Swing Hacks

Animate Transitions Between Tabs #8

Chapter 1, Basic JComponents

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37

HACK

Another Example

Because TransitionTabbedPane makes it so easy to build new animations, I

thought I’d add another one. This is the old venetian blinds effect, where

vertical bars cover the old screen and uncover the new one; Example 1-19

puts it together.

JTabbedPane tab = new InOutPane( );

tab.addTab("t1",new JButton("Test Button 1"));

tab.addTab("t2",new JButton("Test Button 2"));

frame.getContentPane( ).add(tab);

frame.pack( );

frame.show( );

}

}

Figure 1-23. Two tabs, before transition effect begins

Figure 1-24. Tab transition at mid-point

Example 1-18. Testing out tabbed animation transitions (continued)

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Chapter 1, Basic JComponents

#8 Animate Transitions Between Tabs

HACK

Just like InOutPane, VenetianPane selectively draws the old tab and then cal-

culates the placement of animated rectangles. In this case, there is a blind

rectangle that spans the entire screen from top to bottom, but has the width

of the current step. As a result of the step growing, this rectangle gets bigger

Example 1-19. Creating a venetian blinds effect

public class VenetianPane extends TransitionTabbedPane {

public void paintTransition(Graphics2D g2, int step,

Rectangle size, Image prev) {

int length = getAnimationLength( );

int half = length/2;

// create a blind

Rectangle blind = new Rectangle( );

// calculate the fade out part

if(step >= 0 && step < half) {

// draw the saved version of the old tab component

if(prev != null) {

g2.drawImage(prev,(int)size.getX(),(int)size.getY( ),null);

}

// calculate the growing blind

blind = new Rectangle(

(int)size.getX( ),

(int)size.getY( ),

step,

(int)size.getHeight( ));

}

// calculate the fade in part

if(step >= half && step < length) {

// calculate the shrinking blind

blind = new Rectangle(

(int)size.getX( ),

(int)size.getY( ),

length-step,

(int)size.getHeight( ));

blind.translate(step-half,0);

}

// draw the blinds

for(int i=0; i<size.getWidth( )/half; i++) {

g2.setColor(Color.white);

g2.fill(blind);

blind.translate(half,0);

}

}

}