我在画布上有两个点,现在我可以通过使用在这些点之间绘制一条线,如下图所示
这段代码canvas.drawLine(p1.x, p1.y, p2.x, p2.y, paint);
我想画两点之间的弧线,如下图所示。
我怎么画这样的。
最后我从这段代码中得到了解决方案:
float radius = 20;
final RectF oval = new RectF();
oval.set(point1.x - radius, point1.y - radius, point1.x + radius, point1.y+ radius);
Path myPath = new Path();
myPath.arcTo(oval, startAngle, -(float) sweepAngle, true);
要计算startAngle
,请使用以下代码:
int startAngle = (int) (180 / Math.PI * Math.atan2(point.y - point1.y, point.x - point1.x));
在这里,qazxsw poi表示您想要开始绘制Arc的位置。 qazxsw poi表示两条线之间的角度。我们必须通过使用像我的问题图像中的蓝点这样的两个点来计算。
做这样的事情:
point1
我试图做一些不同的事情,而这一切都是关于计算扫描和开始角度。
我想要显示一个圆弧,表示从上到下的圆圈上的进度。
所以我有0 ... 100的进度值,我希望显示一个从上到下开始的弧,当进度为100时填充圆圈。
要计算sweepAngle,我使用:
sweepAngle
接下来是计算startAngle
@Override
protected void onDraw(Canvas canvas) {
Paint p = new Paint();
RectF rectF = new RectF(50, 20, 100, 80);
p.setColor(Color.BLACK);
canvas.drawArc (rectF, 90, 45, true, p);
}
Start Angle以这种方式计算,因为:
所以考虑到我有25%的进步
int sweepAngle = (int) (360 * (getProgress() / 100.f));
如果你想从其他方面(从左到右,从右到左等)进行进度,你只需要在开始角度时替换270。
绘制弧的样本。
int startAngle = 270 - sweepAngle / 2;
一个简单的解决方案被Langkiller建议sweepAngle = 90 degrees (90 degrees is quarter of a circle)
start angle = 225 (45 degrees away from 270)
。这绘制了从起点到控制点到终点的立方线。
public static Bitmap clipRoundedCorner(Bitmap bitmap, float r, boolean tr, boolean tl, boolean bl, boolean br)
{
int W = bitmap.getWidth();
int H = bitmap.getHeight();
if (r < 0)
r = 0;
int smallLeg = W;
if(H < W )
smallLeg = H;
if (r > smallLeg)
r = smallLeg / 2;
float lineStop = r/2;
Path path = new Path();
path.moveTo(0,0);
if(tr)
{
path.moveTo(0, lineStop);
path.arcTo(new RectF(0,0, r,r), 180, 90, false);
}
path.lineTo(W-lineStop, 0);
if(tl)
path.arcTo(new RectF(W-r,0, W,r), 270, 90, false);
else
path.lineTo(W, 0);
path.lineTo(W, H-lineStop);
if(bl)
path.arcTo(new RectF(W-r,H-r, W,H), 0, 90, false);
else
path.lineTo(W, H);
path.lineTo(lineStop, H);
if(br)
path.arcTo(new RectF(0,H-r, r,H), 90, 90, false);
else
path.lineTo(0,H);
if(tr)
path.lineTo(0,lineStop);
else
path.lineTo(0,0);
Bitmap output = Bitmap.createBitmap(W, H, Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.BLACK);
canvas.drawPath(path, paint);
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, 0, 0, paint);
return output;
}
我可能迟到了,但我得到了更多的信息。
在here之后,有两种方法可以解决这个问题
public void drawArc(RectF oval,float startAngle,float sweepAngle,boolean useCenter,Paint paint)
public void drawArc(float left,float top,float right,float bottom,float startAngle,float sweepAngle,boolean useCenter,Paint paint)
用法:
Path path = new Path();
float startX = 0;
float startY = 2;
float controlX = 2;
float controlY = 4;
float endX = 4
float endY = 2
conePath.cubicTo(startX, startY, controlX, controlY,endX, endY);
Paint paint = new Paint();
paint.setARGB(200, 62, 90, 177);
paint.setStyle(Paint.Style.FILL);
canvas.drawPath(path, paint)
扫描角度不过是顺时针绘制的扇形角度,例如。以下代码
Android Lollipop
结果将如下所示
RectF rectF = new RectF(left, top, right, bottom);
// method 1
canvas.drawArc (rectF, 90, 45, true, paints[0]);
// method 2
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
canvas.drawArc (left, top, right, bottom, 0, 45, true, paints[1]);
}
在定义Paths的帮助下,然后在onDraw方法中迭代它们就可以实现同样的效果,如下面的代码片段所示:
private void drawArcs(Canvas canvas) {
RectF rectF = new RectF(left, top, right, bottom);
// white arc
canvas.drawArc (rectF, 90, 45, true, paints[0]);
// Green arc
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
canvas.drawArc (left, top, right, bottom, 0, 45, true, paints[1]);
}
// Red stroked arc
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
canvas.drawArc (left, top, right, bottom, 180, 45, true, paints[2]);
}
}
完整源代码: