このオプションを使用すると、コンポーネントに透明なカラーグラデーションをペイントできます。
@Override
public void paintComponent(Graphics g){
super.paintComponent( g );
Graphics2D g2=(Graphics2D)g.create();
int h = getHeight();
int w = getWidth();
g2.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, .5f));
g2.setPaint(new GradientPaint(0, 0, Color.yellow, 0, h, Color.red));
g2.fillRect(0, 0, w, h);
g2.dispose();
}
(要求に応じて)フェードインする他のかなり良い例。使用しRadialGradientPaint
ました。あなたはで遊ぶことができますAlphaComposite
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .4f));
ここで、4f
透明レベル40%を表します
@Override
public void paintComponent(Graphics g){
super.paintComponent( g );
Graphics2D g2=(Graphics2D)g.create();
int h = getHeight();
int w = getWidth();
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .5f));
Point2D center = new Point2D.Float(100, 50);
float radius = 150;
float[] dist = {0.0f, 1.0f};
Color[] colors = {Color.yellow, Color.red};
RadialGradientPaint p = new RadialGradientPaint(center, radius, dist, colors);
g2.setPaint(p);
g2.fillRect(0, 0, w, h);
g2.dispose();
}
最後に、アルファを動的に操作できます。彼女は完全なコードです。アルファを0から9に、またはその逆に変更する単純なスレッドを作成しました。どうぞ:
public class Fader extends JFrame{
private static final long serialVersionUID = 1L;
static JButton button;
public static float mTransparent = .0f;
Fader(){
super("A fading button");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new FlowLayout());
setSize(400,400);
JButton button = new CustomButton("Submit");
add(button);
setVisible(true);
Blink blink = new Blink(this);
blink.start();
}
public static void main(String args[]){
SwingUtilities.invokeLater(new Runnable(){public void run(){new Fader();}});
}
public static float getTransparentLevel() {
return mTransparent;
}
public void setTransparentLevel(float newVal) {
mTransparent = newVal;
if(button != null){
button.repaint();
}
repaint();
}
}
class Blink extends Thread{
Fader fader;
public Blink(Fader fader) {
this.fader = fader;
}
@Override
public void run(){
while(true){
if(Fader.getTransparentLevel() == 0.0f){
//increase to 1f
for(int i=1; i<10; i++){
fader.setTransparentLevel((float)i/10);
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
else if(Fader.getTransparentLevel() == 0.9f){
//increase to 1f
for(int i=10; i>=0; i--){
fader.setTransparentLevel((float)i/10);
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}
}
class CustomButton extends JButton {
private static final long serialVersionUID = 1L;
public CustomButton(String s) {
super(s);
}
@Override
public void paintComponent(Graphics g){
super.paintComponent( g );
Graphics2D g2=(Graphics2D)g.create();
int h = getHeight();
int w = getWidth();
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, Fader.getTransparentLevel()));
Point2D center = new Point2D.Float(100, 50);
float radius = 150;
float[] dist = {0.0f, 1.0f};
Color[] colors = {Color.yellow, Color.red};
RadialGradientPaint p = new RadialGradientPaint(center, radius, dist, colors);
g2.setPaint(p);
g2.fillRect(0, 0, w, h);
g2.dispose();
}
public Dimension getPreferredSize(){
return new Dimension(200,100);
}
}
スリープ時に.0から.9の透明度まで300ミリ秒点滅し、.9から.0まで戻ります。
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