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);
作者：香沙小熊
链接：https://www.jianshu.com/p/13073ae50e4d
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/1729/viewspace-2822013/ ，如需转载，请注明出处，否则将追究法律责任。
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