如何创建 Rect 的数组或数组列表

发布于 2024-11-09 04:45:54 字数 772 浏览 0 评论 0原文

我要疯狂地想弄清楚这一点。我正在尝试创建一个 Rect（矩形）数组或数组列表，我可以更新坐标并在屏幕上绘制（以使它们移动）。

现在我有一个名为 Fire 的单独类，在其中每次迭代时我都会在其自己的 onDraw() 方法中使用新坐标创建一个新矩形。在 View 的 onDraw() 方法的第一次迭代中，我将一个新的 Fire 添加到数组列表中。

在 Fire 类中，我有：

public void onDraw(Canvas canvas){
    moveF();
    Rect r = new Rect(_l,_t,_r,_b);
    canvas.drawRect(r, paint);
}

在 View 类中，我有：

protected void onDraw(Canvas canvas) {
    int i = 0;
    canvas.drawColor(Color.WHITE);
    if(i==0){
        fires.add(new Fire(20,100,40,120));
        i++;
    }
    for(Fire fire : fires){
        fire.onDraw(canvas);
    }
}

我删除了无意义的代码部分，但这是重要的东西。矩形打印，但是它也打印之前的所有位置，我不明白为什么。我一直在努力解决这个问题，如果你们能提供任何帮助，我将不胜感激。我能够轻松地在java中实现这个，但是android给我带来了问题。

提前致谢！！！

原文

I am going crazy trying to figure this out. I am trying to make an array or arraylist of Rect (rectangles) that I can update the coordinates and draw on the screen(to make them move).

Right now I have a separate class called Fire in which I make a new rectangle each iteration with the new coordinates in its own onDraw() method. In the View's onDraw() method's first iteration I add a new Fire to an arraylist.

In the Fire class I have:

public void onDraw(Canvas canvas){
    moveF();
    Rect r = new Rect(_l,_t,_r,_b);
    canvas.drawRect(r, paint);
}

In the View class I have:

protected void onDraw(Canvas canvas) {
    int i = 0;
    canvas.drawColor(Color.WHITE);
    if(i==0){
        fires.add(new Fire(20,100,40,120));
        i++;
    }
    for(Fire fire : fires){
        fire.onDraw(canvas);
    }
}

I got rid of pointless parts of code, but this is the important stuff. The Rectangle prints, however it prints all the previous locations as well and I don't understand why. I have been trying to fix this forever and any help you guys could give would be greatly appreciated. I was able to implement this in java easy, but android is giving me problems.

Thanks in advance!!!

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感受沵的脚步 2024-11-16 04:45:54

在代码中，您将新的矩形添加到列表中，然后绘制每个矩形。但从描述来看，您似乎只想绘制一个带有更新坐标的矩形。

不必每次都创建一个新的 Rect，而是重用一个矩形并使用 set(...) 更新其坐标。

第二个问题是，您设置了 i=0，然后立即检查 i==0，这始终为真。尝试这样的事情：

static final Rect rect = new Rect();

// your code here

protected void onDraw(Canvas canvas) {
    canvas.drawColor(Color.WHITE);

    moveF();
    rect.set(_l,_t,_r,_b);
    canvas.drawRect(rect, paint);

}

From the code, you are adding new rectangles to the list, and then drawing each rectangle. But from the description, it seems that you just want to draw a single rectangle, with updated coordinates.

Instead of creating a new Rect each time, reuse a rectangle and update its coordinates with set(...).

A second problem is that you set i=0 and then immediately check for i==0, which would be always true. Try something like this instead:

static final Rect rect = new Rect();

// your code here

protected void onDraw(Canvas canvas) {
    canvas.drawColor(Color.WHITE);

    moveF();
    rect.set(_l,_t,_r,_b);
    canvas.drawRect(rect, paint);

}

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