本人分享一下，自己写的一个消息提醒小红点控件，支持圆、矩形、椭圆、圆角矩形、正方形五种图形样式，可带文字，支持链式操作。
先看一下实现效果，随便测了几个控件（TextView、ImageView、RadioButton、LinearLayout、RelativeLayout、FrameLayout），不确定其他会不会有问题。
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); } }
可自由定制自己喜欢的控件，为了方便使用这里还采用工厂模式封装一些基本方法，如下：
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); } }
源码下载：Android实现消息提醒小红点
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。