自定义流式布局控件FlowLayout

最新推荐文章于 2024-01-06 14:53:41 发布

原创最新推荐文章于 2024-01-06 14:53:41 发布 · 728 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#界面 #android #布局 #xml

android 自定义控件专栏收录该内容

3 篇文章

订阅专栏

本文深入解析FlowLayout布局的用法，包括如何实现自动换行及调整水平垂直间距，提供实例代码帮助开发者更好地理解并应用此布局。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

/**
 * 流式布局 FlowLayout 用法和LineLayout一样,可自动换行
 */
public class FlowLayout extends ViewGroup {

    private static final int DEFAULT_HORIZONTAL_SPACING = 5;
    private static final int DEFAULT_VERTICAL_SPACING = 5;

    private int mVerticalSpacing;
    private int mHorizontalSpacing;
    
    public FlowLayout(Context context) {
        super(context);
    }

    public FlowLayout(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.FlowLayout);
        try {
            mHorizontalSpacing = a.getDimensionPixelSize(
                    R.styleable.FlowLayout_horizontal_spacing, DEFAULT_HORIZONTAL_SPACING);
            mVerticalSpacing = a.getDimensionPixelSize(
                    R.styleable.FlowLayout_vertical_spacing, DEFAULT_VERTICAL_SPACING);
        } finally {
            a.recycle();
        }
    }


    public void setHorizontalSpacing(int pixelSize) {
        mHorizontalSpacing = pixelSize;
    }

    public void setVerticalSpacing(int pixelSize) {
        mVerticalSpacing = pixelSize;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int myWidth = resolveSize(0, widthMeasureSpec);

        int paddingLeft = getPaddingLeft();
        int paddingTop = getPaddingTop();
        int paddingRight = getPaddingRight();
        int paddingBottom = getPaddingBottom();

        int childLeft = paddingLeft;
        int childTop = paddingTop;

        int lineHeight = 0;

        // Measure each child and put the child to the right of previous child
        // if there's enough room for it, otherwise, wrap the line and put the child to next line.
        for (int i = 0, childCount = getChildCount(); i < childCount; ++i) {
            View child = getChildAt(i);
            if (child.getVisibility() != View.GONE) {
                measureChild(child, widthMeasureSpec, heightMeasureSpec);
            } else {
                continue;
            }

            int childWidth = child.getMeasuredWidth();
            int childHeight = child.getMeasuredHeight();

            lineHeight = Math.max(childHeight, lineHeight);

            if (childLeft + childWidth + paddingRight > myWidth) {
                childLeft = paddingLeft;
                childTop += mVerticalSpacing + lineHeight;
                lineHeight = childHeight;
            } else {
                childLeft += childWidth + mHorizontalSpacing;
            }
        }

        int wantedHeight = childTop + lineHeight + paddingBottom;

        setMeasuredDimension(myWidth, resolveSize(wantedHeight, heightMeasureSpec));
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int myWidth = r - l;

        int paddingLeft = getPaddingLeft();
        int paddingTop = getPaddingTop();
        int paddingRight = getPaddingRight();

        int childLeft = paddingLeft;
        int childTop = paddingTop;

        int lineHeight = 0;

        for (int i = 0, childCount = getChildCount(); i < childCount; ++i) {
            View childView = getChildAt(i);

            if (childView.getVisibility() == View.GONE) {
                continue;
            }

            int childWidth = childView.getMeasuredWidth();
            int childHeight = childView.getMeasuredHeight();

            lineHeight = Math.max(childHeight, lineHeight);

            if (childLeft + childWidth + paddingRight > myWidth) {
                childLeft = paddingLeft;
                childTop += mVerticalSpacing + lineHeight;
                lineHeight = childHeight;
            }

            childView.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);
            childLeft += childWidth + mHorizontalSpacing;
        }
    }
}

需要添加的style

<declare-styleable name="FlowLayout">
    <attr name="horizontal_spacing" format="dimension" />
    <attr name="vertical_spacing" format="dimension" />
</declare-styleable>