Drawing-Turtle-and-AWT课件.ppt

Drawing Rectangles gObj.drawRect(topLeftX,topLeftY,width,height); Will draw a rectangle that has the top left corner at location topLeftX, topLeftY and the specified width and height gObj.fillRect(topLeftX,topLeftY,width,height); Will draw a filled rectangle that has the top left corner at location topLeftX, topLeftY and the specified width and height 精品文档 width height topLeftX,topLeftY addBox Method /** * Method to add a solid red rectangle to the current picture */ public void addBox() { // get the graphics context from the picture Graphics g = this.getGraphics(); // set the color to red g.setColor(Color.red); // draw the box as a filled rectangle g.fillRect(150,200,50,50); } 精品文档 Testing addBox public static void main(String[] args) { String filename = FileChooser.getMediaPath(beach-smaller.jpg); Picture p = new Picture(filename); p.addBox(); p.show(); } 精品文档 A more general addBox method public void drawBox(Color color, int topLeftX, int topLeftY, int width, int height) { // get the graphics context for drawing Graphics g = this.getGraphics(); // set the current color g.setColor(color); // draw the filled rectangle g.fillRect(topLeftX,topLeftY,width,height); } 精品文档 Comments You should add comments to your methods To help explain what the method is for And to explain what a statement is doing There are 3 types of comments in Java /** Javadoc type */ /* multi-line comment */ // comments out from there to the end of the line Javadoc is the Java utility that creates the API documentation from Java source code 精品文档 精品文档 Drawing Circles and Ellipses gObj.drawOval(x,y,width, height) gObj.fillOval(x,y,width, height) Give the x and y of the upper left corner of the enclosing rectangle Not a point on the circle or ellipse Give the width and height of the enclosing rectangle To make a circle use the same value for the width and height x,y width height 精品文