java - 怎么画曲线

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请有人帮我在圆中间的 A 点(720,1140)和 B 点(375,490)之间画一条红色的线

 Bitmap bitmap = Bitmap.createBitmap((int) getWindowManager()
            .getDefaultDisplay().getWidth(), (int) getWindowManager()
            .getDefaultDisplay().getHeight(), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    drawingImageView.setImageBitmap(bitmap);
    DisplayMetrics metrics = this.getResources().getDisplayMetrics();
    int x = metrics.widthPixels;
    int y = metrics.heightPixels;
    Paint paint1 = new Paint () ;
    paint1.setStrokeWidth(10);
    int margin = 100;
    int margin1 = 300;
    int top = 0 + margin;
    int bottom = canvas.getHeight() - margin;
    int left = 0 + margin1;
    int right = canvas.getWidth() - margin1;
    int centerX = x / 2;
    int centerY = y / 2;
    canvas.drawCircle(x / 2, y / 2, 50, paint1);
    canvas.drawLine(centerX, top, centerX, bottom,paint1);
    canvas.drawLine(left, centerY, right, centerY,paint1);

Answer 1

这是我所做的:

• 找到两个给定点之间的点
• 计算出 2 点之间的 90 度角
• 使用之前计算的度数计算距离中点 X 像素的点。
• 将“path.cubicTo”与这 3 个点一起使用(同时取负数和正数值来确定线应弯曲的方式)。

这是我的代码!

public PaintApplication drawCurve(int x1, int y1, int x2, int y2, int curveRadius, int padding, int color, int lineWidth) {

        Paint paint  = new Paint();
        paint.setAntiAlias(true);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(lineWidth);
        paint.setColor(ContextCompat.getColor(context, color));

        final Path path = new Path();
        int midX            = x1 + ((x2 - x1) / 2);
        int midY            = y1 + ((y2 - y1) / 2);
        float xDiff         = midX - x1;
        float yDiff         = midY - y1;
        double angle        = (Math.atan2(yDiff, xDiff) * (180 / Math.PI)) - 90;
        double angleRadians = Math.toRadians(angle);
        float pointX        = (float) (midX + curveRadius * Math.cos(angleRadians));
        float pointY        = (float) (midY + curveRadius * Math.sin(angleRadians));

        path.moveTo(x1, y1);
        path.cubicTo(x1,y1,pointX, pointY, x2, y2);
        canvas.drawPath(path, paint);

        return this;
    }

我根据这个编码思想创建了一个 Paint 应用程序。

屏幕截图请参阅here

希望这有帮助!!