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/*******************************************************************************
* Copyright (c) 2006, 2015 IBM Corporation and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.swt.examples.graphics;
import java.util.LinkedList;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Device;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Path;
import org.eclipse.swt.graphics.Transform;
/**
* This tab uses alpha blending to simulate "ghosting" of a ball in movement.
*/
public class BallTab extends AnimatedGraphicsTab {
BallCollection[] bc;
/**
* This inner class serves as a container for the data needed to display a
* collection of balls.
*/
static class BallCollection {
float x, y; // position of ball
float incX, incY; // values by which to move the ball
int ball_size; // size (diameter) of the ball
int capacity; // number of balls in the collection
LinkedList<Float> prevx, prevy; // collection of previous x and y positions
// of ball
Color[] colors; // colors used for this ball collection
public BallCollection(float x, float y, float incX, float incY,
int ball_size, int capacity, Color[] colors) {
this.x = x;
this.y = y;
this.incX = incX;
this.incY = incY;
this.ball_size = ball_size;
this.capacity = capacity;
prevx = new LinkedList<>();
prevy = new LinkedList<>();
this.colors = colors;
}
}
@Override
public void dispose() {
bc[0] = bc[1] = bc[2] = bc[3] = bc[4] = null;
}
public BallTab(GraphicsExample example) {
super(example);
bc = new BallCollection[5];
}
@Override
public String getCategory() {
return GraphicsExample.getResourceString("Alpha"); //$NON-NLS-1$
}
@Override
public String getText() {
return GraphicsExample.getResourceString("Ball"); //$NON-NLS-1$
}
@Override
public String getDescription() {
return GraphicsExample.getResourceString("BallDescription"); //$NON-NLS-1$
}
@Override
public int getInitialAnimationTime() {
return 10;
}
@Override
public void next(int width, int height) {
for (int i = 0; i < bc.length; i++) {
if (bc[i] == null) return;
if (bc[i].prevx.isEmpty()) {
bc[i].prevx.addLast(Float.valueOf(bc[i].x));
bc[i].prevy.addLast(Float.valueOf(bc[i].y));
} else if (bc[i].prevx.size() == bc[i].capacity) {
bc[i].prevx.removeFirst();
bc[i].prevy.removeFirst();
}
bc[i].x += bc[i].incX;
bc[i].y += bc[i].incY;
float random = (float) Math.random();
// right
if (bc[i].x + bc[i].ball_size > width) {
bc[i].x = width - bc[i].ball_size;
bc[i].incX = random * -width / 16 - 1;
}
// left
if (bc[i].x < 0) {
bc[i].x = 0;
bc[i].incX = random * width / 16 + 1;
}
// bottom
if (bc[i].y + bc[i].ball_size > height) {
bc[i].y = (height - bc[i].ball_size) - 2;
bc[i].incY = random * -height / 16 - 1;
}
// top
if (bc[i].y < 0) {
bc[i].y = 0;
bc[i].incY = random * height / 16 + 1;
}
bc[i].prevx.addLast(Float.valueOf(bc[i].x));
bc[i].prevy.addLast(Float.valueOf(bc[i].y));
}
}
@Override
public void paint(GC gc, int width, int height) {
if (!example.checkAdvancedGraphics()) return;
Device device = gc.getDevice();
if (bc[0] == null) {
bc[0] = new BallCollection(0, 0, 5, 5, 20, 20, new Color[] { device
.getSystemColor(SWT.COLOR_GREEN) });
bc[1] = new BallCollection(50, 300, 10, -5, 50, 10,
new Color[] { device.getSystemColor(SWT.COLOR_BLUE) });
bc[2] = new BallCollection(250, 100, -5, 8, 25, 12,
new Color[] { device.getSystemColor(SWT.COLOR_RED) });
bc[3] = new BallCollection(150, 400, 5, 8, 35, 14,
new Color[] { device.getSystemColor(SWT.COLOR_BLACK) });
bc[4] = new BallCollection(100, 250, -5, -18, 100, 5,
new Color[] { device.getSystemColor(SWT.COLOR_MAGENTA) });
}
for (BallCollection ballCollection : bc) {
for (int i = 0; i < ballCollection.prevx.size(); i++) {
Transform transform = new Transform(device);
transform.translate(ballCollection.prevx.get(ballCollection.prevx.size()
- (i + 1)).floatValue(), ballCollection.prevy
.get(ballCollection.prevy.size() - (i + 1)).floatValue());
gc.setTransform(transform);
transform.dispose();
Path path = new Path(device);
path.addArc(0, 0, ballCollection.ball_size, ballCollection.ball_size, 0, 360);
gc.setAlpha(255 - i * (255 / ballCollection.capacity));
gc.setBackground(ballCollection.colors[0]);
gc.fillPath(path);
gc.drawPath(path);
path.dispose();
}
}
}
}
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