TextStroke.java

/*
Copyright 2006 Jerry Huxtable

Licensed 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 com.jhlabs.awt;

import java.awt.Font;
import java.awt.Shape;
import java.awt.Stroke;
import java.awt.font.FontRenderContext;
import java.awt.font.GlyphVector;
import java.awt.geom.AffineTransform;
import java.awt.geom.FlatteningPathIterator;
import java.awt.geom.GeneralPath;
import java.awt.geom.PathIterator;
import java.awt.geom.Point2D;

import org.apache.commons.math3.util.FastMath;

/**
 * Stroke that paint a text.
 * 
 * Slightly adapted to OTP from original source.
 * 
 * @see <a
 *      href="http://www.jhlabs.com/java/java2d/strokes/">http://www.jhlabs.com/java/java2d/strokes/</a>
 * 
 */
public class TextStroke implements Stroke {
    private String text;

    private Font font;

    private boolean stretchToFit = false;

    private boolean repeat = false;

    private AffineTransform t = new AffineTransform();

    private static final float FLATNESS = 1;

    public TextStroke(String text, Font font) {
        this(text, font, true, false);
    }

    public TextStroke(String text, Font font, boolean stretchToFit, boolean repeat) {
        this.text = text;
        this.font = font;
        this.stretchToFit = stretchToFit;
        this.repeat = repeat;
    }

    public Shape createStrokedShape(Shape shape) {
        FontRenderContext frc = new FontRenderContext(null, true, true);
        GlyphVector glyphVector = font.createGlyphVector(frc, text);

        GeneralPath result = new GeneralPath();
        PathIterator it = new FlatteningPathIterator(shape.getPathIterator(null), FLATNESS);
        float points[] = new float[6];
        float moveX = 0, moveY = 0;
        float lastX = 0, lastY = 0;
        float thisX = 0, thisY = 0;
        int type = 0;
        float next = 0;
        int currentChar = 0;
        int length = glyphVector.getNumGlyphs();

        if (length == 0)
            return result;

        float factor = stretchToFit ? measurePathLength(shape)
                / (float) glyphVector.getLogicalBounds().getWidth() : 1.0f;
        float height = (float) glyphVector.getLogicalBounds().getHeight();
        float nextAdvance = 0;

        while (currentChar < length && !it.isDone()) {
            type = it.currentSegment(points);
            switch (type) {
            case PathIterator.SEG_MOVETO:
                moveX = lastX = points[0];
                moveY = lastY = points[1];
                result.moveTo(moveX, moveY);
                nextAdvance = glyphVector.getGlyphMetrics(currentChar).getAdvance() * 0.5f;
                next = nextAdvance;
                break;

            case PathIterator.SEG_CLOSE:
                points[0] = moveX;
                points[1] = moveY;
                // Fall into....

            case PathIterator.SEG_LINETO:
                thisX = points[0];
                thisY = points[1];
                float dx = thisX - lastX;
                float dy = thisY - lastY;
                float distance = (float) FastMath.sqrt(dx * dx + dy * dy);
                if (distance >= next) {
                    float r = 1.0f / distance;
                    float angle = (float) FastMath.atan2(dy, dx);
                    while (currentChar < length && distance >= next) {
                        Shape glyph = glyphVector.getGlyphOutline(currentChar);
                        Point2D p = glyphVector.getGlyphPosition(currentChar);
                        float px = (float) p.getX();
                        float py = (float) p.getY();
                        float x = lastX + next * dx * r;
                        float y = lastY + next * dy * r;
                        float advance = nextAdvance;
                        nextAdvance = currentChar < length - 1 ? glyphVector.getGlyphMetrics(
                                currentChar + 1).getAdvance() * 0.5f : 0;
                        t.setToTranslation(x, y);
                        t.rotate(angle);
                        t.translate(-px - advance, -py + height * factor / 2.0f);
                        result.append(t.createTransformedShape(glyph), false);
                        next += (advance + nextAdvance) * factor;
                        currentChar++;
                        if (repeat)
                            currentChar %= length;
                    }
                }
                next -= distance;
                lastX = thisX;
                lastY = thisY;
                break;
            }
            it.next();
        }

        return result;
    }

    public float measurePathLength(Shape shape) {
        PathIterator it = new FlatteningPathIterator(shape.getPathIterator(null), FLATNESS);
        float points[] = new float[6];
        float moveX = 0, moveY = 0;
        float lastX = 0, lastY = 0;
        float thisX = 0, thisY = 0;
        int type = 0;
        float total = 0;

        while (!it.isDone()) {
            type = it.currentSegment(points);
            switch (type) {
            case PathIterator.SEG_MOVETO:
                moveX = lastX = points[0];
                moveY = lastY = points[1];
                break;

            case PathIterator.SEG_CLOSE:
                points[0] = moveX;
                points[1] = moveY;
                // Fall into....

            case PathIterator.SEG_LINETO:
                thisX = points[0];
                thisY = points[1];
                float dx = thisX - lastX;
                float dy = thisY - lastY;
                total += (float) Math.sqrt(dx * dx + dy * dy);
                lastX = thisX;
                lastY = thisY;
                break;
            }
            it.next();
        }

        return total;
    }

}