Decorative elements

Zebkit supplies “zebkit.draw” package that collects classes and interfaces are responsible for rendering different objects: borders, graphical elements, texts and so on. As soon a developer needs to render a re-usable decorative element it makes sense to implement it basing on the package abstraction.

In general there are two base classes for implementing rendered objects:

Random color board view
zebkit.require("draw","ui", function(draw, ui) {
    var ColorBoardView = new zebkit.Class(draw.View,[
        // implement "paint" method
        function paint(g,x,y,w,h,c) {
            var cl =['#59031A','#5BA68A','#D9C45B',
                     '#D95829','#D90404', '#FFCCDD'],
                size = 20, 
                rows = Math.floor(h / size),
                cols = Math.floor(w / size);
            for (var i = 0; i < rows * cols; i++) {
                g.fillStyle= cl[Math.floor(Math.random()*cl.length)];
                g.fillRect((i % cols) * size, 
                           Math.floor(i / cols) * size, size, size);
    // create canvas
    var canvas = new ui.zCanvas();
    // instantiate and set the implemented view as, for instance,
    // the canvas root UI component background
    canvas.root.setBackground(new ColorBoardView());
Draw target fiction for the given interval
  zebkit.require("draw", "ui",function(draw, ui) {
    var FunctionRender = zebkit.Class(draw.Render, [
        function(fn, x1, x2) { // fn is target rendered object
            this.x1 = x1;  // start x
            this.x2 = x2;  // end   x

        function paint(g,x,y,w,h,c) {
          var fy=[],dx=(this.x2-this.x1)/200,my=-1000000,mny=1000000;
          // calculate function values for the given range and 
          // the function minimal and maximal values 
          for(var x = this.x1,i = 0; x < this.x2; x+= dx,i++) {
              fy[i] =; // call target function 
              if (fy[i] > my) my = fy[i];
              if (fy[i] < mny) mny = fy[i];
          var cx = (w - 8) / (this.x2 - this.x1), 
              cy = (h - 8) / (maxy - miny);
          g.lineWidth = 4;
          g.moveTo(4, 4 + (fy[0] - miny) * cy);
          for(var vx = dx, i = 1; i < fy.length; vx += dx, i++) {
              g.lineTo(4 + vx * cx),
                       4 + (fy[i] - miny) * cy));
    var canvas = new ui.zCanvas(400, 200);
    // implemented render as, the canvas root background
    canvas.root.setBackground(new FunctionRender(function(x) {
        return Math.cos(x) * Math.sin(x) - 2 * Math.sin(x*x);
    }, -2, 5));

Standard views and renders

Zebkit provides rich set of various predefined views and renders.

Border view (zebkit.draw.Border)

Border view allows developers to render borders of with the given color, size and radius.

Border view variations

Developers can specify which parts (“top”, “left”, “right”, “bottom”) of a border have to be painted:

Partially rendered border view

Round border view (zebkit.draw.RoundBorder)

Round border view allows developer to render round or oval views and also shape UI components with the view.

Round border view variations
zebkit.require("draw","ui", function(draw, ui) {
    var canvas = new ui.zCanvas("roundView1", 600, 200);

    var br = new draw.RoundBorder("red", 4);
    canvas.root.add(new ui.Panel()).setBorder(br).setPreferredSize(150, 150);  

    var br = new draw.RoundBorder("orange", 1);
    canvas.root.add(new ui.Panel()).setBorder(br).setPreferredSize(150, 200);  

    var br = new draw.RoundBorder("red", 4);
    canvas.root.add(new ui.Panel()).setBorder(br).setPreferredSize(200, 150);  

Classic border views

Set of old-style, windows-like borders views (“zebkit.draw.Sunken”, “zebkit.draw.Raised”, “zebkit.draw.Etched”, “zebkit.draw.Dotted”).

Classic, old-style borders views

Gradient (zebkit.draw.Gradient, zebkit.draw.Radial)

Zebkit supplies views for vertical, horizontal and radial gradients rendering.

Gradient views
zebkit.require("draw","ui", function(draw, ui) {
    var c = new ui.zCanvas("gradientView1", 600, 200);

    var gr = new draw.Gradient("red", "orange");
    c.root.add(new ui.Panel()).setBackground(gr).setPreferredSize(150, 150);  

    var gr = new draw.Gradient("red", "orange", "horizontal");
    c.root.add(new ui.Panel()).setBackground(gr).setPreferredSize(150, 150);  

    var gr = new draw.Radial("yellow", "red");
    c.root.add(new ui.Panel()).setBackground(gr).setPreferredSize(150, 150);  

Pattern (zebkit.draw.Pattern)

Pattern render paints the given picture repeatedly on the given area.

