Java Context2d.bezierCurveTo方法代碼示例

import com.google.gwt.canvas.dom.client.Context2d; //導入方法依賴的package包/類
/**
 * based on http://stackoverflow.com/questions/2172798/how-to-draw-an-oval-in-html5-canvas/2173084#2173084
 */
private static void drawEllipseHelper(Context2d ctx, boolean drawOuterLine, double x, double y, double w, double h) {
	double kappa = .5522848f;
	double ox = w / 2 * kappa; // control point offset horizontal
	double oy = h / 2 * kappa; // control point offset vertical
	double xe = x + w; // x-end
	double ye = y + h; // y-end
	double xm = x + w / 2; // x-middle
	double ym = y + h / 2; // y-middle

	ctx.beginPath();
	ctx.moveTo(x, ym);
	ctx.bezierCurveTo(x, ym - oy, xm - ox, y, xm, y);
	ctx.bezierCurveTo(xm + ox, y, xe, ym - oy, xe, ym);
	ctx.bezierCurveTo(xe, ym + oy, xm + ox, ye, xm, ye);
	ctx.bezierCurveTo(xm - ox, ye, x, ym + oy, x, ym);
	ctx.fill();
	if (drawOuterLine) {
		ctx.stroke();
	}
}
 

import com.google.gwt.canvas.dom.client.Context2d; //導入方法依賴的package包/類
public static void drawPath(Path path, Context2d context) {
	context.beginPath();
	for (PathElement e : path.getElements()) {
		switch (e.getType()) {
			case ClosePath:
				context.closePath();
				break;
			case CubicCurveTo:
				CubicCurveTo c = (CubicCurveTo) e;
				context.bezierCurveTo(c.cp1.x, c.cp1.y, c.cp2.x, c.cp2.y, c.p.x, c.p.y);
				break;
			case LineTo:
				LineTo l = (LineTo) e;
				context.lineTo(l.p.x, l.p.y);
				break;
			case MoveTo:
				MoveTo m = (MoveTo) e;
				context.moveTo(m.p.x, m.p.y);
				break;
			case QuadraticCurveTo:
				QuadraticCurveTo q = (QuadraticCurveTo) e;
				context.quadraticCurveTo(q.cp.x, q.cp.y, q.p.x, q.p.y);
				break;
		}
	}
}
 

import com.google.gwt.canvas.dom.client.Context2d; //導入方法依賴的package包/類
/**
 * Draw a cone. Does not call beginPath().
 */
public static void drawCone(Context2d g, double x, double y, double radius, double height) {
  double kappa = .5522848;
  double w = (2 * radius) * SQRT1_5;
  double h = (2 * radius) * SQRT0_5;
  double xm = w / 2f; // x-middle
  double ym = h / 2f; // y-middle
  double ox = xm * kappa; // control point offset horizontal
  double oy = ym * kappa; // control point offset vertical

  g.translate(x, y);
  g.moveTo(w, ym);
  g.bezierCurveTo(w, ym + oy, xm + ox, h, xm, h);
  g.bezierCurveTo(xm - ox, h, 0, ym + oy, 0, ym);
  g.lineTo(xm, ym - height);
  g.closePath();
  g.translate(-x, -y);
}
 

import com.google.gwt.canvas.dom.client.Context2d; //導入方法依賴的package包/類
/**
 * Draw an ellipse. Does not call beginPath().
 */
public static void drawEllipse(Context2d g, double x, double y, double w, double h) {
  double kappa = .5522848;
  double xm = w / 2f; // x-middle
  double ym = h / 2f; // y-middle
  double ox = xm * kappa; // control point offset horizontal
  double oy = ym * kappa; // control point offset vertical

  g.translate(x, y);
  g.moveTo(0, ym);
  g.bezierCurveTo(0, ym - oy, xm - ox, 0, xm, 0);
  g.bezierCurveTo(xm + ox, 0, w, ym - oy, w, ym);
  g.bezierCurveTo(w, ym + oy, xm + ox, h, xm, h);
  g.bezierCurveTo(xm - ox, h, 0, ym + oy, 0, ym);
  g.translate(-x, -y);
}
 

import com.google.gwt.canvas.dom.client.Context2d; //導入方法依賴的package包/類
/**
 * Draw a rounded rect. Does not call beginPath().
 */
public static void drawRoundedRect(Context2d g, double x, double y, double width, double height,
    double topLeftRadiusX, double topLeftRadiusY, double topRightRadiusX, double topRightRadiusY,
    double bottomLeftRadiusX, double bottomLeftRadiusY, double bottomRightRadiusX,
    double bottomRightRadiusY) {
  
  g.translate(x, y);
  g.moveTo(topLeftRadiusX, 0);
  g.lineTo(width - topRightRadiusX, 0);
  x = width;
  y = 0;
  g.bezierCurveTo(x, y, x, y, width, topRightRadiusY);
  g.lineTo(width, height - bottomRightRadiusY);
  x = width;
  y = height;
  g.bezierCurveTo(x, y, x, y, width - bottomRightRadiusX, height);
  g.lineTo(bottomLeftRadiusX, height);
  x = 0;
  y = height;
  g.bezierCurveTo(x, y, x, y, 0, height - bottomLeftRadiusY);
  g.lineTo(0, topLeftRadiusY);
  x = 0;
  y = 0;
  g.bezierCurveTo(x, y, x, y, topLeftRadiusX, 0);
  g.translate(-x, -y);
}
 

import com.google.gwt.canvas.dom.client.Context2d; //導入方法依賴的package包/類
void replay(Context2d ctx) {
  ctx.beginPath();

  int len = list.length(), i = 0;
  double x = 0, y = 0;
  while (i < len) {
    switch ((int) list.get(i++)) {
      case CMD_MOVE: {
        x = list.get(i++);
        y = list.get(i++);
        ctx.moveTo(x, y);
        break;
      }
      case CMD_LINE: {
        x = list.get(i++);
        y = list.get(i++);
        ctx.lineTo(x, y);
        break;
      }
      case CMD_QUAD: {
        double cpx = list.get(i++);
        double cpy = list.get(i++);
        x = list.get(i++);
        y = list.get(i++);
        ctx.quadraticCurveTo(cpx, cpy, x, y);
        break;
      }
      case CMD_BEZIER: {
        double c1x = list.get(i++), c1y = list.get(i++);
        double c2x = list.get(i++), c2y = list.get(i++);
        x = list.get(i++);
        y = list.get(i++);
        ctx.bezierCurveTo(c1x, c1y, c2x, c2y, x, y);
        break;
      }
      case CMD_CLOSE: {
        ctx.closePath();
        break;
      }

      default:
        throw new AssertionError("Corrupt command list");
    }
  }
}