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comparison src/nabble/view/web/util/GradientImage.java @ 0:7ecd1a4ef557

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author Franklin Schmidt <fschmidt@gmail.com>
date Thu, 21 Mar 2019 19:15:52 -0600
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1 package nabble.view.web.util;
2
3 import fschmidt.util.java.IoUtils;
4 import fschmidt.util.servlet.JtpContext;
5 import nabble.view.lib.UrlMappable;
6
7 import javax.imageio.ImageIO;
8 import javax.servlet.ServletException;
9 import javax.servlet.http.HttpServlet;
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12 import java.awt.Color;
13 import java.awt.GradientPaint;
14 import java.awt.Graphics2D;
15 import java.awt.image.BufferedImage;
16 import java.awt.image.RenderedImage;
17 import java.io.ByteArrayInputStream;
18 import java.io.ByteArrayOutputStream;
19 import java.io.IOException;
20 import java.io.InputStream;
21 import java.io.OutputStream;
22 import java.util.HashMap;
23 import java.util.Map;
24 import java.util.regex.Matcher;
25 import java.util.regex.Pattern;
26
27 /**
28 * @author Hugo Teixeira
29 */
30 public class GradientImage extends HttpServlet implements UrlMappable {
31
32 private static final Pattern URL_PATTERN = Pattern.compile("/gradients/(v|h)(\\d+)_([A-Fa-f0-9]{6})([A-Fa-f0-9]{2})?_([A-Fa-f0-9]{6})([A-Fa-f0-9]{2})?$");
33
34 public Map<String,String[]> getParameterMapFromUrl(HttpServletRequest request,String mappedUrl) {
35 Matcher m = URL_PATTERN.matcher(mappedUrl);
36 if( !m.find() )
37 throw new RuntimeException();
38 Map<String,String[]> params = new HashMap<String,String[]>();
39 String direction = m.group(1);
40 params.put("direction",new String[]{"v".equals(direction)? "vertical" : "horizontal"});
41 String size = m.group(2);
42 params.put("size",new String[]{size});
43 String fromColor = m.group(3) + (m.group(4) == null? "" : m.group(4));
44 params.put( "from", new String[]{fromColor} );
45 String toColor = m.group(5) + (m.group(6) == null? "" : m.group(6));
46 params.put( "to", new String[]{toColor} );
47 return params;
48 }
49
50 public Pattern getUrlPattern() {
51 return URL_PATTERN;
52 }
53
54 protected void service(HttpServletRequest request, HttpServletResponse response)
55 throws ServletException, IOException
56 {
57 OutputStream out = response.getOutputStream();
58 response.setContentType("image/png");
59
60 JtpContext jtpContext = (JtpContext)getServletContext().getAttribute(JtpContext.attrName);
61 jtpContext.setEtag(request,response);
62
63 String direction = request.getParameter("direction");
64 String size = request.getParameter("size");
65 String fromColor = request.getParameter("from");
66 String toColor = request.getParameter("to");
67
68 ByteArrayOutputStream baos = new ByteArrayOutputStream();
69 ImageIO.write(createImage(direction, size, fromColor, toColor), "png", baos);
70 final byte[] bytes = baos.toByteArray();
71
72 InputStream in = new ByteArrayInputStream(bytes);
73 try {
74 IoUtils.copyAll(in,out);
75 } finally {
76 in.close();
77 }
78 }
79
80 private RenderedImage createImage(String direction, String size, String fromColor, String toColor) {
81 boolean isVertical = "vertical".equals(direction);
82 int width = isVertical? 1 : Integer.valueOf(size);
83 int height = isVertical? Integer.valueOf(size) : 1;
84 Color from = parseColor(fromColor);
85 Color to = parseColor(toColor);
86 BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
87 Graphics2D g2 = img.createGraphics();
88 GradientPaint paint;
89 if (isVertical)
90 paint = new GradientPaint(0, 0, from, 0, height, to);
91 else
92 paint = new GradientPaint(0, 0, from, width, 0, to);
93 g2.setPaint(paint);
94 g2.fillRect(0, 0, width, height);
95 g2.dispose();
96 return img;
97 }
98
99 private Color parseColor(String c) {
100 if (c.length() == 6)
101 return Color.decode("0x"+c);
102 int r = Integer.parseInt(c.substring(0,2), 16);
103 int g = Integer.parseInt(c.substring(2,4), 16);
104 int b = Integer.parseInt(c.substring(4,6), 16);
105 int a = Integer.parseInt(c.substring(6,8), 16);
106 return new Color(r, g, b, a);
107 }
108 }