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com.orsonpdf.util.TextUtils Maven / Gradle / Ivy

/* =====================================================================
 * OrsonPDF : a fast, light-weight PDF library for the Java(tm) platform
 * =====================================================================
 * 
 * (C)opyright 2013-2015, by Object Refinery Limited.  All rights reserved.
 *
 * Project Info:  http://www.object-refinery.com/orsonpdf/index.html
 * 
 * This program 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.
 *
 * This program 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 this program.  If not, see .
 * 
 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
 * Other names may be trademarks of their respective owners.]
 * 
 * If you do not wish to be bound by the terms of the GPL, an alternative
 * commercial license can be purchased.  For details, please see visit the
 * Orson PDF home page:
 * 
 * http://www.object-refinery.com/orsonpdf/index.html
 * 
 */

package com.orsonpdf.util;

import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics2D;
import java.awt.font.FontRenderContext;
import java.awt.font.LineMetrics;
import java.awt.geom.AffineTransform;
import java.awt.geom.Rectangle2D;
import java.text.AttributedString;

/**
 * Text utility functions.
 */
public class TextUtils {

    private TextUtils() {
        // no need to instantiate this.
    }
    
    /**
     * Draws a string such that the specified anchor point is aligned to the
     * given {@code (x, y)} location.
     *
     * @param text  the text.
     * @param g2  the graphics device.
     * @param x  the x coordinate (Java 2D).
     * @param y  the y coordinate (Java 2D).
     * @param anchor  the anchor location.
     *
     * @return The text bounds (adjusted for the text position).
     */
    public static Rectangle2D drawAlignedString(String text,
            Graphics2D g2, float x, float y, TextAnchor anchor) {

        Rectangle2D textBounds = new Rectangle2D.Double();
        float[] adjust = deriveTextBoundsAnchorOffsets(g2, text, anchor,
                textBounds);
        // adjust text bounds to match string position
        textBounds.setRect(x + adjust[0], y + adjust[1] + adjust[2],
            textBounds.getWidth(), textBounds.getHeight());
        g2.drawString(text, x + adjust[0], y + adjust[1]);
        return textBounds;
    }

    /**
     * A utility method that calculates the anchor offsets for a string.
     * Normally, the {@code (x, y)} coordinate for drawing text is a point on 
     * the baseline at the left of the text string.  If you add these offsets to
     * {@code (x, y)} and draw the string, then the anchor point should 
     * coincide with the {@code (x, y)} point.
     *
     * @param g2  the graphics device (not {@code null}).
     * @param text  the text.
     * @param anchor  the anchor point.
     *
     * @return  The offsets.
     */
    private static float[] deriveTextBoundsAnchorOffsets(Graphics2D g2,
            String text, TextAnchor anchor) {

        float[] result = new float[2];
        FontRenderContext frc = g2.getFontRenderContext();
        Font f = g2.getFont();
        FontMetrics fm = g2.getFontMetrics(f);
        Rectangle2D bounds = getTextBounds(text, g2, fm);
        LineMetrics metrics = f.getLineMetrics(text, frc);
        float ascent = metrics.getAscent();
        float halfAscent = ascent / 2.0f;
        float descent = metrics.getDescent();
        float leading = metrics.getLeading();
        float xAdj = 0.0f;
        float yAdj = 0.0f;

        if (anchor.isHorizontalCenter()) {
            xAdj = (float) -bounds.getWidth() / 2.0f;
        } else if (anchor.isRight()) {
            xAdj = (float) -bounds.getWidth();
        }

        if (anchor.isTop()) {
            yAdj = -descent - leading + (float) bounds.getHeight();
        } else if (anchor.isHalfAscent()) {
            yAdj = halfAscent;
        } else if (anchor.isHalfHeight()) {
            yAdj = -descent - leading + (float) (bounds.getHeight() / 2.0);
        } else if (anchor.isBaseline()) {
            yAdj = 0.0f;
        } else if (anchor.isBottom()) {
            yAdj = -metrics.getDescent() - metrics.getLeading();
        }
        result[0] = xAdj;
        result[1] = yAdj;
        return result;
    }

