Android 画一个太极图实例代码

2019-12-12 05:11:33

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今天练手一下，一起来画个太极图吧~

最终效果如下：

最终效果

一般都是先讲原理，我就反其道而行，先讲实现吧。

1.继承实现初始化方法

继承View，实现基本的构造函数：

public TestView(Context context) {  this(context, null);}public TestView(Context context, AttributeSet attrs) {  this(context, attrs, 0);}public TestView(Context context, AttributeSet attrs, int defStyleAttr) {  this(context, attrs, defStyleAttr, 0);}@TargetApi(Build.VERSION_CODES.LOLLIPOP)public TestView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {  super(context, attrs, defStyleAttr, defStyleRes);  init();}

在init()方法中，进行初始化操作，这里初始化一下画笔就好。

private Paint mPaint;private void init() {  initPaint();}/** * 初始化画笔 */private void initPaint() {  mPaint = new Paint();        //创建画笔对象  mPaint.setColor(Color.BLACK);    //设置画笔颜色  mPaint.setStyle(Paint.Style.FILL); //设置画笔模式为填充  mPaint.setStrokeWidth(10f);     //设置画笔宽度为10px  mPaint.setAntiAlias(true);     //设置抗锯齿  mPaint.setAlpha(255);        //设置画笔透明度}

在onSizeChanged()方法中获取高宽，便于之后绘制计算。

private int mWidth;private int mHeight;  @Overrideprotected void onSizeChanged(int w, int h, int oldw, int oldh) {  super.onSizeChanged(w, h, oldw, oldh);  mWidth = w;  mHeight = h;}

创建两个路径，一下计算就在这两个路径中进行。

private Path path0 = new Path();private Path path1 = new Path();

然后到最关键的onDraw()方法了，这里会分几步来演示。

1.移动布局到中间

@Overrideprotected void onDraw(Canvas canvas) {  super.onDraw(canvas);  //移动布局到中间  canvas.translate(mWidth / 2, mHeight / 2);}

ps：为了简洁，之后的代码都是在onDraw()中逐层增加的，之后就不写onDraw()的外出括号了。

2.画背景黄色

mPaint.setColor(0xffffff00);  path0.addRect(-400, -400, 400, 400, Path.Direction.CW);  canvas.drawPath(path0, mPaint);

第二步.png

3.画白色圆背景，即太极图的白鱼部分。

mPaint.setColor(0xffffffff);path0.rewind();path0.addCircle(0, 0, 200, Path.Direction.CW);canvas.drawPath(path0, mPaint);

4.画黑色圆背景，即太极图的黑鱼部分，和白鱼一样大小位置，只是把白鱼盖住了，这里就需要用一些boolean运算进行绘制了。

//白鱼的背景mPaint.setColor(0xffffffff);path0.rewind();path0.addCircle(0, 0, 200, Path.Direction.CW);canvas.drawPath(path0, mPaint);//黑鱼的背景mPaint.setColor(0xff000000);path1.addCircle(0, 0, 200, Path.Direction.CW);canvas.drawPath(path0, mPaint);//这一段注意，之后要删除

第四步.png

5.对黑鱼（path1）进行boolean计算，把不需要的部分去掉。这里就是要把圆的右半边消除，这里就需要用到path.op()方法了。

mPaint.setColor(0xffffffff);path0.rewind();path0.addCircle(0, 0, 200, Path.Direction.CW);canvas.drawPath(path0, mPaint);mPaint.setColor(0xff000000);path1.addCircle(0, 0, 200, Path.Direction.CW);path0.rewind();path0.addRect(0, -200, 200, 200, Path.Direction.CW);path1.op(path0, Path.Op.DIFFERENCE);canvas.drawPath(path0, mPaint);//这一段注意，之后要删除

第五步.png

6.这时候我们已经把不需要的另一半黑色去掉了，但是黑鱼应该有个圆的头，那么我们就拼接一个头给它。

mPaint.setColor(0xffffffff);path0.rewind();path0.addCircle(0, 0, 200, Path.Direction.CW);canvas.drawPath(path0, mPaint);mPaint.setColor(0xff000000);path1.addCircle(0, 0, 200, Path.Direction.CW);path0.rewind();path0.addRect(0, -200, 200, 200, Path.Direction.CW);path1.op(path0, Path.Op.DIFFERENCE);path0.rewind();path0.addCircle(0, -100, 100, Path.Direction.CW);path1.op(path0, Path.Op.UNION);canvas.drawPath(path1, mPaint);//这一段注意，之后要删除

