Represents an arrangement of many images that is output as a single image when the user calls drawscene(). More...

#include "scene.h"

Public Member Functions
	Scene (int max)
	Initializes this Scene object to be able to hold "max" number of images with indices 0 through max-1. More...

	~Scene ()
	Frees all space that was dynamically allocated by this Scene. More...

	Scene (const Scene &source)
	The copy constructor makes this Scene an independent copy of the source. More...

const Scene &	operator= (const Scene &source)
	The assignment operator for the Scene class. More...

void	changemaxlayers (int newmax)
	Modifies the size of the array of Image pointers without changing their indices. More...

void	addpicture (const char *FileName, int index, int x, int y)
	This function will add a picture to the scene, by placing it in the array cell corresponding to the given index, and storing its x coordinate and y coordinate. More...

void	changelayer (int index, int newindex)
	Moves an Image from one layer to another. More...

void	translate (int index, int xcoord, int ycoord)
	Changes the x and y coordinates of the Image in the specified layer. More...

void	deletepicture (int index)
	Deletes the Image at the given index. More...

Image *	getpicture (int index) const
	This function will return a pointer to the Image at the specified index, not a copy of it. More...

Image	drawscene () const
	Draws the whole scene on one Image and returns that Image by value. More...

Detailed Description

Represents an arrangement of many images that is output as a single image when the user calls drawscene().

Constructor & Destructor Documentation

Scene::Scene ( int max )

Initializes this Scene object to be able to hold "max" number of images with indices 0 through max-1.

This function will set up the Scene to hold "max" Images by (1) dynamically allocating an array of Image pointers of size "max", (2) initializing all of them to NULL, (3) creating storage for the coordinates, and (4) storing "max" as a member variable.

Parameters

max	The maximum number of layers in this Scene

Note: You may assume that max > 0.

Scene::~Scene ( )

Frees all space that was dynamically allocated by this Scene.

Scene::Scene ( const Scene & source )

The copy constructor makes this Scene an independent copy of the source.

Hint: Create a copy() helper function and call it here.

Parameters

source The other Scene object to copy data from

Member Function Documentation

const Scene & Scene::operator= ( const Scene & source )

The assignment operator for the Scene class.

It does the following: (1) checks for self assignment, (2) then deletes everything this Scene has allocated, (3) then makes this Scene an independent copy of the source, (4) then returns a reference to the current instance.

Hint: Create copy() and clear() helper functions and call them here.

Parameters

source The other Scene object to copy data from

Returns: a constant Scene reference

void Scene::changemaxlayers ( int newmax )

Modifies the size of the array of Image pointers without changing their indices.

The new set of valid indices will be from 0 to (newmax - 1).

A new array of Image pointers of size newmax will be allocated, and the non-null pointers in the old array will be copied over before the old array is deleted. If this cannot be done because there are non-null pointers outside the range [0, newmax-1], use the following code to print an error message:

cout << "invalid newmax" << endl;

In the case of an error this function call should not cause any change to the Scene.

Parameters

newmax The new value for the maximum number of Images in the Scene.

Note: You may assume newmax is greater than zero.

void Scene::addpicture	(	const char *	FileName,
		int	index,
		int	x,
		int	y
	)

This function will add a picture to the scene, by placing it in the array cell corresponding to the given index, and storing its x coordinate and y coordinate.

If there is already an Image in cell location index it should be replaced by the new Image. If the index is not within the range [0, max-1], use the following code to print an error message:

cout << "index out of bounds" << endl;

Hint: Make use of the PNG member function (which was inherited by the Image class) for loading an Image from a file.

Parameters

FileName	The name of the image file to read in
index	Which "layer" this png resides in
x	The x location of the new png
y	The y location of the new png

Note: You may assume that x and y are integers in the range [0, MAXINT].

void Scene::changelayer	(	int	index,
		int	newindex
	)

Moves an Image from one layer to another.

You are not allowed to dynamically allocate anything in this function. Rather, just move the pointer.

If the new index is the same as the old index, do nothing and return. If the destination is already occupied, delete the image there. The source index should be marked vacant by making it value NULL. If either index is invalid, do nothing and use the following code to print an error message:

cout << "invalid index" << endl;

Parameters

index	The source index location
newindex	The destination index location

Note that we do not prevent the user from requesting that a NULL Image pointer be moved to an occupied spot.

void Scene::translate	(	int	index,
		int	xcoord,
		int	ycoord
	)

Changes the x and y coordinates of the Image in the specified layer.

If the index is invalid or if it contains a NULL pointer, do nothing and use the following code to print an error message:

cout << "invalid index" << endl;

Parameters

index	Which layer to operate on
xcoord	The x coordinate value to move the png to
ycoord	The y coordinate value to move the png to

Note: You may assume that x and y are integers in the range [0, MAXINT].

void Scene::deletepicture ( int index )

Deletes the Image at the given index.

If the index is invalid or if it contains a NULL pointer, do nothing and use the following code to print an error message:

cout << "invalid index" << endl;

Parameters

index The layer in which to delete the png

Image * Scene::getpicture ( int index ) const

This function will return a pointer to the Image at the specified index, not a copy of it.

That way, the user can modify the Image. If the index is invalid, return NULL and print an error message:

cout << "invalid index" << endl;

Returns: a pointer to a specific Image in the Scene

Image Scene::drawscene ( ) const

Draws the whole scene on one Image and returns that Image by value.

Images in the scene will be drawn in order from index 0 to index (max-1) at the stored coordinates. Do not use the alpha channel or any other transparency.

Hint: The x and y coordinates of an Image are the coordinates of its upper-left corner pixel in the output of this function.

Hint: First determine the minimum width and height necessary to ensure that none of the images go off of the bottom or the right edge of the returned image, and make sure your returned image has that width and height.

Returns: an Image object representing the drawn scene

The documentation for this class was generated from the following files:

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation