Why won't my image display in my Java Applet? -

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when use following code:

    public void paint(graphics g){      //displays version number , name.     g.setfont(new font("courier", font.plain, 10));     g.drawstring("dcoder " + execute.execute.version, 2, 10);      //displays logo in center.     g.drawimage(logo, centeralign(logo.getwidth(null)), 50, this);   }  private int width(){     //gets , returns width of applet.     int width = getsize().width;     return width; } private int height(){     //gets , returns height of applet.     int height = getsize().height;     return height; }  private int centeralign(int obwidth){     int align = (width()-obwidth)/2;     return align; }

in java applet, image not display until call repaint() (by resizing applet viewer window)? why won't image display?

an asynchronous loaded image has handled thus.

logo.getwidth(this); // indicate asynchronous imageobserver

...

@override public boolean imageupdate(image img,               int infoflags,               int x,               int y,               int width,               int height) {     if ((infoflags & imageobserver.allbits) == imageobserver.allbits) {         // image entirely read.         repaint();     } }

when asynchronous reading image, getwidth(null) return 0 till width determined etcetera. therefore 1 needs bit careful.

explanation

loading images designed done asynchronously. image available, before being read getwidth and/or getheight -1. can pass imageobserver getwidth/getheight, notified during image reading. japplet imageobserver, can pass this.

the reading code passed/registered imageobserver's method imageupdate signal change; width known, somebits (= not all), 1 draw preview, in jpeg pixelized preview.

this asynchrone technique in earlier days of slow internet needed.

if want read image simpler, use imageio.read(...).


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