在前一篇文章裡面，我們介紹了在 TMapView 上面標示地點的作法，在本篇文章中，我們要介紹更進一步的功能：在地圖上面畫線。
常使用Google Map網頁版開發功能的朋友們大都已經使用過 Google Map API的強大功能之一：direction API, 也就是我們常使用的『導航功能』。通常我們比較常用的是在兩個地點之間試圖繪製出最佳的交通路線，這是 Google Map Direction API 的基本功能之一，且讓我們娓娓道來。
導航功能的思路，一般會包含幾個步驟：
- 地點的選定(可能只有起點與終點，也可能加入中途點)
- 交通工具的選定
- 路線的繪製
而這些也恰好都是 Google Map Direction API的基本功能。要使用Google Map Direction API，跟前一篇文章的介紹中會有些重疊之處，例如需要申請Google API Key，需要在App裡面作些基本設定，這些基本設定請參考前一篇文章：在 Delphi 當中使用 TMapView 顯示地圖之一：程式設定與加上地點標示。
在使用 Google Map Direction API之前，則有一組金鑰得先申請，您可以到 Google Map Direction API 的頁面申請。申請完畢以後，就可以一起來看這組 API 的強大功能了。
Google Map Direction API 的使用
如果是直接透過瀏覽器來使用，我們可以在網址列輸入以下這個網址:
https://maps.googleapis.com/maps/api/directions/json?origin=25.0416460,121.5362860&destination=23.5531950,120.3472670&key=您的GoogleAPIKey
在上面的網址中，我們可以看到主要網址後是以json開始帶入參數，依照Google Map Direction API 的說明，這代表我們是要索取以JSON作為輸出格式的資料。
之後的參數有兩組， origin跟destination，分別是兩個座標代表起點跟終點，如果您在網址列上面輸入了上面的文字，就按下了Enter，則畫面應該會顯示如下圖的資訊：
這些資訊就包含了導航的相關資訊、每一段路之間的座標、一共有多少段路、起始點與目的地的座標等資訊。
我們在Delphi當中，取得了這些資訊之後，就可以來找出其中有用的資訊了，先來看看完整的訊息有哪些:
{
"geocoded_waypoints" : [
{
"geocoder_status" : "OK",
"place_id" : "EicxMDblj7DngaPlj7DljJfluILlpKflronljYDlj7A157eaOTTomZ8iGhIYChQKEgkpEFFufalCNBHcc2G4xJNGAxBe",
"types" : [ "street_address" ]
},
{
"geocoder_status" : "OK",
"place_id" : "ChIJKbHLslW9bjQRGOc7frCCI6Q",
"types" : [ "street_address" ]
}
],
"routes" : [
{
"bounds" : {
"northeast" : {
"lat" : 25.0782095,
"lng" : 121.5376204
},
"southwest" : {
"lat" : 23.5496167,
"lng" : 120.3473252
}
},
"copyrights" : "地圖資料©2018 Google",
"legs" : [
{
"distance" : {
"text" : "246 公里",
"value" : 246382
},
"duration" : {
"text" : "2 小時 41 分",
"value" : 9643
},
"end_address" : "616台灣嘉義縣新港鄉中山路116號",
"end_location" : {
"lat" : 23.5531974,
"lng" : 120.3473666
},
"start_address" : "106台灣台北市大安區台5線94號",
"start_location" : {
"lat" : 25.0417488,
"lng" : 121.5363047
},
"steps" : [
{
"distance" : {
"text" : "59 公尺",
"value" : 59
},
"duration" : {
"text" : "1 分",
"value" : 17
},
"end_location" : {
"lat" : 25.0416756,
"lng" : 121.5368846
},
"html_instructions" : "往\u003cb\u003e東\u003c/b\u003e走\u003cb\u003e忠孝東路\u003c/b\u003e/\u003cb\u003e忠孝東路三段\u003c/b\u003e/\u003cb\u003e台5線\u003c/b\u003e朝\u003cb\u003e建國南路一段\u003c/b\u003e前進",
"polyline" : {
"points" : "}}ywC{pxdV@QDi@Dw@"
},
"start_location" : {
"lat" : 25.0417488,
"lng" : 121.5363047
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "0.1 公里",
"value" : 111
},
"duration" : {
"text" : "1 分",
"value" : 27
},
"end_location" : {
"lat" : 25.0407313,
"lng" : 121.5372438
},
