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Monday, 19 March 2012

How to implement a volume slider in Blackberry

here is the function to implement the volume slider in your app , what you need is to make a class with the name "SliderField" and copy this function in it....you can use your own images for the slider as i did in my apps....and the constructor will give you the arguments you need to pass to this field....can be initialized as we initialize other fields in Blackberry...

package mypackage;

import java.lang.Math;

import net.rim.device.api.system.*;
import net.rim.device.api.ui.*;

public class SliderField extends Field
{
    Bitmap _imageThumb;
   
    Bitmap _imageSlider;
    Bitmap _imageSliderLeft;
    Bitmap _imageSliderCenter;
    Bitmap _imageSliderRight;
   
    Bitmap _imageSliderFocus;
    Bitmap _imageSliderFocusLeft;
    Bitmap _imageSliderFocusCenter;
    Bitmap _imageSliderFocusRight;

    private int _numStates;
    private int _currentState;
    private boolean _selected;

    private int _xLeftBackMargin;
    private int _xRightBackMargin;
   
    private int _thumbWidth;
    private int _thumbHeight;
       
    private int _totalHeight;
    private int _totalWidth;
   
    private int _rop;

    private int _backgroundColours[];
    private int _backgroundSelectedColours[];

    private int _defaultSelectColour = 0x977DED;
    private int _defaultBackgroundColour = 0x009ACD32;
    private int _defaultHoverColour = 0x999999;
   
 
    public SliderField( Bitmap thumb
                , Bitmap sliderBackground
                , int numStates
                , int initialState
                , int xLeftBackMargin
                , int xRightBackMargin )
    {
        this( thumb, sliderBackground, sliderBackground, numStates, initialState, xLeftBackMargin, xRightBackMargin, FOCUSABLE );
    }
   
    public SliderField( Bitmap thumb
                , Bitmap sliderBackground
                , int numStates
                , int initialState
                , int xLeftBackMargin
                , int xRightBackMargin
                , long style )
    { 
        this( thumb, sliderBackground, sliderBackground, numStates, initialState, xLeftBackMargin, xRightBackMargin, style );
    }
   
    public SliderField( Bitmap thumb
                , Bitmap sliderBackground
                , Bitmap sliderBackgroundFocus
                , int numStates
                , int initialState
                , int xLeftBackMargin
                , int xRightBackMargin )
    {
        this( thumb, sliderBackground, sliderBackgroundFocus, numStates, initialState, xLeftBackMargin, xRightBackMargin, FOCUSABLE );
    }
   
    public SliderField( Bitmap thumb
                , Bitmap sliderBackground
                , Bitmap sliderBackgroundFocus
                , int numStates
                , int initialState
                , int xLeftBackMargin
                , int xRightBackMargin
                , long style )
    {
        super( style );

        if( initialState > numStates || numStates < 2 ){
        }
        _imageThumb = thumb;
        _imageSlider = sliderBackground;
        _imageSliderFocus = sliderBackgroundFocus;
        _numStates = numStates;
        setState( initialState );

        _xLeftBackMargin = xLeftBackMargin;
        _xRightBackMargin = xRightBackMargin;

        _rop = _imageSlider.hasAlpha() ? Graphics.ROP_SRC_ALPHA : Graphics.ROP_SRC_COPY;

        _thumbWidth = thumb.getWidth();
        _thumbHeight = thumb.getHeight();
        initBitmaps();
    }             
    public SliderField( Bitmap thumb
                , Bitmap sliderBackground
                , int numStates
                , int initialState
                , int xLeftBackMargin
                , int xRightBackMargin
                , int[] colours
                , int[] selectColours )
    {
        this(thumb, sliderBackground, sliderBackground, numStates, initialState, xLeftBackMargin, xRightBackMargin, FOCUSABLE );

        if( colours.length != numStates+1 ){
            throw new IllegalArgumentException();
        }
        _backgroundColours = colours;
        _backgroundSelectedColours = selectColours;
    }
    public void initBitmaps()
    {
        int height = _imageSlider.getHeight();

