Android studio中实现CANVAS（用JAVA绘制各种图形以及渐变动画）

方法一：直接在JAVA类中写图形定义（4个参数均为坐标，指的是以上边界和左边界为原点的坐标，即边界距离）

public class DrawView extends View {public DrawView(Context context) {super(context);}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);/** 方法 说明 drawRect 绘制矩形 drawCircle 绘制圆形 drawOval 绘制椭圆 drawPath 绘制任意多边形* drawLine 绘制直线 drawPoin 绘制点*/// 创建画笔Paint p = new Paint();p.setColor(Color.RED);// 设置红色canvas.drawText("画圆：", 10, 20, p);// 画文本canvas.drawCircle(60, 20, 10, p);// 小圆p.setAntiAlias(true);// 设置画笔的锯齿效果。 true是去除，大家一看效果就明白了canvas.drawCircle(120, 20, 20, p);// 大圆canvas.drawText("画线及弧线：", 10, 60, p);p.setColor(Color.GREEN);// 设置绿色canvas.drawLine(60, 40, 100, 40, p);// 画线canvas.drawLine(110, 40, 190, 80, p);// 斜线//画笑脸弧线p.setStyle(Paint.Style.STROKE);//设置空心RectF oval1=new RectF(150,20,180,40);canvas.drawArc(oval1, 180, 180, false, p);//小弧形oval1.set(190, 20, 220, 40);canvas.drawArc(oval1, 180, 180, false, p);//小弧形oval1.set(160, 30, 210, 60);canvas.drawArc(oval1, 0, 180, false, p);//小弧形canvas.drawText("画矩形：", 10, 80, p);p.setColor(Color.GRAY);// 设置灰色p.setStyle(Paint.Style.FILL);//设置填满canvas.drawRect(60, 60, 80, 80, p);// 正方形canvas.drawRect(60, 90, 160, 100, p);// 长方形canvas.drawText("画扇形和椭圆:", 10, 120, p);/* 设置渐变色 这个正方形的颜色是改变的 */Shader mShader = new LinearGradient(0, 0, 100, 100,new int[] {Color.RED, Color.GREEN, Color.BLUE, Color.YELLOW,Color.LTGRAY }, null, Shader.TileMode.REPEAT); // 一个材质,打造出一个线性梯度沿著一条线。p.setShader(mShader);// p.setColor(Color.BLUE);RectF oval2 = new RectF(60, 100, 200, 240);// 设置个新的长方形，扫描测量canvas.drawArc(oval2, 200, 130, true, p);// 画弧，第一个参数是RectF：该类是第二个参数是角度的开始，第三个参数是多少度，第四个参数是真的时候画扇形，是假的时候画弧线//画椭圆，把oval改一下oval2.set(210,100,250,130);canvas.drawOval(oval2, p);canvas.drawText("画三角形：", 10, 200, p);// 绘制这个三角形,你可以绘制任意多边形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);// 你可以绘制很多任意多边形，比如下面画六连形p.reset();//重置p.setColor(Color.LTGRAY);p.setStyle(Paint.Style.STROKE);//设置空心Path path1=new Path();path1.moveTo(180, 200);path1.lineTo(200, 200);path1.lineTo(210, 210);path1.lineTo(200, 220);path1.lineTo(180, 220);path1.lineTo(170, 210);path1.close();//封闭canvas.drawPath(path1, p);/** Path类封装复合(多轮廓几何图形的路径* 由直线段*、二次曲线,和三次方曲线，也可画以油画。drawPath(路径、油漆),要么已填充的或抚摸* (基于油漆的风格),或者可以用于剪断或画画的文本在路径。*///画圆角矩形p.setStyle(Paint.Style.FILL);//充满p.setColor(Color.LTGRAY);p.setAntiAlias(true);// 设置画笔的锯齿效果canvas.drawText("画圆角矩形:", 10, 260, p);RectF oval3 = new RectF(80, 260, 200, 300);// 设置个新的长方形canvas.drawRoundRect(oval3, 20, 15, p);//第二个参数是x半径，第三个参数是y半径//画贝塞尔曲线canvas.drawText("画贝塞尔曲线:", 10, 310, p);p.reset();p.setStyle(Paint.Style.STROKE);p.setColor(Color.GREEN);Path path2=new Path();path2.moveTo(100, 320);//设置Path的起点path2.quadTo(150, 310, 170, 400); //设置贝塞尔曲线的控制点坐标和终点坐标canvas.drawPath(path2, p);//画出贝塞尔曲线//画点p.setStyle(Paint.Style.FILL);canvas.drawText("画点：", 10, 390, p);canvas.drawPoint(60, 390, p);//画一个点canvas.drawPoints(new float[]{60,400,65,400,70,400}, p);//画多个点//画图片，就是贴图Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);canvas.drawBitmap(bitmap, 250,360, p);}}

方法二：在DRAWABLE下面创建circle.xml文件，编写图形OVAL的形状和参数

<TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:gravity="center"android:text="1"android:textSize="20sp"android:textColor="#ffffff"android:background="@drawable/text_shape6"/><TextViewandroid:layout_width="51dp"android:layout_height="wrap_content"android:layout_marginTop="20dp"android:gravity="center"android:text="2"android:textSize="20sp"android:textColor="#ffffff"android:background="@drawable/text_shape7"/><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginTop="20dp"android:gravity="center"android:text="3"android:textSize="20sp"android:textColor="#ff0000"android:background="@drawable/text_shape8"/><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginTop="20dp"android:gravity="center"android:text="4"android:textSize="20sp"android:textColor="#ffffff"android:background="@drawable/text_shape9"/><TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_marginTop="20dp"android:gravity="center"android:text="5"android:textSize="20sp"android:textColor="#ff0000"android:background="@drawable/text_shape10"/>

<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="/apk/res/android"android:shape="oval"><solidandroid:color="#990000ff"/><paddingandroid:bottom="5dp"android:left="5dp"android:right="5dp"android:top="5dp" /><sizeandroid:width="50dp"android:height="30dp"/></shape>text_shape7<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="/apk/res/android"android:shape="oval"><solidandroid:color="#990000ff"/><sizeandroid:width="50dp"android:height="50dp"/></shape>text_shape8<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="/apk/res/android"android:shape="oval"><solidandroid:color="#ffffff"/><sizeandroid:width="50dp"android:height="50dp"/><strokeandroid:width="1dp"android:color="#00ff00"/></shape>text_shape9<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="/apk/res/android"android:shape="oval"><solidandroid:color="#0000ff"/><sizeandroid:width="50dp"android:height="50dp"/><gradientandroid:startColor="#0000ff"android:endColor="#00ff00"android:gradientRadius="40dp"android:type="radial"/></shape>text_shape10<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="/apk/res/android"android:shape="oval"><solidandroid:color="#ffffff"/><sizeandroid:width="50dp"android:height="50dp"/><strokeandroid:width="1dp"android:color="#00ff00"android:dashWidth="4dp"android:dashGap="4dp"/></shape>

效果：

如果需要做成圆形，也就是把上和左的size改成一样的值即可