Android实现消息提醒小红点效果

import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.graphics.RectF; 
import android.util.AttributeSet; 
import android.util.Log; 
import android.view.Gravity; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.FrameLayout; 
import android.widget.TabWidget; 
 
public class BadgeView extends View { 
 protected static final String LOG_TAG = "BadgeView"; 
 // 该控件的背景图形类型 
 public static final int SHAPE_CIRCLE = 1; 
 public static final int SHAPE_RECTANGLE = 2; 
 public static final int SHAPE_OVAL = 3; 
 public static final int SHAPTE_ROUND_RECTANGLE = 4; 
 public static final int SHAPE_SQUARE = 5; 
 // 该框架内容的文本画笔 
 private Paint mTextPaint; 
 // 该控件的背景画笔 
 private Paint mBgPaint; 
 
 private int mHeight = 0; 
 private int mWidth = 0; 
 private int mBackgroundShape = SHAPE_CIRCLE; 
 private int mTextColor = Color.WHITE; 
 private int mTextSize; 
 private int mBgColor = Color.RED; 
 private String mText = ""; 
 private int mGravity = Gravity.RIGHT | Gravity.TOP; 
 private RectF mRectF; 
 private float mtextH; 
 private boolean mIsShow = false; 
 
 public BadgeView(Context context) { 
 this(context, null); 
 } 
 
 public BadgeView(Context context, AttributeSet attrs) { 
 this(context, attrs, 0); 
 } 
 
 public BadgeView(Context context, AttributeSet attrs, int defStyleAttr) { 
 super(context, attrs, defStyleAttr); 
 
 mRectF = new RectF(); 
 
 mTextSize = dip2px(context, 1); 
 mTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG); 
 mTextPaint.setColor(mTextColor); 
 mTextPaint.setStyle(Paint.Style.FILL); 
 mTextPaint.setTextSize(mTextSize); 
 mTextPaint.setTextAlign(Paint.Align.CENTER); 
 mBgPaint = new Paint(Paint.ANTI_ALIAS_FLAG); 
 mBgPaint.setColor(mBgColor); 
 mBgPaint.setStyle(Paint.Style.FILL); 
 FrameLayout.LayoutParams params = new FrameLayout.LayoutParams( 
  FrameLayout.LayoutParams.WRAP_CONTENT, 
  FrameLayout.LayoutParams.WRAP_CONTENT); 
 params.gravity = mGravity; 
 setLayoutParams(params); 
 } 
 
 @Override 
 protected void onDraw(Canvas canvas) { 
 super.onDraw(canvas); 
 mRectF.set(0, 0, getMeasuredWidth(), getMeasuredHeight()); 
 Paint.FontMetrics fontMetrics = mTextPaint.getFontMetrics(); 
 mtextH = fontMetrics.descent - fontMetrics.ascent; 
 switch (mBackgroundShape) { 
  case SHAPE_CIRCLE: 
  canvas.drawCircle(getMeasuredWidth() / 2f, 
   getMeasuredHeight() / 2f, getMeasuredWidth() / 2, mBgPaint); 
  canvas.drawText(mText, getMeasuredWidth() / 2f, getMeasuredHeight() 
   / 2f + (mtextH / 2f - fontMetrics.descent), mTextPaint); 
  break; 
  case SHAPE_OVAL: 
 
  canvas.drawOval(mRectF, mBgPaint); 
  canvas.drawText(mText, getMeasuredWidth() / 2f, getMeasuredHeight() 
   / 2f + (mtextH / 2f - fontMetrics.descent), mTextPaint); 
  break; 
  case SHAPE_RECTANGLE: 
  canvas.drawRect(mRectF, mBgPaint); 
  canvas.drawText(mText, getMeasuredWidth() / 2f, getMeasuredHeight() 
   / 2f + (mtextH / 2f - fontMetrics.descent), mTextPaint); 
  break; 
  case SHAPE_SQUARE: 
  int sideLength = Math.min(getMeasuredHeight(), getMeasuredWidth()); 
  mRectF.set(0, 0, sideLength, sideLength); 
  canvas.drawRect(mRectF, mBgPaint); 
  canvas.drawText(mText, sideLength / 2f, sideLength / 2f 
   + (mtextH / 2f - fontMetrics.descent), mTextPaint); 
  break; 
  case SHAPTE_ROUND_RECTANGLE: 
  canvas.drawRoundRect(mRectF, dip2px(getContext(), getMeasuredWidth()/2), 
   dip2px(getContext(), getMeasuredWidth()/2), mBgPaint); 
  canvas.drawText(mText, getMeasuredWidth() / 2f, getMeasuredHeight() 
   / 2f + (mtextH / 2f - fontMetrics.descent), mTextPaint); 
  break; 
 } 
 
