Question

有谁知道如何使用黑莓JDE API创建类似于Blackberry App World中的特色商品屏幕的屏幕幻灯片动画？我知道在黑莓5.0中，有一些过渡api来执行它。但我希望在4.6版操作系统上做到这一点。它使用黑莓粗体滚动球具有很好的滚动效果。

感谢。

Answer 1

作为屏幕截图/位图方法的替代方法......

在屏幕的paint方法中，您可以使用Graphics.pushContext（..）来推送剪切区域和绘制偏移。为了获得最佳结果，您需要在runnable中进行转换，并在事件锁定上进行同步。这将确保您的屏幕可以在转换过程中被解除。

粗略的例子：



class TransitionScreen extends Screen {
    private int transitionOffset;
    private boolean isTransitionHorizontal;
    private ScreenTransition currentTransition;

    public TransitionScreen(boolean isTransitionHorizontal) {
        this.isTransitionHorizontal = isTransitionHorizontal;

        transitionOffset = getTransitionMaximum(); // So the screen starts offset
    }

    protected void paint(Graphics graphics) {
        // use transitionOffset as x or y depending on isTransitionHorizontal
        graphics.pushContext(...);
    }

    protected void onExposed() {
        transitionToOffset(0);
    }

    protected void onObscured() {
        int target = getTransitionMaximum();

        transitionToOffset(target);
    }

    private int getTransitionMaximum() {
        return isTransitionHorizontal ? Display.getWidth() : Display.getHeight();
    }

    private void transitionToOffset(int target) {
        if (currentTransition != null) {
            currentTransition.stop();
        }

        currentTransition = new ScreenTransition(target);

        getApplication().invokeLater(currentTransition);
    }
}

class ScreenTransition implements Runnable {
    private boolean animating;
    private int target;

    public ScreenTransitionUpdater(int target) {
        this.target = target;
    }

    public void stop() {
        animating = false;
    }

    public void run() {
        while(animating) {
            Object eventLock = getApplication().getEventLock();

            synchronized(eventLock) {
                // Interpolate myOffset to target

                // Set animating = false if myOffset = target

                invalidate();
            }
        }
    }
}

class TransitionScreen extends Screen { private int transitionOffset; private boolean isTransitionHorizontal; private ScreenTransition currentTransition; public TransitionScreen(boolean isTransitionHorizontal) { this.isTransitionHorizontal = isTransitionHorizontal; transitionOffset = getTransitionMaximum(); // So the screen starts offset } protected void paint(Graphics graphics) { // use transitionOffset as x or y depending on isTransitionHorizontal graphics.pushContext(...); } protected void onExposed() { transitionToOffset(0); } protected void onObscured() { int target = getTransitionMaximum(); transitionToOffset(target); } private int getTransitionMaximum() { return isTransitionHorizontal ? Display.getWidth() : Display.getHeight(); } private void transitionToOffset(int target) { if (currentTransition != null) { currentTransition.stop(); } currentTransition = new ScreenTransition(target); getApplication().invokeLater(currentTransition); } } class ScreenTransition implements Runnable { private boolean animating; private int target; public ScreenTransitionUpdater(int target) { this.target = target; } public void stop() { animating = false; } public void run() { while(animating) { Object eventLock = getApplication().getEventLock(); synchronized(eventLock) { // Interpolate myOffset to target // Set animating = false if myOffset = target invalidate(); } } } }

无需将动画标记为易变，因为此平台会忽略它。

Answer 2

也许使用计时器来改变paint方法中图像的坐标位置

如何创建类似于Blackberry App World的黑莓屏幕幻灯片动画？

2 个答案: