Draw Gradient in Java ME
kiran10182
(Talk | contribs) m (Category added and formatted an article) |
(A class to draw gradients in J2ME) |
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| Line 23: | Line 23: | ||
for(int i = 0; i < max; i++) | for(int i = 0; i < max; i++) | ||
{ | { | ||
| − | int color = midColor(color1, color2, | + | int color = midColor(color1, color2, max * (max - 1 - i) / (max - 1), max); |
g.setColor(color); | g.setColor(color); | ||
| Line 34: | Line 34: | ||
} | } | ||
| − | static int midColor(int color1, int color2, int prop) | + | static int midColor(int color1, int color2, int prop, int max) |
{ | { | ||
int red = | int red = | ||
(((color1 >> 16) & 0xff) * prop + | (((color1 >> 16) & 0xff) * prop + | ||
| − | ((color2 >> 16) & 0xff) * ( | + | ((color2 >> 16) & 0xff) * (max - prop)) / max; |
int green = | int green = | ||
(((color1 >> 8) & 0xff) * prop + | (((color1 >> 8) & 0xff) * prop + | ||
| − | ((color2 >> 8) & 0xff) * ( | + | ((color2 >> 8) & 0xff) * (max - prop)) / max; |
int blue = | int blue = | ||
(((color1 >> 0) & 0xff) * prop + | (((color1 >> 0) & 0xff) * prop + | ||
| − | ((color2 >> 0) & 0xff) * ( | + | ((color2 >> 0) & 0xff) * (max - prop)) / max; |
int color = red << 16 | green << 8 | blue; | int color = red << 16 | green << 8 | blue; | ||
| Line 53: | Line 53: | ||
} | } | ||
} | } | ||
| + | |||
</code> | </code> | ||
Revision as of 10:44, 9 June 2008
Here is a J2ME class for gradients drawing, supporting both horizontal and vertical gradients.
This could be useful to substitute background gradient images with graphics drawn by code.
package com.jappit.wiki.gradientrect.graphics;
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;
}
}
and here is a sample Canvas using the gradientBox method (the final effect is shown in the screenshot at beginning of this article):
package com.jappit.wiki.gradientrect.display;
import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Graphics;
import com.jappit.wiki.gradientrect.graphics.Gradient;
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);
}
}
