KeywordsTrayLayout.java

import android.content.Context;
import android.support.annotation.UiThread;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.widget.TextView;

import java.util.ArrayList;

/**
 * Created by Wang Xuanyu on 16/4/15.
 */
@UiThread
public class KeywordsTrayLayout extends ViewGroup {

    private ArrayList<String> mWords;

    public KeywordsTrayLayout(Context context) {
        this(context, null);
    }

    public KeywordsTrayLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public KeywordsTrayLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        ArrayList<String> words = new ArrayList<String>();
        words.add("今天天气好晴朗");
        words.add("处处闻啼鸟");
        words.add("让我们荡起双桨");
        words.add("歌唱我们亲爱的祖国");
        words.add("唱出我们的歌");
        words.add("东方红");
        words.add("实在编不下去了");
        words.add("谁来帮我唱两句");
        words.add("没办法了");
        words.add("赶紧调试");
        words.add("我要出去玩");
        words.add("不要捣乱了");
        setWords(words);
    }

    /**
     * Any layout manager that doesn't scroll will want this.
     */
    @Override
    public boolean shouldDelayChildPressedState() {
        return false;
    }


    @Override
    public LayoutParams generateLayoutParams(AttributeSet attrs) {
        return new MarginLayoutParams(getContext(), attrs);
    }

    @Override
    protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
        return new MarginLayoutParams(p);
    }

    @Override
    protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
        return p instanceof MarginLayoutParams;
    }

    @Override
    public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
        super.onInitializeAccessibilityEvent(event);
        event.setClassName(getClass().getSimpleName());
    }

    @Override
    public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
        super.onInitializeAccessibilityNodeInfo(info);
        info.setClassName(getClass().getSimpleName());
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        // Measurement will ultimately be computing these values.
        int maxHeight = 0;
        int maxWidth = 0;
        int childState = 0;
        int lineWidth = 0;
        int lineHeight = 0;

        final int count = getChildCount();

        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (child.getVisibility() != GONE) {
                measureChild(child, widthMeasureSpec, heightMeasureSpec);
                final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

                lineWidth += child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
                lineHeight = Math.max(lineHeight,
                        child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin);
                childState = combineMeasuredStates(childState, child.getMeasuredState());
                if (lineWidth >= MeasureSpec.getSize(widthMeasureSpec)) {
                    maxHeight += lineHeight;
                    lineWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
                    lineHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
                }
            }
        }
        maxHeight += lineHeight;
        // Check against our minimum height and width
        maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight());
        maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth());

        // Report our final dimensions.
        setMeasuredDimension(resolveSizeAndState(maxWidth, widthMeasureSpec, childState),
                resolveSizeAndState(maxHeight, heightMeasureSpec,
                        childState << MEASURED_HEIGHT_STATE_SHIFT));
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        final int count = getChildCount();

        int leftPos = getPaddingLeft();
        int topPos = getPaddingTop();

        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (child.getVisibility() != GONE) {
                final LayoutParams lp = (LayoutParams) child.getLayoutParams();

                final int width = child.getMeasuredWidth();
                final int height = child.getMeasuredHeight();

                if (leftPos + width >= right - left - getPaddingRight()) {
                    leftPos = getPaddingLeft();
                    topPos += height;
                }

                child.layout(leftPos, topPos, leftPos + width, topPos + height);
                leftPos += width;
            }
        }
    }

    public void setWords(ArrayList<String> words) {
        this.mWords = words;
        for (String word : words) {
            addViewInLayout(obtainView(word), -1, new MarginLayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT), true);
        }
        invalidate();
        requestLayout();
    }

    private TextView obtainView(String word) {
        TextView view = new TextView(getContext());
        view.setText(word);
        view.setBackgroundResource(R.drawable.text_bg);
        return view;
    }

}