Android简明开发教程十六：Button 画刷示例

将RadioButton 换成Button ，类似的在res/layout 中新建brush.xml：

<?xml version=”1.0″ encoding=”utf-8″?>
<LinearLayout xmlns:android=”http://schemas.android.com/apk/res/android”
android:orientation=”vertical”
android:background=”@drawable/white”
android:layout_width=”fill_parent”
android:layout_height=”fill_parent”>
<com.pstreets.graphics2d.GuidebeeGraphics2DView
android:id=”@+id/graphics2dview”
android:layout_weight=”1″
android:layout_width=”fill_parent”
android:layout_height=”wrap_content”/>
<LinearLayout xmlns:android=”http://schemas.android.com/apk/res/android”
android:layout_width=”wrap_content” android:layout_height=”wrap_content”
android:orientation=”horizontal”

>

<Button android:text=”Pattern”
android:id=”@+id/btnPattern”
android:layout_width=”wrap_content”
android:textColor=”@color/black”
android:checked=”true”
android:layout_height=”wrap_content”>
</Button>
<Button android:text=”Gradients”
android:id=”@+id/btnGradients”
android:layout_width=”wrap_content”
android:textColor=”@color/black”
android:layout_height=”wrap_content”>
</Button>

</LinearLayout>

</LinearLayout>

修改Brushes.java ,完整代码如下：

public class Brushes extends Graphics2DActivity
implements OnClickListener {

private Button btnPattern;
private Button btnGradients;

public void onCreate(Bundle savedInstanceState) {
super .onCreate(savedInstanceState);
setContentView(R.layout.brush);
graphic2dView = (GuidebeeGraphics2DView)
findViewById(R.id.graphics2dview);
btnPattern = (Button) findViewById(R.id.btnPattern);
btnGradients = (Button) findViewById(R.id.btnGradients);
btnPattern.setOnClickListener( this );
btnGradients.setOnClickListener( this );
}

@Override
protected void drawImage() {
drawPatterns();

}

@Override
public void onClick(View view) {
if (view == btnPattern) {
drawPatterns();
} else {
drawGradient();
}
graphic2dView.refreshCanvas();

}

private void drawPatterns() {
TextureBrush brush1;
TextureBrush brush2;
TextureBrush brush3;

AffineTransform matrix1 = new AffineTransform();
AffineTransform matrix2 = new AffineTransform();
Bitmap bitmap
= BitmapFactory.decodeResource(getResources(),
R.drawable.brick);
int [] rgbData = new int [bitmap.getHeight()
* bitmap.getWidth()];
bitmap.getPixels(rgbData, 0 , bitmap.getWidth(), 0 , 0 ,
bitmap.getWidth(), bitmap.getHeight());
brush1 = new TextureBrush(rgbData, bitmap.getWidth(),
bitmap.getHeight());

bitmap = BitmapFactory.decodeResource(getResources(),
R.drawable.bird);
rgbData = new int [bitmap.getHeight() * bitmap.getWidth()];
bitmap.getPixels(rgbData, 0 , bitmap.getWidth(), 0 , 0 ,
bitmap.getWidth(), bitmap.getHeight());
brush2 = new TextureBrush(rgbData, bitmap.getWidth(),
bitmap.getHeight());
brush3 = new TextureBrush(rgbData, bitmap.getWidth(),
bitmap.getHeight(), 127 );
matrix2.translate( 50 , 50 );
// Clear the canvas with white color.
graphics2D.clear(Color.WHITE);
graphics2D.setAffineTransform(matrix1);
graphics2D.fillRectangle(brush1,
new Rectangle( 20 , 50 , 100 , 100 ));
graphics2D.fillOval(brush2, 10 , 10 , 80 , 80 );
graphics2D.setAffineTransform(matrix2);
graphics2D.fillOval(brush3, 10 , 10 , 80 , 80 );

}

private void drawGradient() {
/* The linear gradient color */
LinearGradientBrush brush1;
/* The radial gradient color */
RadialGradientBrush brush2;
/* The second radial gradient color */
RadialGradientBrush brush3;

char [] engText = "Brush" .toCharArray();

FontEx font = FontEx.getSystemFont();

int fontSize = 44 ;
int X = 15 ;
int Y = 50 ;
int [] fractions = new int [] { 13 , 242 };
Color[] colors = new Color[] { new Color( 0xffff6600 ),
new Color( 0xffffff66 ) };
brush1 = new LinearGradientBrush( 50 , 50 , 150 , 125 ,
fractions, colors,
Brush.NO_CYCLE);

fractions = new int [] { 13 , 128 , 255 };
colors = new Color[] { new Color( 0xffff6600 ),
new Color( 0xffffff66 ),
new Color( 0xffff6600 ) };
brush2 = new RadialGradientBrush( 90 , 100 , 50 ,
fractions, colors);

fractions = new int [] { 0 , 255 };
colors = new Color[] { new Color( 0xFFFFFF00 ),
new Color( 0xFF000000 ) };
brush3 = new RadialGradientBrush( 50 , 50 , 100 ,
fractions, colors);
// Clear the canvas with white color.
graphics2D.clear(Color.white);
graphics2D.fillRectangle(brush1,
new Rectangle( 10 , 75 , 120 , 80 ));

Pen pen = new Pen(brush2, 8 );
graphics2D.drawOval(pen, 20 , 60 , 100 , 50 );
graphics2D.setDefaultBrush(brush3);
pen = new Pen(brush2, 2 );
graphics2D.setDefaultPen(pen);
graphics2D.drawChars(font, fontSize, engText, 0 ,
engText.length, X, Y);
}

}

介绍了RadioButton和Button 后，这时应该对使用Android提供的控件的用法有了基本的认识。 控件提供了onClick(),onLongClick(),onFocusChange(),onKey(),onTouch(),onCreateContextMenu()等多种事件以相应用户。用多种方法来处理用户事件。一种是示例代码同过Activity实现OnClickListener接口，再有是采用如下代码为Button支持事件处理方法：

// Create an anonymous implementation of OnClickListenerprivate
OnClickListener mCorkyListener = new OnClickListener() {
public void onClick(View v) {
// do something when the button is clicked
}
};

protected void onCreate(Bundle savedValues) {
...
// Capture our button from layout
Button button = (Button)findViewById(R.id.corky);
// Register the onClick listener with the implementation above
button.setOnClickListener(mCorkyListener);
...
}

在创建自定义控件时，也可以重载onKeyDown(int, KeyEvent),onKeyUp(int, KeyEvent) ,onTouchEvent(MotionEvent)等来处理用户事件。