"html_instructions" : "於\u003cb\u003e建國南路一段\u003c/b\u003e向\u003cb\u003e右\u003c/b\u003e轉",
"maneuver" : "turn-right",
"polyline" : {
"points" : "o}ywCotxdVj@Mb@KlBm@"
},
"start_location" : {
"lat" : 25.0416756,
"lng" : 121.5368846
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "0.2 公里",
"value" : 165
},
"duration" : {
"text" : "1 分",
"value" : 77
},
"end_location" : {
"lat" : 25.0417789,
"lng" : 121.5372723
},
"html_instructions" : "於\u003cb\u003e迴轉道\u003c/b\u003e處\u003cb\u003e迴轉\u003c/b\u003e",
"maneuver" : "uturn-left",
"polyline" : {
"points" : "qwywCwvxdVI{A_@N}@Za@Li@P]H"
},
"start_location" : {
"lat" : 25.0407313,
"lng" : 121.5372438
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "0.3 公里",
"value" : 297
},
"duration" : {
"text" : "1 分",
"value" : 32
},
"end_location" : {
"lat" : 25.0443566,
"lng" : 121.5366898
},
"html_instructions" : "上匝道，往\u003cb\u003e福爾摩沙高速公路\u003c/b\u003e方向走",
"polyline" : {
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},
"start_location" : {
"lat" : 25.0417789,
"lng" : 121.5372723
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "1.6 公里",
"value" : 1615
},
"duration" : {
"text" : "1 分",
"value" : 88
},
"end_location" : {
"lat" : 25.058881,
"lng" : 121.5369893
},
"html_instructions" : "走\u003cb\u003e建國高架道路\u003c/b\u003e",
"maneuver" : "merge",
"polyline" : {
"points" : "gnzwCisxdVs@A]?]?w@?uCC_A?S?SAK?W?WAaHE[?w@AcBAy@?UAW?qGEaDA]?_@AgDCcBAcBA{BAI?UAY?eBAO?K?M?gBAO?M?yBCM?K?cCCa@?a@AoA?a@A_@?W?"
},
"start_location" : {
"lat" : 25.0443566,
"lng" : 121.5366898
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "1.0 公里",
"value" : 982
},
"duration" : {
"text" : "1 分",
"value" : 57
},
"end_location" : {
"lat" : 25.0669266,
"lng" : 121.5348117
},
"html_instructions" : "靠\u003cb\u003e左\u003c/b\u003e繼續走\u003cb\u003e建國高架道路\u003c/b\u003e/\u003cb\u003e建國高架道路(國1桃園/濱江街基隆)\u003c/b\u003e\u003cdiv style=\"font-size:0.9em\"\u003e收費路段\u003c/div\u003e",
"maneuver" : "keep-left",
"polyline" : {
"points" : "_i}wCeuxdVsB?K?M?}BCO?M?w@A{HG_@AA?M?O?sECC?M?K?c@?[@Q@O@e@Fc@FMBYJA?WHQFQHOF[Tc@V_@ZGHQNWZU\\W\\q@bAeAtA_@f@"
},
"start_location" : {
"lat" : 25.058881,
"lng" : 121.5369893
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "1.2 公里",
"value" : 1234
},
"duration" : {
"text" : "1 分",
"value" : 81
},
"end_location" : {
"lat" : 25.0739412,
"lng" : 121.52885
},
"html_instructions" : "靠\u003cb\u003e左\u003c/b\u003e繼續走\u003cb\u003e建國高架道路\u003c/b\u003e/\u003cb\u003e圓山交流道 號出口\u003c/b\u003e\u003cdiv style=\"font-size:0.9em\"\u003e收費路段\u003c/div\u003e",
"maneuver" : "keep-left",
