character, such as properties 'kerning',
     * 'letter-spacing' and 'word-spacing' and adjustments
     * due to attributes x, y, dx and dy. If multiple
     * consecutive characters are rendered inseparably
     * (e.g., as a single glyph or a sequence of glyphs),
     * then each of the inseparable characters will return
     * the end position for the last glyph.
     *
     * @param charnum The index of the character, where the
     *    first character has an index of 0.
     * @return The character's end position.
     */
    Point2D getEndPositionOfChar(int charnum);

    /**
     * Returns the rotation value relative to the current
     * user coordinate system used to render the glyph(s)
     * corresponding to the specified character. If
     * multiple glyph(s) are used to render the given
     * character and the glyphs each have different
     * rotations (e.g., due to text-on-a-path), the user
     * agent shall return an average value (e.g., the
     * rotation angle at the midpoint along the path for
     * all glyphs used to render this character). The
     * rotation value represents the rotation that is
     * supplemental to any rotation due to properties
     * 'glyph-orientation-horizontal' and
     * 'glyph-orientation-vertical'; thus, any glyph
     * rotations due to these properties are not included
     * into the returned rotation value. If multiple
     * consecutive characters are rendered inseparably
     * (e.g., as a single glyph or a sequence of glyphs),
     * then each of the inseparable characters will
     * return the same rotation value.
     *
     * @param charnum The index of the character, where the
     *    first character has an index of 0.
     * @return The character's rotation angle.
     */
    float getRotationOfChar(int charnum);
    /**
     * Causes the specified substring to be selected
     * just as if the user selected the substring interactively.
     *
     * @param charnum : The index of the start character
     *   which is at the given point, where the first
     *   character has an index of 0.
     * @param nchars : The number of characters in the
     *   substring. If nchars specifies more characters
     *   than are available, then the substring will
     *   consist of all characters starting with charnum
     *   until the end of the list of characters.
     */
    void selectSubString(int charnum, int nchars);

    float getComputedTextLength();

    float getSubStringLength(int charnum, int nchars);

    int getCharNumAtPosition(float x, float y);
}