BACKENDS: Fix GraphicsManager handling of empty cursors

The SDL graphics manager was just ignoring calls from CursorMan to
set the cursor to a blank cursor, which meant engines that did not
immediately send a cursor to CursorMan at startup would still show
the launcher's cursor (usually with a broken palette).

The OpenGL graphics manager would try to generate and draw an
invalid cursor surface when receiving an empty cursor.

1 files changed, 12 insertions, 5 deletions

diff --git a/backends/graphics/opengl/opengl-graphics.cpp b/backends/graphics/opengl/opengl-graphics.cpp
index f3ea372b2a..7bac4c85cb 100644
--- a/backends/graphics/opengl/opengl-graphics.cpp
+++ b/backends/graphics/opengl/opengl-graphics.cpp
@@ -567,6 +567,18 @@ void applyColorKey(DstPixel *dst, const SrcPixel *src, uint w, uint h, uint dstP
 } // End of anonymous namespace
 
 void OpenGLGraphicsManager::setMouseCursor(const void *buf, uint w, uint h, int hotspotX, int hotspotY, uint32 keycolor, bool dontScale, const Graphics::PixelFormat *format) {
+
+	_cursorKeyColor = keycolor;
+	_cursorHotspotX = hotspotX;
+	_cursorHotspotY = hotspotY;
+	_cursorDontScale = dontScale;
+
+	if (!w || !h) {
+		delete _cursor;
+		_cursor = nullptr;
+		return;
+	}
+
 	Graphics::PixelFormat inputFormat;
 #ifdef USE_RGB_COLOR
 	if (format) {
@@ -602,11 +614,6 @@ void OpenGLGraphicsManager::setMouseCursor(const void *buf, uint w, uint h, int
 		_cursor->enableLinearFiltering(_currentState.filtering);
 	}
 
-	_cursorKeyColor = keycolor;
-	_cursorHotspotX = hotspotX;
-	_cursorHotspotY = hotspotY;
-	_cursorDontScale = dontScale;
-
 	_cursor->allocate(w, h);
 	if (inputFormat.bytesPerPixel == 1) {
 		// For CLUT8 cursors we can simply copy the input data into the