ArrowButton

Кнопка со стрелкой.

/**

* This class draws simple arrow buttons.

*/

final class ArrowButton extends Button {

 static final int NORTH = 0;

 static final int UP = 0;

 static final int WEST = 1;

 static final int RIGHT = 1;

 static final int SOUTH = 2;

 static final int DOWN = 2;

 static final int EAST = 3;

 static final int LEFT = 3;

 /** The default size of the Arrow buttons. */

 private static final float DEFAULT_SIZE = 9f;

 /** The Polygon that points up. */

 private static final float[] UP_POLY_X = new float[] { 0, 4, 8 };

 private static final float[] UP_POLY_Y = new float[] { 6, 2, 6 };

 /** The Polygon that points down. */

 private static final float[] DOWN_POLY_X = new float[] { 0, 4, 8 };

 private static final float[] DOWN_POLY_Y = new float[] { 2, 6, 2 };

 /** The Polygon that points left. */

 private static final float[] LEFT_POLY_X = new float[] { 6, 2, 6 };

 private static final float[] LEFT_POLY_Y = new float[] { 0, 4, 8 };

 /** The Polygon that points right. */

 private static final float[] RIGHT_POLY_X = new float[] { 2, 6, 2 };

 private static final float[] RIGHT_POLY_Y = new float[] { 0, 4, 8 };

 /** The direction to point in. */

 private int mDirection;

 ArrowButton(Context context, int direction) {

         super( context );

         setDirection( direction );

 }

 /**

  * This method returns the direction of the arrow.

  *

  * @return The direction of the arrow.

  */

 final int getDirection() {

         return mDirection;

 }

 /**

  * This method changes the direction of the arrow.

  *

  * @param dir The new direction of the arrow.

  */

 final void setDirection(final int dir) {

         mDirection = dir;

 }

 @Override

 protected final void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

         super.onMeasure( widthMeasureSpec, heightMeasureSpec );

         final int h = getMeasuredHeight();

         setMeasuredDimension( (h << 1) / 3, h );

 }

 @Override

 protected final void onDraw(Canvas canvas) {

         super.onDraw( canvas );

         float[] xpts = DOWN_POLY_X;

         float[] ypts = DOWN_POLY_Y;

         switch( mDirection ) {

         case UP:

                 xpts = UP_POLY_X;

                 ypts = UP_POLY_Y;

                 break;

         case RIGHT:

                 xpts = RIGHT_POLY_X;

                 ypts = RIGHT_POLY_Y;

                 break;

         case LEFT:

                 xpts = LEFT_POLY_X;

                 ypts = LEFT_POLY_Y;

                 break;

         }

         final int w = getWidth();

         final int h = getHeight();

         final float size = (float)(Math.min( w, h ) >> 1);

         final float[] xp = new float[xpts.length];

         final float[] yp = new float[ypts.length];

         final float scale = size / DEFAULT_SIZE;

         for( int i = 0, len = xp.length; i < len; i++ ) {

                 xp[i] = xpts[i] * scale;

                 yp[i] = ypts[i] * scale;

         }

         xpts = xp;

         ypts = yp;

         final float x = ((float)w - size) * 0.5f;

         final float y = ((float)h - size) * 0.5f;

         canvas.translate( x, y );

         //

         final Paint paint = new Paint();

         paint.setColor( getTextColors().getColorForState( getDrawableState(), Color.TRANSPARENT ) );

         paint.setStyle( Style.FILL );

         paint.setAntiAlias( true );

         //

         final Path path = new Path();

         path.moveTo( xpts[0], ypts[0] );

         for( int i = 0, len = xpts.length; i < len; i++ ) {

                 path.lineTo( xpts[i], ypts[i] );

         }

         path.close();

         //

         canvas.drawPath( path, paint );

         canvas.translate( -x, -y );

 }

}