    /**
     * A utility method that calculates the anchor offsets for a string.
     * Normally, the {@code (x, y)} coordinate for drawing text is a point on 
     * the baseline at the left of the text string.  If you add these offsets to
     * {@code (x, y)} and draw the string, then the anchor point should 
     * coincide with the {@code (x, y)} point.
     *
     * @param g2  the graphics device (not {@code null}).
     * @param text  the text.
     * @param anchor  the anchor point.
     * @param textBounds  the text bounds (if not {@code null}, this
     *                    object will be updated by this method to match the
     *                    string bounds).
     *
     * @return  The offsets.
     */
    private static float[] deriveTextBoundsAnchorOffsets(Graphics2D g2,
            String text, TextAnchor anchor, Rectangle2D textBounds) {

        float[] result = new float[3];
        FontRenderContext frc = g2.getFontRenderContext();
        Font f = g2.getFont();
        FontMetrics fm = g2.getFontMetrics(f);
        Rectangle2D bounds = getTextBounds(text, g2, fm);
        LineMetrics metrics = f.getLineMetrics(text, frc);
        float ascent = metrics.getAscent();
        result[2] = -ascent;
        float halfAscent = ascent / 2.0f;
        float descent = metrics.getDescent();
        float leading = metrics.getLeading();
        float xAdj = 0.0f;
        float yAdj = 0.0f;

        if (anchor.isHorizontalCenter()) {
            xAdj = (float) -bounds.getWidth() / 2.0f;
        } else if (anchor.isRight()) {
            xAdj = (float) -bounds.getWidth();
        }

        if (anchor.isTop()) {
            yAdj = -descent - leading + (float) bounds.getHeight();
        } else if (anchor.isHalfAscent()) {
            yAdj = halfAscent;
        } else if (anchor.isHalfHeight()) {
            yAdj = -descent - leading + (float) (bounds.getHeight() / 2.0);
        } else if (anchor.isBaseline()) {
            yAdj = 0.0f;
        } else if (anchor.isBottom()) {
            yAdj = -metrics.getDescent() - metrics.getLeading();
        }
        if (textBounds != null) {
            textBounds.setRect(bounds);
        }
        result[0] = xAdj;
        result[1] = yAdj;
        return result;
    }

    /**
     * Returns the bounds for the specified text.
     *
     * @param text  the text ({@code null} permitted).
     * @param g2  the graphics context (not {@code null}).
     * @param fm  the font metrics (not {@code null}).
     *
     * @return The text bounds ({@code null} if the {@code text}
     *         argument is {@code null}).
     */
    public static Rectangle2D getTextBounds(String text, Graphics2D g2, 
            FontMetrics fm) {
        double width = fm.stringWidth(text);
        double height = fm.getHeight();
        return new Rectangle2D.Double(0.0, -fm.getAscent(), width, height);
    }

    /**
     * Draws a string that is aligned by one anchor point and rotated about
     * another anchor point.
     *
     * @param text  the text.
     * @param g2  the graphics device.
     * @param x  the x-coordinate for positioning the text.
     * @param y  the y-coordinate for positioning the text.
     * @param textAnchor  the text anchor.
     * @param angle  the rotation angle.
     * @param rotationX  the x-coordinate for the rotation anchor point.
     * @param rotationY  the y-coordinate for the rotation anchor point.
     */
    public static void drawRotatedString(String text, Graphics2D g2, float x, 
            float y, TextAnchor textAnchor, double angle,
            float rotationX, float rotationY) {

        if (text == null || text.equals("")) {
            return;
        }
        float[] textAdj = deriveTextBoundsAnchorOffsets(g2, text, textAnchor);
        drawRotatedString(text, g2, x + textAdj[0], y + textAdj[1], angle,
                rotationX, rotationY);
    }