 } 
 
 /** 
 * 设置该控件的背景颜色 
 * 
 * @param color 
 *  背景颜色 
 * @return BadgeView 
 */ 
 public BadgeView setBadgeBackgroundColor(int color) { 
 mBgColor = color; 
 mBgPaint.setColor(color); 
 invalidate(); 
 return this; 
 } 
 
 /** 
 * 设置该控件的背景图形 
 * 
 * @param shape 
 *  图形 
 * @return 
 */ 
 public BadgeView setBackgroundShape(int shape) { 
 mBackgroundShape = shape; 
 invalidate(); 
 return this; 
 } 
 
 /** 
 * 设置该控件的宽 
 * 
 * @param width 
 *  宽 
 * @return BadgeView 
 */ 
 public BadgeView setWidth(int width) { 
 this.mWidth = width; 
 this.setBadgeLayoutParams(width, mHeight); 
 return this; 
 
 } 
 
 /** 
 * 设置该控件的高 
 * 
 * @param height 
 *  高 
 * @return BadgeView 
 */ 
 public BadgeView setHeight(int height) { 
 this.mHeight = height; 
 this.setBadgeLayoutParams(mWidth, height); 
 return this; 
 } 
 
 /** 
 * 设置该控件的高和宽 
 * 
 * @param width 
 *  宽 
 * @param height 
 *  高 
 * @return 
 */ 
 public BadgeView setBadgeLayoutParams(int width, int height) { 
 this.mWidth = width; 
 this.mHeight = height; 
 FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) getLayoutParams(); 
 params.width = dip2px(getContext(), width); 
 params.height = dip2px(getContext(), height); 
 setLayoutParams(params); 
 return this; 
 } 
 
 /** 
 * 设置该控件的位置 
 * 
 * @param gravity 
 *  位置 
 * @return BadgeView 
 */ 
 public BadgeView setBadgeGravity(int gravity) { 
 mGravity = gravity; 
 FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) getLayoutParams(); 
 params.gravity = gravity; 
 setLayoutParams(params); 
 return this; 
 } 
 
 /** 
 * 设置该控件的高和宽、位置 
 * 
 * @param width 
 *  宽 
 * @param height 
 *  高 
 * @param gravity 
 *  位置 
 * @return BadgeView 
 */ 
 public BadgeView setBadgeLayoutParams(int width, int height, int gravity) { 
 FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) getLayoutParams(); 
 params.width = dip2px(getContext(), width); 
 params.height = dip2px(getContext(), height); 
 setLayoutParams(params); 
 setBadgeGravity(gravity); 
 return this; 
 } 
 
 /** 
 * 设置该控件的文本大小 
 * 
 * @param size 
 *  文本大小（sp） 
 * @return 
 */ 
 public BadgeView setTextSize(int size) { 
 mTextSize = sp2px(getContext(), size); 
 mTextPaint.setTextSize(sp2px(getContext(), size)); 
 invalidate(); 
 return this; 
 } 
 
 /** 
 * 设置该控件的文本颜色 
 * 
 * @param color 
 *  文本颜色 
 * @return BadgeView 
 */ 
 public BadgeView setTextColor(int color) { 
 mTextColor = color; 
 mTextPaint.setColor(color); 
 invalidate(); 
 return this; 
 } 
 
 /** 
 * 设置该控件的文本是否为粗体 
 * 
 * @param flag 
 */ 
 public void setBadgeBoldText(boolean flag) { 
 mTextPaint.setFakeBoldText(flag); 
 invalidate(); 
 } 
 
 /** 
 * 设置该控件要显示的整数文本 
 * 
 * @param count 
 *  要显示的整数文本 
 * @return BadgeView 
 */ 
 public BadgeView setBadgeText(int count) { 
 mText = String.valueOf(count); 
 invalidate(); 
 return this; 
 } 
 
 /** 
 * 设置该控件要显示的整数文本数字，超过指定上限显示为指定的上限内容 
 * 
 * @param count 
 *  要显示的整数文本 
 * @param maxCount 
 *  数字上限 
 * @param text 
 *  超过上限要显示的字符串文本 
 * @return BadgeView 
 */ 
 public BadgeView setBadgeText(int count, int maxCount, String text) { 
 if (count <= maxCount) { 
  mText = String.valueOf(count); 
 } else { 
  mText = text; 
 } 
 invalidate(); 
 return this; 
 } 
 
 /** 
 * 设置该控件要显示的字符串文本 
 * 
 * @param text 
 *  要显示的字符串文本 
 * @return BadgeView 
 */ 
 public BadgeView setBadgeText(String text) { 
 mText = text; 
 invalidate(); 
 return this; 
 } 
 
