Blackberry点击事件

Question

我在VerticalFieldManager中有一个ImageButton，在HorizontalFieldManager中有VFM。当我单击周围字段中的任意位置时，将触发ImageButton单击事件。我希望单击事件仅在单击ImageButton时触发，而不是字段(VFM或HFM)。

代码如下：

ImageButton Login = new ImageButton(configModel.getLoginButton(), FOCUSABLE|Field.FIELD_RIGHT, "login.png", "plogin.png",0x9cbe95);
HorizontalFieldManager hfm = new HorizontalFieldManager(USE_ALL_WIDTH);
VerticalFieldManager loginButtonVfm = new VerticalFieldManager(USE_ALL_WIDTH);

loginButtonVfm.add(Login);
hfm.add(loginButtonVfm);
add(hfm);


FieldChangeListener loginListener = new FieldChangeListener() { 
public void fieldChanged(Field field, int context) {
     Dialog.alert("Fired");
    }
}
Login.setChangeListener(loginListener); 

ImageButton类代码如下：

public class ImageButton extends Field{

        //Image Button Class 
        private String _label;
        private int _labelHeight;
        private int _labelWidth;
        private Font _font;

        private Bitmap _currentPicture;
        private Bitmap _onPicture;
        private Bitmap _offPicture;
        int color;

        public ImageButton(String text, long style ,String img, String img_hvr, int color){
            super(style);

            _offPicture = Bitmap.getBitmapResource(img);
            _onPicture = Bitmap.getBitmapResource(img_hvr);

            _font = Font.getDefault().derive(Font.BOLD, 7, Ui.UNITS_pt);
            _label = text;


            _labelHeight = _onPicture.getHeight();  
            _labelWidth = _onPicture.getWidth();

            this.color = color;

            _currentPicture = _offPicture;
        }
        public void setImage(String img){

            _offPicture = Bitmap.getBitmapResource(img); 
            _currentPicture = _offPicture;
        }

        /**
         * @return The text on the button
         */
        public void setText(String text){
            _label = text;
        }
            String getText(){
            return _label;
        }

        /**
         * Field implementation.
         * @see net.rim.device.api.ui.Field#getPreferredHeight()
         */
        public int getPreferredHeight(){
            return _labelHeight;
        }
        /**
         * Field implementation.
         * @see net.rim.device.api.ui.Field#getPreferredWidth()
         */
        public int getPreferredWidth(){
            return _labelWidth;
        }

        /**
         * Field implementation.  Changes the picture when focus is gained.
         * @see net.rim.device.api.ui.Field#onFocus(int)
         */
        protected void onFocus(int direction) {

             _currentPicture = _onPicture;
          //  invalidate();
            super.onFocus(direction);
        }

        /**
         * Field implementation.  Changes picture back when focus is lost.
         * @see net.rim.device.api.ui.Field#onUnfocus()
         */
        protected void onUnfocus() {
            _currentPicture = _offPicture;
            invalidate();
            super.onUnfocus();
        }

        /**
         * Field implementation.  
         * @see net.rim.device.api.ui.Field#drawFocus(Graphics, boolean)
         */
//      protected void drawFocus(Graphics graphics, boolean on) {
//          // Do nothing
//      }
        protected void drawFocus(Graphics graphics, boolean on) {
            if (on) {
                     //draw your own custom focus.
                    }
                }
        /**
         * Field implementation.
         * @see net.rim.device.api.ui.Field#layout(int, int)
         */
        protected void layout(int width, int height) {
            setExtent(Math.min( width, getPreferredWidth()),
            Math.min( height, getPreferredHeight()));
        }
        /**
         * Field implementation.
         * @see net.rim.device.api.ui.Field#paint(Graphics)
         */
        protected void paint(Graphics graphics){      
            // First draw the background colour and picture
            graphics.setColor(this.color);
            graphics.fillRect(0, 0, getWidth(), getHeight());
            graphics.drawBitmap(0, 0, getWidth(), getHeight(), _currentPicture, 0, 0);

            // Then draw the text
            graphics.setColor(Color.WHITE);
            graphics.setFont(_font);
            graphics.setFont(graphics.getFont().derive(Font.BOLD)); 
            graphics.drawText(_label, 5,9,
                (int)( getStyle() & DrawStyle.ELLIPSIS | DrawStyle.VALIGN_MASK | DrawStyle.HALIGN_MASK),
                getWidth() - 6 );

        }

        /**
         * Overridden so that the Event Dispatch thread can catch this event
         * instead of having it be caught here..
         * @see net.rim.device.api.ui.Field#navigationClick(int, int)
         */
        protected boolean navigationClick(int status, int time){
            fieldChangeNotify(1);
            return true;
        } 
}

Answer 1

当您尝试自己编写自定义字段时，这类事情实际上很容易找到bug。)这不是你的错。BlackBerry Java使这件事变得比实际情况下更难！)

我认为解决这个问题最简单的方法是重用别人已经测试过的东西。我建议您查看BlackBerry Advanced UI库，特别是这两个类：

BaseButtonField

BitmapButtonField

因为我认为他们做的就是你需要的。我认为您需要更改或添加到ImageButton类中的重要代码如下：

protected boolean keyChar( char character, int status, int time ) 
{
    if( character == Characters.ENTER ) {
        clickButton();
        return true;
    }
    return super.keyChar( character, status, time );
}

protected boolean navigationClick( int status, int time ) 
{
    if (status != 0) clickButton(); 
    return true;    
}

protected boolean trackwheelClick( int status, int time )
{        
    if (status != 0) clickButton();    
    return true;
}

protected boolean invokeAction( int action ) 
{
    switch( action ) {
        case ACTION_INVOKE: {
            clickButton(); 
            return true;
        }
    }
    return super.invokeAction( action );
}    

protected boolean touchEvent( TouchEvent message )
{
    int x = message.getX( 1 );
    int y = message.getY( 1 );
    if( x < 0 || y < 0 || x > getExtent().width || y > getExtent().height ) {
        // Outside the field
        return false;
    }
    switch( message.getEvent() ) {

        case TouchEvent.UNCLICK:
            clickButton();
            return true;
    }
    return super.touchEvent( message );
}

/**
 * A public way to click this button
 */
public void clickButton() 
{
    fieldChangeNotify( 0 );
}

然后，您将能够像现在一样使用FieldChangeListener，但图像按钮将不会调用它，除非单击按钮上的。

如果您愿意，当然可以将上面的代码更改为使用

    fieldChangeNotify( 1 );

如果1对您来说是一个有意义的上下文值。重要的是添加其他方法，并更改navigationClick()。