Fix world map overlay to draw pixel perfect on the World Map

runelite-client/src/main/java/net/runelite/client/ui/overlay/worldmap/WorldMapOverlay.java

@@ -182,17 +182,31 @@ public class WorldMapOverlay extends Overlay
 
 		Float pixelsPerTile = ro.getWorldMapZoom();
 
-		Point worldMapPosition = ro.getWorldMapPosition();
-		int xWorldDiff = worldPoint.getX() - worldMapPosition.getX();
-		int yWorldDiff = worldPoint.getY() - worldMapPosition.getY();
-		yWorldDiff = -yWorldDiff;
-
 		Widget map = clientProvider.get().getWidget(WidgetInfo.WORLD_MAP_VIEW);
 		if (map != null)
 		{
 			Rectangle worldMapRect = map.getBounds();
-			int xGraphDiff = (int) (xWorldDiff * pixelsPerTile + worldMapRect.getWidth() / 2 + worldMapRect.getX());
-			int yGraphDiff = (int) (yWorldDiff * pixelsPerTile + worldMapRect.getHeight() / 2 + worldMapRect.getY());
+
+			int widthInTiles = (int) Math.ceil(worldMapRect.getWidth() / pixelsPerTile);
+			int heightInTiles = (int) Math.ceil(worldMapRect.getHeight() / pixelsPerTile);
+
+			Point worldMapPosition = ro.getWorldMapPosition();
+
+			//Offset in tiles from anchor sides
+			int yTileMax = worldMapPosition.getY() - heightInTiles / 2;
+			int yTileOffset = (yTileMax - worldPoint.getY() - 1) * -1;
+			int xTileOffset = worldPoint.getX() + widthInTiles / 2 - worldMapPosition.getX();
+
+			int xGraphDiff = ((int) (xTileOffset * pixelsPerTile));
+			int yGraphDiff = (int) (yTileOffset * pixelsPerTile);
+
+			//Center on tile.
+			yGraphDiff -= pixelsPerTile - Math.ceil(pixelsPerTile / 2);
+			xGraphDiff += pixelsPerTile - Math.ceil(pixelsPerTile / 2);
+
+			yGraphDiff = worldMapRect.height - yGraphDiff;
+			yGraphDiff += (int) worldMapRect.getY();
+			xGraphDiff += (int) worldMapRect.getX();
 
 			return new Point(xGraphDiff, yGraphDiff);
 		}

runelite-mixins/src/main/java/net/runelite/mixins/WorldMapManagerMixin.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2018, Morgan Lewis <https://github.com/MESLewis>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package net.runelite.mixins;
+
+import net.runelite.api.mixins.Mixin;
+import net.runelite.api.mixins.Replace;
+import net.runelite.api.mixins.Shadow;
+import net.runelite.rs.api.RSClient;
+import net.runelite.rs.api.RSWorldMapManager;
+
+@Mixin(RSWorldMapManager.class)
+public abstract class WorldMapManagerMixin implements RSWorldMapManager
+{
+	@Shadow("clientInstance")
+	static RSClient client;
+
+	/*
+	 The worldMapZoom is essentially pixels per tile. In most instances
+	 getPixelsPerTile returns the same as worldMapZoom.
+
+	 At some map widths when 100% zoomed in the Jagex version of this function
+	 returns 7.89 instead of 8.0 (the worldMapZoom at this level).
+	 This would cause both the x and y positions of the map to shift
+	 slightly when the map was certain widths.
+
+	 This mixin function replaces Jagex calculation with getWorldMapZoom.
+	 This small change makes the world map tile sizing predictable.
+	 */
+	@Replace("getPixelsPerTile")
+	@Override
+	public float getPixelsPerTile(int graphicsDiff, int worldDiff)
+	{
+		return client.getRenderOverview().getWorldMapZoom();
+	}
+
+}

runescape-api/src/main/java/net/runelite/rs/api/RSWorldMapManager.java

@@ -38,4 +38,7 @@ public interface RSWorldMapManager extends WorldMapManager
 
 	@Import("mapSurfaceBaseOffsetY")
 	int getSurfaceOffsetY();
+
+	@Import("getPixelsPerTile")
+	float getPixelsPerTile(int graphicsDiff, int worldDiff);
 }