需求
1.数字为1位,显示圆形
2.数字为2位图形拉伸，左右各半圆
3.数字大于999，显示999+
4.自定义文字颜色，自定义背景色
效果(好吧，看起来挺low的)
本身并不复杂，不过作为一道计算题还是很不错的
1.自定义属性
<?xml version="1.0" encoding="utf-8"?><resources> <!--计数TextView--> <declare-styleable name="CountTextView"> <attr name="z_ctv_font_size" format="reference|dimension"/> <attr name="z_ctv_num" format="integer"/> <attr name="z_bg_color" format="reference|color"/> <attr name="z_txt_color" format="reference|color"/> </declare-styleable></resources>
2.分析
使用圆角矩形来画背景,Paint.getTextBounds来获取文字边界矩形
1).先绘制文字，将文字左顶点与屏幕左顶点重合
2).通过计算，画出一个数时的圆角矩形两个顶点(如下图)
3).通过数字位数来控制圆角矩形两顶点的X
4).通过画布平移让圆角矩形左顶点处于画布顶点
5).计算圆角矩形的宽高，设置View大小
public class CountTextView extends View { private int mCtvFontSize = sp(100); private int mCtvNum = 5; private int mCtvBgColor = 0xffBFF3F7; private int mCtvTxtColor = Color.WHITE; private Paint mPaint;//主画笔 private Paint mTxtPaint; private Rect mRect; private String mStr; private int mOffSet; public CountTextView(Context context) { this(context, null); } public CountTextView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public CountTextView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CountTextView); mCtvFontSize = (int) a.getDimension(R.styleable.CountTextView_z_ctv_font_size, mCtvFontSize); mCtvNum = a.getInteger(R.styleable.CountTextView_z_ctv_num, mCtvNum); mCtvTxtColor = a.getColor(R.styleable.CountTextView_z_txt_color, mCtvTxtColor); mCtvBgColor = a.getColor(R.styleable.CountTextView_z_bg_color, mCtvBgColor); a.recycle(); init(); } private void init() { //初始化主画笔 mTxtPaint = new Paint(Paint.ANTI_ALIAS_FLAG); mTxtPaint.setColor(mCtvTxtColor); mTxtPaint.setTextSize(mCtvFontSize); mRect = new Rect(); mStr = mCtvNum + ""; if (mCtvNum >= 1000) { mStr = "999+"; } mTxtPaint.getTextBounds(mStr, 0, mStr.length(), mRect); int AChartLen = mRect.width() / mStr.length(); mOffSet = (int) ((mStr.length() - 1) * AChartLen * 0.7f); mPaint = new Paint(Paint.ANTI_ALIAS_FLAG); mPaint.setColor(mCtvBgColor); mPaint.setStrokeWidth(mRect.height()); mPaint.setStrokeCap(Paint.Cap.ROUND); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //文字左侧距圆心的偏移 int offsetX = mRect.height() - mRect.width() / 2 + mOffSet; setMeasuredDimension(2 * offsetX + mRect.width(), 2 * mRect.height()); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.save(); int offsetX = mRect.height() - mRect.width() / 2 + mOffSet; canvas.translate(offsetX, mRect.height() / 2); //圆角矩形左上点 int topX = mRect.width() / 2 - mRect.height(); int topY = -mRect.height() / 2; //圆角矩形右下点 int bottomX = mRect.height() + mRect.width() / 2; int bottomY = mRect.height() / 2 + mRect.height(); canvas.drawRoundRect(topX - mOffSet, topY, bottomX + mOffSet, bottomY, mRect.height(), mRect.height(), mPaint); canvas.drawText(mStr, 0, mRect.height(), mTxtPaint); canvas.restore(); } private int sp(float sp) { return (int) TypedValue.applyDimension( TypedValue.COMPLEX_UNIT_SP, sp, getResources().getDisplayMetrics()); }}
3.使用
<com.toly1994.c.view.CountTextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginTop="8dp" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" app:z_ctv_font_size="40sp" app:z_ctv_num="30"/>