第六步.png

7.到这里，我们看到，只需要在绘制一个白鱼的头就可以了，那么也和第五步一样，使用一个boolean运算把多余的黑色去掉即可。

mPaint.setColor(0xffffffff);path0.rewind();path0.addCircle(0, 0, 200, Path.Direction.CW);canvas.drawPath(path0, mPaint);mPaint.setColor(0xff000000);path1.addCircle(0, 0, 200, Path.Direction.CW);path0.rewind();path0.addRect(0, -200, 200, 200, Path.Direction.CW);path1.op(path0, Path.Op.DIFFERENCE);path0.rewind();path0.addCircle(0, -100, 100, Path.Direction.CW);path1.op(path0, Path.Op.UNION);path0.rewind();path0.addCircle(0, 100, 100, Path.Direction.CW);path1.op(path0, Path.Op.DIFFERENCE);canvas.drawPath(path1, mPaint);

第七步.png

8.至此，已经绘制好了八卦图的背景了，只需要在绘制鱼的眼睛即可。

//画黑色小圆path0.rewind();path0.addCircle(0, 100, 50, Path.Direction.CW);mPaint.setColor(0xff000000);canvas.drawPath(path0, mPaint);//画白色小圆path0.rewind();path0.addCircle(0, -100, 50, Path.Direction.CW);mPaint.setColor(0xffffffff);canvas.drawPath(path0, mPaint);

第八步.png

完成，最后上完整的代码。代码写得有点乱，不过也是练习而已，哈哈。至于其中的boolean运算什么的，之后在我的自定义View的笔记中在写吧。

import android.annotation.TargetApi;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Path;import android.os.Build;import android.util.AttributeSet;import android.view.View;/** * Created by Whitelaning on 2016/6/28. * Email: whitelaning@qq.com */public class TestView extends View {  private Paint mPaint;  private int mWidth;  private int mHeight;  public TestView(Context context) {    this(context, null);  }  public TestView(Context context, AttributeSet attrs) {    this(context, attrs, 0);  }  public TestView(Context context, AttributeSet attrs, int defStyleAttr) {    this(context, attrs, defStyleAttr, 0);  }  @TargetApi(Build.VERSION_CODES.LOLLIPOP)  public TestView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {    super(context, attrs, defStyleAttr, defStyleRes);    init();  }  private void init() {    initPaint();  }  /**   * 初始化画笔   */  private void initPaint() {    mPaint = new Paint();        //创建画笔对象    mPaint.setColor(Color.BLACK);    //设置画笔颜色    mPaint.setStyle(Paint.Style.FILL); //设置画笔模式为填充    mPaint.setStrokeWidth(10f);     //设置画笔宽度为10px    mPaint.setAntiAlias(true);     //设置抗锯齿    mPaint.setAlpha(255);        //设置画笔透明度  }  @Override  protected void onSizeChanged(int w, int h, int oldw, int oldh) {    super.onSizeChanged(w, h, oldw, oldh);    mWidth = w;    mHeight = h;  }  private Path path0 = new Path();  private Path path1 = new Path();  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    //移动布局到中间    canvas.translate(mWidth / 2, mHeight / 2);    //画大背景颜色    mPaint.setColor(0xffffff00);    path0.addRect(-400, -400, 400, 400, Path.Direction.CW);    canvas.drawPath(path0, mPaint);    mPaint.setColor(0xffffffff);    path0.rewind();    path0.addCircle(0, 0, 200, Path.Direction.CW);    canvas.drawPath(path0, mPaint);    mPaint.setColor(0xff000000);    path1.addCircle(0, 0, 200, Path.Direction.CW);    path0.rewind();    path0.addRect(0, -200, 200, 200, Path.Direction.CW);    path1.op(path0, Path.Op.DIFFERENCE);    path0.rewind();    path0.addCircle(0, -100, 100, Path.Direction.CW);    path1.op(path0, Path.Op.UNION);    path0.rewind();    path0.addCircle(0, 100, 100, Path.Direction.CW);    path1.op(path0, Path.Op.DIFFERENCE);    canvas.drawPath(path1, mPaint);    //画黑色小圆    path0.rewind();    path0.addCircle(0, 100, 50, Path.Direction.CW);    mPaint.setColor(0xff000000);    canvas.drawPath(path0, mPaint);    //画白色小圆    path0.rewind();    path0.addCircle(0, -100, 50, Path.Direction.CW);    mPaint.setColor(0xffffffff);    canvas.drawPath(path0, mPaint);  }}

Whitelaning
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以上就是对Android 实现太极的实例代码，有兴趣朋友可以参考下，谢谢大家对本站的支持！

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