June 2018 Update

Task/Bitmap-Write-a-PPM-file/REXX/bitmap-write-a-ppm-file.rexx

@@ -1,17 +1,21 @@
-/*REXX program to write a  PPM  formatted image file,  P6 (binary).     */
-oFID   = 'IMAGE.PPM'                   /*name of the output file.       */
-green  = '00 ff 00'x
-image. = green                         /*define all IMAGE RGB's to green*/
- width = 20                            /*define the  width of  IMAGE.   */
-height = 20                            /*  "     "  height  "    "      */
-   sep = '9'x
-call put 'P6'width||sep||height||sep||255||sep      /*write header info.*/
-
-  do j      =1  for width
-        do k=1  for height
-        call put image.j.k             /*write IMAGE, 3 bytes at a time.*/
-        end   /*k*/
-  end         /*j*/
-exit                                   /*stick a fork in it, we're done.*/
-/*─────────────────────────────────────subroutines──────────────────────*/
-put:  call charout oFID,arg(1); return /*write out character(s) to file.*/
+/*REXX program writes a  PPM  formatted image file, also known as a  P6  (binary) file. */
+green  = 00ff00                                  /*define a pixel with the color green. */
+parse arg oFN width height color .               /*obtain optional arguments from the CL*/
+if    oFN=='' |    oFN==","  then    oFN='IMAGE' /*Not specified?  Then use the default.*/
+if  width=='' |  width==","  then  width=   20   /* "      "         "   "   "     "    */
+if height=='' | height==","  then height=   20   /* "      "         "   "   "     "    */
+if  color=='' |  color==","  then  color= green  /* "      "         "   "   "     "    */
+oFID= oFN'.PPM'                                  /*define  oFID  by adding an extension.*/
+ @. = x2c(color)                                 /*set all pixels of image a hex color. */
+ $  = '9'x                                       /*define the separator (in the header).*/
+ #  = 255                                        /*  "     "  max value for all colors. */
+call charout oFID, ,  1                          /*set the position of the file's output*/
+call charout oFID,'P6'width || $ || height || $ || # || $     /*write file header info. */
+_=
+       do j     =1  for width
+            do k=1  for height;  _=_ || @.j.k    /*write the PPM file, 1 pixel at a time*/
+            end   /*k*/                          /* ↑    a pixel contains three bytes,  */
+       end        /*j*/                          /* └────which defines the pixel's color*/
+call charout oFID, _                             /*write the image's raster to the file.*/
+call charout oFID                                /*close the output file just to be safe*/
+                                                 /*stick a fork in it,  we're all done. */