Android 超级好用的均分布局AverageLayout

开篇

  很久没有更新博客了。本篇给同学们分享一个简单的超级好用的均分布局，提升你的开发效率。

场景

  在日常开发中会经常用到均分布局，而我们通常的做法是用LinearLayout和android:layout_weight配合完成。但是有时候，child并不需要占用1个比重，这时候为了满足android:layout_weight居中，不得不给child再包一层父类。而此控件就是为了解决这个问题因运而生！当然，通过ConstraintLayout经过复杂的约束也能达到这个效果，只是AverageLayout比ConstraintLayout更简洁方便。

效果截屏

立即体验

扫描以下二维码下载体验App(从0.2.3版本开始，体验App内嵌版本更新检测功能)：

JSCKit库传送门：https://github.com/JustinRoom/JSCKit

简析源码

AverageLayout.java

public class AverageLayout extends ViewGroup implements IViewAttrDelegate{}

• 1、测量

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int childCount = getChildCount();
        if (childCount > 0){
            measureChildren(widthMeasureSpec, heightMeasureSpec);
            LayoutParams params = getLayoutParams();
            int width = 0;
            int height = 0;
            switch (orientation){
                case HORIZONTAL:
                    width = getPaddingLeft() + getPaddingRight();
                    for (int i = 0; i < childCount; i++) {
                        View child = getChildAt(i);
                        width += child.getMeasuredWidth();
                        height = Math.max(height, child.getMeasuredHeight());
                    }
                    height = height + getPaddingTop() + getPaddingBottom();
                    if (params.width == LayoutParams.WRAP_CONTENT){
                        widthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY);
                    }
                    if (params.height == LayoutParams.WRAP_CONTENT){
                        heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
                    }
                    break;
                case VERTICAL:
                    height = getPaddingTop() + getPaddingBottom();
                    for (int i = 0; i < childCount; i++) {
                        View child = getChildAt(i);
                        height += child.getMeasuredHeight();
                        width = Math.max(width, child.getMeasuredWidth());
                    }
                    width = width + getPaddingLeft() + getPaddingRight();
                    if (params.height == LayoutParams.WRAP_CONTENT){
                        heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
                    }
                    if (params.width == LayoutParams.WRAP_CONTENT){
                        widthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY);
                    }
                    break;
            }
        }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

• 2、放置

protected void onLayout(boolean changed, int l, int t, int r, int b)

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int childCount = getChildCount();
        int width = getMeasuredWidth();
        int height = getMeasuredHeight();
        int left, top, right, bottom;
        if (childCount > 0){
            switch (orientation){
                case HORIZONTAL:
                    int[] widths = calculateAverageValue(width - getPaddingLeft() - getPaddingRight(), childCount);
                    int startX = getPaddingLeft();
                    for (int i = 0; i < childCount; i++) {
                        View child = getChildAt(i);
                        LayoutParams childParams = child.getLayoutParams();
                        if (childParams.width == LayoutParams.MATCH_PARENT) {
                            left = startX;
                            right = left + widths[i];
                        } else {
                            left = startX + (widths[i] - child.getMeasuredWidth()) / 2;
                            right = left + child.getMeasuredWidth();
                        }

                        if (childParams.height == LayoutParams.MATCH_PARENT) {
                            top = getPaddingTop();
                            bottom = height - getPaddingBottom();
                        } else {
                            top = (height - child.getMeasuredHeight()) / 2;
                            bottom = top + child.getMeasuredHeight();
                        }
                        child.layout(left, top, right, bottom);
                        startX += widths[i];
                    }
                    break;
                case VERTICAL:
                    int[] heights = calculateAverageValue(height - getPaddingTop() - getPaddingBottom(), childCount);
                    int startY = getPaddingTop();
                    for (int i = 0; i < childCount; i++) {
                        View child = getChildAt(i);
                        LayoutParams childParams = child.getLayoutParams();
                        if (childParams.width == LayoutParams.MATCH_PARENT) {
                            left = getPaddingLeft();
                            right = width - getPaddingRight();
                        } else {
                            left = (width - child.getMeasuredWidth()) / 2;
                            right = left + child.getMeasuredWidth();
                        }

                        if (childParams.height == LayoutParams.MATCH_PARENT) {
                            top = startY;
                            bottom = top + heights[i];
                        } else {
                            top = startY + (heights[i] - child.getMeasuredHeight()) / 2;
                            bottom = top + child.getMeasuredHeight();
                        }
                        child.layout(left, top, right, bottom);
                        startY += heights[i];
                    }
                    break;
            }
        }
    }

    private int[] calculateAverageValue(int value, int childCount) {
        int tempAverageValue = value / childCount;
        int rest = value - tempAverageValue * childCount;
        int[] averageValues = new int[childCount];
        for (int i = 0; i < childCount; i++) {
            if (rest > 0) {
                averageValues[i] = tempAverageValue + 1;
                rest --;
            } else {
                averageValues[i] = tempAverageValue;
            }
        }
        return averageValues;
    }

使用示例

其他的不多说了，请自行安装体验app体验，用过才会知道它的好。
童鞋们，如果你们觉得不错的话给我点个吧，谢谢！！！

篇尾

  Wechat:eoy9527。

在人生的道路上，当你的希望一个个落空的时候，你也要坚定，要沉着。 —— 朗费罗