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); 
 } 
 
}