Android之给控件添加标签（类似右上角消息提醒数字）

知识点

1、给控件添加提醒标签，类似右上角的消息提醒；

首先，给用户提醒一个类似你有多少条未读消息或者是购物车里头一共有多少物品，在底部的tab，是一个很友好的用户体验。

按着传统的做法，我们会用一个framelayout布局或者是相对布局，然后使得两个空间重叠，达到右上角提醒的功能。但是这样的做法是比较麻烦的，至少写的代码多了不少。现在我们有一个很简单的做法，我们可以自定义控件啊，只要集成textview或者其它控件，然后在实现我们需要的功能就OK了。

下面就是一个自定义的控件，只需要几行代码就可以实现上面所说的布局，而且文件只有一个，真的只有一个哦；

先看图：



代码很简单，如下

btn_signIn = (Button) findViewById(R.id.btn_signIn);
btn_signIn.setOnClickListener(this);
BadgeView badgeView = new BadgeView(this, btn_signIn);
badgeView.setText("99+");
//设置位置为居中
//        badgeView.setBadgePosition(BadgeView.POSITION_CENTER);
/* 显示，不调用此方法，不会显示，同理，也可以隐藏.hide() */
badgeView.show();
badgeView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
toast(R.string.app_name);
}
});
badgeView.setBadgeBackgroundColor(Color.GREEN);
badgeView.setBadgeMargin(10);
//        badgeView.setAnimation();
//        badgeView.setWidth();
//        badgeView.setAlpha();

我们也可以设置位置，例如我们调用这个方法，可以设置不同的位置

//设置位置为居中
badgeView.setBadgePosition(BadgeView.POSITION_CENTER);

常用的位置有：

/* 位于控件左上角 */
public static final int POSITION_TOP_LEFT = 1;
/* 位于控件右上角 */
public static final int POSITION_TOP_RIGHT = 2;
/* 位于控件右下角 */
public static final int POSITION_BOTTOM_LEFT = 3;
/* 位于控件左下角 */
public static final int POSITION_BOTTOM_RIGHT = 4;
/* 位于控件正中央 */
public static final int POSITION_CENTER = 5;

效果图如下：



最后我们奉上此类：

package com.yaojt.wegit;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Color;
import android.graphics.Typeface;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.RoundRectShape;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.view.ViewParent;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.DecelerateInterpolator;
import android.widget.FrameLayout;
import android.widget.TabWidget;
import android.widget.TextView;

/**
* 给控件加入一个标签，类似于购物车右上角的显示有多少个物品的标签
* <p>
* A simple text label view that can be applied as a "badge" to any given {@link View}.
* This class is intended to be instantiated at runtime rather than included in XML layouts.
*/
public class BadgeView extends TextView {

/* 位于控件左上角 */
public static final int POSITION_TOP_LEFT = 1;
/* 位于控件右上角 */
public static final int POSITION_TOP_RIGHT = 2;
/* 位于控件右下角 */
public static final int POSITION_BOTTOM_LEFT = 3;
/* 位于控件左下角 */
public static final int POSITION_BOTTOM_RIGHT = 4;
/* 位于控件正中央 */
public static final int POSITION_CENTER = 5;

/* 默认margin */
private static final int DEFAULT_MARGIN_DIP = 5;
/* 默认左右padding */
private static final int DEFAULT_LR_PADDING_DIP = 5;
/* 默认添加控件的圆角 */
private static final int DEFAULT_CORNER_RADIUS_DIP = 8;
/* 默认位置:右上角 */
private static final int DEFAULT_POSITION = POSITION_TOP_RIGHT;
/* 默认标签的背景色为红色 */
private static final int DEFAULT_BADGE_COLOR = Color.parseColor("#CCFF0000");
/* 默认标签颜色为白色 */
private static final int DEFAULT_TEXT_COLOR = Color.WHITE;

/* 动画 */
private static Animation fadeIn;
private static Animation fadeOut;

private Context context;
private View target;

private int badgePosition;
private int badgeMarginH;
private int badgeMarginV;
private int badgeColor;

private boolean isShown;

private ShapeDrawable badgeBg;

private int targetTabIndex;

public BadgeView(Context context) {
this(context, (AttributeSet) null, android.R.attr.textViewStyle);
}

public BadgeView(Context context, AttributeSet attrs) {
this(context, attrs, android.R.attr.textViewStyle);
}

/**
* Constructor -
* <p>
* create a new BadgeView instance attached to a target {@link View}.
*
* @param context context for this view.
* @param target  the View to attach the badge to.
*/
public BadgeView(Context context, View target) {
this(context, null, android.R.attr.textViewStyle, target, 0);
}

