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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,134 @@ | ||
| extends ../common/index.pug | ||
|
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||
| block mainTutorial | ||
| :markdown-it | ||
| # Tutorial - Lines | ||
| Add a line feature to a geospatial context. Lines can vary many | ||
| properties, including stroke width, color, opacity, and offset, line join | ||
| and cap, and closure. | ||
|
|
||
| First, create a map and a feature layer. | ||
|
|
||
| +codeblock('javascript', 1). | ||
| var map = geo.map({ | ||
| node: "#map", | ||
| center: {x: 25, y: 20}, | ||
| zoom: 5 | ||
| }); | ||
| // create a layer that supports drawing line features | ||
| var layer = map.createLayer('feature', {features: ['line']}); | ||
|
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||
| :markdown-it | ||
| Specify some data. A line feature is an array of data elements, each of | ||
| which has a list of vertices. | ||
|
|
||
| +codeblock('javascript', 2). | ||
| var lineData = [ | ||
| [{x: 20, y: 10}, {x: 25, y: 10}], | ||
| [{x: 30, y: 10}, {x: 35, y: 12}, {x: 32, y: 15}], | ||
| [{x: 30, y: 20}, {x: 35, y: 22}, {x: 32, y: 25}], | ||
| [{x: 30, y: 30}, {x: 35, y: 32}, {x: 32, y: 35}, {x: 30, y: 30}], | ||
| [{x: 20, y: 20}, {x: 22, y: 20}, {x: 24, y: 20}, {x: 26, y: 20}], | ||
| [{x: 20, y: 30}, {x: 25, y: 32}, {x: 22, y: 35}, {x: 20, y: 35}] | ||
| ]; | ||
|
|
||
| :markdown-it | ||
| Create the line feature and set some styles on it. | ||
|
|
||
| +codeblock('javascript', 3). | ||
| line = layer.createFeature('line') | ||
| // set the data to our example data | ||
| .data(lineData) | ||
| // add some styles | ||
| .style({ | ||
| // use a function for determining if the line should be closed based | ||
| // on where it is in our list of data. | ||
| closed: function (item, itemIndex) { | ||
| return itemIndex === 1 || itemIndex === 3 || itemIndex === 5; | ||
| }, | ||
| strokeColor: 'black', | ||
| strokeWidth: 2 | ||
| }); | ||
| // draw the feature | ||
| line.draw(); | ||
| +codeblock_test('map has a feature layer with six lines', [ | ||
| 'map.layers().length === 1', | ||
| 'map.layers()[0] instanceof geo.featureLayer', | ||
| 'map.layers()[0].features()[0] instanceof geo.lineFeature', | ||
| 'map.layers()[0].features()[0].data().length === 6' | ||
| ]) | ||
|
|
||
| :markdown-it | ||
| Specify some more complex data. Our data elements are now objects with | ||
| various properties, which will require ``line`` and ``position`` functions | ||
| for the line feature to access. | ||
|
|
||
| +codeblock('javascript', 4, 1, false, 'Step 2-B'). | ||
| var lineData = [{ | ||
| coord: [[20, 10], [25, 10]] | ||
| }, { | ||
| coord: [[30, 10], [35, 12], [32, 15]], | ||
| closed: true | ||
| }, { | ||
| coord: [[30, 20], [35, 22], [32, 25]], | ||
| strokeColor: 'blue', | ||
| strokeWidth: 5 | ||
| }, { | ||
| coord: [[30, 30], [35, 32], [32, 35], [30, 30]], | ||
| closed: true | ||
| }, { | ||
| coord: [ | ||
| {x: 20, y: 20, width: 20}, | ||
| {x: 22, y: 20, width: 5}, | ||
| {x: 24, y: 20, width: 2}, | ||
| {x: 26, y: 20, width: 2} | ||
| ] | ||
| }, { | ||
| coord: [[20, 30], [25, 32], [22, 35], [20, 35]], | ||
| strokeWidth: 10, | ||
| lineJoin: 'bevel', | ||
| closed: true | ||
| }]; | ||
|
|
||
| :markdown-it | ||
| Create the line feature and specify functions to access the data and set | ||
| styles. Our style functions are more complex, as they get information from | ||
| the line data items. | ||
|
|
||
| +codeblock('javascript', 5, undefined, true, 'Step 3-B'). | ||
| line = layer.createFeature('line') | ||
| // set the data to our example data | ||
| .data(lineData) | ||
| // get the vertex list from the coord element of the line item | ||
| .line(function (item, itemIdx) { | ||
| return item.coord; | ||
| }) | ||
| // the position can be an object or an array of [x, y] | ||
| .position(function (vertex, vertexIndex, item, itemIndex) { | ||
| return vertex.x === undefined ? {x: vertex[0], y: vertex[1]} : vertex; | ||
| }) | ||
| // for styles, use the value specified by the line item if present | ||
| .style({ | ||
| closed: function (item, itemIndex) { | ||
| return item.closed; | ||
| }, | ||
| lineJoin: function (vertex, vertexIndex, item, itemIndex) { | ||
| return item.lineJoin; | ||
| }, | ||
| strokeColor: function (vertex, vertexIndex, item, itemIndex) { | ||
| return item.strokeColor === undefined ? 'black' : item.strokeColor; | ||
| }, | ||
| // stroke width might change by vertex | ||
| strokeWidth: function (vertex, vertexIndex, item, itemIndex) { | ||
| return vertex.width === undefined ? ( | ||
| item.strokeWidth === undefined ? 1 : item.strokeWidth) : vertex.width; | ||
| } | ||
| }); | ||
| // draw the feature | ||
| line.draw(); | ||
| +codeblock_test('map has a feature layer with six lines', [ | ||
| 'map.layers().length === 1', | ||
| 'map.layers()[0] instanceof geo.featureLayer', | ||
| 'map.layers()[0].features()[0] instanceof geo.lineFeature', | ||
| 'map.layers()[0].features()[0].data().length === 6' | ||
| ]) |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,8 @@ | ||
| { | ||
| "title": "Lines", | ||
| "hideNavbar": true, | ||
| "level": 0, | ||
| "about": { | ||
| "text": "Place lines with different styles in a geospatial context." | ||
| } | ||
| } |