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Stefan Haustein 2016-04-09 00:39:53 +02:00
parent 155131131b
commit a882cd6158
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src/main/java/TerminalImageViewer.java Normal file
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import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.Arrays;
import javax.imageio.ImageIO;
public class TerminalImageViewer {
/**
* Main method, handles command line arguments and loads and scales images.
*/
public static void main(String[] args) throws IOException {
if (args.length == 0) {
System.out.println("Image file name required. Use -w to set the width in characters (default: 80).");
return;
}
int w = 80 * 4;
for (int i = 0; i < args.length; i++) {
String name = args[i];
if (name.equals("-w")) {
w = 4 * Integer.parseInt(args[++i]);
continue;
}
BufferedImage original;
if (name.startsWith("http://") || name.startsWith("https://")) {
URL url = new URL(name);
original = ImageIO.read(url);
} else {
original = ImageIO.read(new File(args[0]));
}
int ow = original.getWidth();
int oh = original.getHeight();
int h = oh * w / ow;
BufferedImage image = original;
if (w != ow) {
image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D graphics = image.createGraphics();
graphics.drawImage(original, 0, 0, w, h, null);
}
ImageData imageData = new ImageData(w, h);
byte[] data = imageData.data;
int[] rgbArray = new int[w];
for (int y = 0; y < image.getHeight(); y++) {
image.getRGB(0, y, image.getWidth(), 1, rgbArray, 0, w);
int pos = y * w * 4;
for (int x = 0; x < w; x++) {
int rgb = rgbArray[x];
data[pos++] = (byte) (rgb >> 16);
data[pos++] = (byte) (rgb >> 8);
data[pos++] = (byte) rgb;
pos++;
}
}
System.out.println(imageData.dump());
}
}
/**
* ANSI control code helpers
*/
static class Ansi {
public static final String RESET = "\u001b[0m";
public static String fgColor(int r, int g, int b) {
return "\u001b[38;2;" + (r & 255) + ";" + (g & 255) + ";" + (b & 255) + "m";
}
public static String bgColor(int r, int g, int b) {
return "\u001b[48;2;" + (r & 255) + ";" + (g & 255) + ";" + (b & 255) + "m";
}
}
/**
* Converts 4x8 RGB pixel to a unicode character and a foreground and background character.
* Uses a variation of the median cut algorithm to determine a two-color palette for the
* character, then creates a corresponding bitmap for the partial image covered by the
* character and finds the best match in the character bitmap table.
*/
static class BlockChar {
/**
* Assumed bitmaps of the supported characters
*/
static int[] BITMAPS = new int[] {
0x00000000, ' ',
0x000ff000, '\u2501',
0x000cc000, '\u2578',
0x00033000, '\u257a',
0xffff0000, '\u2580', // upper 1/2
0x0000000f, '\u2581', // lower 1/8
0x000000ff, '\u2582', // lower 1/4
0x00000fff, '\u2583',
0x0000ffff, '\u2584', // lower 1/2
0x000fffff, '\u2585',
0x00ffffff, '\u2586', // lower 3/4
0x0fffffff, '\u2587',
0xffffffff, '\u2588', // full
0xeeeeeeee, '\u258a', // left 3/4
0xcccccccc, '\u258c', // left 1/2
0x88888888, '\u258e', // left 1/4
0x0000cccc, '\u2596', // quadrant lower left
0x00003333, '\u2597', // quadrant lower right
0xcccc0000, '\u2598', // quadrant upper left
0xccccffff, '\u2599', // ...
0xcccc3333, '\u259a',
0xffffcccc, '\u259b',
0xffff3333, '\u259c',
0x33330000, '\u259d',
0x3333cccc, '\u259e',
0x3333ffff, '\u259f',
0x0006ff60, '\u25cf', // Black circle
0x000137f0, '\u25e2', // Triangles
0x0008cef0, '\u25e3',
0x000fec80, '\u25e4',
0x000f7310, '\u25e5'
};
/** Minimum value for each color channel. */
int[] min = new int[3];
/** Maximum value for each color channel. */
int[] max = new int[3];
/** Red, green and blue components of the selected background color. */
int[] bgColor = new int[3];
/** Red, green and blue components of the selected background color. */
int[] fgColor = new int[3];
/** The selected character. */
char character;
/**
* Converts a set of pixels to a unicode character and a background and foreground color.
