/*
 * 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.
 */

/* $Id: ScaledBaselineTable.java 1293736 2012-02-26 02:29:01Z gadams $ */

package org.apache.fop.layoutmgr.inline;

import org.apache.fop.fo.Constants;
import org.apache.fop.traits.WritingMode;


The FOP specific incarnation of the XSL-FO scaled baseline table.
All baseline tables are scaled to the font size of the font they
apply to. This class uses a coordinate system with its origin
where the dominant baseline intersects the start edge of the box.
All measurements are in mpt.
/**
 * The FOP specific incarnation of the XSL-FO scaled baseline table.
 * All baseline tables are scaled to the font size of the font they
 * apply to. This class uses a coordinate system with its origin
 * where the dominant baseline intersects the start edge of the box.
 * All measurements are in mpt.
 */
final class ScaledBaselineTable {

    private static final float HANGING_BASELINE_FACTOR = 0.8f;

    private static final float MATHEMATICAL_BASELINE_FACTOR = 0.5f;

    private final int altitude;

    private final int depth;

    private final int xHeight;

    private final int dominantBaselineIdentifier;

    private final WritingMode writingMode;

    private final int dominantBaselineOffset;

    private int beforeEdgeOffset;

    private int afterEdgeOffset;


    
Creates a new instance of BasicScaledBaselineTable for the given
altitude, depth, xHeight, baseline and writing mode.
Params:
altitude – the height of the box or the font ascender
depth – the font descender or 0
xHeight – the font xHeight
dominantBaselineIdentifier – the dominant baseline given as an integer constant
writingMode – the writing mode given as an integer constant/**
     *
     * Creates a new instance of BasicScaledBaselineTable for the given
     * altitude, depth, xHeight, baseline and writing mode.
     * @param altitude the height of the box or the font ascender
     * @param depth the font descender or 0
     * @param xHeight the font xHeight
     * @param dominantBaselineIdentifier the dominant baseline given as an integer constant
     * @param writingMode the writing mode given as an integer constant
     */
    ScaledBaselineTable(int altitude,
            int depth,
            int xHeight,
            int dominantBaselineIdentifier,
            WritingMode writingMode) {
        this.altitude = altitude;
        this.depth = depth;
        this.xHeight = xHeight;
        this.dominantBaselineIdentifier = dominantBaselineIdentifier;
        this.writingMode = writingMode;
        this.dominantBaselineOffset = getBaselineDefaultOffset(this.dominantBaselineIdentifier);
        this.beforeEdgeOffset = altitude - dominantBaselineOffset;
        this.afterEdgeOffset = depth - dominantBaselineOffset;
    }

    
Return the dominant baseline for this baseline table.
Returns:
the dominant baseline/**
     * Return the dominant baseline for this baseline table.
     * @return the dominant baseline
     */
    int getDominantBaselineIdentifier() {
        return this.dominantBaselineIdentifier;
    }

    
Return the writing mode for this baseline table.
Returns:
the writing mode/**
     * Return the writing mode for this baseline table.
     * @return the writing mode
     */
    WritingMode getWritingMode() {
        return this.writingMode;
    }