        _imageSliderLeft = new Bitmap( _xLeftBackMargin, height );
        _imageSliderCenter = new Bitmap( _imageSlider.getWidth() - _xRightBackMargin - _xLeftBackMargin, height);
        _imageSliderRight = new Bitmap( _xRightBackMargin, height );

        copy( _imageSlider, 0, 0, _xLeftBackMargin, height, _imageSliderLeft );
        copy( _imageSlider, _xLeftBackMargin, 0, _imageSlider.getWidth() - _xRightBackMargin - _xLeftBackMargin, height, _imageSliderCenter);
        copy( _imageSlider, _imageSlider.getWidth() - _xRightBackMargin, 0, _xRightBackMargin, height, _imageSliderRight);
       
        _imageSliderFocusLeft = new Bitmap( _xLeftBackMargin, height );
        _imageSliderFocusCenter = new Bitmap( _imageSlider.getWidth() - _xRightBackMargin - _xLeftBackMargin, height);
        _imageSliderFocusRight = new Bitmap( _xRightBackMargin, height );
       
        copy( _imageSliderFocus, 0, 0, _xLeftBackMargin, height, _imageSliderFocusLeft );
        copy( _imageSliderFocus, _xLeftBackMargin, 0, _imageSlider.getWidth() - _xRightBackMargin - _xLeftBackMargin, height, _imageSliderFocusCenter);
        copy( _imageSliderFocus, _imageSlider.getWidth() - _xRightBackMargin, 0, _xRightBackMargin, height, _imageSliderFocusRight);
    }
    private void copy(Bitmap src, int x, int y, int width, int height, Bitmap dest) {
        int[] argbData = new int[width * height];
        src.getARGB(argbData, 0, width, x, y, width, height);
        for(int tx = 0; tx < dest.getWidth(); tx += width) {
            for(int ty = 0; ty < dest.getHeight(); ty += height) {
                dest.setARGB(argbData, 0, width, tx, ty, width, height);
            }
        }
    }
    public void setState(int newState) {
        if( newState > _numStates ){
            throw new IllegalArgumentException();
        } else {
            _currentState = newState;
            invalidate();
        }
    }
    public int getState() {
        return _currentState;
    }
    public int getNumStates() {
        return _numStates;
    }
    public int getColour() {
        if(_backgroundSelectedColours != null) {
            return _backgroundSelectedColours[getState()];
        }
        return 0x000000;
    }
   
    public int getPreferredWidth() {
        return _totalWidth;
    }

    public int getPreferredHeight() {
        return _totalHeight;
    }
    protected void layout( int width, int height ) {
        if (width < 0 || height < 0)
            throw new IllegalArgumentException();
        _totalWidth = width;
        _totalHeight = Math.max(_imageSlider.getHeight(), _imageThumb.getHeight());
       
        setExtent( _totalWidth, _totalHeight );
    }

    public void paint( Graphics g )
    {
        int sliderHeight = _imageSlider.getHeight();
        int sliderBackYOffset = ( _totalHeight - sliderHeight ) >> 1;
        int backgroundColor = _defaultBackgroundColour;
        if( _backgroundSelectedColours != null || _backgroundColours != null ) {
           
            if( _selected ) {
                backgroundColor = _backgroundSelectedColours != null ? _backgroundSelectedColours[getState()] : _defaultSelectColour;
            } else if(g.isDrawingStyleSet(Graphics.DRAWSTYLE_FOCUS)) {
                backgroundColor = _backgroundColours != null ? _backgroundColours[getState()] : _defaultHoverColour;
            } else {
                backgroundColor = _defaultBackgroundColour;
            }
        }
        g.setColor( backgroundColor );
        g.fillRect( 1, sliderBackYOffset + 1, _totalWidth - 2, sliderHeight - 2 );
   
        if(g.isDrawingStyleSet(Graphics.DRAWSTYLE_FOCUS)) {   
            paintSliderBackground( g, _imageSliderFocusLeft, _imageSliderFocusCenter, _imageSliderFocusRight );
        } else {
            paintSliderBackground( g, _imageSliderLeft, _imageSliderCenter, _imageSliderRight );
        }
        int thumbXOffset = ( ( _totalWidth - _thumbWidth ) * _currentState ) / _numStates;
        g.drawBitmap( thumbXOffset, ( _totalHeight - _thumbHeight ) >> 1, _thumbWidth, _thumbHeight, _imageThumb, 0, 0 );
    }

