Android绘图机制（二）——自定义View绘制形, 圆形, 三角形, 扇形, 椭圆, 曲线,文字和图片的坐标讲解

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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….

新建一个项目

然后我们创建一个listview,每个图案一个Activity,这样看起来是不是很顺眼

     <ListView
        android:id="@+id/listview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

编写ListView

private ListView listview;
//item上的数据源
 private String[] name = {"矩形", "圆形", "三角形", "扇形", "椭圆", "曲线","文字和图片"};
//listview的adapter
private ArrayAdapter<String>adapter;

private void initView() {
        //实例化listview
        listview = (ListView) findViewById(R.id.listview);
        //实例化数据源
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, name);
        //listview设置adapter
        listview.setAdapter(adapter);
        //listview设置点击事件
        listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                //判断点击了第几个
                if (id == 0) {
                    //矩形
                    startActivity(new Intent(MainActivity.this, RectActivity.class));
                } else if (id == 1) {
                    //圆形
                    startActivity(new Intent(MainActivity.this, CircleActivity.class));
                } else if (id == 2) {
                    //三角形
                    startActivity(new Intent(MainActivity.this, TrigonActivity.class));
                } else if (id == 3) {
                    //扇形
                    startActivity(new Intent(MainActivity.this, SectorActivity.class));
                } else if (id == 4) {
                    //椭圆
                    startActivity(new Intent(MainActivity.this, OvalActivity.class));
                } else if (id == 5) {
                    //曲线
                    startActivity(new Intent(MainActivity.this, PathActivity.class));
                }else if (id == 6) {
                    //曲线
                    startActivity(new Intent(MainActivity.this, TvIvActivity.class));
                }
            }
        });
    }

效果是这样的

后续可以添加

1.矩形——RectActivity

好的，上面写ListView的代码是不是很简单？拿我们新建一个RectActivity去画点了，首先我们要新建一个RectView继承View

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
 * Created by LGL on 2016/1/7.
 */
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);

    }
}

大致的坐标思维

截图

1.圆形——CircleActivity

我们还是新建一个CircleActivity去画点了，首先我们要新建一个CircleView继承View

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
 * Created by LGL on 2016/1/7.
 */
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);
    }
}

大致的坐标思维

截图

3.三角形——TrigonActivity

我们还是新建一个TrigonActivity去画点了，首先我们要新建一个trigonView继承View

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
 * Created by LGL on 2016/1/7.
 */
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);

    }
}

大致的坐标思维

截图

4.扇形——SectorActivity

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
 * Created by LGL on 2016/1/8.
 */
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);
    }
}

大致的坐标思维

截图

5.椭圆——OvalActivity

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
 * Created by LGL on 2016/1/8.
 */
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);
    }
}

椭圆的思路和扇形是一样的，这里就不演示了

截图

6.曲线——PathActivity

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;

/**
 * Created by LGL on 2016/1/8.
 */
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);
    }
}

大致的坐标思维

截图

7.文字和图片——TvIvActivity

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;

/**
 * Created by LGL on 2016/1/8.
 */
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);
    }
}

文字和图片感觉不用多说，图片加载需要一个bitmap，而加载bitmap又需要一个工厂类，就是这样

大致的坐标思维

截图

相信看到这里，一些基础的图案都是可以绘制了，那么我们就可以进入下一节了

Demo下载地址：会在本系列最后一节放出，现在还没写完

PPT：http://download.csdn.net/detail/qq_26787115/9396627

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Android绘图机制（三）——自定义View的三种实现方式以及实战项目操作