Ideas for Higher Levels of the Tiling Program

• A call like this can copy the image from the image file into the buffer:

  getImage(buffer, filename, imgHeight, imgWidth) ;

  (Which of the parameters above are input, output, and input/output? Answer the same question for all your functions -- you'll have disasterous and hard-to-figure-out problems if you don't decide properly which parameters should be value params and which should be reference params.)
  
  
• What should the call above do? It could create an input file stream called "inFile" bound to the filename, read the first line of the file to get the values of imgHeight and imgWidth, then after making sure that input is set to start at the beginning of the second line, get the image by making a function call like this:

  getImageLine(buffer, inFile, lineNum, imgWidth); 

  one time for each value of lineNum from 0 to imgHeight-1. The job of getImageLine would be to copy the next line of the image file into the proper row of the buffer.
  
  After getImage loops through its calls to getImageLine, it should close the image file.
  
  
• What should this call do?

  getImageLine(buffer, inFile, lineNum, imgWidth); 

  It needs to copy each character individually with a call like this:

  inFile.get(buffer[lineNum][colNum]);

  This statement gets the next character from inFile and puts a copy into a particular location in the buffer. It puts it into the position whose row index is "lineNum" and whose column index is "colNum."
  
  getImageLine should contain a loop that executes this "get" statement once for each value of colNum from 0 to imgWidth-1. The value of lineNum should remain fixed within each call to getImageLine. (getImage takes care of getting all the lines into the buffer by calling getImageLine many times, each time with a new value of lineNum.)
  
  After copying all the characters on the current line getImageLine would have to read the newline character at the end of the line. That way the next time the program does some reading, the reading starts at the beginning of the next line.
  
  Since the "get" is a built-in function that operates on the input file stream that we have named "inFile" here, we don't have to worry about how to make the "get" do what it does. Therefore there are no more details regarding getting the image that need to be considered. (Yay!)
  
  
• A call like this can perform the tiling:

  doTileJob(buffer, numTileRows, numTileCols, imgHeight, imgWidth)

• What should function "doTileJob" do? It could do the tiling one row at a time by making a function call like this:

  makeRow(buffer,numTileCols,imgHeight,imgWidth)

  numTileRows times.
  
  (doTileJob has to make some blank lines before and after the loop in order to get the spacing to look right -- look closely at the sample run -- there are two blank lines in the output before the tiling starts and two more after it ends. )
  
  
• What should function "makeRow" do? It could make one row of the tiling by making this function call:

  makeRowLine(lineNum, buffer, numTileCols, imgWidth)

  once for each value of lineNum from 0 to imgHeight-1. Each call would make one line of the tiling on the screen.
  
  
• What should the function call:

  makeRowLine(lineNum, buffer, numTileCols, imgWidth)

  do? This function has to copy the same line out of the buffer repeatedly until it has made enough for the number of tiles that are supposed to go across in the tiling. It could make one line of the tiling by making this function call:

  writeBufRow(lineNum, buffer, imgWidth)

  numTileCols times. Each call would copy one line of the buffer to the output one time.
  
  At the very end, makeRowLine would have to output a newline character so that the next time the program does some writing, it starts at the beginning of a new line.
  
  
• What should the function call:

  writeBufRow(lineNum, buffer, imgWidth)

  do? The job of this function is just to execute this statement in a loop:

  cout << buffer[lineNum][charNum]

  The statement outputs a character in the buffer. It outputs the character in the row indexed by "lineNum" and the column indexed by "charNum." To write out a specific line in the buffer we need to hold lineNum fixed and vary charNum from 0 to imgWidth-1 in the loop.