* data contains the rgba values, p0 is the start point in data and scanWidth the number
* of bytes in each row of data.
*/
void load(byte[] data, int p0, int scanWidth) {
Arrays.fill(min, 255);
Arrays.fill(max, 0);
Arrays.fill(bgColor, 0);
Arrays.fill(fgColor, 0);
// Determine the minimum and maximum value for each color channel
int pos = p0;
for (int y = 0; y < 8; y++) {
for (int x = 0; x < 4; x++) {
for (int i = 0; i < 3; i++) {
int d = data[pos++] & 255;
min[i] = Math.min(min[i], d);
max[i] = Math.max(max[i], d);
}
pos++; // Alpha
}
pos += scanWidth - 16;
}
// Determine the color channel with the greatest range.
int splitIndex = 0;
int bestSplit = 0;
for (int i = 0; i < 3; i++) {
if (max[i] - min[i] > bestSplit) {
bestSplit = max[i] - min[i];
splitIndex = i;
}
}
// We just split at the middle of the interval instead of computing the median.
int splitValue = min[splitIndex] + bestSplit / 2;
// Compute a bitmap using the given split and sum the color values for both buckets.
int bits = 0;
int fgCount = 0;
int bgCount = 0;
pos = p0;
for (int y = 0; y < 8; y++) {
for (int x = 0; x < 4; x++) {
bits = bits << 1;
int[] avg;
if ((data[pos + splitIndex] & 255) > splitValue) {
avg = fgColor;
bits |= 1;
fgCount++;
} else {
avg = bgColor;
bgCount++;
}
for (int i = 0; i < 3; i++) {
avg[i] += data[pos++] & 255;
}
pos++; // Alpha
}
pos += scanWidth - 16;
}
// Calculate the average color value for each bucket
for (int i = 0; i < 3; i++) {
if (bgCount != 0) {
bgColor[i] /= bgCount;
}
if (fgCount != 0) {
fgColor[i] /= fgCount;
}
}
// Find the best bitmap match by counting the bits that don't match, including
// the inverted bitmaps.
int bestDiff = Integer.MAX_VALUE;
boolean invert = false;
for (int i = 0; i < BITMAPS.length; i += 2) {
int diff = Integer.bitCount(BITMAPS[i] ^ bits);
if (diff < bestDiff) {
character = (char) BITMAPS[i + 1];
bestDiff = diff;
invert = false;
}
diff = Integer.bitCount((~BITMAPS[i]) ^ bits);
if (diff < bestDiff) {
character = (char) BITMAPS[i + 1];
bestDiff = diff;
invert = true;
}
}
// If the match is quite bad, use a shade image instead.
if (bestDiff > 12) {
invert = false;
character = " \u2591\u2592\u2593\u2588".charAt(Math.min(4, fgCount * 5 / 32));
}
// If we use an inverted character, we need to swap the colors.
if (invert) {
int[] tmp = bgColor;
bgColor = fgColor;
fgColor = tmp;
}
}
}
/**
* Roughly modeled after the corresponding HTML 5 class.
*/
static class ImageData {
public final int width;
public final int height;
public final byte[] data;
public ImageData(int width, int height) {
this.width = width;
this.height = height;
this.data = new byte[width * height * 4];
}
/**
* Convert the image to an Ansi control character string setting the colors
*/
public String dump() {
StringBuilder sb = new StringBuilder();
BlockChar blockChar = new BlockChar();
for (int y = 0; y < height - 7; y += 8) {
int pos = y * width * 4;
String lastFg = "";
String lastBg = "";
for (int x = 0; x < width - 3; x += 4) {
blockChar.load(data, pos, width * 4);
String fg = Ansi.fgColor(blockChar.fgColor[0], blockChar.fgColor[1], blockChar.fgColor[2]);
String bg = Ansi.bgColor(blockChar.bgColor[0], blockChar.bgColor[1], blockChar.bgColor[2]);
if (!fg.equals(lastFg)) {
sb.append(fg);
lastFg = fg;
}
if (!bg.equals(lastBg)) {
sb.append(bg);
lastBg = bg;
}
sb.append(blockChar.character);
pos += 16;
}
sb.append(Ansi.RESET).append("\n");
}
return sb.toString();
}
}
}