From 7ad164e3c29e4ffadee33a002755ee5a061f6f4b Mon Sep 17 00:00:00 2001 From: hrj Date: Mon, 19 Apr 2021 16:59:14 +0530 Subject: [PATCH] GifCaptcha: show letters at different offsets Signed-off-by: hrj --- src/main/java/lc/captchas/GifCaptcha.java | 55 ++++++++++++++++++----- 1 file changed, 45 insertions(+), 10 deletions(-) diff --git a/src/main/java/lc/captchas/GifCaptcha.java b/src/main/java/lc/captchas/GifCaptcha.java index 94c0c87..4138057 100644 --- a/src/main/java/lc/captchas/GifCaptcha.java +++ b/src/main/java/lc/captchas/GifCaptcha.java @@ -3,9 +3,13 @@ package lc.captchas; import java.awt.Font; import java.awt.RenderingHints; import java.awt.Color; +import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Map; +import java.util.function.Consumer; +import java.util.stream.IntStream; +import java.util.LinkedList; import java.util.List; import javax.imageio.stream.MemoryCacheImageOutputStream; @@ -16,16 +20,34 @@ import lc.misc.HelperFunctions; import lc.misc.GifSequenceWriter; public class GifCaptcha implements ChallengeProvider { + private final Font font = new Font("Arial", Font.ROMAN_BASELINE, 48); + private final int width = 250; + private final int height = 100; - private BufferedImage charToImg(final String text) { - final var img = new BufferedImage(250, 100, BufferedImage.TYPE_INT_RGB); - final var font = new Font("Bradley Hand", Font.ROMAN_BASELINE, 48); + private Integer[] computeOffsets(final String text) { + final var img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); + final var graphics2D = img.createGraphics(); + final var frc = graphics2D.getFontRenderContext(); + final var advances = new LinkedList(); + final var spacing = font.getStringBounds(" ", frc).getWidth() / 2; + var currX = 0; + for (int i = 0; i < text.length(); i++) { + final var c = text.charAt(i); + advances.add(currX); + currX += font.getStringBounds(String.valueOf(c), frc).getWidth(); + currX += spacing; + }; + graphics2D.dispose(); + return advances.toArray(new Integer[]{}); + } + + private BufferedImage makeImage(final Consumer f) { + final var img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); final var graphics2D = img.createGraphics(); graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); graphics2D.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON); graphics2D.setFont(font); - graphics2D.setColor(new Color((int) (Math.random() * 0x1000000))); - graphics2D.drawString(text, 45, 45); + f.accept(graphics2D); graphics2D.dispose(); return img; } @@ -34,11 +56,24 @@ public class GifCaptcha implements ChallengeProvider { try { final var byteArrayOutputStream = new ByteArrayOutputStream(); final var output = new MemoryCacheImageOutputStream(byteArrayOutputStream); - final var writer = new GifSequenceWriter(output, 1, 1000, true); - for (int i = 0; i < text.length(); i++) { - final var nextImage = charToImg(String.valueOf(text.charAt(i))); - writer.writeToSequence(nextImage); - } + final var writer = new GifSequenceWriter(output, 1, 600, true); + final var advances = computeOffsets(text); + final var prevColor = Color.getHSBColor(0f, 0f, 0.1f); + IntStream.range(0, text.length()).forEach(i -> { + final var color = Color.getHSBColor(HelperFunctions.randomNumber(0, 100)/100.0f, 0.6f, 1.0f); + final var prevI = (i - 1 + text.length()) % text.length(); + final var nextImage = makeImage((g) -> { + g.setColor(prevColor); + g.drawString(String.valueOf(text.charAt(prevI)), advances[prevI], 45); + g.setColor(color); + g.drawString(String.valueOf(text.charAt(i)), advances[i], 45); + }); + try { + writer.writeToSequence(nextImage); + } catch (final IOException e) { + e.printStackTrace(); + } + }); writer.close(); output.close(); return byteArrayOutputStream.toByteArray();