Android 高级UI8 Canvas的使用

作者: 香沙小熊 | 来源:发表于2019-02-22 21:54 被阅读6次

    Android 高级UI 目录

    1.Canvas基本绘制

    1.1drawLine 绘制直线
    public class MyView extends View {
    
        public MyView(Context context) {
            super(context);
        }
    
        public MyView(Context context,
                @Nullable AttributeSet attrs) {
            super(context, attrs);
            /**
             *Paint最好在结构体中绘制
             *这里创建
             */
            //Paint paint = new Paint();
        }
    
        @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);
            //绘制直线
            /**
             * Paint最好在结构体中绘制
             * 避免在onDraw中重复绘制
             */
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.FILL);
            paint.setStrokeWidth(5);
    
            canvas.drawLine(0, 0, 300, 300, paint);
        }
    }
    
    1.2drawLines 绘制虚线
        Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.FILL);
            paint.setStrokeWidth(5);
    
            //canvas.drawLine(0, 0, 300, 300, paint);
            float[] pts = {0,0,100,100,200,200,300,300};
            canvas.drawLines(pts,paint);
    
    1.3drawPoints 绘制点
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.FILL);
            paint.setStrokeWidth(10);
    
            //canvas.drawLine(0, 0, 300, 300, paint);
            float[] pts = {0,0,100,100,200,200,300,300};
            //canvas.drawLines(pts,paint);
            canvas.drawPoints(pts,paint);
    
    1.4drawRect 绘制矩形
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.FILL);
            paint.setStrokeWidth(10);
            RectF rectF = new RectF(100,100,400,500);
            canvas.drawRect(rectF,paint);
    
    1.5drawRoundRect 绘制圆角矩形
          Paint paint = new Paint();
          paint.setColor(Color.RED);
          paint.setStyle(Style.FILL);
          paint.setStrokeWidth(10);
          RectF rectF = new RectF(100,100,400,500);
    
          /**
           * x-radius , y-radius圆角的半径
           * 半径30
           */
          canvas.drawRoundRect(rectF,30,30,paint);
    
    1.6drawCircle 绘制圆形
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.FILL);
            paint.setStrokeWidth(10);
    
            /**
             * @param cx 圆心点x坐标
             * @param cy 圆心点y坐标
             * @param radius 圆点半径
             * @param paint The paint used to draw the circle
             */
            canvas.drawCircle(200,200,100,paint);
    
    1.7drawOval绘制椭圆
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            /**
             * 设置空心圆
             */
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
    
    
            RectF rectF = new RectF(100,100,400,500);
    
            canvas.drawRect(rectF,paint);
    
            paint.setColor(Color.GREEN);
            /**
             * 默认内切圆
             */
            canvas.drawOval(rectF,paint);
    
    1.8drawArc绘制弧线
         Paint paint = new Paint();
            paint.setColor(Color.RED);
            /**
             * 设置空心圆
             */
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
    
            RectF rectF = new RectF(100, 100, 400, 500);
    
            canvas.drawRect(rectF, paint);
    
            paint.setColor(Color.GREEN);
            /**
             * @param oval The bounds of oval used to define the shape and size of the arc
             * @param startAngle 起始角度,相对X轴正方向
             * @param sweepAngle 画多少角度的弧度
             * @param useCenter boolean,false:只有一个纯弧线 true:闭合的边
             * @param paint The paint used to draw the arc
             */
            canvas.drawArc(rectF,0,90,true,paint);
    
    1.9drawPath 绘制路径
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
    
            Path path = new Path();
            path.moveTo(100, 100);//画笔落笔的位置
            //移动
            path.lineTo(200,100);
            path.lineTo(200,200);
    
    
    
            canvas.drawPath(path, paint);
            //圆角矩形路径
    
            Path path2 = new Path();
            path2.moveTo(300, 100);//画笔落笔的位置
            //移动
            path2.lineTo(400,100);
            path2.lineTo(400,200);
            //自动闭合
            path2.close();
    
            canvas.drawPath(path2, paint);
    
