2018-03-18 图片处理(五)----画图形

笔记如下

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如图:
Video_2018-03-19_100057.gif

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1.画线

    public void line(View view){
        //1.划线
        //8888:高清图
        //先准备画布
        Bitmap bitmap = Bitmap.createBitmap(500,500, Bitmap.Config.ARGB_8888);

        //2.准备画板
        Canvas canvas = new Canvas(bitmap);
        Paint paint = new Paint();

        //3.划线
        canvas.drawLine(100,100,500,500,paint);

        iv.setImageBitmap(bitmap);


    }

2.画矩形

drawRect(float left, float top, float right, float bottom, @NonNull Paint paint)
矩形的实现方法left和right参照同一边,top和bottom也是一样

    public void rect(View view){
        //1.划矩形
        //8888:高清图
        Bitmap bitmap = Bitmap.createBitmap(500,500, Bitmap.Config.ARGB_8888);

        //2.准备画布
        Canvas canvas = new Canvas(bitmap);
        Paint paint = new Paint();
        //设置颜色
        paint.setColor(Color.RED);
        //设置画笔的样式
        paint.setStyle(Paint.Style.STROKE);//中空
        paint.setStrokeWidth(5);//设置粗细
        //3.划线
        canvas.drawRect(30,30,500,500,paint);

        iv.setImageBitmap(bitmap);


    }
    
    

3.画圆

    public void circle(View view){
        //1.划圆
        //8888:高清图
        Bitmap bitmap = Bitmap.createBitmap(500,500, Bitmap.Config.ARGB_8888);

        //2.准备画布
        Canvas canvas = new Canvas(bitmap);
        Paint paint = new Paint();
        //设置颜色
        paint.setColor(Color.RED);
        //设置画笔的样式
        //paint.setStyle(Paint.Style.STROKE);//中空
        //paint.setStrokeWidth(10);//设置粗细
        //3.划线
        canvas.drawCircle(250,250,200,paint);

        //cx,cy:指定圆心
        //radius:指定半径
        iv.setImageBitmap(bitmap);

    }
    

4.画扇形

    public void arc(View view){
        //1.划扇形
        //8888:高清图
        Bitmap bitmap = Bitmap.createBitmap(500,500, Bitmap.Config.ARGB_8888);

        //2.准备画布
        Canvas canvas = new Canvas(bitmap);
        Paint paint = new Paint();
        //设置颜色
        paint.setColor(Color.RED);
        //设置画笔的样式
        //paint.setStyle(Paint.Style.STROKE);//中空
        //paint.setStrokeWidth(10);//设置粗细
        //3.划扇形

        RectF rect = new RectF(20,20,500,500);
        float startAngle = 0;//起始角度
        float sweepAngle = 120;//以起始角度为开始,扫过120度
        boolean userCenter = true;//是否画中心
        canvas.drawArc(rect,startAngle,sweepAngle,userCenter,paint);

        iv.setImageBitmap(bitmap);


    }

5.雨滴
就是一个三角形和一个扇形
如何画三角形呢?
可以指定画的路径,连接指定的点

        Path path = new Path();
        path.moveTo(x1,y1);//将画笔移动到点1
        path.lineTo(x2,y2);//连线点2

    public void trangle(View view){
        //1.划三角形
        //8888:高清图
        Bitmap bitmap = Bitmap.createBitmap(500,500, Bitmap.Config.ARGB_8888);

        //2.准备画布
        Canvas canvas = new Canvas(bitmap);
        Paint paint = new Paint();
        //设置颜色
        paint.setColor(Color.RED);
        //设置画笔的样式
        //paint.setStyle(Paint.Style.STROKE);//中空
        //paint.setStrokeWidth(10);//设置粗细
        //3.划三角形

        //RectF rect = new RectF(20,20,500,500);

        float x1 = 250;
        float y1 = 0;

        float x2 = 200;
        float y2 = 300;

        float x3 = 300;
        float y3 = 300;


        Path path = new Path();
        path.moveTo(x1,y1);//将画笔移动到点1
        path.lineTo(x2,y2);//连线点2
        path.arcTo(new RectF(200,250,300,350),0,180);
        path.lineTo(x3,y3);//连线点3
        path.lineTo(x1,y1);//连线点4
        path.close();

        canvas.drawPath(path,paint);

        iv.setImageBitmap(bitmap);


    }