    /**
     * Draws a string that is aligned by one anchor point and rotated about
     * another anchor point.
     *
     * @param text  the text.
     * @param g2  the graphics device.
     * @param x  the x-coordinate for positioning the text.
     * @param y  the y-coordinate for positioning the text.
     * @param textAnchor  the text anchor.
     * @param angle  the rotation angle (in radians).
     * @param rotationAnchor  the rotation anchor.
     */
    public static void drawRotatedString(String text, Graphics2D g2,
            float x, float y, TextAnchor textAnchor,
            double angle, TextAnchor rotationAnchor) {

        if (text == null || text.equals("")) {
            return;
        }
        float[] textAdj = deriveTextBoundsAnchorOffsets(g2, text, textAnchor);
        float[] rotateAdj = deriveRotationAnchorOffsets(g2, text, 
                rotationAnchor);
        drawRotatedString(text, g2, x + textAdj[0], y + textAdj[1],
                angle, x + textAdj[0] + rotateAdj[0],
                y + textAdj[1] + rotateAdj[1]);
    }
    
    /**
     * A utility method that calculates the rotation anchor offsets for a
     * string.  These offsets are relative to the text starting coordinate
     * ({@code BASELINE_LEFT}).
     *
     * @param g2  the graphics device.
     * @param text  the text.
     * @param anchor  the anchor point.
     *
     * @return  The offsets.
     */
    private static float[] deriveRotationAnchorOffsets(Graphics2D g2,
            String text, TextAnchor anchor) {

        float[] result = new float[2];
        FontRenderContext frc = g2.getFontRenderContext();
        LineMetrics metrics = g2.getFont().getLineMetrics(text, frc);
        FontMetrics fm = g2.getFontMetrics();
        Rectangle2D bounds = TextUtils.getTextBounds(text, g2, fm);
        float ascent = metrics.getAscent();
        float halfAscent = ascent / 2.0f;
        float descent = metrics.getDescent();
        float leading = metrics.getLeading();
        float xAdj = 0.0f;
        float yAdj = 0.0f;

        if (anchor.isLeft()) {
            xAdj = 0.0f;
        } else if (anchor.isHorizontalCenter()) {
            xAdj = (float) bounds.getWidth() / 2.0f;
        } else if (anchor.isRight()) {
            xAdj = (float) bounds.getWidth();
        }

        if (anchor.isTop()) {
            yAdj = descent + leading - (float) bounds.getHeight();
        } else if (anchor.isHalfHeight()) {
            yAdj = descent + leading - (float) (bounds.getHeight() / 2.0);
        } else if (anchor.isHalfAscent()) {
            yAdj = -halfAscent;
        } else if (anchor.isBaseline()) {
            yAdj = 0.0f;
        } else if (anchor.isBottom()) {
            yAdj = metrics.getDescent() + metrics.getLeading();
        }
        result[0] = xAdj;
        result[1] = yAdj;
        return result;
    }
    
    /**
     * A utility method for drawing rotated text.
     * 

     * A common rotation is {@code -Math.PI/2} which draws text 'vertically' 
     * (with the top of the characters on the left).
     *
     * @param text  the text.
     * @param g2  the graphics device.
     * @param angle  the angle of the (clockwise) rotation (in radians).
     * @param x  the x-coordinate.
     * @param y  the y-coordinate.
     */
    public static void drawRotatedString(String text, Graphics2D g2,
            double angle, float x, float y) {
        drawRotatedString(text, g2, x, y, angle, x, y);
    }

    /**
     * A utility method for drawing rotated text.
     * 

     * A common rotation is {@code -Math.PI/2} which draws text 'vertically' 
     * (with the top of the characters on the left).
     *
     * @param text  the text.
     * @param g2  the graphics device.
     * @param textX  the x-coordinate for the text (before rotation).
     * @param textY  the y-coordinate for the text (before rotation).
     * @param angle  the angle of the (clockwise) rotation (in radians).
     * @param rotateX  the point about which the text is rotated.
     * @param rotateY  the point about which the text is rotated.
     */
    public static void drawRotatedString(String text, Graphics2D g2,
            float textX, float textY, double angle,
            float rotateX, float rotateY) {

        if ((text == null) || (text.equals(""))) {
            return;
        }

        final AffineTransform saved = g2.getTransform();

        // apply the rotation...
        AffineTransform rotate = AffineTransform.getRotateInstance(angle, 
                rotateX, rotateY);
        g2.transform(rotate);

        AttributedString as = new AttributedString(text, 
                g2.getFont().getAttributes());
        g2.drawString(as.getIterator(), textX, textY);
        g2.setTransform(saved);

    }
}