在地图视图叠加使用不同的颜色路径段 [英] Use different color for path segment in the map view overlay
问题描述
我的应用程序可以使用JSON给出的路径/方向。我怎样才能在不同的颜色改变由JSON给定的路径？
My application can give a path/direction using JSON. How can I change in different colors in on path given by JSON?
例如，形式A点到B点为红色，B到C是黄色，C到D为绿色，等等。
For example, form point A to point B is red, B to C is yellow, C to D is green, and so on.
在code是：
获取点JSON。
private void parsing(GeoPoint start, GeoPoint end) throws ClientProtocolException, IOException, JSONException, URISyntaxException{
HttpClient httpclient = new DefaultHttpClient();
StringBuilder urlstring = new StringBuilder();
urlstring.append("https://maps.googleapis.com/maps/api/directions/json?origin=")
.append(Double.toString((double)start.getLatitudeE6()/1E6)).append(",").append(Double.toString((double)start.getLongitudeE6()/1E6)).append("&destination=")
.append(Double.toString((double)end.getLatitudeE6()/1E6)).append(",").append(Double.toString((double)end.getLongitudeE6()/1E6))
.append("&sensor=false");
//urlstring.append("http://maps.googleapis.com/maps/api/directions/json?origin=Toronto&destination=Montreal&sensor=true");
url = new URI(urlstring.toString());
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
InputStream is = null;
is = entity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
sb.append(reader.readLine() + "\n");
String line = "0";
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
reader.close();
String result = sb.toString();
JSONObject jsonObject = new JSONObject(result);
JSONArray routeArray = jsonObject.getJSONArray("routes");
JSONObject routes = routeArray.getJSONObject(0);
JSONObject overviewPolylines = routes.getJSONObject("overview_polyline");
String encodedString = overviewPolylines.getString("points");
List<GeoPoint> pointToDraw = decodePoly(encodedString);
//Added line:
mv_mapview.getOverlays().add(new RoutePathOverlay(pointToDraw));
}
由JSON给出Geopoints列表。
List of Geopoints given by JSON.
private List<GeoPoint> decodePoly(String encoded) {
List<GeoPoint> poly = new ArrayList<GeoPoint>();
int index = 0, len = encoded.length();
int lat = 0, lng = 0;
while (index < len) {
int b, shift = 0, result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lat += dlat;
shift = 0;
result = 0;
do {
b = encoded.charAt(index++) - 63;
result |= (b & 0x1f) << shift;
shift += 5;
} while (b >= 0x20);
int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
lng += dlng;
GeoPoint p = new GeoPoint((int) (((double) lat / 1E5) * 1E6), (int) (((double) lng / 1E5) * 1E6));
//n = new Node(p,);
poly.add(p);
}
return poly;
}
和叠加类
public class RoutePathOverlay extends Overlay {
private int _pathColor;
private final List<GeoPoint> _points;
private boolean _drawStartEnd;
public RoutePathOverlay(List<GeoPoint> points) {
this(points, Color.GREEN, true);
}
public RoutePathOverlay(List<GeoPoint> points, int pathColor, boolean drawStartEnd) {
_points = points;
_pathColor = pathColor;
_drawStartEnd = drawStartEnd;
}
private void drawOval(Canvas canvas, Paint paint, Point point) {
Paint ovalPaint = new Paint(paint);
ovalPaint.setStyle(Paint.Style.FILL_AND_STROKE);
ovalPaint.setStrokeWidth(2);
int _radius = 6;
RectF oval = new RectF(point.x - _radius, point.y - _radius, point.x + _radius, point.y + _radius);
canvas.drawOval(oval, ovalPaint);
}
public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when) {
Projection projection = mapView.getProjection();
if (shadow == false && _points != null) {
Point startPoint = null, endPoint = null;
Path path = new Path();
//We are creating the path
for (int i = 0; i < _points.size(); i++) {
GeoPoint gPointA = _points.get(i);
Point pointA = new Point();
projection.toPixels(gPointA, pointA);
//if()
if (i == 0) { //This is the start point
startPoint = pointA;
path.moveTo(pointA.x, pointA.y);
} else {
if (i == _points.size() - 1)//This is the end point
endPoint = pointA;
path.lineTo(pointA.x, pointA.y);
}
}
Paint paint = new Paint();
paint.setAntiAlias(true);
// if(){
paint.setColor(_pathColor);
//}
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(5);
paint.setAlpha(90);
if (getDrawStartEnd()) {
if (startPoint != null) {
drawOval(canvas, paint, startPoint);
}
if (endPoint != null) {
drawOval(canvas, paint, endPoint);
}
}
if (!path.isEmpty())
canvas.drawPath(path, paint);
}
return super.draw(canvas, mapView, shadow, when);
}
public boolean getDrawStartEnd() {
return _drawStartEnd;
}
public void setDrawStartEnd(boolean markStartEnd) {
_drawStartEnd = markStartEnd;
}
}
推荐答案
您仅解码 overview_polyline 。
此行的每一部分（步骤响应JSON数组）被定义为
Each part of the trip (steps array in response JSON) is defined as
{
distance: {
text: "89 m",
value: 89
},
duration: {
text: "1 min",
value: 8
},
end_location: {
lat: 45.51101000000001,
lng: -73.5545
},
html_instructions: "Enter <b>Rue Saint Antoine E</b>",
polyline: {
points: "cvwtG~d}_MaBs@s@W"
},
start_location: {
lat: 45.51026,
lng: -73.55488000000001
},
travel_mode: "DRIVING"
},
正如你可以看到有每个步骤的折线。您是否尝试解码单步，将它们存储在一个数组，然后想象每个部分（使用不同的颜色为旅行的每个部分）？
这会给你一个行程的部门的决议，但它可能是一个很好的起点。
As you can see there is a polyline for each step. Have you tried decoding single steps, store them in an array and then visualize each section (using a different color for each part of the trip)? This will give you a resolution of a "sector" of the trip, but it could be a good start point.
或者你可以尝试生成 overview_polyline 的每一个secton数组（因为它由点定义你可以创建单行：如果你的折线通过槽A，B， C和D可以定义3段AB BC CD）。
OR you could try to generate an array for every secton of overview_polyline (since its defined by points you could create single lines: if your polyline passes trough A, B, C and D you can define 3 segments A-B B-C C-D).
我不知道多少，这（产生和可视化有很多在这件覆盖）会影响性能，因为我从来没有使用地图API以这种方式（我用它来获得ETA一段跳闸），所以我'M只是猜测：D
I don't know how much this (generate and visualize an overlay with a lot of pieces in it) will affect performance since i never used Maps API in this way (i used it to get ETA for some trip) so i'm just guessing :D
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