问题
How do I implement an image button in BlackBerry?
回答1:
here you go, complete code:
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.ui.Graphics;
import net.rim.device.api.ui.component.ButtonField;
/**
* Button field with a bitmap as its label.
*/
public class BitmapButtonField extends ButtonField {
private Bitmap bitmap;
private Bitmap bitmapHighlight;
private boolean highlighted = false;
/**
* Instantiates a new bitmap button field.
*
* @param bitmap the bitmap to use as a label
*/
public BitmapButtonField(Bitmap bitmap, Bitmap bitmapHighlight) {
this(bitmap, bitmapHighlight, ButtonField.CONSUME_CLICK|ButtonField.FIELD_HCENTER|ButtonField.FIELD_VCENTER);
}
public BitmapButtonField(Bitmap bitmap, Bitmap bitmapHighlight, long style) {
super(style);
this.bitmap = bitmap;
this.bitmapHighlight = bitmapHighlight;
}
/* (non-Javadoc)
* @see net.rim.device.api.ui.component.ButtonField#layout(int, int)
*/
protected void layout(int width, int height) {
setExtent(getPreferredWidth(), getPreferredHeight());
}
/* (non-Javadoc)
* @see net.rim.device.api.ui.component.ButtonField#getPreferredWidth()
*/
public int getPreferredWidth() {
return bitmap.getWidth();
}
/* (non-Javadoc)
* @see net.rim.device.api.ui.component.ButtonField#getPreferredHeight()
*/
public int getPreferredHeight() {
return bitmap.getHeight();
}
/* (non-Javadoc)
* @see net.rim.device.api.ui.component.ButtonField#paint(net.rim.device.api.ui.Graphics)
*/
protected void paint(Graphics graphics) {
super.paint(graphics);
int width = bitmap.getWidth();
int height = bitmap.getHeight();
Bitmap b = bitmap;
if (highlighted)
b = bitmapHighlight;
graphics.drawBitmap(0, 0, width, height, b, 0, 0);
}
public void setHighlight(boolean highlight)
{
this.highlighted = highlight;
}
}
回答2:
Use RIM's Advanced UI Pack.
http://supportforums.blackberry.com/t5/Java-Development/Implement-advanced-buttons-fields-and-managers/ta-p/488276
This contains a BitmapButton field and a great number of of useful UI tools.
(No doubt Reflogs example is good, but I think for new BB developers landing on this page the Advanced UI pack is more beneficial)
回答3:
perfect ImageButton for Blackberry , According to user point of view a Imagebutton should have four states
1. Normal
2. Focus
3. Selected Focus
4. Selected unfocus
the Following code maintain all four states (Field-Change-Listener and Navigation)
if you want to maintain all four states than use 1st Constructor, If you just want to handle Focus/Un-Focu state of the button than use 2nd one
########################################
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.Graphics;
public class ImageButton extends Field
{
Bitmap mNormalIcon;
Bitmap mFocusedIcon;
Bitmap mActiveNormalIcon;
Bitmap mActiveFocusedIcon;
Bitmap mActiveBitmap;
String mActiveText;
int mHeight;
int mWidth;
boolean isStateActive = false;
boolean isTextActive = false;
public boolean isStateActive()
{
return isStateActive;
}
public ImageButton(Bitmap normalIcon, Bitmap focusedIcon)
{
super(Field.FOCUSABLE | FIELD_VCENTER);
mNormalIcon = normalIcon;
mFocusedIcon = focusedIcon;
mActiveBitmap = normalIcon;
mActiveFocusedIcon = focusedIcon;
mActiveNormalIcon = normalIcon;
// isTextActive = false;
}
public ImageButton(Bitmap normalIcon, Bitmap focusedIcon, Bitmap activeNormalIcon, Bitmap activeFocusedIcon)
{
super(Field.FOCUSABLE | FIELD_VCENTER);
mNormalIcon = normalIcon;
mFocusedIcon = focusedIcon;
mActiveFocusedIcon = activeFocusedIcon;
mActiveNormalIcon = activeNormalIcon;
mActiveBitmap = normalIcon;
// isTextActive = true;
}
protected void onFocus(int direction)
{
if ( !isStateActive )
{
mActiveBitmap = mFocusedIcon;
}
else
{
mActiveBitmap = mActiveFocusedIcon;
}
}
protected void onUnfocus()
{
super.onUnfocus();
if ( !isStateActive )
{
mActiveBitmap = mNormalIcon;
}
else
{
mActiveBitmap = mActiveNormalIcon;
}
}
protected boolean navigationClick(int status, int time)
{
mActiveBitmap = mActiveNormalIcon;
toggleState();
invalidate();
fieldChangeNotify(1);
return true;
}
public void toggleState()
{
isStateActive = !isStateActive;
}
public int getPreferredWidth()
{
return mActiveBitmap.getWidth() + 20;
}
public int getPreferredHeight()
{
return mActiveBitmap.getHeight() + 10;
}
protected void layout(int width, int height)
{
mWidth = getPreferredWidth();
mHeight = getPreferredHeight();
setExtent(mWidth, mHeight);
}
protected void paint(Graphics graphics)
{
graphics.drawBitmap(0, 5, mWidth, mHeight, mActiveBitmap, 0, 0);
// graphics.setColor(0xff0000);
// graphics.drawText(mActiveText, ( mActiveBitmap.getWidth() -
// this.getFont().getAdvance("ON") ) / 2, mActiveBitmap.getHeight());
}
protected void drawFocus(Graphics graphics, boolean on)
{
}
public void activate()
{
mActiveBitmap = mActiveNormalIcon;
isStateActive = true;
invalidate();
}
public void deactivate()
{
mActiveBitmap = mNormalIcon;
isStateActive = false;
invalidate();
}
}
回答4:
easiest way to do that:
step 1:draw a image with specific coordinates(imageX,imageY). step 2:add a method in your Code:
void pointerControl(int x, int y) {
if (x>imageX && x<imageX+imageName.getWidth() && y>imageY && y < imageY+imageName.getHeight) {
//to do code here
}
}
where imageName:name of image
imageX=x coordinate of image(Top-Left)
imageY=y coordinate of image(Top-Left)
来源：https://stackoverflow.com/questions/2912223/image-button-in-blackberry