"polyline" : {
"points" : "i{~wCqgxdVc@v@OTQTs@bAa@j@IJONMHSNIDOFUHQFSBMBQ@W@O?MAYAi@Es@Ec@CgACqACI?QAKAeA@kCAaA?g@@Y@OBaAN[F[Ja@POHk@f@YRGFEFGJGJCJEJELEPGVAJCRA^?V@V@d@BZDZBND`@JbABn@?P?T?J@HALAVARATIl@ALEVGZAHAN?H"
},
"start_location" : {
"lat" : 25.0669266,
"lng" : 121.5348117
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "11.4 公里",
"value" : 11423
},
"duration" : {
"text" : "8 分",
"value" : 467
},
"end_location" : {
"lat" : 25.0641299,
"lng" : 121.4194995
},
"html_instructions" : "走\u003cb\u003e國道一號\u003c/b\u003e\u003cdiv style=\"font-size:0.9em\"\u003e收費路段\u003c/div\u003e",
"maneuver" : "merge",
"polyline" : {
"points" : "cg`xCibwdVGTITW~@o@dCGVITOj@Oj@K\\_@zA_@nA{@hDGVIVs@lCSt@ER_@~A_A~Dg@dCg@lCSdAIf@_@vBIj@UxA_@zCq@`GKdAI~@Kt@Gz@Gl@Ej@CXAZMdBCd@E~@GbA?BIhBGtBA^A^Cl@A`@Af@?d@Ab@ChAA~AArEEf@@dA?b@?d@@b@?P@p@@n@@RF|ADtBHrBL|CRtDPpCB^D^VjDBRBR@B?D@F@D@L@JDZB\\NrAFd@p@pFNfADRBP`D`Ub@`CVxAFb@Hb@j@|DnA~IBVDTx@rFJt@Lr@dBlLNbAP`A^fCp@~GBRDt@d@vI@~A@n@?l@BlBSzGIfBY~CUvBg@~Da@~BO`AEZ]rBO|@Kl@mApHs@pEg@~C]lCWvBOdBKvBCj@?J@LCVCp@?@KdDAbACjD?t@@jB@`AJ~DFpAJ`BLpBDZDZLxA\\lDt@zEDTBVFX^hBFXFZDRDRdLfk@zIva@zAlHtCfNH`@J`@DTlA|IBTf@bGTxCRzC\\dF@d@Bd@D`ANvGHzCBjBL~IJbFFzBDnAJzATrBFd@XdBNn@R|@XbA\\fA\\bAVp@Nb@BDj@tAj@hAp@nAPZz@xAb@x@j@fAxC|GFLHRHRp@dAh@~@"
},
"start_location" : {
"lat" : 25.0739412,
"lng" : 121.52885
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "0.3 公里",
"value" : 290
},
"duration" : {
"text" : "1 分",
"value" : 12
},
"end_location" : {
"lat" : 25.0625881,
"lng" : 121.417177
},
"html_instructions" : "靠\u003cb\u003e左\u003c/b\u003e以繼續行駛\u003cb\u003e國道一號\u003c/b\u003e\u003cdiv style=\"font-size:0.9em\"\u003e收費路段\u003c/div\u003e",
"maneuver" : "keep-left",
"polyline" : {
"points" : "yi~wC{vadV`@p@p@fAR^|BbElApB"
},
"start_location" : {
"lat" : 25.0641299,
"lng" : 121.4194995
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "17 公尺",
"value" : 17
},
"duration" : {
"text" : "1 分",
"value" : 1
},
"end_location" : {
"lat" : 25.0626106,
"lng" : 121.4170086
},
"html_instructions" : "在\u003cb\u003e泰山收费站\u003c/b\u003e出口下交流道\u003cdiv style=\"font-size:0.9em\"\u003e收費路段\u003c/div\u003e",
"maneuver" : "ramp-right",
"polyline" : {
"points" : "e`~wCkhadVCT?J"
},
"start_location" : {
"lat" : 25.0625881,
"lng" : 121.417177
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "23.5 公里",
"value" : 23496
},
"duration" : {
"text" : "15 分",
"value" : 879
},
"end_location" : {
"lat" : 24.9788469,
"lng" : 121.2266636
},
"html_instructions" : "靠\u003cb\u003e右\u003c/b\u003e，然後併入\u003cb\u003e國道一號\u003c/b\u003e\u003cdiv style=\"font-size:0.9em\"\u003e收費路段\u003c/div\u003e",
