绘制自定义组件

问题描述

这是2个问题：

1）是组件 paint 成员吗？使用代号 1的简单2D图形游戏的最佳方法？还是我什至不应该尝试呢？

2）为什么下面的代码绘制我的 Component 只是为了立即擦除它？

This is kind of 2 questions:
1) Is the overriding the paint member of a Component the best approach for a simple 2D graphics game using codename one? Or should I not even be attempting it??
2) Why does the code below draw my Component only to erase it instantly?

我像这样初始化组件：

protected void StartGame()
{
    final Component newC = new PaintedComponent();

    Container mv = findContainerMainVisual();

    mv.addComponent(newC);
    mv.setShouldCalcPreferredSize(true);
    mv.animateLayout(200);
}

然后该组件将覆盖 paint 成员函数如下：

And then the component overrides the paint member function like this:

public class PaintedComponent extends Component {
    private int nextColour;

    public PaintedComponent() {
        super();
        setSize(new Dimension(200,200));
        nextColour = 0x8f8f8f;
    }


    @Override
    public void paint(Graphics g) {
        super.paint(g); // I've tried without this, but it's the same
        g.setColor(0xffffff);
        g.fillRadialGradient(0xffffff, nextColour, 0,0,this.getWidth(), this.getHeight());
    }
}

推荐答案

检查在中您可以在最新一批的演示中看到代号 Codename One，它采用了一种非常不同的方法，尽管覆盖油漆也可以正常工作。

Check out the Poker demo in Codename One which you can see in the latest batch of demos, it takes a very different approach although overriding paint should work just fine too.

该组件不起作用的原因之所以显示，是因为当animateLayout（）方法验证屏幕时，其大小为0。您应该将其放置在边框布局的中心（占用所有可用空间并禁用滚动），或者覆盖calcPreferredSize（）以返回合理的大小。

The reason the component isn't showing is because its sized to 0 when the animateLayout() method validates the screen. You should either place it in the center of a border layout (to take up all available space and disable scrolling) or override calcPreferredSize() to return a sensible size.

I建议避免使用径向梯度，因为在某些平台上，它们的速度确实很慢。参见关于效果。

I would suggest avoiding radial gradients since they are REALLY slow on some platforms. See this about performance.

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