September 2017 Update

Task/Greyscale-bars-Display/FreeBASIC/greyscale-bars-display.freebasic

@@ -0,0 +1,35 @@
+' version 01-09-2017
+'    compile with: fbc -s console
+' or compile with: fbc -s gui
+' hit any key to stop
+
+Dim As UInteger d, blocks, blocksize, ps, col, h, w, x, y1, y2
+
+ScreenInfo w, h
+' create display size window, 8bit color (palette), no frame
+ScreenRes w, h, 8,, 8
+
+For x = 0 To 255        ' create grayscale palette for
+    Palette x, x, x, x  ' the window we just opened
+Next
+
+h = h \ 4 : y2 = h -1
+
+If w Mod 64 <> 0 Then w -= (w Mod 64)
+blocks = 8 : blocksize = w \ 8
+
+For ps = 1 To 4
+    For x = 0 To blocks -1
+        col = 255 * x \ (blocks -1)              ' from black to white
+        If (ps And 1) = 0 Then col = 255 - col   ' from white to black
+        Line (x * blocksize, y1) - (((x +1) * blocksize) -1, y2), col, bf
+    Next
+    y1 += h : y2 += h
+    blocks *= 2 : blocksize \= 2
+Next
+
+' empty keyboard buffer
+While Inkey <> "" : Wend
+
+Sleep
+End

Task/Greyscale-bars-Display/Gambas/greyscale-bars-display.gambas

@@ -0,0 +1,29 @@
+Public Sub Form_Open()
+Dim iRow, iCol, iClr As Integer                                     'For Row, Column and Colour
+Dim iInc As Integer = 4                                             'To calculate RGB colour
+Dim h1Panel As Panel                                                'Panels to display colours
+
+With Me                                                             'Setup the Form
+  .Arrangement = Arrange.Row                                        'Arrange children in rows
+  .Border = False                                                   'No Border
+  .Height = Desktop.Height                                          'Fill the screen
+  .Width = Desktop.Width                                            'Fill the screen
+  .Fullscreen = True                                                'Set the Form to Fullscreen
+End With
+
+For iRow = 1 To 4                                                   'For each row..
+  iInc += iInc                                                      'Increase iInc by itself
+  For iCol = 0 To iInc - 1                                          'For each column..
+    iClr = iCol * (256 / iInc)                                      'Set the RGB colour
+    If iRow = 2 Or iRow = 4 Then iClr = 255 - (iCol * (256 / iInc)) 'If row 2 or 4 then reverse the colours
+    h1Panel = New Panel(Me)                                         'Create a new Panel
+    With h1Panel                                                    'With the Panel..
+      .Width = Desktop.Width / iInc                                 'Set the width
+      .Height = Desktop.Height / 4                                  'Set the height
+      .Background = Color.RGB(iClr, iClr, iClr)                     'Set the Background colour
+      .Border = Border.Plain                                        'Set a Border (It's easier to see the colour changes)
+    End With
+  Next
+Next
+
+End

Task/Greyscale-bars-Display/Java/greyscale-bars-display.java

@@ -16,21 +16,22 @@ public class Greybars extends JFrame {
 
     public void paint ( Graphics g ) {
       int run = 0 ;
-      int colorcomp = 0 ; //component of the color
+      double colorcomp = 0.0 ; //component of the color
       for ( int columncount = 8 ; columncount < 128 ; columncount *= 2 ) {
-	 int colorgap = 255 / columncount ; //by this gap we change the background color
+	 double colorgap = 255.0 / (columncount - 1) ; //by this gap we change the background color
 	 int columnwidth = width / columncount ;
 	 int columnheight = height / 4 ;
 	 if ( run % 2 == 0 ) //switches color directions with every for loop
-	    colorcomp = 0 ;
+	    colorcomp = 0.0 ;
 	 else {
-	    colorcomp = 255 ;
-	    colorgap *= -1 ;
+	    colorcomp = 255.0 ;
+	    colorgap *= -1.0 ;
 	 }
 	 int ystart = 0 + columnheight * run ;
 	 int xstart = 0 ;
 	 for ( int i = 0 ; i < columncount ; i++ ) {
-	    Color nextColor = new Color( colorcomp, colorcomp, colorcomp ) ;
+            int icolor = (int)Math.round(colorcomp) ; //round to nearer integer
+	    Color nextColor = new Color( icolor , icolor, icolor ) ;
 	    g.setColor( nextColor ) ;
 	    g.fillRect( xstart , ystart , columnwidth , columnheight ) ;
 	    xstart += columnwidth ;