/**
* Constructor -
* <p>
* create a new BadgeView instance attached to a target {@link TabWidget}
* tab at a given index.
*
* @param context context for this view.
* @param target  the TabWidget to attach the badge to.
* @param index   the position of the tab within the target.
*/
public BadgeView(Context context, TabWidget target, int index) {
this(context, null, android.R.attr.textViewStyle, target, index);
}

public BadgeView(Context context, AttributeSet attrs, int defStyle) {
this(context, attrs, defStyle, null, 0);
}

public BadgeView(Context context, AttributeSet attrs, int defStyle, View target, int tabIndex) {
super(context, attrs, defStyle);
init(context, target, tabIndex);
}

private void init(Context context, View target, int tabIndex) {

this.context = context;
this.target = target;
this.targetTabIndex = tabIndex;

// apply defaults
badgePosition = DEFAULT_POSITION;
badgeMarginH = dipToPixels(DEFAULT_MARGIN_DIP);
badgeMarginV = badgeMarginH;
badgeColor = DEFAULT_BADGE_COLOR;

setTypeface(Typeface.DEFAULT_BOLD);
int paddingPixels = dipToPixels(DEFAULT_LR_PADDING_DIP);
setPadding(paddingPixels, 0, paddingPixels, 0);
setTextColor(DEFAULT_TEXT_COLOR);

fadeIn = new AlphaAnimation(0, 1);
fadeIn.setInterpolator(new DecelerateInterpolator());
fadeIn.setDuration(200);

fadeOut = new AlphaAnimation(1, 0);
fadeOut.setInterpolator(new AccelerateInterpolator());
fadeOut.setDuration(200);

isShown = false;

if (this.target != null) {
applyTo(this.target);
} else {
show();
}

}

private void applyTo(View target) {

LayoutParams lp = target.getLayoutParams();
ViewParent parent = target.getParent();
FrameLayout container = new FrameLayout(context);

if (target instanceof TabWidget) {

// set target to the relevant tab child container
target = ((TabWidget) target).getChildTabViewAt(targetTabIndex);
this.target = target;

((ViewGroup) target).addView(container,
new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

this.setVisibility(View.GONE);
container.addView(this);

} else {

// TODO verify that parent is indeed a ViewGroup
ViewGroup group = (ViewGroup) parent;
int index = group.indexOfChild(target);

group.removeView(target);
group.addView(container, index, lp);

container.addView(target);

this.setVisibility(View.GONE);
container.addView(this);

group.invalidate();

}

}

/**
* Make the badge visible in the UI.
*/
public void show() {
show(false, null);
}

/**
* Make the badge visible in the UI.
*
* @param animate flag to apply the default fade-in animation.
*/
public void show(boolean animate) {
show(animate, fadeIn);
}

/**
* Make the badge visible in the UI.
*
* @param anim Animation to apply to the view when made visible.
*/
public void show(Animation anim) {
show(true, anim);
}

/**
* Make the badge non-visible in the UI.
*/
public void hide() {
hide(false, null);
}

/**
* Make the badge non-visible in the UI.
*
* @param animate flag to apply the default fade-out animation.
*/
public void hide(boolean animate) {
hide(animate, fadeOut);
}

/**
* Make the badge non-visible in the UI.
*
* @param anim Animation to apply to the view when made non-visible.
*/
public void hide(Animation anim) {
hide(true, anim);
}

/**
* Toggle the badge visibility in the UI.
*/
public void toggle() {
toggle(false, null, null);
}

/**
* Toggle the badge visibility in the UI.
*
* @param animate flag to apply the default fade-in/out animation.
*/
public void toggle(boolean animate) {
toggle(animate, fadeIn, fadeOut);
}

/**
* Toggle the badge visibility in the UI.
*
* @param animIn  Animation to apply to the view when made visible.
* @param animOut Animation to apply to the view when made non-visible.
*/
public void toggle(Animation animIn, Animation animOut) {
toggle(true, animIn, animOut);
}

private void show(boolean animate, Animation anim) {
if (getBackground() == null) {
if (badgeBg == null) {
badgeBg = getDefaultBackground();
}
setBackgroundDrawable(badgeBg);
}
applyLayoutParams();

if (animate) {
this.startAnimation(anim);
}
this.setVisibility(View.VISIBLE);
isShown = true;
}

private void hide(boolean animate, Animation anim) {
this.setVisibility(View.GONE);
if (animate) {
this.startAnimation(anim);
}
isShown = false;
}

private void toggle(boolean animate, Animation animIn, Animation animOut) {
if (isShown) {
hide(animate && (animOut != null), animOut);
} else {
show(animate && (animIn != null), animIn);
}
}

