Android自定义View【实战教程】3⃣️----Paint类、Path类以及PathEffect类详解

public class DemoView extends View {
    Paint paint = new Paint();
    Path path = new Path();

    public DemoView(Context context) {
        this(context,null);
    }

    public DemoView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs,0);
    }

    public DemoView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        init();
    }

    private void init(){
        paint.setAntiAlias(false);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(10);
        paint.setColor(Color.parseColor("#ff0000"));

        //path在后面进行讲解
        path = new Path();
        path.moveTo(150, 400);
        path.lineTo(450, 400);
        path.lineTo(300, 150);
        path.close();

    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        canvas.drawPath(path,paint);
    }
}

paint.setAlpha(100);

 paint.setAntiAlias(false);

 paint.setAntiAlias(true);

paint.setStyle(Paint.Style.STROKE);

paint.setStyle(Paint.Style.FILL);

setStrokeWidth(int width)

    private void init(){
        paint.setAntiAlias(true);
        paint.setColor(Color.parseColor("#ff0000"));
        paint.setTextSize(50);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawText("自定义View",200,200,paint);
    }

    private void init() {
        paint.setAntiAlias(true);
        paint.setColor(Color.parseColor("#ff0000"));
        paint.setTextSize(50);
        int[] colors = new int[] { Color.RED, Color.GREEN, Color.BLUE };
        Shader shader = new RadialGradient(100, 100, 80,colors, null, TileMode.REPEAT);
        paint.setShader(shader·);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawText("自定义View", 200, 200, paint);
    }

 paint.setTextScaleX(2);

 paint.setTypeface(Typeface.DEFAULT_BOLD);  //加粗

paint.setUnderlineText(true);

        BlurMaskFilter maskFilter = new BlurMaskFilter(10, BlurMaskFilter.Blur.SOLID);

        paint.setMaskFilter(maskFilter);

public DemoView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        paint.setAntiAlias(true);
        paint.setColor(Color.parseColor("#ff0000"));
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(10);
}

        path.moveTo(150, 400); ／／起点 （150，400）
        path.lineTo(450, 400); ／／移动到（450，400）
        path.lineTo(300, 150); ／／移动到（300，150）
        path.close(); ／／回到起点

    path.moveTo(100, 100);
    path.LineTo(200, 200);

    path.moveTo(100, 100);
    path.rLineTo(200, 200);

//quadTo方法其中 (x1,y1) 为控制点，(x2,y2)为结束点。
public void quadTo(float x1, float y1, float x2, float y2) 

        path = new Path();
        path.moveTo(150, 400);
        path.quadTo(200, 200, 400, 400);

／／cubicTo方法比quadTo方法多了一个点坐标，那么其中(x1,y1) 为控制点，(x2,y2)为控制点，(x3,y3) 为结束点。
public void cubicTo(float x1, float y1, float x2, float y2, float x3, float y3)

path.moveTo(100, 400);
        path.cubicTo(200, 200, 300, 200, 400, 400);

    path.moveTo(100, 100);
    RectF oval = new RectF(100, 100, 200, 200);
    path.arcTo(oval, 0, 90);

    path.moveTo(100, 100);
    RectF oval = new RectF(100, 100, 200, 200);
    path.arcTo(oval, 0, 90,true);

    path.moveTo(100, 100);
    path.rLineTo(200, 200);
    RectF oval = new RectF(100, 100, 200, 200);
    path.addArc(oval, 0, 90);

    path = new Path();
    path.moveTo(100, 100);
    path.rLineTo(200, 200);
    RectF oval = new RectF(100, 100, 300, 300);
    path.addRect(oval, Path.Direction.CW);

     path = new Path();
     RectF oval = new RectF(100, 100, 300, 300);
     path.addRect(oval, Path.Direction.CW);
     canvas.drawPath(path,paint);
     paint.setTextSize(60);
     canvas.drawTextOnPath("12345",path,0,0,paint);

    Path path1 = new Path();
    path1.addCircle(120, 120, 100, Path.Direction.CW);
    Path path2 = new Path();
    path2.addCircle(200, 200, 100, Path.Direction.CW);

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
        path1.op(path2, Path.Op.UNION); ／／这边使用不同属性效果如下表
    }
    canvas.drawPath(path1, paint);

paint = new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(4);
        //创建,并初始化Path
        path = new Path();
        path.moveTo(100, 100);
        path.rLineTo(90,0);
        path.rLineTo(-80,50);
        path.rLineTo(35,-80);
        path.rLineTo(45,80);
        path.close();

        //初始化七个颜色
        colors = new int[] {
                Color.BLACK,Color.BLUE,Color.CYAN,
                Color.GREEN,Color.MAGENTA,Color.RED,Color.YELLOW,Color.BLACK
        };

 @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        //将背景填充成白色
        canvas.drawColor(Color.WHITE);
        //-------下面开始初始化7中路径的效果
        //使用路径效果
        effects[0] = null;
        //使用CornerPathEffect路径效果
        effects[1] = new CornerPathEffect(10);
        //初始化DiscretePathEffect
        effects[2] = new DiscretePathEffect(3.0f,5.0f);
        //初始化DashPathEffect
        effects[3] = new DashPathEffect(new float[]{20,10,5,10},phase);
        //初始化PathDashPathEffect
        Path p = new Path();
        p.addRect(0, 0, 8, 8, Path.Direction.CCW);
        effects[4] = new PathDashPathEffect(p,12,phase,PathDashPathEffect.Style.ROTATE);
        //初始化PathDashPathEffect
        effects[5] = new ComposePathEffect(effects[2],effects[4]);
        effects[6] = new SumPathEffect(effects[4],effects[3]);
        //将画布移到8,8处开始绘制
        canvas.translate(8, 8);
        //依次使用7中不同路径效果,7种不同的颜色来绘制路径
        for(int i = 0; i < effects.length; i++)
        {
            paint.setPathEffect(effects[i]);
            paint.setColor(colors[i]);
            canvas.drawPath(path, paint);
            canvas.translate(0, 60);
        }
        //改变phase值,形成动画效果
        phase += 1;
        invalidate();
}