android使用贝塞尔曲线自定义心形View

贝塞尔曲线(Bézier curve)，又称贝兹曲线或贝济埃曲线，是应用于二维图形应用程序的数学曲线。

绘制心形需要Path类中的两个方法分别是：

moveTo(float x,float y) 贝塞尔曲线的起始位置，

cubicTo(float x1, float y1, float x2, float y2, float x3, float y3)

Add a cubic bezier from the last point, approaching control points (x1,y1) and (x2,y2), and ending at (x3,y3).

添加两个控制点(x1,y1)，(x2,y2)终点是（x3,y3）

代码：

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.View;

/**
 * Created by dell on 2016/5/26.
 */
public class HeartView extends View {

    private int mMeasureWidth;
    private int mWidthMode;
    private int mMeasureHeight;
    private int mHeightMode;
    private Paint paint;
    private int heartColor; 
    public HeartView(Context context){
        super(context);

    }

    public HeartView(Context context,AttributeSet attrs){
        super(context,attrs);
        TypedArray ta = context.obtainStyledAttributes(attrs,R.styleable.HeartView);
        heartColor = ta.getColor(R.styleable.HeartView_heartColor, Color.BLUE);
        ta.recycle();

    }

    public HeartView(Context context,AttributeSet attrs,int defStyleAttrs){
        super(context,attrs,defStyleAttrs);
    }
   
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        mWidthMode = MeasureSpec.getMode(widthMeasureSpec);
        mHeightMode = MeasureSpec.getMode(heightMeasureSpec);
        mMeasureWidth = MeasureSpec.getSize(widthMeasureSpec);
        mMeasureHeight = MeasureSpec.getSize(heightMeasureSpec);
        if(mWidthMode == MeasureSpec.AT_MOST && mHeightMode == MeasureSpec.AT_MOST){
            setMeasuredDimension(200,200);
        }else if(mWidthMode == MeasureSpec.AT_MOST){
            setMeasuredDimension(200,mMeasureHeight);
        }else if(mHeightMode == MeasureSpec.AT_MOST){
            setMeasuredDimension(mMeasureWidth,200);
        }else{
            setMeasuredDimension(mMeasureWidth,mMeasureHeight);
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        paint = new Paint();
        paint.setStrokeWidth(6);
        paint.setAntiAlias(true);
        paint.setColor(heartColor);
        int width = getWidth();
        int height = getHeight();

       // 绘制心形
        Path path = new Path();
        path.moveTo(width/2,height/4);
        path.cubicTo((width*6)/7,height/9,(width*12)/13,(height*2)/5,width/2,(height*7)/12);
        canvas.drawPath(path,paint);

        Path path2 = new Path();
        path2.moveTo(width/2,height/4);
        path2.cubicTo(width / 7, height / 9, width / 13, (height * 2) / 5, width / 2, (height * 7) / 12);
        canvas.drawPath(path2,paint);

    }
}

该HeartView有一个自定义属性heartColor

定义一个attrs.xml文件在里面编写

把HeartView当做普通VIew控件使用，在引用时注意要用包的全名

运行效果图