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Draw Gradient in Java ME

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[[Category:Java ME]][[Category:Code Examples]][[Category:UI]][[Category:Graphics]]
 
[[Category:Java ME]][[Category:Code Examples]][[Category:UI]][[Category:Graphics]]
 
 
 
 
 
{{Abstract|Here is a [[J2ME]] class for gradients drawing, supporting both horizontal and vertical gradients.}}
 
{{Abstract|Here is a [[J2ME]] class for gradients drawing, supporting both horizontal and vertical gradients.}}
  
[[Image:J2me_gradients.jpg]]
+
[[File:J2me_gradients.jpg]]
  
 
This could be useful to substitute background gradient images with graphics drawn by code.
 
This could be useful to substitute background gradient images with graphics drawn by code.

Revision as of 01:05, 23 January 2012

Here is a J2ME class for gradients drawing, supporting both horizontal and vertical gradients.

J2me gradients.jpg

This could be useful to substitute background gradient images with graphics drawn by code.

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;
 
int color1RGB[] = new int[]{(color1>>16) & 0xff,(color1>>8) & 0xff,color1 & 0xff};
int color2RGB[] = new int[]{(color2>>16) & 0xff,(color2>>8) & 0xff,color2 & 0xff};
 
int colorCalc[] = new int[]{
(( color2RGB[0] - color1RGB[0] )<<16)/max,
(( color2RGB[1] - color1RGB[1] )<<16)/max,
(( color2RGB[2] - color1RGB[2] )<<16)/max
};
 
for(int i = max; i > -1; i--)
{
 
g.setColor(
(color1RGB[0]+((i*colorCalc[0])>>16)) <<16 |
(color1RGB[1]+((i*colorCalc[1])>>16)) <<8 |
(color1RGB[2]+((i*colorCalc[2])>>16))
);
 
if(orientation == VERTICAL)
g.drawLine(left, top + i, left + width - 1, top + i);
else
g.drawLine(left + i, top, left + i, top + height - 1);
}
}
}

and here is a sample Canvas using the gradientBox method (the final effect is shown in the screenshot at beginning of this article):

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);
}
 
}
Article Metadata
Code ExampleTested with
Devices(s): Nokia 7373, Nokia N82
Compatibility
Platform(s): Series 40, Symbian
Series 40
Symbian
S60 3rd Edition FP2
Device(s): MIDP2.0/CLDC 1.1
Article
Keywords: Draw, Gradient, Canvas, Graphics
Created: jappit (11 Apr 2008)
Updated: tiviinik (16 Jan 2012)
Last edited: hamishwillee (23 Jan 2012)
217 page views in the last 30 days.
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