    
Return the offset of the given baseline from the dominant baseline.
Params:
baselineIdentifier – a baseline identifier
Returns:
the offset from the dominant baseline/**
     * Return the offset of the given baseline from the dominant baseline.
     *
     * @param baselineIdentifier a baseline identifier
     * @return the offset from the dominant baseline
     */
    int getBaseline(int baselineIdentifier) {
        int offset = 0;
        if (!isHorizontalWritingMode()) {
            switch (baselineIdentifier) {
                case Constants.EN_TOP:
                case Constants.EN_TEXT_TOP:
                case Constants.EN_TEXT_BOTTOM:
                case Constants.EN_BOTTOM:
                throw new IllegalArgumentException("Baseline " + baselineIdentifier
                        + " only supported for horizontal writing modes");
                default: // TODO
            }
        }
        switch (baselineIdentifier) {
            case Constants.EN_TOP: // fall through
            case Constants.EN_BEFORE_EDGE:
                offset = beforeEdgeOffset;
                break;
            case Constants.EN_TEXT_TOP:
            case Constants.EN_TEXT_BEFORE_EDGE:
            case Constants.EN_HANGING:
            case Constants.EN_CENTRAL:
            case Constants.EN_MIDDLE:
            case Constants.EN_MATHEMATICAL:
            case Constants.EN_ALPHABETIC:
            case Constants.EN_IDEOGRAPHIC:
            case Constants.EN_TEXT_BOTTOM:
            case Constants.EN_TEXT_AFTER_EDGE:
                offset = getBaselineDefaultOffset(baselineIdentifier) - dominantBaselineOffset;
                break;
            case Constants.EN_BOTTOM: // fall through
            case Constants.EN_AFTER_EDGE:
                offset = afterEdgeOffset;
                break;
            default: throw new IllegalArgumentException(String.valueOf(baselineIdentifier));
        }
        return offset;
    }

    private boolean isHorizontalWritingMode() {
        return writingMode.isHorizontal();
    }

    
Return the baseline offset measured from the font's default
baseline for the given baseline.
Params:
baselineIdentifier – the baseline identifier
Returns:
the baseline offset/**
     * Return the baseline offset measured from the font's default
     * baseline for the given baseline.
     * @param baselineIdentifier the baseline identifier
     * @return the baseline offset
     */
    private int getBaselineDefaultOffset(int baselineIdentifier) {
        int offset = 0;
        switch (baselineIdentifier) {
            case Constants.EN_TEXT_BEFORE_EDGE:
                offset = altitude;
                break;
            case Constants.EN_HANGING:
                offset = Math.round(altitude * HANGING_BASELINE_FACTOR);
                break;
            case Constants.EN_CENTRAL:
                offset = (altitude - depth) / 2 + depth;
                break;
            case Constants.EN_MIDDLE:
                offset = xHeight / 2;
                break;
            case Constants.EN_MATHEMATICAL:
                offset = Math.round(altitude * MATHEMATICAL_BASELINE_FACTOR);
                break;
            case Constants.EN_ALPHABETIC:
                offset = 0;
                break;
            case Constants.EN_IDEOGRAPHIC: // Fall through
            case Constants.EN_TEXT_AFTER_EDGE:
                offset = depth;
                break;
            default: throw new IllegalArgumentException(String.valueOf(baselineIdentifier));
        }
        return offset;
    }

    
Sets the position of the before and after baselines.
This is usually only done for line areas. For other
areas the position of the before and after baselines
are fixed when the table is constructed.
Params:
beforeBaseline – the offset of the before-edge baseline from the dominant baseline
afterBaseline – the offset of the after-edge baseline from the dominant baseline/**
     * Sets the position of the before and after baselines.
     * This is usually only done for line areas. For other
     * areas the position of the before and after baselines
     * are fixed when the table is constructed.
     * @param beforeBaseline the offset of the before-edge baseline from the dominant baseline
     * @param afterBaseline the offset of the after-edge baseline from the dominant baseline
     */
    void setBeforeAndAfterBaselines(int beforeBaseline, int afterBaseline) {
        beforeEdgeOffset = beforeBaseline;
        afterEdgeOffset = afterBaseline;
    }

    
Return a new baseline table for the given baseline based
on the current baseline table.
Params:
baselineIdentifier – the baseline identifer
Returns:
a new baseline with the new baseline/**
     * Return a new baseline table for the given baseline based
     * on the current baseline table.
     * @param baselineIdentifier the baseline identifer
     * @return a new baseline with the new baseline
     */
    ScaledBaselineTable deriveScaledBaselineTable(int baselineIdentifier) {
        ScaledBaselineTable bac = new ScaledBaselineTable(altitude, depth, xHeight,
                baselineIdentifier, this.writingMode);
        return bac;
    }

}