imageset.java

一个j2me的游戏的实现.需要添加一个mathfp类来支持浮点数.

import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.Graphics;
import java.io.IOException;

/**
 * A container for sets of image frames; typically sprites. A single set
 * is made up of one or more states. Each state represents an animation sequence
 * including Image objects for the frames, animation timing and frame
 * dimensions. An example use of this class would be to animate a little dude.
 * If he had two states of existence, standing (which has short breathing
 * animation) and walking (which has a much longer animation). This would be
 * implemented by creating an ImageSet object and then adding two states, each
 * with their own Image array for all the animation frames (use the static
 * methods at the end of this class to load a clipped file image and then
 * extract the image frame array from it). You can then use a Sprite class
 * associated with this ImageSet to draw the character to the screen as well as
 * keep track of animation frames.
 * @author Martin J. Wells
 */
public class ImageSet
{
   private int totalStates;		// incremented by addState method only
   private Image[][] stateFrames;
   private int[] stateAnimTime, stateFrameWidth, stateFrameHeight;

   /**
    * Constructor for a new image. You will need to call addState to add the
    * various states (and their associated images and animation data) before
    * the object is really usable.
    * @param numStates The initial number of states (since ImageSet uses an
    * array internally (for speed) it costs a lot to expand the internal size
    * beyond this number -- typically you'll know the exact number of states
    * beforehand anyway. If not, the addState code will expand the array when
    * required.
    */
   public ImageSet(int numStates)
   {
      stateAnimTime = new int[numStates];
      stateFrameWidth = new int[numStates];
      stateFrameHeight = new int[numStates];
      stateFrames = new Image[numStates][];
   }

   /**
    * Adds a new state to the ImageSet including an array of images and the
    * number of milliseconds to animate the entire state (NOT each frame). If
    * this is not an animating set then just use 0 for the animtime. To animate
    * you will need to create a Sprite object linked to this ImageSet.
    * @param frames An array of javax.microedition.lcdui.Image objects.
    * @param animTime The number of milliseconds delay to animate ALL frames.
    */
   public final void addState(Image frames[], int animTime)
   {
      int state = totalStates++;

      if (state >= stateFrames.length)
      {
         // expand the number of states
         stateAnimTime = Tools.expandArray(stateAnimTime, 1);
         stateFrameWidth = Tools.expandArray(stateFrameWidth, 1);
         stateFrameHeight = Tools.expandArray(stateFrameHeight, 1);
         stateFrames = Tools.expandArray(stateFrames, 1);
      }

      stateAnimTime[state] = animTime;
      stateFrameWidth[state] = frames[0].getWidth();
      stateFrameHeight[state] = frames[0].getHeight();
      stateFrames[state] = frames;
   }

   /**
    * Gets the number of frames for a particular state in the ImageSet.
    * @param state The state you want to know about.
    * @return The number of frames in that state.
    */
   public final int getTotalFrames(int state)
   {
      return stateFrames[state].length;
   }

   /**
    * Gets the total amount time to animate all the frames of a given state.
    * Note this is not the delay per frame.
    * @param state The state you want to know about.
    * @return The animation delay (in milliseconds) corresponding to the given
    * state.
    */
   public final int getAnimTime(int state)
   {
      return stateAnimTime[state];
   }

   /**
    * Gets the amount of time to spend on each frame of a set to animate it.
    * This is just a convenience method that returns the animation time for
    * a state divided by the total number of frames.
    * @param state The state you want to know about.
    * @return The number of milliseconds delay for each frame of a given state.
    */
   public final int getAnimTimePerFrame(int state)
   {
      return stateAnimTime[state] / stateFrames[state].length;
   }

   /**
    * Draws a specific frame of this sprite onto a graphics context.
    * @param target The target graphics context to draw on.
    * @param state The state corresponding to the frame being drawn.
    * @param frame The number of the frame you want to draw.
    * @param targetX The x-position to draw the frame.
    * @param targetY The y-position to draw the frame.
    */
   public final void draw(Graphics target, int state, int frame, int targetX, int targetY)
   {
      if (stateFrames[state][frame] != null)
         target.drawImage(stateFrames[state][frame],
                          targetX, targetY, Tools.GRAPHICS_TOP_LEFT);
   }

