Draw arrow head in canvas using Angle

Question

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);

Note: I have four directions, each will come in different scenarios.

enum PathDirection {
    TopLeftToBottomRight,
    TopRightToBottomLeft,
    BottomLeftToTopRight,
    BottomRightToTopLeft
}

Above code I tried for TopRightToBottomLeft.

Sample Outputs

Pic 1: RectF values: [180.0,560.0][820.0,740.0]

Pic 2: RectF values: [240.0,480.0][640.0,980.0]

Update

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();

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.

Screenshot

Comments are not for extended discussion; this conversation has been [moved to chat](https://chat.stackoverflow.com/rooms/209813/discussion-on-question-by-gunaseelan-draw-arrow-head-in-canvas-using-angle). — Samuel Liew, Mar 18 '20 at 01:08

Gunaseelan · Accepted Answer · 2020-03-18T08:26:33.260

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.

Draw arrow head in canvas using Angle

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