 /** 
 * 设置绑定的控件 
 * 
 * @param view 
 *  要绑定的控件 
 * @return BadgeView 
 */ 
 public BadgeView setBindView(View view) { 
 mIsShow = true; 
 if (getParent() != null) 
  ((ViewGroup) getParent()).removeView(this); 
 if (view == null) 
  return this; 
 if (view.getParent() instanceof FrameLayout) { 
  ((FrameLayout) view.getParent()).addView(this); 
 } else if (view.getParent() instanceof ViewGroup) { 
  ViewGroup parentContainer = (ViewGroup) view.getParent(); 
  int viewIndex = ((ViewGroup) view.getParent()).indexOfChild(view); 
  ((ViewGroup) view.getParent()).removeView(view); 
  FrameLayout container = new FrameLayout(getContext()); 
  ViewGroup.LayoutParams containerParams = view.getLayoutParams(); 
  container.setLayoutParams(containerParams); 
  container.setId(view.getId()); 
  view.setLayoutParams(new ViewGroup.LayoutParams( 
   ViewGroup.LayoutParams.MATCH_PARENT, 
   ViewGroup.LayoutParams.MATCH_PARENT)); 
  container.addView(view); 
  container.addView(this); 
  parentContainer.addView(container, viewIndex); 
 } else if (view.getParent() == null) { 
  Log.e(LOG_TAG, "View must have a parent"); 
 } 
 return this; 
 } 
 
 /** 
 * 设置绑定的控件 
 * 
 * @param view 要绑定的控件 
 * @param tabIndex 要绑定的控件的子项 
 */ 
 public void setBindView(TabWidget view, int tabIndex) { 
 View tabView = view 
  .getChildTabViewAt(tabIndex); 
 this.setBindView(tabView); 
 } 
 
 /** 
 * 移除绑定的控件 
 * 
 * @return BadgeView 
 */ 
 public boolean removebindView() { 
 if (getParent() != null) { 
  mIsShow = false; 
  ((ViewGroup) getParent()).removeView(this); 
  return true; 
 } 
 return false; 
 } 
 
 /** 
 * @return 改控件的显示状态 
 */ 
 public boolean isShow() { 
 return mIsShow; 
 } 
 
 /** 
 * @return 控件的字符串文本 
 */ 
 public String getBadgeText() { 
 return mText; 
 } 
 
 private int dip2px(Context context, int dip) { 
 return (int) (dip 
  * getContext().getResources().getDisplayMetrics().density + 0.5f); 
 } 
 
 private int sp2px(Context context, float spValue) { 
 final float fontScale = context.getResources().getDisplayMetrics().scaledDensity; 
 return (int) (spValue * fontScale + 0.5f); 
 } 
 
} 

import android.content.Context; 
import android.view.Gravity; 
 
public class BadgeFactory { 
 
 public static BadgeView create(Context context) { 
 return new BadgeView(context); 
 } 
 
 public static BadgeView createDot(Context context) { 
 return new BadgeView(context).setBadgeLayoutParams(10, 10) 
  .setTextSize(0) 
  .setBadgeGravity(Gravity.RIGHT | Gravity.TOP) 
  .setBackgroundShape(BadgeView.SHAPE_CIRCLE); 
 } 
 
 public static BadgeView createCircle(Context context) { 
 return new BadgeView(context).setBadgeLayoutParams(16, 16) 
  .setTextSize(12) 
  .setBadgeGravity(Gravity.RIGHT | Gravity.TOP) 
  .setBackgroundShape(BadgeView.SHAPE_CIRCLE); 
 } 
 
 public static BadgeView createRectangle(Context context) { 
 return new BadgeView(context).setBadgeLayoutParams(2, 20) 
  .setTextSize(12) 
  .setBadgeGravity(Gravity.RIGHT | Gravity.TOP) 
  .setBackgroundShape(BadgeView.SHAPE_RECTANGLE); 
 } 
 
 public static BadgeView createOval(Context context) { 
 return new BadgeView(context).setBadgeLayoutParams(25, 20) 
  .setTextSize(12) 
  .setBadgeGravity(Gravity.RIGHT | Gravity.TOP) 
  .setBackgroundShape(BadgeView.SHAPE_OVAL); 
 } 
 
 public static BadgeView createSquare(Context context) { 
 return new BadgeView(context).setBadgeLayoutParams(20, 20) 
  .setTextSize(12) 
  .setBadgeGravity(Gravity.RIGHT | Gravity.TOP) 
  .setBackgroundShape(BadgeView.SHAPE_SQUARE); 
 } 
 
 public static BadgeView createRoundRect(Context context) { 
 return new BadgeView(context).setBadgeLayoutParams(25, 20) 
  .setTextSize(12) 
  .setBadgeGravity(Gravity.RIGHT | Gravity.TOP) 
  .setBackgroundShape(BadgeView.SHAPTE_ROUND_RECTANGLE); 
 } 
 
}