From bb5fe944392b0928340034b8e6ebb721619cb8fc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Manuel=20V=C3=B6gele?= <develop@manuel-voegele.de>
Date: Sun, 21 Feb 2021 12:13:14 +0100
Subject: [PATCH] Allow speed providers to disable Drag Ruler on a per-token
 basis (resolves #24)

---
 CHANGELOG.md          |  1 +
 src/api.js            |  1 +
 src/main.js           |  4 +++-
 src/speed_provider.js | 10 ++++++++++
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f742d0d..e7e27c4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ This release introduces a new API that is incompatible with the old API. The new
 The following things have changed with the new API:
 - Colors used by speed providers can now be changed by the user via configuration
 - Speed Providers can now offer settings to the user that will be integrated into Drag Ruler's settings menu
+- Speed Providers can now conditionally disable Drag Ruler for some tokens
 
 
 ## 1.2.2
diff --git a/src/api.js b/src/api.js
index 2e65855..bcd139d 100644
--- a/src/api.js
+++ b/src/api.js
@@ -12,6 +12,7 @@ function register(module, type, speedProvider) {
 	}
 	else {
 		speedProvider.id = id
+		speedProvider.usesRuler = () => true
 		providerInstance = speedProvider
 	}
 	setupProvider(providerInstance)
diff --git a/src/main.js b/src/main.js
index c286f8f..6919e31 100644
--- a/src/main.js
+++ b/src/main.js
@@ -1,6 +1,6 @@
 "use strict"
 
-import {getRangesFromSpeedProvider, getUnreachableColorFromSpeedProvider, initApi, registerModule, registerSystem} from "./api.js"
+import {currentSpeedProvider, getRangesFromSpeedProvider, getUnreachableColorFromSpeedProvider, initApi, registerModule, registerSystem} from "./api.js"
 import {getHexSizeSupportTokenGridCenter} from "./compatibility.js"
 import {measure, moveTokens, onMouseMove} from "./foundry_imports.js"
 import {performMigrations} from "./migration.js"
@@ -142,6 +142,8 @@ function onKeyShift(up) {
 }
 
 function onTokenLeftDragStart(event) {
+	if (!currentSpeedProvider.usesRuler(this))
+		return
 	const ruler = canvas.controls.ruler
 	ruler.draggedToken = this
 	let tokenCenter
diff --git a/src/speed_provider.js b/src/speed_provider.js
index 09ee50b..9843542 100644
--- a/src/speed_provider.js
+++ b/src/speed_provider.js
@@ -73,6 +73,16 @@ export class SpeedProvider {
 		}
 	}
 
+	/**
+	 * Returns a boolean indicating whether this token will use a Ruler or not.
+	 * If this is returns `false` for a token Drag Ruler will be disabled for that token. Dragging a token for which this function
+	 * returns false will behave as if Drag Ruler wasn't installed.
+	 * If usesRuler returns `false` it's guranteed that the `getRanges` function won't be called for that token.
+	 */
+	usesRuler(token) {
+		return true
+	}
+
 	/**
 	 * Constructs a new instance of he speed provider
 	 *