    private void paintSliderBackground( Graphics g, Bitmap left, Bitmap middle, Bitmap right )
    {
        int sliderHeight = _imageSlider.getHeight();
        int sliderBackYOffset = ( _totalHeight - sliderHeight ) >> 1;
        g.drawBitmap( 0, sliderBackYOffset, _xLeftBackMargin, sliderHeight, left, 0, 0 );
        g.tileRop( _rop, _xRightBackMargin, sliderBackYOffset, _totalWidth - _xLeftBackMargin - _xRightBackMargin, sliderHeight, middle, 0, 0 );
        g.drawBitmap( _totalWidth - _xRightBackMargin, sliderBackYOffset, _xRightBackMargin, sliderHeight, right, 0, 0 );
    }

    public void paintBackground( Graphics g )
    {
    }

    protected void drawFocus( Graphics g, boolean on )
    {
        boolean oldDrawStyleFocus = g.isDrawingStyleSet( Graphics.DRAWSTYLE_FOCUS );
        try {
            if( on ) {
                g.setDrawingStyle( Graphics.DRAWSTYLE_FOCUS, true );
            }
            paint( g );
        } finally {
            g.setDrawingStyle( Graphics.DRAWSTYLE_FOCUS, oldDrawStyleFocus );
        }
    }
    protected boolean touchEvent(TouchEvent message)
    {
        boolean isConsumed = false;
        boolean isOutOfBounds = false;
        int x = message.getX(1);
        int y = message.getY(1);
        if(x < 0 || y < 0 || x > getExtent().width || y > getExtent().height) {
            isOutOfBounds = true;
        }
        switch(message.getEvent()) {
            case TouchEvent.CLICK:
            case TouchEvent.MOVE:
                if(isOutOfBounds) return true;
                _selected = true;
               
                int stateWidth = getExtent().width / _numStates;
                int numerator = x / stateWidth;
                int denominator = x % stateWidth;
                if( denominator > stateWidth / 2 ) {
                    numerator++;
                }
                _currentState = numerator;
                invalidate();
               
                isConsumed = true;
                break;
            case TouchEvent.UNCLICK:
                if(isOutOfBounds) {
                    _selected = false;
                    return true;
                }
                _selected = false;
                stateWidth = getExtent().width / _numStates;
                numerator = x / stateWidth;
                denominator = x % stateWidth;
                if( denominator > stateWidth / 2 ) {
                    numerator++;
                }
                _currentState = numerator;
                invalidate();
                fieldChangeNotify(0);
                isConsumed = true;
                break;
        }
        return isConsumed;
    }
    protected boolean navigationMovement(int dx, int dy, int status, int time)
    {
        if( _selected )
        {
            if(dx > 0 || dy > 0) {
                incrementState();
                fieldChangeNotify( 0 );
                return true;
            } else if(dx < 0 || dy < 0) {
                decrementState();
                fieldChangeNotify( 0 );
                return true;
            }
        }
        return super.navigationMovement( dx, dy, status, time);
    }
    public void decrementState() {
        if(_currentState > 0) {
            _currentState--;
            invalidate();
        }
    }
    public void incrementState() {
        if(_currentState < _numStates) {
            _currentState++;
            invalidate();
        }
    }
    protected boolean invokeAction(int action) {
        switch(action) {
            case ACTION_INVOKE: {
                toggleSelected();
                return true;
            }
        }
        return false;
    }
    protected boolean keyChar( char key, int status, int time ) {
        if( key == Characters.SPACE || key == Characters.ENTER ) {
            toggleSelected();
            return true;
        }

        return false;
    }
    protected boolean trackwheelClick( int status, int time ) {
        if( isEditable() ) {
            toggleSelected();
            return true;
        }
        return super.trackwheelClick(status, time);
    }
    private void toggleSelected() {
        _selected = !_selected;
        invalidate();
    }
    public void setDirty( boolean dirty )
    { 
    }
    public void setMuddy( boolean muddy )
    {
    }
}

You can get the volume control of the player as you may know....and then just as we do with buttons...set a change listener for this SliderField and you can set the volume by using getState() function of this sliderField and setting it to the setLevel() of volumeControl of the player's.

Comment for any queries.....

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