Android自定义view实现动态柱状图

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;
}
}

<?xml version="1.0" encoding="utf-8"? 
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
<View
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="0.2"/ 
<com.mieasy.myhistogramview.Histogram
android:id="@+id/column_one"
android:layout_width="0dp"
android:layout_height="300dp"
android:layout_weight="0.8"/ 
<View
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="2.4"/ 
<com.mieasy.myhistogramview.Histogram
android:id="@+id/column_two"
android:layout_width="0dp"
android:layout_height="300dp"
android:layout_weight="1"/ 
<View
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="2.4"/ 
<com.mieasy.myhistogramview.Histogram
android:id="@+id/column_three"
android:layout_width="0dp"
android:layout_height="300dp"
android:layout_weight="1"/ 
<View
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="0.2"/ 
</LinearLayout 

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
}