自定义 view - paint

ps：本文并不长于详细讲解 paint ，只在于记录常用的 API 和设置

详细讲解 paint 的技术文章请看：

paint 常用 API :

// 设置颜色
paint.setColor(int color) 
// color 的取值
Color.RED  
Color.rgb(255,100,100)
Color.argb(50,255,100,100)
getResources().getColor(android.R.color.holo_blue_bright)

// 参数 alpha 透明度
paint.setAlpha(int a)

// 设置抗锯齿
paint.setAntiAlias(boolean aa) 

// 设置文本缩放倍数
paint.setTextScaleX(float scaleX)

// 设置字符之间的间距
paint.setLetterSpacing(float size)

// 设置字体大小
paint.setTextSize(float textSize)

// 设置下划线
paint.setUnderlineText(true)

// 设置文本删除线
paint.setStrikeThruText(true);

// 设置画笔的粗细
paint.setStrokeWidth(10);

下面我们来说说本文重点吧，paint 的特性

Style 填充模式

API:

mPaint.setStyle(Paint.Style.FILL);

paint 的 Style 有3种：

STROKE - 描边
FILL - 填充
FILL_AND_STROKE - 描边加填充

做个演示看的清楚

Paint paint = new Paint();
paint.setColor(Color.BLUE);
paint.setStrokeWidth(40);     //为了实验效果明显，特地设置描边宽度非常大

// 描边
paint.setStyle(Paint.Style.STROKE);
canvas.drawCircle(200,200,100,paint);

// 填充
paint.setStyle(Paint.Style.FILL);
canvas.drawCircle(200,500,100,paint);

// 描边加填充
paint.setStyle(Paint.Style.FILL_AND_STROKE);
canvas.drawCircle(200, 800, 100, paint);

005Xtdi2jw1f8f0j4t36dj308c0ett8n.jpg

StrokeCap 字帽

啥叫字帽，简单来说就是画一条线，左边和右边起始点的样式

API:

paint.setStrokeCap(Paint.Cap.BUTT);

StrokeCap 字帽有3种：

BUTT - 无线冒
ROUND - 圆形线冒
SQUARE - 方形线冒

跑个例子看看:

private void drawStrokeCap(Canvas canvas) {
        Paint paint = new Paint();

        paint.setAntiAlias(true);
        paint.setStrokeWidth(200);
        paint.setColor(Color.parseColor("#00ff00"));
        // 线帽，即画的线条两端是否带有圆角，butt，无圆角
        paint.setStrokeCap(Paint.Cap.BUTT);       
        canvas.drawLine(200, 200, 500, 200, paint);

        paint.setColor(Color.parseColor("#ff0000"));
        // 线帽，即画的线条两端是否带有圆角，ROUND，圆角
        paint.setStrokeCap(Paint.Cap.ROUND);       
        canvas.drawLine(200, 500, 500, 500, paint);

        paint.setColor(Color.parseColor("#0000ff"));
        // 线帽，即画的线条两端是否带有圆角，SQUARE，矩形
        paint.setStrokeCap(Paint.Cap.SQUARE);      
        canvas.drawLine(200, 800, 500, 800, paint);
    }

StrokeJoin 折线样式

折线样式，简单说就是线段折叠处的处理样式

API：

 paint.setStrokeJoin(Paint.Join.MITER);

StrokeJoin 折线样式有3种：

Paint.Join.MITER - 结合处为锐角
Paint.Join.Round - 结合处为圆弧
Paint.Join.BEVEL - 结合处为直线

跑个例子看看:

Paint paint = new Paint();

        paint.setAntiAlias( true );
        paint.setStrokeWidth( 80 );
        paint.setStyle(Paint.Style.STROKE ); // 默认是填充 Paint.Style.FILL
        paint.setColor( Color.parseColor("#0000ff") );

        Path path = new Path();
        path.moveTo(100, 100);
        path.lineTo(400, 100);
        path.lineTo(100, 300);
        paint.setStrokeJoin(Paint.Join.MITER);
        canvas.drawPath(path, paint);

        path.moveTo(100, 500);
        path.lineTo(400, 500);
        path.lineTo(100, 700);
        paint.setStrokeJoin(Paint.Join.ROUND);
        canvas.drawPath(path, paint);

        path.moveTo(100, 900);
        path.lineTo(400, 900);
        path.lineTo(100, 1100);
        paint.setStrokeJoin(Paint.Join.BEVEL);
        canvas.drawPath(path, paint);