/**
* Increment the numeric badge label. If the current badge label cannot be converted to
* an integer value, its label will be set to "0".
*
* @param offset the increment offset.
*/
public int increment(int offset) {
CharSequence txt = getText();
int i;
if (txt != null) {
try {
i = Integer.parseInt(txt.toString());
} catch (NumberFormatException e) {
i = 0;
}
} else {
i = 0;
}
i = i + offset;
setText(String.valueOf(i));
return i;
}

/**
* Decrement the numeric badge label. If the current badge label cannot be converted to
* an integer value, its label will be set to "0".
*
* @param offset the decrement offset.
*/
public int decrement(int offset) {
return increment(-offset);
}

private ShapeDrawable getDefaultBackground() {

int r = dipToPixels(DEFAULT_CORNER_RADIUS_DIP);
float[] outerR = new float[]{r, r, r, r, r, r, r, r};

RoundRectShape rr = new RoundRectShape(outerR, null, null);
ShapeDrawable drawable = new ShapeDrawable(rr);
drawable.getPaint().setColor(badgeColor);

return drawable;

}

private void applyLayoutParams() {

FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);

switch (badgePosition) {
case POSITION_TOP_LEFT:
lp.gravity = Gravity.LEFT | Gravity.TOP;
lp.setMargins(badgeMarginH, badgeMarginV, 0, 0);
break;
case POSITION_TOP_RIGHT:
lp.gravity = Gravity.RIGHT | Gravity.TOP;
lp.setMargins(0, badgeMarginV, badgeMarginH, 0);
break;
case POSITION_BOTTOM_LEFT:
lp.gravity = Gravity.LEFT | Gravity.BOTTOM;
lp.setMargins(badgeMarginH, 0, 0, badgeMarginV);
break;
case POSITION_BOTTOM_RIGHT:
lp.gravity = Gravity.RIGHT | Gravity.BOTTOM;
lp.setMargins(0, 0, badgeMarginH, badgeMarginV);
break;
case POSITION_CENTER:
lp.gravity = Gravity.CENTER;
lp.setMargins(0, 0, 0, 0);
break;
default:
break;
}

setLayoutParams(lp);

}

/**
* Returns the target View this badge has been attached to.
*/
public View getTarget() {
return target;
}

/**
* Is this badge currently visible in the UI?
*/
@Override
public boolean isShown() {
return isShown;
}

/**
* Returns the positioning of this badge.
* <p>
* one of POSITION_TOP_LEFT, POSITION_TOP_RIGHT, POSITION_BOTTOM_LEFT, POSITION_BOTTOM_RIGHT, POSTION_CENTER.
*/
public int getBadgePosition() {
return badgePosition;
}

/**
* Set the positioning of this badge.
*
* @param layoutPosition one of POSITION_TOP_LEFT, POSITION_TOP_RIGHT, POSITION_BOTTOM_LEFT, POSITION_BOTTOM_RIGHT, POSTION_CENTER.
*/
public void setBadgePosition(int layoutPosition) {
this.badgePosition = layoutPosition;
}

/**
* Returns the horizontal margin from the target View that is applied to this badge.
*/
public int getHorizontalBadgeMargin() {
return badgeMarginH;
}

/**
* Returns the vertical margin from the target View that is applied to this badge.
*/
public int getVerticalBadgeMargin() {
return badgeMarginV;
}

/**
* Set the horizontal/vertical margin from the target View that is applied to this badge.
*
* @param badgeMargin the margin in pixels.
*/
public void setBadgeMargin(int badgeMargin) {
this.badgeMarginH = badgeMargin;
this.badgeMarginV = badgeMargin;
}

/**
* Set the horizontal/vertical margin from the target View that is applied to this badge.
*
* @param horizontal margin in pixels.
* @param vertical   margin in pixels.
*/
public void setBadgeMargin(int horizontal, int vertical) {
this.badgeMarginH = horizontal;
this.badgeMarginV = vertical;
}

/**
* Returns the color value of the badge background.
*/
public int getBadgeBackgroundColor() {
return badgeColor;
}

/**
* Set the color value of the badge background.
*
* @param badgeColor the badge background color.
*/
public void setBadgeBackgroundColor(int badgeColor) {
this.badgeColor = badgeColor;
badgeBg = getDefaultBackground();
}

private int dipToPixels(int dip) {
Resources r = getResources();
float px = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dip, r.getDisplayMetrics());
return (int) px;
}

}

谢谢！