8. Images

8. Images
	Chapter 10. Graphic User Interface

8.1. Loading Images

The Applet class uses two getImage() methods to load images:

public Image getImage(URL url)
public Image getImage(URL url, String name)

The Toolkit class declares two more getImage() methods to load images:

public abstract Image getImage(URL url)
public abstract Image getImage(String filename)

Toolkit toolkit = Toolkit.getDefaultToolkit();
Image image1 = toolkit.getImage("imageFile.gif");
Image image2 = toolkit.getImage(new URL("http://java.sun.com/graphics.gif"));

8.1.1. Creating Images with MemoryImageSource

With the help of an image producer such as the MemoryImageSource class, you can construct images from scratch:

int w = 100;
int h = 100;
int[] pix = new int[w * h];
int index = 0;
for (int y = 0; y < h; y++) {
    int red = (y * 255) / (h - 1);
    for (int x = 0; x < w; x++) {
          int blue = (x * 255) / (w - 1);
          pix[index++] = (255 << 24) | (red << 16) | blue;
    }
}
Image img = createImage(new MemoryImageSource(w, h, pix, 0, w));

8.2. Displaying Images

Normal size in the upper left corner of the Component area (0, 0):
g.drawImage(image, 0, 0, this);
Scaled to be 300 pixels wide and 62 pixels tall, starting at the coordinates (90, 0):
g.drawImage(myImage, 90, 0, 300, 62, this);

	Note
	The `drawImage()` method returns after displaying the image data that has been loaded, so far.

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8.3. Image Filters

Figure 10.37. Image Filters

An image producer: It produces raw data for Image objects and implements the ImageProducer interface.
An image consumer: It is an object interested in data produced by image producers and implements the ImageConsumer interface.
An image consumer: It is an object interested in data produced by image producers and implements the ImageConsumer interface.

8.3.1. Using an Image Filter

Code for a rotation filter:

ImageFilter filter = new RotateFilter(angle);
ImageProducer producer = new FilteredImageSource(sourceImage.getSource(), filter);
resultImage = createImage(producer);
repaint();

8.3.2. Writing an Image Filter

Creating an ImageFilter subclass:

Image filters implement the ImageConsumer interface.

void setDimensions(int width, int height);
void setProperties(Hashtable props);
void setColorModel(ColorModel model);
void setHints(int hintflags);
void setPixels(int x, int y, int w, int h,
               ColorModel model, byte pixels[],
               int off, int scansize);
void setPixels(int x, int y, int w, int h,
               ColorModel model, int pixels[],
               int off, int scansize);
void imageComplete(int status);