"maneuver" : "keep-right",
"polyline" : {
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},
"start_location" : {
"lat" : 25.0626106,
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},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "1.5 公里",
"value" : 1466
},
"duration" : {
"text" : "1 分",
"value" : 58
},
"end_location" : {
"lat" : 24.9698095,
"lng" : 121.2160748
},
"html_instructions" : "走\u003cb\u003e國道一號\u003c/b\u003e\u003cdiv style=\"font-size:0.9em\"\u003e收費路段\u003c/div\u003e",
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"lat" : 24.9788469,
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},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "105 公里",
"value" : 104969
},
"duration" : {
"text" : "1 小時 4 分",
"value" : 3865
},
"end_location" : {
"lat" : 24.2754319,
"lng" : 120.6933458
},
"html_instructions" : "分岔路口靠\u003cb\u003e左\u003c/b\u003e以繼續行駛\u003cb\u003e國道一號\u003c/b\u003e\u003cdiv style=\"font-size:0.9em\"\u003e收費路段\u003c/div\u003e",
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"end_location" : {
"lat" : 23.5555297,
"lng" : 120.4127124
},
"html_instructions" : "走\u003cb\u003e縣道164號\u003c/b\u003e",
"maneuver" : "merge",
"polyline" : {
"points" : "mownC}j}}UEHeBtCc@x@c@t@"
},
"start_location" : {
"lat" : 23.5546293,
"lng" : 120.4140711
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "6.1 公里",
"value" : 6139
},
"duration" : {
"text" : "7 分",
"value" : 443
},
"end_location" : {
"lat" : 23.5559742,
"lng" : 120.3543138
},
"html_instructions" : "繼續直行，並繼續走\u003cb\u003e縣道164號\u003c/b\u003e",
"maneuver" : "straight",
"polyline" : {
"points" : "auwnCmb}}Uq@dAuErIa@t@U\\UZo@r@_EvCA?g@`@[TKFEDSJOD@RBjA?DBvA?B?hD@j@@TDbD@VHvG@XNdKD`D@h@?hDLnD?^D`BJvFH|C@LHvC?RVlFR~EPdDNvCXdFJlBHjA@NDdAXvHNfD?PHhBB\\?Fh@lLB`@VlGBb@XpHBb@VvFN|CHzA@\\dA~T@\\P~DJnBBd@^nIB\\j@|L@\\`@jIPdF@TFrA?D@RN~CFpB?|@An@Ar@CpACh@EvAIrCANCz@Aj@Cp@EbBE`AC`ACn@?JAVWfJEhAEfBAJAXG~BAf@ClA"
},
"start_location" : {
"lat" : 23.5555297,
"lng" : 120.4127124
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "1.0 公里",
"value" : 1034
},
"duration" : {
"text" : "2 分",
"value" : 111
},
"end_location" : {
"lat" : 23.5496167,
"lng" : 120.3476798
},
"html_instructions" : "於\u003cb\u003e嘉民路\u003c/b\u003e向\u003cb\u003e左\u003c/b\u003e轉",
"maneuver" : "turn-left",
"polyline" : {
"points" : "ywwnCmuq}Uf@ZfAl@~AbAzCjBxA|@h@ZfC~AxD`CdAj@z@j@xBxAVTNPX\\JPR\\LXN^Ph@FXHd@`@dE@dB"
},
"start_location" : {
"lat" : 23.5559742,
"lng" : 120.3543138
