Creating and Enriching Graphical User Interfaces - Beginning Java 7 - page 687

Figure 7-32. Select Negative from the Process menu to invert pixel components.
EXERCISES
ThefollowingexercisesaredesignedtotestyourunderstandingofAWT,Swing,and
Java 2D:
1. Create an AWT application named RandomCircles that presents a can-
vasfordisplayingfilledcircularovals(renderedvia fillOval() ).Anew
randomly colored, randomly positioned, and randomly sized (from 5 to 35
pixels for both the width and height—use the same value for each extent)
filledcircleisdisplayedbythe paint() methodatapplicationstartupand
eachtimethemousebuttonispressedwhilethemousepointerappearsover
the canvas. At startup, you might notice that the canvas first displays one
randomlycolored/positioned/sizedcircleandimmediatelydisplaysanother.
This has to do with AWT invoking the paint() method at least twice at
startup.Becauseyoudon'tknowhowmanytimes paint() willbecalled,
neverrelyon paint() tochangethestateofthecomponent.Instead,you
must only use this method to render the component in response to the cur-
rent state.
2. Modify Listing 7-6 ' s Swing-based TempVerter application to install the
Nimbus Look and Feel before the GUI is created.
3. Swing's AbstractButton class, which JButton extends, declares a
void setMnemonic(int mnemonic) methodforsettingakeyboard
mnemonic (memoryaid),whichservesasakeyboardshortcutalternativeto
clickingamousebutton.Theargumentpassedto mnemonic isoneofthe
virtual key constants declared in the KeyEvent class (e.g., VK_C ). When
you invoke this method, the first occurrence of the character (from left to
rightonthebuttonlabel)definedbythemnemonicisunderlined.Whenyou
press this key with the current look and feel's mouseless modifier (typic-
ally the Alt key), the button is clicked. Modify Listing 7-6 ' s Swing-based
TempVerter applicationtoassignthe VK_C mnemonictotheConvertto
Celsius button and the VK_F mnemonic to the Fahrenheit button.
4. The pseudo-splash screen created by Listing 7-3 ' s SplashCanvas class
suffersfromaliasingthatmakesthetextandgraphicslookjagged.Youcan
fixthisproblembyinstallingtheantialiasingrenderinghintbeforerendering
graphics.Createanewversionof SplashCanvas thattakesadvantageof
antialiasing.