IS311 Programming Concepts J AVA. Abstract Window Toolkit. (part 2: Graphics2D)

Transcription

1 IS311 Programming Concepts J AVA Abstract Window Toolkit (part 2: Graphics2D)

2 Graphics2D เป น subclass ของ Graphics เพ มความสามารถ ในการควบค มร ปทรงเรขาคณ ตท ซ บซ อนมากข น เช น Draw lines of any thickness Fill shapes with gradients and textures Move, rotate, scale, and shear text and graphics Composite overlapping text and graphics

3 Drawing Shapes Old AWT way (can still use) drawxxxx fillxxxx OR - Create a Shape object and the draw or fill

4 Shape Interface To draw, use things that implement Shape such as: Area CubicCurve2D GeneralPath Line2D Polygon QuadCurve2D Rectangle RectangularShape These use double's or float's for parameters

5 Package java.awt.geom Classes and interfaces related to the definition of geometric primitives: AffineTransform Arc2D Arc2D.Double Arc2D.Float Area CubicCurve2D CubicCurve2D.Double CubicCurve2D.Float Dimension2D Ellipse2D Ellipse2D.Double Ellipse2D.Float FlatteningPathIterator GeneralPath Line2D Line2D.Double Line2D.Float PathIterator Point2D Point2D.Double Point2D.Float QuadCurve2D QuadCurve2D.Double QuadCurve2D.Float Rectangle2D Rectangle2D.Double Rectangle2D.Float RectangularShape RoundRectangle2D RoundRectangle2D.Double RoundRectangle2D.Float

6 Graphics2D object Used to draw Shape objects Has rendering attributes: Pen Style (solid, dotted, dashed) Fill Compositing (used when objects overlap) Transform (scale, rotate, translate, shear) Clip area Font

7 Graphics2D setting attributes setstroke() setpaint() pen style that is applied to the outline of a shape fill style that is applied to a shape's interior setcomposite() compositing style that is used when rendered objects overlap existing objects settransform() transform that is applied during rendering to convert the rendered object from user space to device-space coordinates setclip() setfont() restricts rendering to the area within the outline of the Shape font used to convert text strings to glyphs

8 Graphics2D Rendering Methods draw renders outline of graphics primitive using stroke and paint attributes fill fills shape with given paint attribute (color or pattern) drawstring draw string with given font and paint attribute drawimage draw an image

9 Graphics2D shape methods public void draw(shape s) Draws the outline of the given shape using this Graphics2D's current pen. public void fill(shape s) Draws outline and fills inside of given shape. rotate, scale, translate, shear, transform Perform various coordinate transformations on the Graphics2D context.

10 Shapes (in package java.awt.geom) Arc2D.Double(double x, double y, double w, double h, double start, double extent, int type) An arc, which is a portion of an ellipse. Ellipse2D.Double(double x, double y, double w, double h) An ellipse, which is a generalization of a circle. Line2D.Double(double x1, double y1, double x2, double y2) Line2D.Double(Point p1, Point p2) A line between two points.

11 Shapes Rectangle2D.Double(double x, double y, double w, double h) A rectangle, which is a generalization of a square. RoundRectangle2D.Double( double x, double y, double w, double h, double arcx, double arcy) A rounded rectangle. GeneralPath() A customizable polygon.

12 Methods of to all shapes public boolean contains(double x, double y) public boolean contains(point2d p) Whether the given point is contained inside the bounds of this shape. public Rectangle getbounds() A rectangle representing the bounding box around this shape. public double getcenterx() / getcentery() public double getminx() / getminy() public double getmaxx() / getmaxy() Various corner or center coordinates within the shape. public boolean intersects(double x, double y, double w, double h) public boolean intersects(rectangle2d r) Whether this shape touches the given rectangular region.

13 Creating Shapes public void paint(graphics g) { Graphics2D g2d = (Graphics2D)g; double x = 50.0; double y = 30.0; double diameter=150.0; Ellipse2D.Double circle = new Ellipse2D.double(x, y, diameter, diameter); g2d.fill(circle); }

14 Graphics2D draw and fill Arguments to the draw and fill must implement the Shape interface Graphics built using objects rather than instructions

15 Rectangles, Ellipses and ARcs Note that many Shape classes have inner constructors Use Rectangle2D inner classes to create: Rectangle2D.Double Retangle2D.Float Ellipse2D: Ellipse2D.Double Ellipse2D.Float Arc2D Arc2D.Double Arc2D.Float

16 Arc2D three different close types Open Pie Chord

17 Lines Create a line using Line2D classes inner class constructors Line2D.Float(), etc. Line2D.Double(), etc. QuadCurve2D 2 end points and a control points CubicCurve2D 2 end points and 2 control points

18 Bounds/Hit Testing Shape has various contains() methods Makes for easy user interaction public void mouseclicked(mouseevent e) { Point2D point = new Point2D.Double(e.getX(), e.gety()); if (shape.contains(point)) { showmessage( Hit me! ); } }