Pattern render
  zebkit.require("draw","ui",function(draw, ui) {
      var c = new ui.zCanvas("patternView1", 300, 320);
      // pass Image to be used as a pattern 
      c.root.setBackground(new draw.Pattern(img)); 

Picture (zebkit.draw.Picture)

Picture rendering.

Picture render
zebkit.require("draw","ui",function(draw, ui) {
    var c = new ui.zCanvas("pictureView1", 300, 380);
    // pass Image as a target 
    c.root.setBackground(new draw.Picture(img));

Composite views (zebkit.draw.CompositeView)

Composite view is supposed to be used to combine number of the specified views together. Below you can see composition from two views: picture and custom “Moustache” view:

Composite view
zebkit.require("draw","ui","layout",function(draw, ui, lay) {
    var c = new ui.zCanvas("compositeView1", 300, 370);
    // implement moustache view 
    var Moustache = new zebkit.Class(draw.View, [
        function paint(g,x,y,w,h,c) {
            g.drawLine(w/2-15, h-h/4, w/2+40, h-h/4+5, 2);
            g.drawLine(w/2-10, h-h/4+10, w/2+40, h-h/4+5, 3);
            g.drawLine(w/2, h-h/4+20, w/2+40, h-h/4 + 5, 2);

            g.drawLine(w/2+60, h-h/4+5, w/2+95, h-h/4-5, 2);
            g.drawLine(w/2+60, h-h/4+5, w/2+100, h-h/4+5, 2);
            g.drawLine(w/2+60, h-h/4+5, w/2+90, h-h/4+15, 3);

    // combine moustache and picture view
    var comp = new draw.CompositeView(new draw.Picture(img), 
                                      new Moustache());

Text (zebkit.draw.TextRender, zebkit.draw.StringRender, etc)

Zebkit supplies different kind of text renders: simple single line text render, multi-lines text render, decorated (underlined, crossed) text render, wrapped text render. The renders e=are widely utilized with zebkit UI components.

Text renders

Wrapped text render:

Wrapped text render

Arrow view (zebkit.draw.ArrowView)

View to render arrows.

Arrow views

View set (zebkit.draw.ViewSet)

View set is special type of container view that hosts set of views identified by its ids. The view set renders only one from the passed set of view that is called active view.

View set
zebkit.require("draw","ui",function(draw, ui) {
    var c = new ui.zCanvas("setView1", 300, 300);
    // set view set as a background view
    var pan = new ui.ViewPan().setBackground(new draw.ViewSet({
        "Pattern"  : new draw.Pattern(ui.imgPattern),
        "Gradient" : new draw.Gradient("red", "green"),
        "+Color"   : "#44AAff"  // active view

    c.root.add("top", new ui.Combo(["Pattern",
        function(src) { 
            // handle combo selection event to switch view in the set

Define view shape

View can define a shape by implementing “outline(g,x,y,w,h,c)” method. This method has to build a path with passed 2D context and return true if the path has to be applied as a shape for a zebkit UI component. To apply the view shape to a zebkit UI component set the view as the component border.

For instance, let’s create a component with a cloud-like shape:

Shaped with the view UI component

The code below implements and sets the cloud shape to a root component:

zebkit.require("draw", "ui", function(draw, ui) {
    var c = new ui.zCanvas("shapeView1", 400, 300);
    // let's create shape view
    var Cloud = zebkit.Class(zebkit.draw.Shape, [
      function outline(g,x,y,w,h,d) {
        g.moveTo(x+w * 0.2, y + h * 0.25);
        g.bezierCurveTo(x+w-1,y,x+w*0.1,y,x+w*0.2,y + h * 0.25);
        return true; // say to clip a component shape with the path  
    // apply the shape to root UI component   
    c.root.setBorder(new Cloud());
    // set background the shaped component has to be filled with

View metrics

view preferred size

Views and renders are supposed to be widely used as various decorative elements of zebkit UI components. Since UI components are ordered with layout managers it is required to know its preferred size. Views and renders can have influence to calculation of preferred size, so knowing a preferred size the given render of view wants to have also is important.

To let know which preferred size the given view wants to have implement “getPreferredSize” method. The expected outcome of the method is { width:intValue, height:intValue } structure:

    var MyView = zebkit.Class(zebkit.draw.View, [
        function paint(g,x,y,w,h,c) {
            ... // paint something
        // tell the size the view wants to have
        function getPreferredSize() {
           return { width: 100, height: 20 };

view gaps

View gaps are important what the given view or render is going to be used as a border view for an UI component. In this case the gaps the given view provides adds extra paddings to the UI component metrics. View gaps have to be defined by implementing “getLeft()”, “getRight()”, “getBottom()”, “getTop()” method or methods:

    var MyView = zebkit.Class(zebkit.draw.View, [
        function paint(g,x,y,w,h,c) {
            ... // paint something
        // get top gap
        function getTop() {
           return 10;