Fix MapCanvas#drawImage

paper-server/src/main/java/org/bukkit/craftbukkit/map/CraftMapCanvas.java

@@ -3,6 +3,7 @@
 import com.google.common.base.Preconditions;
 import java.awt.Color;
 import java.awt.Image;
+import java.awt.image.BufferedImage;
 import java.util.Arrays;
 import org.bukkit.map.MapCanvas;
 import org.bukkit.map.MapCursorCollection;
@@ -92,22 +93,33 @@ protected byte[] getBuffer() {
     @Override
     public void drawImage(int x, int y, Image image) {
         // Paper start - Reduce work done by limiting size of image and using System.arraycopy
-        int width = 128 - x;
-        int height = 128 - y;
-        if (image.getHeight(null) < height)
-            height = image.getHeight(null);
+        final int imageWidth = image.getWidth(null);
+        final int imageHeight = image.getHeight(null);
+
+        // The source x value *may* be negative, meaning we'd need to "offset" the source image before drawing it.
+        final int sourceX = Math.max(-x, 0);
+        final int sourceY = Math.max(-y, 0);
+        final int destX = Math.max(x, 0);
+        final int destY = Math.max(y, 0);
+
+        // The effective width/height to draw on the canvas.
+        final int effectiveWidth = Math.min(imageWidth - sourceX, 128 - destX);
+        final int effectiveHeight = Math.min(imageHeight - sourceY, 128 - destY);
+
+        if (effectiveWidth <= 0 || effectiveHeight <= 0)
+            return;
 
         // Create a subimage if the image is larger than the max allowed size
-        java.awt.image.BufferedImage temp;
-        if (image.getWidth(null) >= width && image instanceof java.awt.image.BufferedImage bImage) {
+        BufferedImage temp;
+        if (imageWidth >= effectiveWidth && image instanceof BufferedImage bImage) {
             // If the image is larger than the max allowed size, get a subimage, otherwise use the image as is
-            if (image.getWidth(null) > width || image.getHeight(null) > height) {
-                temp = bImage.getSubimage(0, 0, width, height);
+            if (imageWidth > effectiveWidth || imageHeight > effectiveHeight) {
+                temp = bImage.getSubimage(sourceX, sourceY, effectiveWidth, effectiveHeight);
             } else {
                 temp = bImage;
             }
         } else {
-            temp = new java.awt.image.BufferedImage(width, height, java.awt.image.BufferedImage.TYPE_INT_ARGB);
+            temp = new BufferedImage(effectiveWidth, effectiveHeight, BufferedImage.TYPE_INT_ARGB);
             java.awt.Graphics2D graphics = temp.createGraphics();
             graphics.drawImage(image, 0, 0, null);
             graphics.dispose();
@@ -117,14 +129,20 @@ public void drawImage(int x, int y, Image image) {
 
         // Since we now control the size of the image, we can safely use System.arraycopy
         // If x is 0, we can just copy the entire image as width is 128 and height is <=(128-y)
-        if (x == 0) {
-            System.arraycopy(bytes, 0, this.buffer, y * 128, width * height);
-            return;
-        }
+        if (x == 0 && effectiveWidth == 128) { // This only works great if the width is 128, otherwise an empty area appears
+            System.arraycopy(bytes, 0, this.buffer, destY * effectiveWidth, effectiveWidth * effectiveHeight);
+        } else {
+            for (int yToCopy = 0; yToCopy < effectiveHeight; ++yToCopy) {
+                final int src = yToCopy * effectiveWidth;
+                final int dest = (destY + yToCopy) * 128 + destX;
 
-        for (int y2 = 0; y2 < height; ++y2) {
-            System.arraycopy(bytes, 0, this.buffer, (y + y2) * 128 + x, width);
+                System.arraycopy(bytes, src, this.buffer, dest, effectiveWidth);
+            }
         }
+
+        // Mark all colors within the image as dirty
+        this.mapView.worldMap.setColorsDirty(destX, destY);
+        this.mapView.worldMap.setColorsDirty(destX + effectiveWidth - 1, destY + effectiveHeight - 1);
         // Paper end
     }