Data commit

Task/Bitmap-Read-a-PPM-file/Kotlin/bitmap-read-a-ppm-file.kotlin

@@ -0,0 +1,130 @@
+// Version 1.2.40
+
+import java.awt.Color
+import java.awt.Graphics
+import java.awt.image.BufferedImage
+import java.io.FileInputStream
+import java.io.PushbackInputStream
+import java.io.File
+import javax.imageio.ImageIO
+
+class BasicBitmapStorage(width: Int, height: Int) {
+    val image = BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR)
+
+    fun fill(c: Color) {
+        val g = image.graphics
+        g.color = c
+        g.fillRect(0, 0, image.width, image.height)
+    }
+
+    fun setPixel(x: Int, y: Int, c: Color) = image.setRGB(x, y, c.getRGB())
+
+    fun getPixel(x: Int, y: Int) = Color(image.getRGB(x, y))
+
+    fun toGrayScale() {
+        for (x in 0 until image.width) {
+            for (y in 0 until image.height) {
+                var rgb  = image.getRGB(x, y)
+                val red   = (rgb shr 16) and 0xFF
+                val green = (rgb shr  8) and 0xFF
+                val blue  =  rgb and 0xFF
+                val lumin = (0.2126 * red + 0.7152 * green + 0.0722 * blue).toInt()
+                rgb = (lumin shl 16) or (lumin shl 8) or lumin
+                image.setRGB(x, y, rgb)
+            }
+        }
+    }
+}
+
+fun PushbackInputStream.skipComment() {
+    while (read().toChar() != '\n') {}
+}
+
+fun PushbackInputStream.skipComment(buffer: ByteArray) {
+    var nl: Int
+    while (true) {
+        nl = buffer.indexOf(10) // look for newline at end of comment
+        if (nl != -1) break
+        read(buffer)  // read another buffer full if newline not yet found
+    }
+    val len = buffer.size
+    if (nl < len - 1) unread(buffer, nl + 1, len - nl - 1)
+}
+
+fun Byte.toUInt() = if (this < 0) 256 + this else this.toInt()
+
+fun main(args: Array<String>) {
+    // use file, output.ppm, created in the Bitmap/Write a PPM file task
+    val pbis = PushbackInputStream(FileInputStream("output.ppm"), 80)
+    pbis.use {
+        with (it) {
+            val h1 = read().toChar()
+            val h2 = read().toChar()
+            val h3 = read().toChar()
+            if (h1 != 'P' || h2 != '6' || h3 != '\n') {
+                println("Not a P6 PPM file")
+                System.exit(1)
+            }
+            val sb = StringBuilder()
+            while (true) {
+                val r = read().toChar()
+                if (r == '#') { skipComment(); continue }
+                if (r == ' ') break  // read until space reached
+                sb.append(r.toChar())
+            }
+            val width = sb.toString().toInt()
+            sb.setLength(0)
+            while (true) {
+                val r = read().toChar()
+                if (r == '#') { skipComment(); continue }
+                if (r == '\n') break  // read until new line reached
+                sb.append(r.toChar())
+            }
+            val height = sb.toString().toInt()
+            sb.setLength(0)
+            while (true) {
+                val r = read().toChar()
+                if (r == '#') { skipComment(); continue }
+                if (r == '\n') break  // read until new line reached
+                sb.append(r.toChar())
+            }
+            val maxCol = sb.toString().toInt()
+            if (maxCol !in 0..255) {
+                println("Maximum color value is outside the range 0..255")
+                System.exit(1)
+            }
+            var buffer = ByteArray(80)
+            // get rid of any more opening comments before reading data
+            while (true) {
+                read(buffer)
+                if (buffer[0].toChar() == '#') {
+                    skipComment(buffer)
+                }
+                else {
+                    unread(buffer)
+                    break
+                }
+            }
+            // read data
+            val bbs = BasicBitmapStorage(width, height)
+            buffer = ByteArray(width * 3)
+            var y = 0
+            while (y < height) {
+                read(buffer)
+                for (x in 0 until width) {
+                    val c = Color(
+                        buffer[x * 3].toUInt(),
+                        buffer[x * 3 + 1].toUInt(),
+                        buffer[x * 3 + 2].toUInt()
+                    )
+                    bbs.setPixel(x, y, c)
+                }
+                y++
+            }
+            // convert to grayscale and save to a file
+            bbs.toGrayScale()
+            val grayFile = File("output_gray.jpg")
+            ImageIO.write(bbs.image, "jpg", grayFile)
+        }
+    }
+}