},
"travel_mode" : "DRIVING"
},
{
"distance" : {
"text" : "0.4 公里",
"value" : 403
},
"duration" : {
"text" : "2 分",
"value" : 108
},
"end_location" : {
"lat" : 23.5531974,
"lng" : 120.3473666
},
"html_instructions" : "於\u003cb\u003e中山路\u003c/b\u003e向\u003cb\u003e右\u003c/b\u003e轉\u003cdiv style=\"font-size:0.9em\"\u003e目的地在左邊\u003c/div\u003e",
"maneuver" : "turn-right",
"polyline" : {
"points" : "cpvnC_lp}U{@XoB^oAJE?q@@yAEc@?eACiACiCB"
},
"start_location" : {
"lat" : 23.5496167,
"lng" : 120.3476798
},
"travel_mode" : "DRIVING"
}
],
"traffic_speed_entry" : [],
"via_waypoint" : []
}
],
"overview_polyline" : {
"points" : "}}ywC{pxdV`DgGiIfCuKn@wcAk@mt@]aJdEwLtOcN?qRpCo@bVkVpmAkBxu@xQjcBjJf}@kLxdA_A`h@|Epa@|a@ltB~Bb]bGh}@j~@phBfFfX_DxV{b@t`@aQz]bAjc@}Gri@pEltAyAhrB`Oxt@zTv]rb@z]nWbVfP|\\t_@|pAbp@rrAbgEnwFt|AnaB`oBl~B~k@z~@b\\j`@~N|Jdl@tQfu@dR~YjWfUvk@lVpm@rGxHt_@jTxl@pOdl@dQdO`QrMnc@di@lzC`Gvf@Ixp@Qzi@pEv]je@piAlEzSvG~bAhLb\\|Z`r@hEbk@sChkAt@`jArNzx@b`@|p@lPvMf\\fNdUv@hKaCbj@}k@fNmLx`@oHpz@|Dvw@h]lw@h\\vu@tK`l@xGrkAh[xrAhBhb@xLvN`LnUls@|^v\\dY|XnWz_@rc@pPnR`Ovk@fv@|Qne@~DnsAfOrh@hQlShP~IfXzFho@dCf_@lQxe@fa@zq@|_@zg@ry@jd@dh@~Lpg@vJ|^xTrRb}@|Mhn@|TzYd]zb@td@nWxI|IHrc@qGtb@rDd_@pOhQL|YmGzXQfd@fQh_@lIbe@aBr]`Fpm@v]fk@dUh`@hf@xf@~Uda@xJva@hRtg@hb@|~@`ZbVzTxMpWlJjPl]pZr]lPpTtS|MlYxO`m@zNxb@`O`QpZhO|YdE`j@}BnkAs^~[wCzVxBlw@h]th@xE~o@fSxl@jCj[hFxz@lJfW`Fd[rQb^j_@ncApm@lbB~r@lp@`\\b}BlkBbb@|[|v@f`@l^lVnn@tj@~a@|VnhAd_@xnB|Td{AvIhyB|MvkA|Iro@hLbp@rWnc@v]h]~d@~Rlc@bt@~gB~_@ff@hf@d\\f_Ad[p[jPzX|Vtf@d\\lh@zKphB`LbbBdH~\\zFjPlHpXh[~It]eDpd@m^nz@mGzk@~Bzd@`Sjd@rjA~aAfOfRtLtd@jGrv@fXrh@zs@xl@va@`Pz[`Gdo@vA||@cE`Zo@``A`D`tAjXhgAdWp~@xM`mBvXfk@tHv|@zDh{B[pr@xGtrAt\\t`@fJ`h@lD|f@cApi@Wx]dDl_AtUnf@~IvbAjHviA`OxsAnRhz@ZnwAsDxnBlHt{@vNzeCbw@`dApUbjAhFp_AiGpd@iJ|r@sRls@yKfR{@t|@pBnr@hMpq@hVdu@h`@xeClpAd_At\\liAxXh~BrZv|B|U~~@fTbzB`~@rgAx_@gB`LmMlT{HnFLlL`BjbAfFphAxJ|gCwAvf@OnGjJxFxUbO`C|El@pIaGdAiMG"
},
"summary" : "國道一號",
"warnings" : [],
"waypoint_order" : []
}
],
"status" : "OK"
}
裡面的 legs, steps, 就是每個轉折點的路徑, 但是用這個路徑資訊來畫圖, 地圖只會變成很醜的線段相連, 不能呈現沿著路畫出漂亮曲線的結果。
但裡面也包含有完美曲線的資訊, 就隱藏在 overview_polyline 這個屬性當中，只是overview_polyline 的資訊已經經過編碼，所以無法直接拿來套用在地圖上。
為了這個遺憾，我把以前在 iOS SDK裡面看過的程式碼改寫成了TMapPolylineDescriptorHelper 這個 class Helper (請參閱 Object Pascal Handbook 的 record helper 與 Class Helper, 中文版Object Pascal程式語言手冊第358頁)：
type
TMapPolylineDescriptorHelper = record helper for TMapPolylineDescriptor
class function CreateByGME(GoogleMapEncodingString: String):
TMapPolylineDescriptor; static;
end;
實作程式碼：
