Add an ability to get player state and execute commands

source/aimpremote/aimpremote.d

@@ -1,6 +1,7 @@
 module aimpremote;
 
 import core.sys.windows.windows;
+import std.typecons : Nullable;
 
 private const wstring AIMPRemoteAccessClass = "AIMP2_RemoteInfo";
 private const int AIMPRemoteAccessMapFileSize = 2048;
@@ -26,6 +27,21 @@ private struct AIMPRemoteFileInfo
     DWORD[6] deprecated2;
 };
 
+private const int WM_AIMP_COMMAND  = WM_USER + 0x75;
+private const int WM_AIMP_NOTIFY   = WM_USER + 0x76;
+private const int WM_AIMP_PROPERTY = WM_USER + 0x77;
+
+private const int AIMP_RA_PROPVALUE_GET = 0;
+private const int AIMP_RA_PROPVALUE_SET = 1;
+private const int AIMP_RA_PROPERTY_MASK = 0xFFFFFFF0;
+
+private const int AIMP_RA_PROPERTY_PLAYER_STATE = 0x40;
+private const int AIMP_RA_PROPERTY_VOLUME = 0x50;
+
+private const int AIMP_RA_CMD_BASE = 10;
+private const int AIMP_RA_CMD_NEXT = AIMP_RA_CMD_BASE + 7;
+private const int AIMP_RA_CMD_PREV = AIMP_RA_CMD_BASE + 8;
+
 private enum TagItem {
     Album, Artist, Date, FileName, Genre, Title
 }
@@ -36,12 +52,55 @@ public struct TrackInfo {
     wstring genre;
 };
 
-public static TrackInfo getInfo() {
+public enum PlayerState {
+    Off, Stopped, Paused, Playing
+}
+
+public static PlayerState getPlayerState() {
+    auto hwnd = findPlayerWindow();
+    if (hwnd == null) {
+        return PlayerState.Off;
+    }
+
+    const auto state = SendMessage(hwnd, WM_AIMP_PROPERTY,
+            AIMP_RA_PROPERTY_PLAYER_STATE | AIMP_RA_PROPVALUE_GET, 0);
+    switch (state) {
+        default: return PlayerState.Stopped;
+        case 1: return PlayerState.Paused;
+        case 2: return PlayerState.Playing;
+    }
+}
+
+public static void setVolume(ubyte volume) {
+    auto hwnd = findPlayerWindow();
+    if (hwnd != null) {
+        SendMessage(hwnd, WM_AIMP_PROPERTY,
+                AIMP_RA_PROPERTY_VOLUME | AIMP_RA_PROPVALUE_SET, volume);
+    }
+}
+
+public static void nextTrack() {
+    auto hwnd = findPlayerWindow();
+    if (hwnd != null) {
+        SendMessage(hwnd, WM_AIMP_COMMAND, AIMP_RA_CMD_NEXT, 0);
+    }
+}
+
+public static Nullable!TrackInfo getInfo() {
     import std.conv : to;
     import std.traits : EnumMembers;
+    Nullable!TrackInfo result = Nullable!TrackInfo.init;
 
     auto haimp = OpenFileMapping(FILE_MAP_READ, 0, AIMPRemoteAccessClass.ptr);
+    if (haimp == null) {
+        result.nullify();
+        return result;
+    }
     const auto hfilemap = MapViewOfFile(haimp, FILE_MAP_READ, 0, 0, AIMPRemoteAccessMapFileSize);
+    if (hfilemap == null) {
+        result.nullify();
+        return result;
+    }
 
     AIMPRemoteFileInfo* info = cast(AIMPRemoteFileInfo*) hfilemap;
     auto bytes = (cast(ubyte*) hfilemap)[0 .. AIMPRemoteAccessMapFileSize];
@@ -65,11 +124,12 @@ public static TrackInfo getInfo() {
         pbuff += length * wcharsize;
     }
 
-    TrackInfo result = {
+    TrackInfo r = {
         artist: trackInfo[TagItem.Artist],
         title: trackInfo[TagItem.Title],
         genre: trackInfo[TagItem.Genre]
     };
+    result = Nullable!TrackInfo(r);
     return result;
 }
 
@@ -86,7 +146,7 @@ private static HWND findPlayerWindow() {
     AIMPRemoteFileInfo* info = cast(AIMPRemoteFileInfo*) hfilemap;
     write("Bitrate: ");
     writeln(info.bitRate);
-    write("Samplerate: ");
+    write("Samlerate: ");
     writeln(info.sampleRate);
     write("fileSize: ");
     writeln(info.fileSize);

source/app.d

@@ -10,6 +10,10 @@ void main()
     http.handle.set(CurlOption.ssl_verifypeer, 0);
 
     auto track = getInfo();
+    if (track.isNull) {
+        writeln("No data");
+        return;
+    }
 
     auto content = post("https://annimon.com/json/nowplay", [
         "login" : "test",