content: package com.test.banner.widget.flowlayout;
  
  import android.content.Context;
  import android.content.res.TypedArray;
  import android.util.AttributeSet;
  import android.view.View;
  import android.view.ViewGroup;
  
  import com.test.banner.R;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * @Description: 流式布局
   * https://github.com/hongyangAndroid/FlowLayout
   */
  public class FlowLayout extends ViewGroup {
      private static final String TAG = "FlowLayout";
      private static final int LEFT = -1;
      private static final int CENTER = 0;
      private static final int RIGHT = 1;
  
      protected List<List<View>> mAllViews = new ArrayList<List<View>>();
      protected List<Integer> mLineHeight = new ArrayList<Integer>();
      protected List<Integer> mLineWidth = new ArrayList<Integer>();
      private int mGravity;
      private List<View> lineViews = new ArrayList<>();
  
      public FlowLayout(Context context) {
          this(context, null);
      }
  
      public FlowLayout(Context context, AttributeSet attrs) {
          this(context, attrs, 0);
      }
  
      public FlowLayout(Context context, AttributeSet attrs, int defStyle) {
          super(context, attrs, defStyle);
          TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.TagFlowLayout);
          mGravity = ta.getInt(R.styleable.TagFlowLayout_tag_gravity, LEFT);
          ta.recycle();
      }
  
      @Override
      protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
          int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
          int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
          int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
          int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
  
          // wrap_content
          int width = 0;
          int height = 0;
  
          int lineWidth = 0;
          int lineHeight = 0;
  
          int cCount = getChildCount();
  
          for (int i = 0; i < cCount; i++) {
              View child = getChildAt(i);
              if (child.getVisibility() == View.GONE) {
                  if (i == cCount - 1) {
                      width = Math.max(lineWidth, width);
                      height += lineHeight;
                  }
                  continue;
  
  
              }
              measureChild(child, widthMeasureSpec, heightMeasureSpec);
              MarginLayoutParams lp = (MarginLayoutParams) child
                      .getLayoutParams();
  
              int childWidth = child.getMeasuredWidth() + lp.leftMargin
                      + lp.rightMargin;
              int childHeight = child.getMeasuredHeight() + lp.topMargin
                      + lp.bottomMargin;
  
              if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {
                  width = Math.max(width, lineWidth);
                  lineWidth = childWidth;
                  height += lineHeight;
                  lineHeight = childHeight;
              } else {
                  lineWidth += childWidth;
                  lineHeight = Math.max(lineHeight, childHeight);
              }
              if (i == cCount - 1) {
                  width = Math.max(lineWidth, width);
                  height += lineHeight;
              }
          }
          setMeasuredDimension(
                  modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width + getPaddingLeft() + getPaddingRight(),
                  modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height + getPaddingTop() + getPaddingBottom()
          );
  
      }
  
  
      @Override
      protected void onLayout(boolean changed, int l, int t, int r, int b) {
          mAllViews.clear();
          mLineHeight.clear();
          mLineWidth.clear();
          lineViews.clear();
  
          int width = getWidth();
  
          int lineWidth = 0;
          int lineHeight = 0;
  
          int cCount = getChildCount();
  
          for (int i = 0; i < cCount; i++) {
              View child = getChildAt(i);
              if (child.getVisibility() == View.GONE) continue;
              MarginLayoutParams lp = (MarginLayoutParams) child
                      .getLayoutParams();
  
              int childWidth = child.getMeasuredWidth();
              int childHeight = child.getMeasuredHeight();
  
              if (childWidth + lineWidth + lp.leftMargin + lp.rightMargin > width - getPaddingLeft() - getPaddingRight()) {
                  mLineHeight.add(lineHeight);
                  mAllViews.add(lineViews);
                  mLineWidth.add(lineWidth);
  
                  lineWidth = 0;
                  lineHeight = childHeight + lp.topMargin + lp.bottomMargin;
                  lineViews = new ArrayList<View>();
              }
              lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
              lineHeight = Math.max(lineHeight, childHeight + lp.topMargin
                      + lp.bottomMargin);
              lineViews.add(child);
  
          }
          mLineHeight.add(lineHeight);
          mLineWidth.add(lineWidth);
          mAllViews.add(lineViews);
  
  
          int left = getPaddingLeft();
          int top = getPaddingTop();
  
          int lineNum = mAllViews.size();
  
          for (int i = 0; i < lineNum; i++) {
              lineViews = mAllViews.get(i);
              lineHeight = mLineHeight.get(i);
  
              // set gravity
              int currentLineWidth = this.mLineWidth.get(i);
              switch (this.mGravity) {
                  case LEFT:
                      left = getPaddingLeft();
                      break;
                  case CENTER:
                      left = (width - currentLineWidth) / 2 + getPaddingLeft();
                      break;
                  case RIGHT:
                      left = width - currentLineWidth + getPaddingLeft();
                      break;
              }
  
              for (int j = 0; j < lineViews.size(); j++) {
                  View child = lineViews.get(j);
                  if (child.getVisibility() == View.GONE) {
                      continue;
                  }
  
                  MarginLayoutParams lp = (MarginLayoutParams) child
                          .getLayoutParams();
  
                  int lc = left + lp.leftMargin;
                  int tc = top + lp.topMargin;
                  int rc = lc + child.getMeasuredWidth();
                  int bc = tc + child.getMeasuredHeight();
  
                  child.layout(lc, tc, rc, bc);
  
                  left += child.getMeasuredWidth() + lp.leftMargin
                          + lp.rightMargin;
              }
              top += lineHeight;
          }
  
      }
  
      @Override
      public LayoutParams generateLayoutParams(AttributeSet attrs) {
          return new MarginLayoutParams(getContext(), attrs);
      }
  
      @Override
      protected LayoutParams generateDefaultLayoutParams() {
          return new MarginLayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
      }
  
      @Override
      protected LayoutParams generateLayoutParams(LayoutParams p) {
          return new MarginLayoutParams(p);
      }
  }
  