class function TMapPolylineDescriptorHelper.CreateByGME(GoogleMapEncodingString: String)
: TMapPolylineDescriptor;
var
dataStr: RawByteString;
coordCount, rawLength: integer;
idx, currentCoordIdx: integer;
APoint: TMapCoordinate;
latitude, longitude, finalLat, finalLon, deltaLat, detlaLon: Double;
Abyte, shift: Byte;
res: Int32;
offset: integer;
begin
dataStr := GoogleMapEncodingString;
rawLength := Length(dataStr);
latitude := 0;
longitude := 0;
{$IFDEF WINDOWS}
offset := 1;
{$ELSE}
offset := 0;
{$ENDIF}
currentCoordIdx := 0;
idx := 0;
while idx < rawLength do begin
AByte := 0;
res := 0;
shift := 0;
repeat
AByte := Byte(dataStr[idx+offset]) - 63;
Inc(idx);
res := res or ((AByte and $1F) shl shift);
Inc(shift, 5);
until (Abyte < $20);
if (res and 1) = 1 then begin
deltaLat := not(res shr 1);
end
else begin
deltaLat := res shr 1;
end;
latitude := latitude + deltaLat;
shift := 0;
res := 0;
repeat
AByte := Byte(dataStr[idx+offset]) - 63;
Inc(idx);
res := res or ((AByte and $1F) shl shift);
Inc(shift, 5);
until (Abyte < $20);
if (res and 1) = 1 then begin
detlaLon := not(res shr 1);
end
else begin
detlaLon := res shr 1;
end;
longitude := longitude + detlaLon;
finalLat := latitude * (0.00001);
finalLon := longitude * (0.00001);
Inc(currentCoordIdx);
setLength(Result.Points.Points, currentCoordIdx);
APoint := TMapCoordinate.Create(finalLat, finalLon);
Result.Points.Points[currentCoordIdx - 1] := APoint;
end;
end;
然後在製作地圖的程式碼裡面，把 overview_polyline 的所有點放進去:
overview_polyline := lv0.GetValue('overview_polyline')
as TJSONObject;
MapPolyline := TMapPolylineDescriptor.CreateByGME
(overview_polyline.GetValue<String>('points'));
MapPolyline.StrokeWidth := 12.0;
MapPolyline.StrokeColor := TAlphaColor($FF5CC2BE);
AMapPolyline := self.MapView2.AddPolyline(MapPolyline);
AMapPolyline.SetVisible(TRUE);
這樣就可以畫出完整、完美的曲線了。
規劃路線的完整 function 如下:
procedure TFormNovMain.btnTrafficRouteClick(Sender: TObject);
var
targetURL, mode: string;
directionJsonStr: string;
routeObj, lv0, leg0, step, startP, endP, overview_polyline: TJSONObject;
route, legs, steps: TJSONArray;
idx: integer;
APoint: TMapCoordinate;
Points: TArray<TMapCoordinate>;
MapPolyline: TMapPolylineDescriptor;
mapCenter: TMapCoordinate;
MyMarker: TMapMarkerDescriptor;
begin
if (self.ComboEditStart.Text <> '') and (self.ComboEditTarget.Text <> '')
then begin
if (txtTrafficTitle.Text = self.TxtPublic.Text) then begin
mode := 'transit';
end
else if (txtTrafficTitle.Text = self.TxtDriveTo.Text) then begin
mode := 'transit';
end
else begin
mode := 'bicycling';
end;
