Android中如何通过自定义view实现动态柱状图

本篇内容主要讲解"Android中如何通过自定义view实现动态柱状图"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"Android中如何通过自定义view实现动态柱状图"吧!

自定义view

public class Histogram extends View { int MAX = 100;//矩形显示的最大值 int corner = 0; //矩形的角度。 设置为0 则没有角度。 double data = 0.0;//显示的数 double tempData = 0; //初始数据 int textPadding = 50; //字体与矩形图的距离  Paint mPaint; int mColor;  Context mContext; //构造函数 public Histogram(Context context) {  super(context);  mContext = context; } public Histogram(Context context, @Nullable AttributeSet attrs) {  super(context, attrs);  mContext = context;  initPaint(); } public Histogram(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {  super(context, attrs, defStyleAttr);  mContext = context;  initPaint(); } //画笔方法 private void initPaint() {  mPaint = new Paint();  mPaint.setAntiAlias(true);  mColor = mContext.getResources().getColor(R.color.gary);  mPaint.setColor(mColor); } @Override public void draw(Canvas canvas) {  super.draw(canvas);  if (data == 0.0) {   mPaint.setTextSize(getWidth() / 2);   RectF oval3 = new RectF(0, getHeight() - DensityUtils.pxTodip(mContext, 20), getWidth(), getHeight());// 设置个新的长方形   canvas.drawRoundRect(oval3, DensityUtils.pxTodip(mContext, corner), DensityUtils.pxTodip(mContext, corner), mPaint);   canvas.drawText("0",     getWidth() * 0.5f - mPaint.measureText("0") * 0.5f,     getHeight() - DensityUtils.pxTodip(mContext, 20) - 2 * DensityUtils.pxTodip(mContext, textPadding),     mPaint);   return;  }  //防止数值很大的的时候，动画时间过长  int step = (int) (data / 100 + 1.0);  if (tempData < data - step) {   tempData = tempData + step;  } else {   tempData = data;  }  //画圆角矩形  String S = tempData + ""; //如果数字后面需要加% 则在""中添加%  //设置显示的字体  Typeface typeface = Typeface.createFromAsset(getContext().getAssets(),"digital-7.ttf");  mPaint.setTypeface(typeface);//  //一个字和两,三个字的字号相同  if (S.length() < 4) {   mPaint.setTextSize(getWidth()/2 );  } else {   mPaint.setTextSize(50); //可以通过getWidth()/2 改变字体大小 也可以通过设置数字来改变自己想要的字体大小 当超出矩形图宽度时不能显示全部  }//  float textH = mPaint.ascent() + mPaint.descent();  float MaxH = getHeight() - textH - 2 * DensityUtils.pxTodip(mContext, textPadding);//  //圆角矩形的实际高度  float realH = (float) (MaxH / MAX * tempData);  RectF oval3 = new RectF(0, getHeight() - realH, getWidth(), getHeight());// 设置个新的长方形  canvas.drawRoundRect(oval3, DensityUtils.pxTodip(mContext, corner), DensityUtils.pxTodip(mContext, corner), mPaint);  //写数字  canvas.drawText(S,    getWidth() * 0.5f - mPaint.measureText(S) * 0.5f,    getHeight() - realH - 2 * DensityUtils.pxTodip(mContext, textPadding),    mPaint);  if (tempData != data) {   postInvalidate();  } } public void setData(double data, int MAX) {  this.data = data;  this.MAX = MAX;  postInvalidate(); } public int getmColor() {  return mColor; } public void setmColor(int mColor) {  this.mColor = mColor; }}

布局

MainActivity调用initAllViews()方法

 private void initAllViews() {  column_one = (Histogram) findViewById(R.id.column_one);  column_two = (Histogram) findViewById(R.id.column_two);  column_three = (Histogram) findViewById(R.id.column_three);  column_one.setData( 20.22, 100);  column_two.setData(30.2, 100);  column_three.setData(40, 100);  column_one.mPaint.setColor(getResources().getColor(R.color.colorAccent)); //改变柱状图的颜色 }

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