Question

我正在尝试制作可触摸的图像，当我通过设备上的可触摸按钮滚动它时，这是可触摸图像的代码：

class TouchBitmapField extends BitmapField {
    Bitmap bitmap;
    boolean second;
    int width;
    public TouchBitmapField(Bitmap startBitmap, long style, int width, boolean second) {
        super(startBitmap, style);
        this.second = second;
        bitmap = startBitmap;
        this.width = width;
    }

    protected void drawFocus(Graphics g, boolean on){
        g.setDrawingStyle(Graphics.DRAWSTYLE_FOCUS, true );
        if(on){
           drawHighlightRegion(g, Field.HIGHLIGHT_FOCUS, on, width-(bitmap.getWidth()/2), 0, bitmap.getWidth(), bitmap.getHeight());
        }

        paint(g);
    }
    protected boolean touchEvent(TouchEvent message) {
        if (TouchEvent.CLICK == message.getEvent()) {
            FieldChangeListener listener = getChangeListener();
            if (null != listener)
                listener.fieldChanged(this, 1);
        }
        return super.touchEvent(message);
    }
}

但问题是只有图像的透明部分可以聚焦，我在创建TouchBitmapField之前调整此Bitmap，因为您可能知道调整位图删除透明部分并将其替换为黑色。我尝试了这个类http://www.patchou.com/2010/10/resizing-transparent-bitmaps-with-the-blackberry-jde/来调整图像大小，但是我的屏幕上有25个图像，效率很低。知道如何在图像上制作边框吗？在drawFocus(Graphics g, boolean on)方法中绘制边框的任何有效方法吗？

Answer 1

您只能对图像的透明部分进行聚焦的原因是（据我所知）drawFocus之前paint被触发，导致最后绘制位图。

我认为这个解决方案是您正在寻找的。如果您想要纯色以外的其他内容作为边框，则可以使用BorderFactory。

class TouchBitmapField extends BitmapField
{
    Bitmap bitmap;
    Border defaultBorder;
    Border focusBorder;

    public TouchBitmapField(Bitmap startBitmap, long style)
    {
        super(startBitmap, style | FOCUSABLE);
        bitmap = startBitmap;

        XYEdges thickness = new XYEdges(5, 5, 5, 5);
        XYEdges colours = new XYEdges(0xff0000, 0xff0000, 0xff0000, 0xff0000);
        XYEdges alpha = new XYEdges(0, 0, 0, 0);

        // Transparent border used by default, so that adding the focus border does not resize the view
        defaultBorder = BorderFactory.createSimpleBorder(thickness, colours, alpha, Border.STYLE_SOLID); 
        focusBorder = BorderFactory.createSimpleBorder(thickness, colours, Border.STYLE_SOLID);

        setBorder(defaultBorder);
    }

    protected void drawFocus(Graphics graphics, boolean on)
    {
        // Override default blue highlight
    }

    protected void onFocus(int direction)
    {
        super.onFocus(direction);
        setBorder(focusBorder);
    }
    protected void onUnfocus()
    {
        super.onUnfocus();
        setBorder(defaultBorder);
    }
}

如果您希望边框与图片重叠，可以覆盖paint方法并根据需要进行绘制。

protected void paint(Graphics graphics)
    {
        super.paint(graphics);

        if(isFocus())
        {
            int tempCol = graphics.getColor();
            int tempAlpha = graphics.getGlobalAlpha();

            graphics.setColor(0xff0000);
            graphics.setGlobalAlpha(128);

            for(int i = 0; i < 5; i++)
            {
                graphics.drawRect(i, i, getWidth() - i * 2, getHeight() - i * 2);
            }

            // Reset back to original state
            graphics.setColor(tempCol);
            graphics.setGlobalAlpha(tempAlpha);
        }
    }

黑莓在焦点时为图像添加边框

1 个答案: