PopupWindow简介
PopupWindow是悬浮在当前activity上的一个容器，用它可以展示任意的内容。 PopupWindow跟位置有关的API有下面几个：
showAsDropDown(View anchor, int xoff, int yoff, int gravity) 显示在anchor的左下角，通过xoff，，yoff调整距离，gravity是popup相对于anchor的对齐方式。如果popup超出屏幕，并且展示内容的根容器是滑动控件，将以滑动方式展示。如果展示内容根容器不是滑动控件，超出屏幕内容将不可见。showAsDropDown (View anchor, int xoff, int yoff) 同上showAsDropDown (View anchor) 同上showAtLocation (View parent, int gravity, int x, int y) 展示在屏幕的特定位置，如果内容超出屏幕将被裁剪。 gravity 为NO_GRAVITY等同于 Gravity.LEFT | Gravity.TOP
showAsDropDown 还是showAtLocation？ 如果有anchor，可以使用showAsDropDown 方法，如果没有anchor可以使用showAtLocation 方法，注意使用showAtLocation 方法popup内容超出屏幕即使内容放到ScrollView里也不会滚动。
使用Path类自绘制PopupWindow背景
这里选择showAtLocation方法，使用Path类自绘制PopupWindow背景。 绘制规则如下：
给定Popup锚点的x坐标，anchorX；y坐标，anchorYDown，anchorYUp，自定义view会自动计算三角绘制位置，以及显示在anchor下方还是上方。默认显示在下方，下方显示不下再显示在上方。不足是内容太长无法滚动显示。
实现package com.xxx;import com.xxx.utils.log.LogUtils;import android.annotation.SuppressLint;import android.content.Context;import android.graphics.Canvas;import android.graphics.Path;import android.graphics.Point;import android.graphics.PointF;import android.graphics.drawable.BitmapDrawable;import android.graphics.drawable.ShapeDrawable;import android.graphics.drawable.shapes.PathShape;import android.util.AttributeSet;import android.util.DisplayMetrics;import android.view.Gravity;import android.view.MotionEvent;import android.view.View;import android.widget.LinearLayout.LayoutParams;import android.widget.PopupWindow;import android.widget.TextView;/** * TextView with popup style background (has triangle on top or bottom). The * anchor triangle will show accurately below or above the anchor position. * * @author wangwenping * @date 2015-6-27 */@SuppressLint(“DrawAllocation”){String TAG = “PopupTextView”;IS_DEBUG = false;/*** x of anchor triangle in the popup*/private float mTriangleX;/*** border color*/private int mBorderColor = 0xff1fc38f;/*** border width*/private int mBorderWidth = 2;/*** background color*/private int mBgColor = 0xffffffff;/*** background color in dark mode*/private int mBgColorDark = 0xff999999;/*** anchor height*/private float mAnchorHeight = 20;/*** anchor width*/private float mAnchorWidth = 30;/*** If content under anchor*/private boolean mShowDown = true;/*** Below items for draw*/private ShapeDrawable mBorderDrawable;private Path mBorderPath;private ShapeDrawable mBgDrawable;private Path mBgPath;private int mWidth;private int mHeight;/*** Keep a record of original padding.*/private int mPadding;/*** Is night mode.*/private boolean mIsNightMode;/*** anchor x, y in screen*/private int mAnchorYUp;private int mAnchorYDown;private int mAnchorX;/*** screen height & width*/private int mScreenHeight;private int mScreenWidth;private float mDensity;private PopupWindow mPopupWindow;private Context mCtx;/*** Touch listener*/private OnTouchListener mOnTouchListener;private boolean mDismissAfterTouch = true;/*** The minimum margin to left or right.*/private int TRIANGLE_MINIMUM_MARGIN = 10;public PopupTextView(Context context){super(context);setFocusable(true);init(context);}public PopupTextView(Context context, AttributeSet attrs, int defStyle){super(context, attrs, defStyle);init(context);}public PopupTextView(Context context, AttributeSet attrs){super(context, attrs);init(context);}(Context c){mCtx = c;mPadding = getPaddingBottom();DisplayMetrics dm = c.getResources().getDisplayMetrics();mScreenHeight = dm.heightPixels;mScreenWidth = dm.widthPixels;mDensity = dm.scaledDensity;}/*** Show as pop up window*/(){if (mPopupWindow != null){mPopupWindow.dismiss();}if (IS_DEBUG){LogUtils.d(TAG, “mAnchorX=” + mAnchorX + ” mWidth=” + mWidth + ” mHeight=” + mHeight);}mPopupWindow = new PopupWindow(this, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);if (mOnTouchListener != null){mPopupWindow.setTouchInterceptor(new OnTouchListener(){(View arg0, MotionEvent arg1){mOnTouchListener.onTouch(arg0, arg1);if (mDismissAfterTouch && arg1.getAction() == MotionEvent.ACTION_UP){mPopupWindow.dismiss();}return false;}});}mPopupWindow.setFocusable(true);mPopupWindow.setTouchable(true);mPopupWindow.setBackgroundDrawable(new BitmapDrawable());int popX = 0, popY = 0;if (mWidth <= 0 || mHeight <= 0){// The first time we showthe pop up window out of the screen to get// the size of itself.popX = mScreenWidth;popY = mScreenHeight;}else{// The second time we calculate the pop up window’s right position.Point pos = getLayoutValue();popX = pos.x;popY = pos.y;mTriangleX = mAnchorX – pos.x;mTriangleX = Math.max(mTriangleX, TRIANGLE_MINIMUM_MARGIN);mTriangleX = Math.min(mTriangleX, mWidth – TRIANGLE_MINIMUM_MARGIN – mAnchorWidth);}mPopupWindow.showAtLocation(this, Gravity.LEFT | Gravity.TOP, popX, popY);}/*** Calculate the pop up window’s right position.** @return*/private Point getLayoutValue(){int x = mAnchorX – mWidth / 2;if (x < 10 * mDensity){x = (int) (10 * mDensity);}else if (x + mWidth > mScreenWidth – 10 * mDensity){x = (int) (mScreenWidth – mWidth – 10 * mDensity);}boolean showDown = mAnchorYDown + mHeight < mScreenHeight || mAnchorYDown <= mScreenHeight / 2;setShowDown(showDown);int y = showDown ? mAnchorYDown : mAnchorYUp – mHeight;return new Point(x, y);}/*** Init drawble path.** @param width* @param height*/(int width, int height){mBorderPath = new Path();mBgPath = new Path();if (mShowDown){/*** ….|<—————-width——–>|<br>* ….|<–archorX——>|<br>* ………………..2<br>* ………………../\ (anchor)<br>* ….0/7————-1 3———–4………..—-<br>* ….|………………………….|………….|<br>* ….|………………………….|………….height<br>* ….|………………………….|………….|<br>* ….6——————————-5…………—<br>*/PointF[] borderPoints = new PointF[] { new PointF(0, mAnchorHeight),new PointF(mTriangleX – mAnchorWidth / 2, mAnchorHeight), new PointF(mTriangleX, 0),new PointF(mTriangleX + mAnchorWidth / 2, mAnchorHeight), new PointF(width, mAnchorHeight),new PointF(width, height), new PointF(0, height), new PointF(0, mAnchorHeight), };mBorderPath = createLIneToPath(borderPoints);PointF[] bgPoints = new PointF[] {new PointF(borderPoints[0].x + mBorderWidth, borderPoints[0].y + mBorderWidth),new PointF(borderPoints[1].x + mBorderWidth, borderPoints[1].y + mBorderWidth),new PointF(borderPoints[2].x, borderPoints[2].y + mBorderWidth),new PointF(borderPoints[3].x – mBorderWidth, borderPoints[3].y + mBorderWidth),new PointF(borderPoints[4].x – mBorderWidth, borderPoints[4].y + mBorderWidth),new PointF(borderPoints[5].x – mBorderWidth, borderPoints[5].y – mBorderWidth),new PointF(borderPoints[6].x + mBorderWidth, borderPoints[6].y – mBorderWidth),new PointF(borderPoints[7].x + mBorderWidth, borderPoints[7].y + mBorderWidth), };mBgPath = createLIneToPath(bgPoints);}else{/*** 0/7—————————–1<br>* |………………………….|<br>* |………………………….|<br>* 6——————5..3———2<br>* ………………..\/<br>* ………………..4<br>*/PointF[] borderPoints = new PointF[] { new PointF(0, 0), new PointF(width, 0),new PointF(width, height – mAnchorHeight),new PointF(mTriangleX + mAnchorWidth / 2, height – mAnchorHeight), new PointF(mTriangleX, height),new PointF(mTriangleX – mAnchorWidth / 2, height – mAnchorHeight),new PointF(0, height – mAnchorHeight), new PointF(0, 0), };mBorderPath = createLIneToPath(borderPoints);PointF[] bgPoints = new PointF[] {new PointF(borderPoints[0].x + mBorderWidth, borderPoints[0].y + mBorderWidth),new PointF(borderPoints[1].x – mBorderWidth, borderPoints[1].y + mBorderWidth),new PointF(borderPoints[2].x – mBorderWidth, borderPoints[2].y – mBorderWidth),new PointF(borderPoints[3].x – mBorderWidth, borderPoints[3].y – mBorderWidth),new PointF(borderPoints[4].x, borderPoints[4].y – mBorderWidth),new PointF(borderPoints[5].x + mBorderWidth, borderPoints[5].y – mBorderWidth),new PointF(borderPoints[6].x + mBorderWidth, borderPoints[6].y – mBorderWidth),new PointF(borderPoints[7].x + mBorderWidth, borderPoints[7].y + mBorderWidth), };mBgPath = createLIneToPath(bgPoints);}}private Path createLIneToPath(PointF[] points){Path path = new Path();if (points != null && points.length > 1){path.moveTo(points[0].x, points[0].y);for (int i = 1; i < points.length; i++){path.lineTo(points[i].x, points[i].y);}}path.close();return path;}(){return mAnchorYUp;}(int mAnchorYUp){this.mAnchorYUp = mAnchorYUp;}(){return mAnchorYDown;}(int mAnchorYDown){this.mAnchorYDown = mAnchorYDown;}(){return mAnchorX;}(int anchorX){this.mAnchorX = anchorX;}(OnTouchListener l){mOnTouchListener = l;}(boolean dismissAfterTouch){mDismissAfterTouch = dismissAfterTouch;}(){return mDismissAfterTouch;}(boolean showDown){mShowDown = showDown;if (mShowDown){setPadding(getPaddingLeft(), (int) mAnchorHeight + mPadding, getPaddingRight(), mPadding);}else{setPadding(getPaddingLeft(), mPadding, getPaddingRight(), (int) mAnchorHeight + mPadding);}}(boolean isNightMode){mIsNightMode = isNightMode;}(int w, int h, int oldw, int oldh){super.onSizeChanged(w, h, oldw, oldh);if (IS_DEBUG){LogUtils.d(TAG, “w=” + w + ” h=” + h + ” oldw=” + oldw + ” oldh=” + oldh);}mWidth = w;mHeight = h;show();}(Canvas canvas){initPath(mWidth, mHeight);mBorderDrawable = new ShapeDrawable(new PathShape(mBorderPath, mWidth, mHeight));mBorderDrawable.getPaint().setColor(mBorderColor);mBgDrawable = new ShapeDrawable(new PathShape(mBgPath, mWidth, mHeight));int bgColor = mBgColor;if (mIsNightMode){bgColor = mBgColorDark;}mBgDrawable.getPaint().setColor(bgColor);int x = 0;int y = 0;mBorderDrawable.setBounds(x, y, x + mWidth, y + mHeight);mBorderDrawable.draw(canvas);mBgDrawable.setBounds(x, y, x + mWidth, y + mHeight);mBgDrawable.draw(canvas);super.onDraw(canvas);}}4 下载
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