Chapter 2, Problem 17PE

Program Plan Intro

  A “DoubleSizePicture” program

Program plan:

• In the file “Picture.java”, import necessary packages, and create a class “Picture”,
  • Declare necessary variables.
  • Define the constructor to construct a blank picture.
  • Define a method “getWidth()” to get the width of this picture.
  • Define a method “getHeight()” to get the height of this picture.
  • Define a method “load()” to load a picture from a given source.
  • Define a method “reload()” to reload the picture.
  • Define a method “pick()” to display a file chooser for picking a picture.
  • Define a method “move()” to move the picture by the given amount in x and y direction.
  • Define a method “scale()” to scale the picture to a new size. If the new size is smaller than the old size, the remainder is filled with transparent pixels. If it is larger, it is clipped.
  • Define a method “border()” to add a black border to the image.
  • Define a method “getColorAt()” to get the color of a pixel.
  • Define a method “setColorAt()” to set the color of a pixel.
  • Define a method “setImage()” to set the image.
• In the file “DoubleSizePicture.java”, create a class “DoubleSizePicture”,
  • Define the “main()” method,
    • Construct a blank picture and load image.
    • Call the method “load()” to load the picture.
    • Compute the center position.
    • Call the method “move()” to shift the picture left and up to clip off the left and top quarter of the original.
    • Compute the updated width and height
    • Call the method “scale()”  to scale the picture to half size.