Paint类常用方法
Paint类代表画笔，用来描述图形的颜色和风格，如线宽、颜色、透明度和填充效果等信息。使用Paint类时，首先要创建它的实例对象，然后通过该类提供的方法来更改Paint对象的默认设置。Paint类提供的常用方法如下：
| 方法 | 描述 |
| — | — |
| setAlpha(int a) | 设置透明度 |
| setARGB(int a, int r, int g, int b) | 绘制颜色 |
| setColor(int color) | 设置颜色 |
| setShader(Shader shader) | 设置渲染效果 |
| setShadowLayer(float radius, float dx, float dy, int color) | 设置阴影 |
| setStrokeWidth(float width) | 设置画笔粗细 |
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// 把整张画布绘制成白色
canvas.drawColor(Color.WHITE);
Paint paint = new Paint();
/**
设置画笔的锯齿效果，去锯齿
设置画笔颜色，蓝色
设置画笔风格，空心
设置空心画笔的宽度，3
*/
paint.setAntiAlias(true);
paint.setColor(Color.BLUE);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(3);
/**
绘制圆形
绘制正方形
绘制矩形
*/
canvas.drawCircle(40, 40, 30, paint);
canvas.drawRect(10, 80, 70, 140, paint);
canvas.drawRect(10, 150, 70, 190, paint);
RectF re1 = new RectF(10, 200, 70, 230);
// 绘制圆角矩形
canvas.drawRoundRect(re1, 15, 15, paint);
RectF re11 = new RectF(10, 240, 70, 270);
// 绘制椭圆
canvas.drawOval(re11, paint);
// 定义一个Path对象，封闭成一个三角形。
Path path1 = new Path();
path1.moveTo(10, 340);
path1.lineTo(70, 340);
path1.lineTo(40, 290);
path1.close();
// 根据Path进行绘制，绘制三角形
canvas.drawPath(path1, paint);
// 定义一个Path对象，封闭成一个五角形。
Path path2 = new Path();
path2.moveTo(26, 360);
path2.lineTo(54, 360);
path2.lineTo(70, 392);
path2.lineTo(40, 420);
path2.lineTo(10, 392);
path2.close();
// 根据Path进行绘制，绘制五角形
canvas.drawPath(path2, paint);
// ----------设置填充风格后绘制----------
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.RED);
canvas.drawCircle(120, 40, 30, paint);
canvas.drawRect(90, 80, 150, 140, paint);
canvas.drawRect(90, 150, 150, 190, paint);
RectF re2 = new RectF(90, 200, 150, 230);
//绘制圆角矩形
canvas.drawRoundRect(re2, 15, 15, paint);
RectF re21 = new RectF(90, 240, 150, 270);
// 绘制椭圆
canvas.drawOval(re21, paint);
Path path3 = new Path();
path3.moveTo(90, 340);
path3.lineTo(150, 340);
path3.lineTo(120, 290);
path3.close();
//绘制三角形
canvas.drawPath(path3, paint);
Path path4 = new Path();
path4.moveTo(106, 360);
path4.lineTo(134, 360);
path4.lineTo(150, 392);
path4.lineTo(120, 420);
path4.lineTo(90, 392);
path4.close();
//绘制五角形
canvas.drawPath(path4, paint);
// ----------设置渐变器后绘制----------
// 为Paint设置渐变器
Shader mShader = new LinearGradient(0, 0, 40, 60
, new
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int[] {Color.RED, Color.GREEN, Color.BLUE, Color.YELLOW }
, null , Shader.TileMode.REPEAT);
paint.setShader(mShader);
//设置阴影
paint.setShadowLayer(45 , 10 , 10 , Color.GRAY);
// 绘制圆形
canvas.drawCircle(200, 40, 30, paint);
// 绘制正方形
canvas.drawRect(170, 80, 230, 140, paint);
// 绘制矩形
canvas.drawRect(170, 150, 230, 190, paint);
RectF re3 = new RectF(170, 200, 230, 230);
// 绘制圆角矩形
canvas.drawRoundRect(re3, 15, 15, paint);
RectF re31 = new RectF(170, 240, 230, 270);
// 绘制椭圆
canvas.drawOval(re31, paint);
Path path5 = new Path();
path5.moveTo(170, 340);
path5.lineTo(230, 340);
path5.lineTo(200, 290);
path5.close();
// 根据Path进行绘制，绘制三角形
canvas.drawPath(path5, paint);
Path path6 = new Path();
path6.moveTo(186, 360);
path6.lineTo(214, 360);
path6.lineTo(230, 392);
path6.lineTo(200, 420);
path6.lineTo(170, 392);
path6.close();
// 根据Path进行绘制，绘制五角形
canvas.drawPath(path6, paint);
// ----------设置字符大小后绘制----------
paint.setTextSize(24);
paint.setShader(null);
// 绘制7个字符串
canvas.drawText(“circle”, 240, 50,paint);
canvas.drawText(“square”, 240, 120,paint);
canvas.drawText(“rect”, 240, 175,paint);
canvas.drawText(“RoundRect”, 230, 220, paint);
canvas.drawText(“Oval”, 240,260, paint);
canvas.drawText(“triangle”, 240, 325,paint);
canvas.drawText(“pentagon”, 240, 390,paint);