bar.cpp

/////////////////////////////////////////////////////////////////////////
// Released under Public Domain.
/////////////////////////////////////////////////////////////////////////

#include <vector>
#include <iostream>

#define VECTOR_MIN -10
#define VECTOR_MAX 500
#define NUM_OF_VALUES 6

using std::cout;
using std::endl;
typedef std::vector<int> myVector;

//scroll bar abstraction
struct bar {
	//Data for the scroll bar abstraction
	int min, max, currPosition;
	
	//Constructor
	bar (int p_min, int p_max)
	:min(p_min), max(p_max), currPosition(p_min){}
	
	//move the scroll bar
	//to the right
	void move_right () {
		if (currPosition<max) ++currPosition;
	}
	//to the left
	void move_left () {
		if (currPosition>min) --currPosition;
	}
};

void print_values(myVector *v, bar b, int printed_values){
	
	//Total Size of the bar
	int bSize = (b.max - b.min);
	//Size of the Vector
	int vSize = (VECTOR_MAX - VECTOR_MIN);
	
	cout<<"\n\nCurrent Bar Position: "<<b.currPosition<<"\n";
	
	//Relative position in the bar.
	//	half the bar is 0.5
	//	one quarter from the left is 0.25
	//Get the current position from the left, from 0 to Size
	//					to abstract MIN and MAX
	float bRelativePosition =( b.currPosition - b.min );
	//Divide by the size to give us the relative position
	bRelativePosition /= (float)bSize;
	
	//Calculate the first value to be shown, using the bar position
	//						and the total size of the vector.
	int firstValue = (int)( (float)vSize * bRelativePosition );
	//Check whether the value need to be clipped in order to
	//			show all the wanted values.
	if ( (VECTOR_MAX - firstValue) < printed_values ) {
		firstValue = VECTOR_MAX - printed_values;
	}
	
	cout<<"Values, ranging from "<<firstValue<<
	" to "<<firstValue + printed_values-1<<" "<<" [position, value]\n";
	for (int i = firstValue; i < firstValue + printed_values; ++i) {
		cout<<"["<<i<<", "<<(*v)[i]<<"] ";
	}
	cout<<endl;
	
	
}

int main () {
	myVector v;
	
	//Create a bar with arbitrary MAX and MIN
	bar b(-30, 200);
	
	//Reserve the necessary memory
	v.reserve(VECTOR_MAX-VECTOR_MIN);
	
	//Go through the vector assigning values
	for (int i = 0; i < VECTOR_MAX-VECTOR_MIN; ++i){
		//Assign double the position value to each entry (arbitrary).
		v[i] = i*2;
	}
	
	
	int c; //Just to control our "console app bar"
	do {
		c = getchar(); //Update c (need to hit Enter)
		if (c == '+') b.move_right(); //numpad + moves it to the right
		else if (c == '-') b.move_left(); //numpad - moves it to the left
		
		print_values(&v, b, NUM_OF_VALUES); //print the numbers
	} while (c!='x'); // x char exits the application
	
	
	return 0;
}