Android FlowLayout 支持 Gravity 布局
最终效果如下
源码如下
public class FlowLayout extends FrameLayout {
//行间距
private int rowPadding = 0;
//item 间间距
private int columPadding = 0;
//朝向
private int flowGravity;
public FlowLayout(@NonNull Context context) {
super(context);
}
public FlowLayout(@NonNull Context context, @Nullable AttributeSet attrs) {
this(context, attrs, 0);
}
public FlowLayout(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.FlowLayout, defStyleAttr, 0);
rowPadding = a.getDimensionPixelSize(R.styleable.FlowLayout_row_padding, 0);
columPadding = a.getDimensionPixelSize(R.styleable.FlowLayout_colum_padding, 0);
}
public void setFlowGravity(int gravity) {
this.flowGravity = gravity;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
//获取控件 可布局宽度
int allowWidth = MeasureSpec.getSize(widthMeasureSpec);
//子控件个数
int childCount = getChildCount();
//当前控件剩余可布局宽度
int currentWidth = 0;
//当前控件高度
int currentTop = 0;
//上个控件的left x值
int lastLeft = 0;
int i = 0;
int j = 0;
do {
if(childCount == 0) break;
View child = getChildAt(i);
int width = child.getMeasuredWidth();
//子控件测量宽度大于 控件宽度时 使用 整个控件宽度
if(width > (allowWidth - rowPadding)) {
width = allowWidth - rowPadding;
}
int height = child.getMeasuredHeight();
//子控件测量宽度大于 控件剩余布局宽度时 换行
if(currentWidth - width - rowPadding >= 0) {
lastLeft = lastLeft + width + rowPadding;
currentWidth = currentWidth - width - rowPadding;
i ++;
} else {
currentWidth = allowWidth;
lastLeft = 0;
currentTop = currentTop + height + columPadding;
}
j ++;
} while (i < childCount);
setMeasuredDimension(widthMeasureSpec, MeasureSpec.makeMeasureSpec(currentTop, MeasureSpec.EXACTLY));
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
layoutChildren(left, top, right, bottom);
}
void layoutChildren(int left, int top, int right, int bottom) {
int childCount = getChildCount();
int layoutWidth = getMeasuredWidth();
int currentWidth = 0;
int currentTop = 0;
int lastHeight = 0;
if((flowGravity & Gravity.BOTTOM) == Gravity.BOTTOM) {
currentTop = getMeasuredHeight();
}
int lastLeft = 0;
if((flowGravity & Gravity.RIGHT) == Gravity.RIGHT) {
lastLeft = getMeasuredWidth();
}
int i = 0;
int j = 0;
do {
if(childCount == 0) break;
View child = getChildAt(i);
int width = child.getMeasuredWidth();
int height = child.getMeasuredHeight();
if(width > (layoutWidth - rowPadding)) {
currentWidth = 0;
if((flowGravity & Gravity.RIGHT) == Gravity.RIGHT) {
lastLeft = layoutWidth;
} else {
lastLeft = 0;
}
if(i != 0) {
if((flowGravity & Gravity.BOTTOM) == Gravity.BOTTOM) {
currentTop = currentTop - lastHeight - columPadding;
} else {
currentTop = currentTop + lastHeight + columPadding;
}
}
int layoutTop = currentTop;
int layoutLeft = 0;
if((flowGravity & Gravity.BOTTOM) == Gravity.BOTTOM) {
layoutTop = currentTop - height;
}
if((flowGravity & Gravity.RIGHT) == Gravity.RIGHT) {
layoutLeft = lastLeft - width;
}
child.layout(layoutLeft, layoutTop,layoutLeft + width, layoutTop + height);
lastHeight = height;
i ++;
}else if(currentWidth - width - rowPadding >= 0) {
int layoutTop = currentTop;
int layoutLeft = lastLeft;
lastHeight = height;
if((flowGravity & Gravity.BOTTOM) == Gravity.BOTTOM) {
layoutTop = currentTop - height;
}
if((flowGravity & Gravity.RIGHT) == Gravity.RIGHT) {
layoutLeft = lastLeft - width;
}
child.layout(layoutLeft, layoutTop,layoutLeft + width, layoutTop + height);
if((flowGravity & Gravity.RIGHT) == Gravity.RIGHT) {
lastLeft = lastLeft - width - rowPadding;
} else {
lastLeft = lastLeft + width + rowPadding;
}
currentWidth = currentWidth - width - rowPadding;
i ++;
} else {
currentWidth = layoutWidth;
if((flowGravity & Gravity.RIGHT) == Gravity.RIGHT) {
lastLeft = layoutWidth;
} else {
lastLeft = 0;
}
if(i != 0) {
if((flowGravity & Gravity.BOTTOM) == Gravity.BOTTOM) {
currentTop = currentTop - lastHeight - columPadding;
} else {
currentTop = currentTop + lastHeight + columPadding;
}
}
}
j ++;
if(j > 200) break;
} while (i < childCount);
}
}