Introduction

Steps

Step 1

Make sure you have this template:

public class ParameterisedShapes{
    public void setupGUI() {
        UI.initialise();
        UI.addButton("Clear", UI::clearPanes);
        UI.addButton("China Flag", this::doChinaFlag);
        UI.addButton("Quit", UI::quit);
        UI.setDivider(0.3);
    }

    public static void main(String[] args){
        ParameterisedShapes ps = new ParameterisedShapes();
        ps.setupGUI();
    }
}

### Step 2
First we will ask the user for the x and y position of the flag, as well as the width of the flag.

## Full Code
```java
import ecs100.*;
import java.awt.Color;

public class ParameterisedShapes{
    public void doChinaFlag() {
        double left = UI.askDouble("Left of flag: ");
        double top = UI.askDouble("Top of flag: ");
    
        double width = UI.askDouble("Width of flag: ");
        double height = width / 3 * 2;
        
        drawChinaFlag(left, top, width, height);
    }

    public void drawChinaFlag(double left, double top, double width, double height) {
        UI.clearGraphics();
        /*# YOUR CODE HERE */

        UI.setColor(new Color(238, 28, 37));
        UI.fillRect(left, top, width, height);
        UI.setColor(new Color(255, 255, 0));

        double square = width / 30;
        drawStar(left + square * 5, top + square * 5, square * 3, 270);

        drawStar(left + square * 10, top + square * 2, square * 1, 270 + 23.04);
        drawStar(left + square * 12, top + square * 4, square * 1, 270 + 46.87);
        drawStar(left + square * 12, top + square * 7, square * 1, 270);
        drawStar(left + square * 10, top + square * 9, square * 1, 270 + 97.13);
    }


    public void drawStar(double midx, double midy, double rad, double angle) {
        double outrad = rad;
        double innrad = rad * 0.382;

        int nPoints = 10;
        double xPoints[] = new double[nPoints];
        double yPoints[] = new double[nPoints];

        for (int i = 0; i < nPoints; i++) {
            if (i % 2 == 0) {
                xPoints[i] = Math.cos(Math.toRadians(i * 36 + angle)) * outrad + midx;
                yPoints[i] = Math.sin(Math.toRadians(i * 36 + angle)) * outrad + midy;
            } else {
                xPoints[i] = Math.cos(Math.toRadians(i * 36 + angle)) * innrad + midx;
                yPoints[i] = Math.sin(Math.toRadians(i * 36 + angle)) * innrad + midy;
            }
        }

        UI.fillPolygon(xPoints, yPoints, nPoints);
    }

    public void setupGUI() {
        UI.initialise();
        UI.addButton("Clear", UI::clearPanes);
        UI.addButton("China Flag", this::doChinaFlag);
        UI.addButton("Quit", UI::quit);
        UI.setDivider(0.3);
    }

    public static void main(String[] args){
        ParameterisedShapes ps = new ParameterisedShapes();
        ps.setupGUI();
    }
}