Android ViewGroup 在所有图纸之上添加子项

Question

我有一个自定义的ViewGroup，我将覆盖它的dispatchDraw 并绘制一些额外的Paths，看起来像这样：

@Override
public void dispatchDraw(Canvas canvas) {
    super.dispatchDraw(canvas);
    canvas.setMatrix(matrix);
    mRegions.clear();
    canvas.drawPicture(mPicture);
    if (drawShader) {
        canvas.drawBitmap(mShader, 0, 0, mBitmapPaint);
    }
    for (int i = 0; i < mPaths.size(); i++) {
        if (mIndex != -1 && mIndex == i) {
            canvas.save();
            canvas.drawRect(mRect, mPaint);
            drawPaths(canvas, mPaths.get(i));
            canvas.clipPath(mPaths.get(i), Region.Op.INTERSECT);
            canvas.drawColor(mOverlayColor);
            Rect f = mRegions.get(i).getBounds();
            mPaint.setColor(Color.RED);
            mPaint.setStyle(Paint.Style.STROKE);
            canvas.drawCircle(f.centerX() - mRadius, f.centerY() - mRadius, mRadius, mPaint);
            canvas.restore();
        } else {
            drawPaths(canvas, mPaths.get(i));
        }
    }
}

现在我想要添加一个孩子，该孩子将放置在dispatchDraw 上绘制的这些东西之上。现在我正在这样做：

    mBalloon = LayoutInflater.from(getContext()).inflate(R.layout.map_balloon, null);
    LayoutParams params = new LayoutParams(500, 150);
    mBalloon.setLayoutParams(params);
    addView(mBalloon);
    bringChildToFront(getChildAt(0));

在我的ViewGroup 的构造函数中调用的init() 方法中，结果是dispatchDraw 中的绘图被放置在mBalloon 之上。

知道如何将我的View - mBalloon 放在来自dispatchDraw 的东西上方吗？

提前致谢！

Answer 1

要在您的额外Path 之上绘制孩子，您应该在绘制Path 之后调用super.dispatchDraw(canvas)。

@Override
public void dispatchDraw(Canvas canvas) {
    canvas.setMatrix(matrix);
    mRegions.clear();
    canvas.drawPicture(mPicture);
    if (drawShader) {
        canvas.drawBitmap(mShader, 0, 0, mBitmapPaint);
    }
    for (int i = 0; i < mPaths.size(); i++) {
        if (mIndex != -1 && mIndex == i) {
            canvas.save();
            canvas.drawRect(mRect, mPaint);
            drawPaths(canvas, mPaths.get(i));
            canvas.clipPath(mPaths.get(i), Region.Op.INTERSECT);
            canvas.drawColor(mOverlayColor);
            Rect f = mRegions.get(i).getBounds();
            mPaint.setColor(Color.RED);
            mPaint.setStyle(Paint.Style.STROKE);
            canvas.drawCircle(f.centerX() - mRadius, f.centerY() - mRadius, mRadius, mPaint);
            canvas.restore();
        } else {
            drawPaths(canvas, mPaths.get(i));
        }
    }
    super.dispatchDraw(canvas);
}

Answer 2

我了解您想要达到的目标的总体思路，我会尝试提出不同的方法。

来自文档：A ViewGroup is a special view that can contain other views (called children.) The view group is the base class for layouts and views containers.

所以 ViewGroup 根本不应该在屏幕上绘制东西。有可能做到吗？是的，但这只会让你的 OO 结构做得不太好。

所以我的建议是使用您喜欢的任何 ViewGroup FrameLayout、RelativeLayout 等。并将路径绘制代码迁移到将在屏幕上绘制所有这些路径的自定义 View，并且在标准 ViewGroup 中您只需定位相应地自定义视图。大概是这样的：

<RelativeLayout>

    <TextView/> // just an example
    <ImageView/> // just an example

    <CustomPathView/> // your custom view

    <FrameLayout/>  // in this frame you can put views to be on top
</RelativeLayout>