Task/Greyscale-bars-Display/Kotlin/greyscale-bars-display.kotlin

@@ -0,0 +1,51 @@
+// version 1.1
+
+import java.awt.Color
+import java.awt.Graphics
+import javax.swing.JFrame
+
+class GreyBars : JFrame("grey bars example!") {
+    private val w: Int
+    private val h: Int
+
+    init {
+        w = 640
+        h = 320
+        setSize(w, h)
+        defaultCloseOperation = JFrame.EXIT_ON_CLOSE
+        isVisible = true
+    }
+
+    override fun paint(g: Graphics) {
+        var run = 0
+        var colorComp: Double  // component of the color
+        var columnCount = 8
+        while (columnCount < 128) {
+            var colorGap = 255.0 / (columnCount - 1) // by this gap we change the background color
+            val columnWidth = w / columnCount
+            val columnHeight = h / 4
+            if (run % 2 == 0)  // switches color directions with each iteration of while loop
+                colorComp = 0.0
+            else {
+                colorComp = 255.0
+                colorGap *= -1.0
+            }
+            val ystart = columnHeight * run
+            var xstart = 0
+            for (i in 0 until columnCount) {
+                val iColor = Math.round(colorComp).toInt()
+                val nextColor = Color(iColor, iColor, iColor)
+                g.color = nextColor
+                g.fillRect(xstart, ystart, columnWidth, columnHeight)
+                xstart += columnWidth
+	        colorComp += colorGap
+	    }
+            run++
+            columnCount *= 2
+        }
+    }
+}
+
+fun main(args: Array<String>) {
+    GreyBars()
+}

Task/Greyscale-bars-Display/Phix/greyscale-bars-display.phix

@@ -0,0 +1,70 @@
+--
+-- demo\rosetta\Greyscale_bars.exw
+--
+include pGUI.e
+
+Ihandle dlg, canvas
+cdCanvas cddbuffer, cdcanvas
+
+function redraw_cb(Ihandle /*ih*/, integer /*posx*/, integer /*posy*/)
+    cdCanvasActivate(cddbuffer)
+    integer {width, height} = IupGetIntInt(canvas, "DRAWSIZE")
+    integer h = ceil(height/4)
+    for row=1 to 4 do
+        integer x = 0, p2 = power(2,row+2), c = floor(255/(p2-1))
+        for n=0 to p2-1 do
+            integer colour = c*n*#010101
+            if and_bits(row,1)=0 then colour = xor_bits(colour,#FFFFFF) end if
+            cdCanvasSetForeground(cddbuffer, colour)
+            integer nx = ceil(width*(n+1)/p2)
+            cdCanvasBox(cddbuffer, x, nx, height-h, height)
+            x = nx
+      end for
+      height -= h
+    end for
+    cdCanvasFlush(cddbuffer)
+    return IUP_DEFAULT
+end function
+
+function map_cb(Ihandle ih)
+    cdcanvas = cdCreateCanvas(CD_IUP, ih)
+    cddbuffer = cdCreateCanvas(CD_DBUFFER, cdcanvas)
+    return IUP_DEFAULT
+end function
+
+function unmap_cb(Ihandle /*ih*/)
+    cdKillCanvas(cddbuffer)
+    cdKillCanvas(cdcanvas)
+    return IUP_DEFAULT
+end function
+
+function esc_close(Ihandle /*ih*/, atom c)
+    if c=K_ESC then return IUP_CLOSE end if
+    return IUP_CONTINUE
+end function
+
+procedure main()
+    IupOpen()
+
+    canvas = IupCanvas(NULL)
+    IupSetAttribute(canvas, "RASTERSIZE", "600x400")
+
+    IupSetCallback(canvas, "MAP_CB", Icallback("map_cb"))
+    IupSetCallback(canvas, "UNMAP_CB", Icallback("unmap_cb"))
+
+    dlg = IupDialog(canvas)
+    IupSetAttribute(dlg, "TITLE", "Greyscale bars")
+    IupSetCallback(canvas, "ACTION", Icallback("redraw_cb"))
+    IupSetCallback(dlg, "K_ANY", Icallback("esc_close"))
+
+    IupMap(dlg)
+    IupSetAttribute(canvas, "RASTERSIZE", NULL)
+
+    IupShowXY(dlg,IUP_CENTER,IUP_CENTER)
+
+    IupMainLoop()
+
+    IupClose()
+end procedure
+
+main()

Task/Greyscale-bars-Display/Zkl/greyscale-bars-display.zkl

@@ -0,0 +1,13 @@
+img:=PPM(640,480);
+foreach q in ([0..3]){		//quarter of screen
+   n:=(8).shiftLeft(q);         //number of bars
+   w:=640/n;			//width of bar (pixels)
+   foreach b in ([0..n-1]){	//for each bar...
+      c:=(255.0/(n-1).toFloat() * (if(q.isOdd) n-1-b else b)).toInt();
+      c:=c.shiftLeft(16) + c.shiftLeft(8) + c;   //RGB color = gray
+      foreach y in ([(3-q)*120 .. (3-q+1)*120-1]){  // flip image vertically
+         img.line(w*b,y, w*(b+1)-1,y, c);
+      }
+   }
+}
+img.write(File("foo.ppm","wb"));