   /**
    * Extract an Image corresponding to a particular state and frame.
    * @param state The state you're after.
    * @param frame The frame you're after.
    * @return The image corresponding to the given frame in the given state.
    */
   public final Image getFrame(int state, int frame)
   {
      return stateFrames[state][frame];
   }

   //
   // STATIC IMAGE TOOLS
   //

   /**
    * Static utility method to loap up a portion of an image from a file. Note
    * that the file must be in your JAR (or otherwise accessible) by the MID in
    * order to be loaded.
    * @param filename The name of the resource file to load.
    * @param originX The starting x position of the file image you want to load.
    * @param originY The starting y position of the file image you want to load.
    * @param width The width of the image you want to clip to.
    * @param height The height of the image you want to clip to.
    * @return A new Image object containing only the rectangle of originX,
    * originY, width and depth.
    */
   public final static Image loadClippedImage(String filename, int originX, int originY, int width,
                                              int height)
   {
      try
      {
         // load full image from file and create a mutable version
         Image fileImage = Image.createImage(filename);
         // use the getImageRegion method to extract out only the bit we want.
         return getImageRegion(fileImage, originX, originY, width, height);
      }

      catch (IOException ioe)
      {
         System.out.println("can't load file: " + filename);
         return null;
      }
   }

   /**
    * Static utility method to loap up a portion of an image from a file. Note
    * that the file must be in your JAR (or otherwise accessible) by the MID in
    * order to be loaded. The width and height of the portion is assumed to be
    * the size of the file image.
    * @param filename The name of the resource file to load.
    * @param originX The starting x position of the file image you want to load.
    * @param originY The starting y position of the file image you want to load.
    * @return A new Image object containing only the rectangle starting at
    * originX, originY.
    */
   public final static Image loadClippedImage(String filename, int originX, int originY)
   {
      try
      {
         // load full image from file and create a mutable version
         Image fileImage = Image.createImage(filename);

         // shortcut out of here so we can avoid creating another image if they
         // are just using this method to load an image normally (no clipping).
         if (originX == 0 && originY == 0) return fileImage;

         // use the getImageRegion method to extract out only the bit we want.
         return getImageRegion(fileImage, originX, originY, fileImage.getWidth(), fileImage.getHeight());
      }

      catch (IOException ioe)
      {
         System.out.println("can't load file: " + filename);
         return null;
      }
   }

   /**
    * Extracts a portion of an image using clipping.
    * @param source The source image.
    * @param x The starting x position of the clipping rectangle.
    * @param y The starting y position of the clipping rectangle.
    * @param width The width of the clipping rectangle.
    * @param height The height of the clipping rectangle.
    * @return A new Image object containing only the portion of the image
    * withing the x, y, width, height rectangle.
    */
   public final static Image getImageRegion(Image source, int x, int y, int width, int height)
   {
      // create a placeholder for our resulting image region
      Image result = Image.createImage(width, height);

      if (x + width > source.getWidth() || y + height > source.getHeight())
         System.out.println("Warning: attempting extract using (" +
                            x + "," + y + "," + width + "," + height + ") when image is " +
                            "(" + source.getWidth() + "," + source.getHeight() + ")");

      // draw the image, offset by the region starting position
      result.getGraphics().drawImage(source, -x, -y, Tools.GRAPHICS_TOP_LEFT);

      return result;
   }

   /**
    * Gets an array of images by breaking a larger image into smaller frames.
    * @param sourceImage The image to extract the frames from.
    * @param sourceX The starting x position in the source image to use.
    * @param sourceY The starting y position in the source image to use.
    * @param framesWide The number of frames across the source image to extract.
    * @param framesHigh The number of frames down the source image to extract.
    * @param frameWidth The width of each of those frames.
    * @param frameHeight The height of each of those frames.
    * @return An array containing an image for each frame.
    */
   public final static Image[] extractFrames(Image sourceImage, int sourceX,
                                             int sourceY,
                                             int framesWide, int framesHigh,
                                             int frameWidth, int frameHeight)
   {
      // extract all the frames from the source image
      Image[] frames = new Image[framesWide * framesHigh];
      int frameCount = 0;

      for (int fy = 0; fy < framesHigh; fy++)
         for (int fx = 0; fx < framesWide; fx++)
            frames[frameCount++] =
                    getImageRegion(sourceImage, sourceX + (fx * frameWidth),
                                   sourceY + (fy * frameHeight),
                                   frameWidth, frameHeight);
      return frames;
   }


}