How to highlight focused custom buttonfield (ImageButtonField) on Blackberry?

问题

I made a custom ButtonField class where I have an image as a button. However, I would like to be able to select this image and to know it is selected, either by partially highlighting it or putting a square around it, whatever. I have a BitmapField in my UI that highlights itself in blue when I select it, but my other images that use ImageButtonField, do not have the blue highlight. I do not want the bitmap to disappear completely when selected.

here is the code :

package mypackage;

import net.rim.device.api.system.Bitmap;
import net.rim.device.api.system.Characters;
import net.rim.device.api.ui.component.BitmapField;

    public class ImageButtonField extends BitmapField{

    public ImageButtonField(Bitmap image) {
        super(image);
    }

    public boolean isFocusable() {
        return true;
    }

    protected boolean navigationClick(int status, int time) {
        fieldChangeNotify(0);
        return true;
    }

    protected boolean trackwheelClick(int status, int time) {
        fieldChangeNotify(0);
        return true;
    }

    protected boolean keyChar(char character, int status, int time) {
        if(Characters.ENTER == character || Characters.SPACE == character) {
            fieldChangeNotify(0);
            return true;
        }
        return super.keyChar(character, status, time);
    }
}

Any help modifying this class so it works would help immensely. I have had no success trying to make this work!

回答1:

To remove default styling attributes you can add following methods:

protected void applyTheme(Graphics arg0, boolean arg1) {
}

protected void drawFocus(Graphics graphics, boolean on) {
}

You can override paint method and do paint whatever you want by checking focus status, e.g. following code will paint a red transparent layer over the bitmap image.

protected void paint(Graphics graphics) {
    super.paint(graphics);
    if (isFocus()) {
        graphics.setGlobalAlpha(128);
        graphics.setColor(0xFF0000);
        graphics.fillRect(0, 0, getWidth(), getHeight());
    }
}

Actually I didn't understand your question well :).

来源：https://stackoverflow.com/questions/9263949/how-to-highlight-focused-custom-buttonfield-imagebuttonfield-on-blackberry

标签

user-interface

blackberry

java-me