在 scala 中创建的图像看起来不像预期的那样。不知道为啥

Posted 2023-03-28

【中文标题】在 scala 中创建的图像看起来不像预期的那样。不知道为啥

【英文标题】：image created in scala does not look as expected. not sure why在 scala 中创建的图像看起来不像预期的那样。不知道为什么

【发布时间】：2020-06-03 00:27:15

【问题描述】：

我首先创建一个值为 2 的二维数组。然后将数组右下角的一些值设置为 5

var map = Array.fill(5, 10)(2);
map(4)(9) = 5
map(3)(9) = 5
map(4)(8) = 5
map(3)(8) = 5

此数组将由图像表示。每个数字 2 应该是一个蓝色方块。其余的应该是白色的

import scala.io.Source
import java.io._
import java.awt.image.BufferedImage
import java.awt.Graphics2D,Color,Font,BasicStroke
import java.awt.geom._

object DRAWPROB 
 def draw(map : Array[Array[Int]])

        val size = (30 * (map(0).length-1), 30 * (map.length-1))
        val canvas = new BufferedImage(size._1, size._2, BufferedImage.TYPE_INT_RGB)
        val g = canvas.createGraphics()
        g.setColor(Color.WHITE)
        g.fillRect(0, 0, canvas.getWidth, canvas.getHeight)
        g.setRenderingHint(java.awt.RenderingHints.KEY_ANTIALIASING,java.awt.RenderingHints.VALUE_ANTIALIAS_ON)
        var d = 0;
            for(d <- 0 to map.length-1)
                  var e = 0;
                  for(e <- 0 to map(0).length-1)
                  g.setColor(Color.BLUE)


                    if(map(d)(e) == 2) g.fill(new Rectangle2D.Double(d*30.0, e*30.0, 30.0, 30.0)); // ill find a way to do this once i can load the image
                    else println("not at "+ d + " " + e)
                                                                                    
                                                                    
g.dispose()
javax.imageio.ImageIO.write(canvas, "png", new java.io.File("island_drawing.png"))

它只是做了 1 个大的蓝色方块，但我希望右下角缺少一个部分

expectation vs reality

我为什么会得到这个

【问题讨论】：

这能回答你的问题吗？ How to combine multiple PNGs into one big PNG file?

【参考方案1】：

此代码部分的主要问题：new Rectangle2D.Double(d*30.0, e*30.0... - 第一个参数是 x 坐标，因此它应该乘以 map 列值，而不是 row ，并且与第二个参数 e*30 相同，即 @ 987654325@ 所以它应该乘以map 行值。

我已经重构了你的代码以便更好地理解，至少对我自己来说，所以请看一个例​​子：

import java.awt.image.BufferedImage
import java.awt.Color, Rectangle, RenderingHints

import javax.imageio.ImageIO

import scala.reflect.ClassTag

/**
 * Immutable table model, possibly empty inside
 */
class Table[T](underlying: Array[Array[T]]) 
  def columnsCount: Int = underlying.headOption.map(_.length).getOrElse(0)
  def rowsCount: Int = underlying.length

  def rows: Seq[Int] = underlying.indices
  def columns: Seq[Int] = underlying.headOption.map(_.indices).getOrElse(Nil)

  def apply(row: Int, column: Int): Option[T] = 
    val rowExists = row < rowsCount && row >= 0
    val columnExists = column < columnsCount && column >= 0
    if(rowExists && columnExists) Some(underlying(row)(column)) else None
  

  def update(row: Int, column: Int, value: T): Table[T] = 
    val copy = underlying.clone()
    copy(row)(column) = value
    new Table[T](copy)
  

  def foreach[U](f: ((Int, Int, T)) => U): Unit = 
    val rowColumnValue = for 
      row <- rows
      column <- columns
      value <- apply(row, column)
     yield (row, column, value)

    rowColumnValue.foreach[U](f)
  

  override def toString: String = underlying.map(_.mkString(",")).mkString("\n")


object Table 
  def apply[T: ClassTag](rows: Int, columns: Int, initValue: T): Table[T] = 
    new Table[T](Array.fill(rows, columns)(initValue))
  


class Draw(cellSize: Int) 

  def draw(table: Table[Int]) 
    val width = cellSize * table.columnsCount
    val height = cellSize * table.rowsCount

    val canvas = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB)
    val graphics = canvas.createGraphics()
    graphics.setColor(Color.WHITE)
    graphics.fillRect(0, 0, canvas.getWidth, canvas.getHeight)
    graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON)

    table.foreach  case (row, column, value) =>
      if (value == 2) 
        graphics.setColor(Color.BLUE)
        // This is main fix part
        val x = column * cellSize
        val y = row * cellSize
        graphics.fill(new Rectangle(x, y, cellSize, cellSize))
      
    

    graphics.dispose()
    ImageIO.write(canvas, "png", new java.io.File("island_drawing.png"))
  



object DrawApp 
  def main(args: Array[String]): Unit = 
    val draw = new Draw(30)
    val table = Table(5, 10, 2)
      .update(4 ,9, 5)
      .update(4, 8, 5)
      .update(3, 9, 5)
      .update(3, 8, 5)
    println(table)

    draw.draw(table)
  

这产生了预期的图像。希望这会有所帮助！