Android 画一个太极图实例代码
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; @Override protected 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
@Override protected 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
It's very easy to be different but very difficult to be better
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!