Blackberry - background image/animation RIM OS 4.5.0 - user-interface

Question

Please help me, how to set a background image for screen and How to do animations on any-field or on text?
Thank You....

Answer 1

Background image
In Screen class there is a protected void paintBackground(Graphics graphics) method.
By some reason we can't use it directly to paint background image in screen. The catch: paintBackground method is derived from Field class, and we can use it in VerticalFieldManager on example:
class BgScreen extends MainScreen implements FieldChangeListener {
ButtonField mButton;
public BgScreen(Bitmap background) {
super();
BGVerticalFieldManager manager =
new BGVerticalFieldManager(background);
add(manager);
mButton = new ButtonField("Button", ButtonField.CONSUME_CLICK);
mButton.setChangeListener(this);
manager.add(mButton);
}
public void fieldChanged(Field field, int context) {
if (mButton == field)
Dialog.inform("You pressed button");
}
}
class BGVerticalFieldManager extends VerticalFieldManager {
Bitmap mBgBitmap = null;
int mBgWidth = -1;
int mBgHeight = -1;
int mBgX = -1;
int mBgY = -1;
public BGVerticalFieldManager(Bitmap background) {
super(USE_ALL_WIDTH | USE_ALL_HEIGHT);
mBgBitmap = background;
mBgWidth = mBgBitmap.getWidth();
mBgHeight = mBgBitmap.getHeight();
mBgX = (Display.getWidth() - mBgWidth) >> 1;
mBgY = (Display.getHeight() - mBgHeight) >> 1;
}
protected void paintBackground(Graphics graphics) {
paintBackgroundBitmap(graphics);
super.paintBackground(graphics);
}
private void paintBackgroundBitmap(Graphics graphics) {
if (null != mBgBitmap) {
graphics.drawBitmap(
mBgX, mBgY, mBgWidth, mBgHeight, mBgBitmap, 0, 0);
}
}
}
GIF animation
To use GIF animation, override protected void paint(Graphics graphics) method and use drawImage of incremented frame index. Use Timer.scheduleAtFixedRate to invalidate field:
class GIFVerticalFieldManager extends VerticalFieldManager {
EncodedImage mGIFImage = null;
int mGIFWidth = -1;
int mGIFHeight = -1;
int mGIFX = -1;
int mGIFY = -1;
int mGIFFrameCount = -1;
int mGIFFrameIndex = -1;
final int mGIFDelay = 30;
public GIFVerticalFieldManager(EncodedImage gifAnimation) {
super(USE_ALL_WIDTH | USE_ALL_HEIGHT);
mGIFImage = gifAnimation;
mGIFWidth = mGIFImage.getWidth();
mGIFHeight = mGIFImage.getHeight();
mGIFX = (Display.getWidth() - mGIFWidth) >> 1;
mGIFY = (Display.getHeight() - mGIFHeight) >> 1;
mGIFFrameCount = mGIFImage.getFrameCount();
mGIFFrameIndex = 0;
Timer timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask() {
public void run() {
invalidate();
}
}, mGIFDelay, mGIFDelay);
}
protected void paint(Graphics graphics) {
paintGifAnimation(graphics);
super.paint(graphics);
}
private void paintGifAnimation(Graphics graphics) {
if (null != mGIFImage) {
graphics.drawImage(
mGIFX, mGIFY, mGIFWidth, mGIFHeight,
mGIFImage, mGIFFrameIndex, 0, 0);
mGIFFrameIndex++;
if (mGIFFrameIndex > mGIFFrameCount - 1)
mGIFFrameIndex = 0;
}
}
}
EDIT: Great article - Direct Screen Drawing