19 Constructive Area Geometry Constructive Area Geometry (CAG) is the process of creating new geometric shapes by performing boolean operations on existing ones. In the Java 2D API a special type of Shape called an Area supports boolean operations. Union (Add) Subtraction Intersection Exclusive-or(XOR) A pear shape from several ellipses

20 Combining Shapes Combine Shape objects using the Area class Area implements Shape can draw using Graphics2D Create: new Area() or new Area(Shape s) Combine: public void add(area a) public void intersect(area a); public void subtract(area a); public void exclusiveor(area a);

21 Painting Paint attribute of Graphics2D Goes way beyond the old color attribute (still useable) getpaint, setpaint Used when fill method is called on a shape Arguments to setpaint must implement the Paint interface

22 Paint related Classes of AWT Color Solid color Same constants as in AWT: Color.red, Color.black, etc. or mix your own Can be transparency GradientPaint Gradient fill gradually combining two colors Can create your own TexturePaint Tiled image as a paint background

23 Colors and paints java.awt.color (a simple single-colored paint) public Color(int r, int g, int b) public Color(int r, int g, int b, int alpha) a partially-transparent color (range 0-255, 0=transparent) public Color brighter(), darker() public static Color black, blue, cyan, darkgray, gray, green, lightgray, magenta, orange, pink, red, white, yellow java.awt.gradientpaint (smooth transition between 2 colors) public GradientPaint(float x1, float y1, Color color1, float x2, float y2, Color color2) java.awt.texturepaint (use an image as a "paint" background)

24 Compositing Process of putting two pictures together Every time object is drawn, source and destination combination process is performed Usually use source over destination

25 Transparency The AlphaComposite class encapsulates various compositing styles, which determine how overlapping objects are rendered. An AlphaComposite can also have an alpha value that specifies the degree of transparency: alpha = 1.0 is totally opaque, alpha = 0.0 totally transparent (clear). Assign transparency (alpha) values to drawing operations Underlying graphics show through Call setcomposite of Graphics2D object AlphaComposite.getInstance

26 Compositing Rules AlphaComposite supports most of the standard Porter-Duff compositing rules shown in the following table. The source pixels are rendered over the destination pixels Only the source pixels in the overlapping area are rendered Only the source pixels outside of the overlapping area are rendered If pixels in the source and the destination overlap, only the source pixels outside of the overlapping area are rendered If the alpha = 1.0, the pixels in the overlapping area are unchanged; if the alpha is 0.0, pixels in the overlapping area are cleared. If the alpha = 1.0, the pixels in the overlapping area are cleared; if the alpha is 0.0, the pixels in the overlapping area are unchanged

27 Using Local Fonts Same logical fonts as in Java 1.1 Serif, SansSerif, Monospaced, Dialog, DialogInput Also, arbitrary local fonts Must lookup entire list May take awhile Use GraphicsEnvironment methods getavailablefontfamilynames getallfonts

28 Printing All Font Names GraphicsEnvironment env = GraphicsEnvironment.getLocalGraphicsEnvironment(); String[] fontnames = env.getavailablefontfamilyname(); System.out.println("Available Fonts:"); for(int i=0; i<fontnames.length; i++) System.out.println(" " + fontnames[i]);

29 Drawing With Local Fonts - Example Query the available fonts using getavailablefontnames of GraphicsEnvironment Set the font in the Graphcis2D object Call g2d.drawstring method

30 Stroke Styles in Java 2D In the old Graphics class, could only do 1-pixel wide lines, no control over how lines are joined Much more flexibility in Java2D can specify: Pen thickness Dashing pattern The way line segments are joined together Create a BasicStroke object (several constructors)

31 Strokes (pen styles) Graphics2D public void setstroke(stroke s) Sets type of drawing pen (color, width, style) that will be used by this Graphics2D. java.awt.basicstroke A pen stroke for drawing outlines public BasicStroke(float width) public BasicStroke(float width, int cap, int join) public BasicStroke(float width, int cap, int join, float miterlimit, float[] dash, float dash_phase) cap: CAP_BUTT, CAP_ROUND, CAP_SQUARE join: JOIN_BEVEL, JOIN_MITER, JOIN_ROUND

32 Coordinate Transformations Java 2D allows you to easily Translate Rotate Scale Shear Use java.awt.geom.affinetransform

33 Advanced: anti-aliasing Onscreen text and shapes can have jagged edges, or aliases. These can be removed by smoothing, or anti-aliasing, the panel. Graphics2D public void setrenderinghint( RenderingHints.Key key, Object value) Example: g2.setrenderinghint(renderinghints.key_antialiasing, RenderingHints.VALUE_ANTIALIAS_ON);

34 Other Capabilities of Java 2D High-quality printing Improved XOR mode Custom color mixing Fancy text operations Low-level image processing Animation

35 Resources 2D Graphics Tutorial