Drawing a spreadsheet like grid in canvas with konva - html5-canvas

Question

I am working on a Gantt-like task display using HTML5 canvas, and the Konvajs canvas library.
Deconstructing a Gantt chart into its components leads me currently to a view as below. Here 1 is the list of tasks, 2 is the task bar area, 3 is a task bar, and 4 is a text cell.
For this question I am seeking code to construct 1 & 4. The data to be displayed will be delivered in plain JS objects with a nested list of tasks where each task has a number, name, assigned-to person name, start date, end date, days duration, and % complete.
So the requirement is to be able to construct a spreadsheet-like panel such as is seen on the left hand side of a Gantt chart.
I have something part developed which I shall post as an answer. However this seems like such as common need that I am hoping there is someone out there with code they can cut & paste into SO to lead the way.
Note: Gantt in sample image is from Vertex42.

Answer 1

So here is my own fumbling attempt at an approach. Can anyone improve upon it or am I going down the wrong road.
EDIT: I now have a fledgling component for drawing text into the spreadsheet-like cells, including the percent complete shading. To keep this answer uncluttered, this additional component is in this codepen.
// this is the object that defines our grid
//
var gridData = { name: 'grid1', width: 350, height: 400, rowHeight: 24, padding: 4, fill: 'azure', gridLineColor: '#ccc', header: {size: 16, fill: 'black', color: 'white' }, data: {size: 16, fill: 'azure', color: 'black' },
row: [
{ cells: // row 1
[
{ width: 50, text: 'Item', style: 'header'},
{ width: 240, text: 'Name', style: 'header'},
{ width: 60, text: 'Status', style: 'header'},
]
},
{ cells: // row 2
[
{ text: '1'},
{ text: 'Find tea pot'},
{ text: '100%'},
]
},
{ cells: // row 3
[
{ text: '2'},
{ text: 'Boil water'},
{ text: '60%'},
]
}
]
}
// From here on could be wrapped into a component that churns out grids. Maybe you pass in the id of the stage container
// and the data model you want to produce, etc.
// Set up the canvas / stage
var stage = new Konva.Stage({container: 'container1', width: 600, height: 300});
// Add a layer
var layer = new Konva.Layer({draggable: false});
stage.add(layer);
// make a main group for the grid, call it a panel. Assigning a name may be handy later
var panel = new Konva.Group({name: gridData.name});
layer.add(panel); // Add the panel to the layer
// a group has no visual properties. Add a background rect to hold the colour fill
var panelRect = new Konva.Rect({width: gridData.width, height: gridData.height, fill: gridData.fill})
panel.add(panelRect);
var topLeft = {x: 0, y: 0}; // Since we are drawing a grid, we need to compute the position of each cell
for (var i = 0; i < gridData.row.length; i = i + 1){
topLeft.x = 0; // reset x at start of each row
// iterate for each cell on the row
for (var j = 0; j < gridData.row[i].cells.length; j = j + 1){
var cell = new Konva.Rect({name: 'cellBg', // assign a name for later searching
x: topLeft.x, y: topLeft.y, // position as computed
width: gridData.row[0].cells[j].width, // use the first row from celldate to get the cell width
height: gridData.rowHeight, // grid has a uniform row height
stroke: gridData.gridLineColor, // and line colour
strokeWidth: 1, // use a set line width but you can add to the gridData object as needed.
fill: (i === 0 ? gridData.header.fill : gridData.data.fill), // use the given header text color
});
panel.add(cell);
// Add text to the cell. Note that if you wanted to be using alignments you would need to draw the text off-screen and
// get width/height of that text then use those values for positioning calculations. Once you have the rect size of the
// text, all the alignments are simple math.
var text = new Konva.Text({ x: topLeft.x + gridData.padding, // add padding to locate the text nicely into the cell
y: topLeft.y + gridData.padding,
// use the given text size
fontSize: (i === 0 ? gridData.header.size : gridData.data.size),
// use the given header text color
fill: (i === 0 ? gridData.header.color : gridData.data.color),
text: gridData.row[i].cells[j].text, // set the text value.
listening: false // stop text interfering with mouse events
});
panel.add(text);
cell.on('mouseover', function(evt){
var shape = evt.target;
$(shape).data('bgColor', shape.fill());
shape.fill('lime');
layer.draw();
})
cell.on('mouseout', function(evt){
var shape = evt.target;
shape.fill($(shape).data('bgColor'));
layer.draw();
})
topLeft.x = topLeft.x + gridData.row[0].cells[j].width; // offset the computed next cell x value by the width of the cell
}
topLeft.y = topLeft.y + gridData.rowHeight; // offset the computed next cell y value by the height of the row
}
layer.draw();
stage.draw();
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/konva/2.5.1/konva.min.js"></script>
<div id='container1' style="width: 300px, height: 200px; background-color: silver;"></div>