Added "GET_PRICE" action.

Q-Apps.md

@@ -76,6 +76,7 @@ Here is a list of currently supported actions:
 - FETCH_BLOCK
 - FETCH_BLOCK_RANGE
 - SEARCH_TRANSACTIONS
+- GET_PRICE
 
 More functionality will be added in the future.
 
@@ -392,6 +393,16 @@ let res = await qortalRequest({
 });
 ```
 
+### Get an estimate of the QORT price
+```
+let res = await qortalRequest({
+    action: "GET_PRICE",
+    blockchain: "LITECOIN",
+    // maxtrades: 10,
+    inverse: true
+});
+```
+
 
 ## Sample App
 

src/main/java/org/qortal/api/apps/resource/AppsResource.java

@@ -12,6 +12,7 @@ import org.qortal.api.*;
 import org.qortal.api.model.NameSummary;
 import org.qortal.api.resource.*;
 import org.qortal.arbitrary.misc.Service;
+import org.qortal.crosschain.SupportedBlockchain;
 import org.qortal.data.account.AccountData;
 import org.qortal.data.arbitrary.ArbitraryResourceInfo;
 import org.qortal.data.arbitrary.ArbitraryResourceStatus;
@@ -214,6 +215,14 @@ public class AppsResource {
         return transactionsResource.searchTransactions(startBlock, blockLimit, txGroupId, txTypes, address, confirmationStatus, limit, offset, reverse);
     }
 
+    @GET
+    @Path("/price")
+    @Hidden // For internal Q-App API use only
+    public long getPrice(@QueryParam("blockchain") SupportedBlockchain foreignBlockchain, @QueryParam("maxtrades") Integer maxtrades, @QueryParam("inverse") Boolean inverse) {
+        CrossChainResource crossChainResource = (CrossChainResource) buildResource(CrossChainResource.class, request, response, context);
+        return crossChainResource.getTradePriceEstimate(foreignBlockchain, maxtrades, inverse);
+    }
+
 
     public static Object buildResource(Class<?> resourceClass, HttpServletRequest request, HttpServletResponse response, ServletContext context) {
         try {

src/main/resources/q-apps/q-apps.js

@@ -190,6 +190,14 @@ window.addEventListener("message", (event) => {
             response = httpGet(url);
             break;
 
+        case "GET_PRICE":
+            url = "/apps/price?";
+            if (data.blockchain != null) url = url.concat("&blockchain=" + data.blockchain);
+            if (data.maxtrades != null) url = url.concat("&maxtrades=" + data.maxtrades);
+            if (data.inverse != null) url = url.concat("&inverse=" + data.inverse);
+            response = httpGet(url);
+            break;
+
         default:
             // Pass to parent (UI), in case they can fulfil this request
             event.data.requestedHandler = "UI";