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Scene graph and style library using Java2D graphics.
There is a newer version: 3.0.16
package com.googlecode.blaisemath.graphics.swing.render;

/*
 * #%L
 * BlaiseGraphics
 * --
 * Copyright (C) 2009 - 2024 Elisha Peterson
 * --
 * 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.
 * #L%
 */

import com.google.common.base.Objects;
import com.google.common.base.Strings;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.googlecode.blaisemath.style.AttributeSet;
import com.googlecode.blaisemath.graphics.Renderer;
import com.googlecode.blaisemath.primitive.Anchor;
import com.googlecode.blaisemath.primitive.AnchoredText;
import com.googlecode.blaisemath.style.Styles;
import org.checkerframework.checker.nullness.qual.Nullable;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.Toolkit;
import java.awt.font.FontRenderContext;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.Collections;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Renders a string of text on a canvas. An anchor is used to position the text relative to a point. The default anchor
 * is SOUTHWEST, with the text drawn to the right/above the point.
 * 
 * @author Elisha Peterson
 */
public class TextRenderer implements Renderer {
    
    /** Assumed monitor resolution, used in bounding box calculations */
    private static final int DOTS_PER_INCH = 72;
    /** Logging */
    private static final Logger LOG = Logger.getLogger(TextRenderer.class.getName());
    /** Static instance */
    private static final TextRenderer INST = new TextRenderer();
    /** Caches expensive computation of font bounds */
    private static final LoadingCache CACHE = CacheBuilder.newBuilder()
            .maximumSize(10000)
            .expireAfterAccess(1, TimeUnit.MINUTES)
            .build(new CacheLoader() {
                @Override
                public Rectangle2D.Double load(TextBoundsInfo textBoundsInfo) {
                    return textDimensions(textBoundsInfo);
                }
            });

    /**
     * Get default static instance of the renderer.
     * @return renderer
     */
    public static TextRenderer getInstance() {
        return INST;
    }
    
    @Override
    public void render(AnchoredText primitive, AttributeSet style, Graphics2D canvas) {
        render(Collections.singleton(primitive), style, canvas);
    }
    
    /**
     * Render a collection of text primitives at one time.
     * @param primitives the primitives to render
     * @param style the style used for rendering
     * @param canvas where to render it
     */
    public void render(Iterable primitives, AttributeSet style, Graphics2D canvas) {
        canvas.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
        canvas.setColor(style.getColor(Styles.FILL, Color.black));
        canvas.setFont(Styles.fontOf(style));
        
        for (AnchoredText at : primitives) {
            if (!Strings.isNullOrEmpty(at.getText())) {
                Rectangle2D bounds = boundingBox(at, style, canvas);
                canvas.drawString(at.getText(), (float) bounds.getX(), (float) (bounds.getMaxY()));
            }
        }
    }

    @Override
    public boolean contains(Point2D point, AnchoredText primitive, AttributeSet style, @Nullable Graphics2D canvas) {
        Rectangle2D bounds = boundingBox(primitive, style, canvas);
        return bounds != null && bounds.contains(point);
    }

    @Override
    public boolean intersects(Rectangle2D rect, AnchoredText primitive, AttributeSet style, @Nullable Graphics2D canvas) {
        Rectangle2D bounds = boundingBox(primitive, style, canvas);
        return bounds != null && bounds.intersects(rect);
    }

    /**
     * Get the bounding box for the given text/style to be rendered on the given canvas. This computation can be expensive, so the
     * results are cached so that if the text, font, and render context do not change, the cached results are used.
     * @param primitive text/location
     * @param style desired style
     * @param canvas where to render
     * @return bounding box for the result
     */
    @Override
    public @Nullable Rectangle2D boundingBox(AnchoredText primitive, AttributeSet style, @Nullable Graphics2D canvas) {
        if (Strings.isNullOrEmpty(primitive.getText())) {
            return null;
        }

        Font font = Styles.fontOf(style);
        FontRenderContext frc = canvas == null ? new FontRenderContext(font.getTransform(), true, false)
                : canvas.getFontRenderContext();
        
        TextBoundsInfo info = new TextBoundsInfo(primitive.getText(), font, frc);
        Rectangle2D.Double dimensions;
        try {
            dimensions = CACHE.get(info);
        } catch (ExecutionException e) {
            LOG.log(Level.FINE, "Unexpected", e);
            dimensions = textDimensions(info);
        }

        Anchor textAnchor = Styles.anchorOf(style, Anchor.SOUTHWEST);
        Point2D offset = style.getPoint2D(Styles.OFFSET, new Point());
        assert offset != null;
        return textAnchor.rectangleAnchoredAt(
                primitive.getX() + offset.getX(),
                primitive.getY() + offset.getY(),
                dimensions.width, dimensions.height);
    }

    private static Rectangle2D.Double textDimensions(TextBoundsInfo info) {
        return textDimensions(info.text, info.font, info.context);
    }

    private static Rectangle2D.Double textDimensions(String text, Font font, FontRenderContext context) {
        double width = font.getStringBounds(text, context).getWidth();
        int height = font.getSize() * DOTS_PER_INCH / Toolkit.getDefaultToolkit().getScreenResolution();
        return new Rectangle2D.Double(0, 0, width, height);
    }

    /** Info required for most expensive font computation. */
    private static class TextBoundsInfo {
        private String text;
        private Font font;
        private FontRenderContext context;

        private TextBoundsInfo(String text, Font font, FontRenderContext context) {
            this.text = text;
            this.font = font;
            this.context = context;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            TextBoundsInfo that = (TextBoundsInfo) o;
            return Objects.equal(text, that.text) &&
                    Objects.equal(font, that.font) &&
                    Objects.equal(context, that.context);
        }

        @Override
        public int hashCode() {
            return Objects.hashCode(text, font, context);
        }
    }
    
}