Gradient

Poniżej prezentuje klasę umożliwiającą rysowanie gradienta poziomo lub pionowo:

import javax.microedition.lcdui.Graphics;

public class Gradient
{
	public static final int VERTICAL = 0;
	public static final int HORIZONTAL = 1;

	public static void gradientBox(Graphics g, int color1, int color2, int left, int top, int width, int height, int orientation)
	{
		int max = orientation == VERTICAL ? height : width;

		for(int i = 0; i < max; i++)
		{
			int color = midColor(color1, color2, max * (max - 1 - i) / (max - 1), max);

			g.setColor(color);

			if(orientation == VERTICAL)
				g.drawLine(left, top + i, left + width - 1, top + i);
			else
				g.drawLine(left + i, top, left + i, top + height - 1);
		}
	}

	static int midColor(int color1, int color2, int prop, int max)
	{
		int red =
			(((color1 >> 16) & 0xff) * prop +
			((color2 >> 16) & 0xff) * (max - prop)) / max;

		int green =
			(((color1 >> 8) & 0xff) * prop +
			((color2 >> 8) & 0xff) * (max - prop)) / max;

		int blue =
			(((color1 >> 0) & 0xff) * prop +
			((color2 >> 0) & 0xff) * (max - prop)) / max;

		int color = red << 16 | green << 8 | blue;

		return color;
	}

	public static int ScrollUp (int O_ILE, int aktualna_wartosc, int KoniecTekstu, int Limit) {
		int Scroll = aktualna_wartosc;
		int i = 0;
		// jezeli nie osiagnieto limitu w przesuwaniu, to mozna przesunac w gore tekst

		for (i = 0; i<O_ILE; i++) {
			if (Scroll < Limit) {
				Scroll = Scroll + 10;
			}
		}

		return Scroll;
	}

	public static int ScrollDown (int O_ILE, int aktualna_wartosc, int KoniecTekstu, int Limit) {
		int Scroll = aktualna_wartosc;
		int i = 0;

		for (i = 0; i<O_ILE; i++) {
			if (KoniecTekstu < Limit) {} else {
				Scroll = Scroll - 10;
			}
		}
		return Scroll;
	}
}

Przykładowe użycie :

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Graphics;
 
public class GradientRectCanvas extends Canvas { 
	protected void paint(Graphics g)
	{
		int halfWidth = getWidth() / 2;
		int halfHeight = getHeight() / 2;
 
		Gradient.gradientBox(g, 0xffffff, 0xff0000, 0, 0, halfWidth, halfHeight, Gradient.HORIZONTAL); 
		Gradient.gradientBox(g, 0xff0000, 0xffffff, halfWidth, 0, halfWidth, halfHeight, Gradient.VERTICAL); 
		Gradient.gradientBox(g, 0xffff00, 0x00ffff, 0, halfHeight, halfWidth, halfHeight, Gradient.VERTICAL); 
		Gradient.gradientBox(g, 0x00ff00, 0x0000ff, halfWidth, halfHeight, halfWidth, halfHeight, Gradient.VERTICAL);
	} 
}

Funkcja zaczerpnięta z forum nokii
http://wiki.forum.nokia.com/index.php/Draw_Gradient_in_Java_ME