if self.ComboEditStart.ItemIndex = 3 then begin
targetURL := Format('https://maps.googleapis.com/maps/api/directions/'
+ 'json?mode=%s&origin=%g,%g&destination=%s&key=AIzaSyCsQG8bTrKou0FRH0IDOvNdk3iWHDcq1iA',
[mode, self.Here.Latitude, self.Here.Longitude,
self.ComboEditTarget.Text]);
end
else begin
targetURL := Format('https://maps.googleapis.com/maps/api/directions/'
+ 'json?mode=%s&origin=%s&destination=%s&key=AIzaSyCsQG8bTrKou0FRH0IDOvNdk3iWHDcq1iA',
[mode, self.ComboEditStart.Text, self.ComboEditTarget.Text]);
end;
self.RESTClient1.baseURL := targetURL;
self.RESTRequest1.Execute;
routeObj := self.RESTResponse1.JSONValue as TJSONObject;
if Assigned(routeObj) then begin
route := routeObj.GetValue<TJSONArray>('routes');
lv0 := route.Items[0] as TJSONObject;
legs := lv0.GetValue<TJSONArray>('legs');
leg0 := legs.Items[0] as TJSONObject;
startP := leg0.GetValue<TJSONObject>('start_location');
mapCenter := TMapCoordinate.Create
(StrToFloat(startP.GetValue<String>('lat')),
StrToFloat(startP.GetValue<String>('lng')));
startCood := mapCenter;
self.MapView2.Location := mapCenter;
if bUsePolyline then begin
legs := lv0.GetValue<TJSONArray>('legs');
leg0 := legs.Items[0] as TJSONObject;
steps := leg0.GetValue<TJSONArray>('steps');
SetLength(Points, steps.Count + 1);
for idx := 0 to steps.Count - 1 do begin
step := steps.Items[idx] as TJSONObject;
startP := step.GetValue<TJSONObject>('start_location');
APoint := TMapCoordinate.Create
(StrToFloat(startP.GetValue<String>('lat')),
StrToFloat(startP.GetValue<String>('lng')));
Points[idx] := APoint;
end;
step := steps.Items[steps.Count - 1] as TJSONObject;
startP := step.GetValue<TJSONObject>('end_location');
APoint := TMapCoordinate.Create
(StrToFloat(startP.GetValue<String>('lat')),
StrToFloat(startP.GetValue<String>('lng')));
Points[steps.Count] := APoint;
MapPolyline := TMapPolylineDescriptor.Create(Points);
MapPolyline.StrokeWidth := 12.0;
MapPolyline.StrokeColor := TAlphaColor($FF5CC2BE);
end
else begin
overview_polyline := lv0.GetValue('overview_polyline')
as TJSONObject;
MapPolyline := TMapPolylineDescriptor.CreateByGME
(overview_polyline.GetValue<String>('points'));
MapPolyline.StrokeWidth := 12.0;
MapPolyline.StrokeColor := TAlphaColor($FF5CC2BE);
end;
AMapPolyline := self.MapView2.AddPolyline(MapPolyline);
AMapPolyline.SetVisible(TRUE);
end;
end
else if self.ComboEditTarget.Text = '' then begin
ShowMessage('請輸入目的地');
end
else begin
ShowMessage('請輸入出發地點');
end;
end;
大家可以試試看用 Android 手機拉一個簡單的範例試試看, 立刻就可以看到完美的地圖出現喔.
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