andriod自定义View绘制形, 圆形, 三角形,...

我们要想画好一些炫酷的View，首先我们得知道怎么去画一些基础的图案，比如矩形，圆形，三角形，多边形等….
1.矩形

package com.lgl.view.view;

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

/**
 * 矩形
 */
public class RectView extends View {

    //无参
    public RectView(Context context) {
        super(context);
    }

    //有参
    public RectView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        // 创建画笔
        Paint p = new Paint();
        //设置实心
        p.setStyle(Paint.Style.FILL);
        // 设置红色
        p.setColor(Color.BLACK);
        // 设置画笔的锯齿效果
        p.setAntiAlias(true);
        //绘制
        canvas.drawRect(50, 100, 300, 300, p);

    }
}

圆形

package com.lgl.view.view;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;
import android.view.WindowManager;

/**
 * 圆
 */
public class CircleView extends View {

    int width;
    int height;

    //无参
    public CircleView(Context context) {
        super(context);
        init();
    }

    //有参
    public CircleView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        //获取屏幕的宽高
        //Android绘图机制（一）——自定义View的基础属性和方法里面有讲
        WindowManager wm = (WindowManager) getContext()
                .getSystemService(Context.WINDOW_SERVICE);

        width = wm.getDefaultDisplay().getWidth();
        height = wm.getDefaultDisplay().getHeight();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        Paint p = new Paint();
        p.setColor(Color.BLACK);
        // 设置画笔的锯齿效果
        p.setAntiAlias(true);
        canvas.drawCircle(width / 2, height / 2, width / 2, p);
    }
}

三角形

package com.lgl.view.view;

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

/**
 * 三角形
 */
public class TrigonView extends View {

    //无参
    public TrigonView(Context context) {
        super(context);
    }

    //有参
    public TrigonView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        Paint p = new Paint();
        p.setColor(Color.BLACK);
        //实例化路径
        Path path = new Path();
        path.moveTo(80, 200);// 此点为多边形的起点
        path.lineTo(120, 250);
        path.lineTo(80, 250);
        path.close(); // 使这些点构成封闭的多边形
        canvas.drawPath(path, p);

    }
}

扇形

package com.lgl.view.view;

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.view.View;

/**
 * 扇形
 */
public class SectorView extends View {

    public SectorView(Context context) {
        super(context);
    }

    public SectorView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        // 创建画笔
        Paint p = new Paint();
        p.setColor(Color.BLACK);
        RectF rectF = new RectF(60, 100, 200, 240);
        canvas.drawArc(rectF, 200, 130, true, p);
    }
}

椭圆

package com.lgl.view.view;

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.view.View;

/**
 * 椭圆
 */
public class OvalView extends View {

    public OvalView(Context context) {
        super(context);
    }

    public OvalView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        // 创建画笔
        Paint p = new Paint();
        p.setColor(Color.BLACK);
        RectF rectF = new RectF(60, 100, 200, 240);
        rectF.set(210,100,250,130);
        canvas.drawOval(rectF, p);
    }
}

曲线

package com.lgl.view.view;

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

public class PathView extends View {

    public PathView(Context context) {
        super(context);
    }

    public PathView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        // 创建画笔
        Paint p = new Paint();
        p.setColor(Color.BLACK);

        p.reset();
        //设置空心
        p.setStyle(Paint.Style.STROKE);
        Path path = new Path();
        path.moveTo(100, 320);//设置Path的起点
        path.quadTo(150, 310, 170, 400);  //设置路径点和终点
        canvas.drawPath(path, p);
    }
}

文字和图片

package com.lgl.view.view;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

import com.lgl.view.R;

public class TvIvView extends View {
    public TvIvView(Context context) {
        super(context);
    }

    public TvIvView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        Paint p = new Paint();
        p.setColor(Color.RED);

        //文本
        canvas.drawText("自定义文本", 250, 330, p);
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);
        //图片
        canvas.drawBitmap(bitmap, 250, 360, p);
    }
}