Creating a volume slider for VLCJ audio

I am trying to create an volume level bar where different level's of volume are represented with an different color here is my approach

I have 2 arrays

Color[] scales gives different color representation for each volume level if the length of this array is lets say 4 then there are 4 volume level's and so on

float[] weights denotes how much percentage/space each color should occupy in the bar

For example

private final Color scales[]={Color.GREEN,Color.YELLOW,Color.RED};
private final float weights[]={0.3f,0.2f,0.5f};

means there are 3 levels of volume where

1. if the current volume is <=30% of max then 30% of the volume bar is covered in GREEN

2. if the current volume is >30% and <= (30+20)=50% the next 20% of the volume bar is covered in YELLOW

3. if the current volume is >50% and <= (50+50)=100% the final 50% of the volume bar is covered in RED

Now the user interacts with the volume bar by clicking & dragging the mouse hence let' say if the volume bar has dimensions (x=120,y=50) and lets say I click or drag till Xposition=25 then

30% of 120=36
XPosition=25
25<36 hence must draw an green color rect of dimensions x=0,y=0,width=36-25=12,height=50

and we continue likewise for the remaining positions calculating where the user clicks and drawing different color rectangles till that point.

Now I think I butchered the explanation but I am not asking for the code I already have it implemented here

final class VolumeBar extends JPanel 
{
VolumeBar()
{
super(new BorderLayout());
add(Box.createRigidArea(new Dimension(500,100)),BorderLayout.NORTH);
add(Box.createRigidArea(new Dimension(500,100)),BorderLayout.SOUTH);
JPanel container=new JPanel(new BorderLayout());
container.add(Box.createRigidArea(new Dimension(120,50)),BorderLayout.WEST);
container.add(Box.createRigidArea(new Dimension(120,50)),BorderLayout.EAST);
container.add(new JVolume(),BorderLayout.CENTER);
add(container,BorderLayout.CENTER);
}
private final class JVolume extends JLabel
{
private final Color scales[]={Color.GREEN,Color.YELLOW,Color.RED};
private final float weights[]={0.6f,0.2f,0.2f};
private int endingX;
private JVolume()
{
addMouseMotionListener(new Drag());
addMouseListener(new Click());
setPreferredSize(new Dimension(260,50));
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2d=(Graphics2D)g;
Dimension size=getSize();
float endPoints[]=new float[scales.length+1];
endPoints[0]=0;
for(int i=1;i<endPoints.length;i++){endPoints[i]=endPoints[i-1]+(size.width*weights[i-1]);}
for(int i=1;i<endPoints.length;i++)
{
float
prev=endPoints[i-1],
current=endPoints[i];
if(endingX>prev) 
{
g2d.setColor(scales[i-1]);
g2d.fill(new Rectangle2D.Float(prev,0,endingX>current?current-prev:endingX-prev,size.height));       
}
else{break;}
}
g2d.setColor(getBackground());
Polygon clear=new Polygon();
clear.addPoint(0,0);
clear.addPoint(size.width,0);
clear.addPoint(0,size.height);
clear.addPoint(0,0);
g2d.fill(clear);  //clear the upper left triangle with background to make it look like an increasing triangle
g2d.setColor(Color.BLACK);  draw the lower right triangle to give the bar some border
Polygon polygon=new Polygon();
polygon.addPoint(1,size.height-1);
polygon.addPoint(size.width-1,1);
polygon.addPoint(size.width-1,size.height-1);
polygon.addPoint(1,size.height-1);
g2d.drawPolygon(polygon);
}
private void compute(MouseEvent m)
{
endingX=m.getX();
repaint();
}
private final class Drag extends MouseMotionAdapter
{
@Override
public void mouseDragged(MouseEvent m){compute(m);}
}
private final class Click extends MouseAdapter
{
@Override
public void mouseClicked(MouseEvent m){compute(m);}
}
}
}

And here is how it look's like just click or drag anywhere on the bar

Look's great for the most part but what I am aiming for is the volume bar in VLC media player

Forgive the blurriness, I had to scale the image up but if you look closely you can notice how the color's blend at the boundary for example there is an gradient from green->yellow making some white in between at the boundary and there is an gradient from yellow->red making some orange in between

I want to achieve this gradient.

Ideas anyone?

As recommended by @AndrewThompson in the comments above you can use MultipleGradientPaint using a LinearGradientPaint.

Currently I'm confused by which of the 2 you need, above you said:

> 1. if the current volume is <=30% of max then 30% of the volume bar is covered in GREEN
>
> 2. if the current volume is >30% and <= (30+20)=50% the next 20% of the volume bar is covered in YELLOW
>
> 3. if the current volume is >50% and <= (50+50)=100% the final 50% of the volume bar is covered in RED

And then you said:

> I need 60% of my bar in green then 20% in yellow not the other way around which is what LinearGradient requires.you see why it's a problem now?

But those are just numbers.

What you can do is create your LinearGradientPaint this way:

Rectangle2D rect = new Rectangle2D.Double(10, 10, 250, 150);
Point2D startPoint = new Point2D.Double(rect.getMinX(), rect.getCenterY());
Point2D endPoint = new Point2D.Double(rect.getMaxX(), rect.getCenterY());
float[] percentages = new float[] {0.0f, 0.6f, 0.8f};
Color[] colors = new Color[] {Color.GREEN, Color.YELLOW, Color.RED};
LinearGradientPaint gradient = new LinearGradientPaint(startPoint, endPoint, percentages, colors, CycleMethod.REPEAT);

You were confused at where you need to start the gradient because I guess your percentages were: 0.6f, 0.2f, 0.2f but instead you need to define the start point and then add the next percentage from there, 0.0f, 0.6f, 0.8f (This will start at 0% then go up to 60% to green, and then up to 80% to yellow, and then the rest to 100% on red.

And you get this output.

MRE for you to test changes:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.LinearGradientPaint;
import java.awt.RenderingHints;
import java.awt.MultipleGradientPaint.CycleMethod;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class LinearGradientExample {
private JFrame frame;
private JPanel pane;
public static void main(String[] args) {
SwingUtilities.invokeLater(new LinearGradientExample()::createAndShowGUI);
}
@SuppressWarnings("serial")
private void createAndShowGUI() {
frame = new JFrame(getClass().getSimpleName());
Rectangle2D rect = new Rectangle2D.Double(10, 10, 250, 150);
Point2D startPoint = new Point2D.Double(rect.getMinX(), rect.getCenterY());
Point2D endPoint = new Point2D.Double(rect.getMaxX(), rect.getCenterY());
float[] percentages = new float[] {0.0f, 0.6f, 0.8f};
Color[] colors = new Color[] {Color.GREEN, Color.YELLOW, Color.RED};
LinearGradientPaint gradient = new LinearGradientPaint(startPoint, endPoint, percentages, colors, CycleMethod.REPEAT);
pane = new JPanel() {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setPaint(gradient);
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.fill(rect);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(300, 200);
}
};
frame.add(pane);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
}