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
    
            Path path = new Path();
    
    
            RectF rectF = new RectF(100, 100, 400, 500);
    
            //圆角矩形路径
            float radius[] ={10,10,10,10,10,10,90,90};
            path.addRoundRect(rectF,radius,Direction.CCW);
            canvas.drawPath(path,paint);
    
    1.10区域迭代器RegionIterator的使用
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
    
            RectF rectF = new RectF(100, 100, 400, 500);
    
            Region region = new Region(100, 100, 200, 200);
    
    
            Path path = new Path();
            path.addOval(rectF,Direction.CCW);
    
            Region region1 = new Region();
            //path的矩形与椭圆取交集的结果
            region1.setPath(path,region);
            //创建一块矩形的区域
            //结合区域迭代器的使用
            RegionIterator iterator = new RegionIterator(region1);
    
            Rect rect = new Rect();
    
            while (iterator.next(rect)) {
                canvas.drawRect(rect, paint);
            }
    
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(1);
    
            RectF rectF = new RectF(100, 100, 400, 500);
    
            Region region = new Region(100, 100, 400, 500);
    
    
            Path path = new Path();
            path.addOval(rectF,Direction.CCW);
    
            Region region1 = new Region();
            //path的矩形与椭圆取交集的结果
            region1.setPath(path,region);
            //创建一块矩形的区域
            //结合区域迭代器的使用
            RegionIterator iterator = new RegionIterator(region1);
    
            Rect rect = new Rect();
    
            while (iterator.next(rect)) {
                canvas.drawRect(rect, paint);
            }
    
    注意:灰色是屏幕截图的原因

    2.Canvas变换技巧

    2.1translate 平移
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
    
    
    
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
    
            RectF rectF = new RectF(100, 100, 400, 500);
            canvas.drawRect(rectF, paint);
            paint.setColor(Color.BLUE);
            //将画布平移
            canvas.translate(50, 50);
            //当canvas执行drawXXX的时候就会创建一个新的画布,但是还是会沿用之前设置的平移变换。不可逆的。(save和restore)
            canvas.drawRect(rectF, paint);
    
    2.2scale缩放
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
            RectF r = new RectF(0,0,400,500);
            canvas.drawRect(r,paint);
            paint.setColor(Color.BLUE);
            /**
             * sx,sy:分别对x/y方向的一个缩放系数
             * 画布的缩放会导致里面所有的绘制的东西否会有一个缩放的效果
             */
            canvas.scale(1.5f,0.5f);
            canvas.drawRect(r,paint);
    
    2.3rotate旋转
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
        
            RectF rectF = new RectF(200, 200, 400, 500);
            canvas.drawRect(rectF, paint);
            paint.setColor(Color.BLUE);
            /**
             * canvas.rotate(45,200, 200);
             * 以(200,200)为原点旋转
             */
            canvas.rotate(45, 200, 200);
            canvas.drawRect(rectF, paint);
    
    2.4skew斜拉画布
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
    
            RectF r = new RectF(100,100,400,500);
            canvas.drawRect(r,paint);
            paint.setColor(Color.BLUE);
            //sx,sy倾斜度:X轴方向上倾斜60度,tan60=根号3
            canvas.skew(1.73f,0);
            canvas.drawRect(r,paint);
    
    2.5clipRect裁剪
            Paint paint = new Paint();
            paint.setColor(Color.RED);
            paint.setStyle(Style.STROKE);
            paint.setStrokeWidth(15);
            RectF r = new RectF(200,200,400,500);
            canvas.drawRect(r,paint);
            paint.setColor(Color.BLUE);
            canvas.clipRect(new Rect(250,250,300,400));
            canvas.drawColor(Color.GREEN);
    

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        本文标题:Android 高级UI8 Canvas的使用

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