使用Angle在画布中绘制箭头 [英] Draw arrow head in canvas using Angle
问题描述
我尝试使用以下代码,但是此代码无法正常工作.实际上,我犹豫要寻求这种简单解决方案的帮助,但是我浪费了很多时间,最后我来到了这里.
I tried with following code, But this code is not working as expected. Actually I hesitated to ask help for this simple solution, But I have wasted lots of time, finally I came here.
deltaX = bounds.right - bounds.left;
deltaY = bounds.bottom - bounds.top;
double distance = Math.sqrt(Math.pow(deltaX, 2) + Math.pow(deltaY, 2));
float arrowLength= (float) (distance / 3);
float lineAngle = (float) Math.atan2(deltaY, deltaX);
float angle = (float) Math.toRadians(20);
float sinValue = (float) Math.sin(lineAngle - angle);
point_x_1 = bounds.left - 20 * sinValue;
point_y_1 = (float) (bounds.bottom - 0.5 * arrowLength* Math.cos(lineAngle - angle));
angle = (float) Math.toRadians(60);
sinValue = (float) Math.sin(lineAngle + angle);
point_x_3 = bounds.left + 20 * sinValue;
point_y_3 = (float) (bounds.bottom + arrowLength* Math.cos(lineAngle + angle));
path.moveTo(bounds.right, bounds.top);
path.lineTo(bounds.left, bounds.bottom);
path.moveTo(point_x_1, point_y_1);
path.lineTo(bounds.left, bounds.bottom);
path.lineTo(point_x_3, point_y_3);
注意:我有四个方向,每个方向都会有不同的情况.
Note: I have four directions, each will come in different scenarios.
enum PathDirection {
TopLeftToBottomRight,
TopRightToBottomLeft,
BottomLeftToTopRight,
BottomRightToTopLeft
}
上面我为TopRightToBottomLeft尝试的代码.
Above code I tried for TopRightToBottomLeft.
示例输出
图片1: RectF值:[180.0,560.0] [820.0,740.0]
Pic 1: RectF values: [180.0,560.0][820.0,740.0]
图片2: RectF值:[240.0,480.0] [640.0,980.0]
Pic 2: RectF values: [240.0,480.0][640.0,980.0]
更新
path.reset();
canvas.save();
canvas.translate(200, 200);
float direction = (float) Math.atan2(400 - 200, 400 - 200);
canvas.rotate(direction);
path.moveTo(0, 0);
float distance = (float) Math.sqrt(200 * 200 + 200 * 200);
path.lineTo(distance, 0);
float x1 = distance - (distance * 20 / 100);
float y1 = -(distance * 15 / 100);
path.moveTo(x1, y1);
path.lineTo(distance, 0);
x1 = distance - (distance * 20 / 100);
y1 = (distance * 15 / 100);
path.lineTo(x1, y1);
canvas.drawPath(path, mPaint);
canvas.restore();
我使用此代码从位置200, 200
到300, 300
绘制线.但这会画出从0, 0
到distance
的界线.
I used this code to draw line from from position 200, 200
to 300, 300
. But this draw the line from 0, 0
to distance
.
屏幕截图
推荐答案
在 pskink 的帮助下,我来到了解决方案,示例代码,它用箭头从200, 200
到400, 400
With help from pskink I came to the solution, Sample code, which draw the line with arrow head from 200, 200
to 400, 400
path.reset();
RectF rectF = new RectF(200, 200, 400, 400);
canvas.save();
canvas.translate(rectF.left, rectF.top);
float direction = (float) Math.atan2(rectF.bottom - rectF.top, rectF.right - rectF.left);
float degree = (float) Math.toDegrees(direction);
canvas.rotate(degree);
canvas.drawColor(Color.parseColor("#E3F2FD"));
path.moveTo(0, 0);
float x = rectF.right - rectF.left;
float y = rectF.bottom - rectF.top;
float distance = (float) Math.sqrt(x * x + y * y);
path.lineTo(distance, 0);
float x1 = distance - (distance * 20 / 100);
float y1 = -(distance * 15 / 100);
path.moveTo(x1, y1);
path.lineTo(distance, 0);
float x2 = distance - (distance * 20 / 100);
float y2 = (distance * 15 / 100);
path.lineTo(x2, y2);
canvas.drawPath(path, mPaint);
canvas.restore();
SC:
Note If you don't want to rotate canvas, you can use Helder Sepulveda's answer, it also works as expected.
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