Add support for VRAM-compressed custom mouse cursor images

No memory is actually saved when using this, so lossless modes are
still recommended as they look better and load faster.

doc/classes/Input.xml

@@ -303,7 +303,7 @@
 				[param image]'s size must be lower than 256×256.
 				[param hotspot] must be within [param image]'s size.
 				[b]Note:[/b] [AnimatedTexture]s aren't supported as custom mouse cursors. If using an [AnimatedTexture], only the first frame will be displayed.
-				[b]Note:[/b] Only images imported with the [b]Lossless[/b], [b]Lossy[/b] or [b]Uncompressed[/b] compression modes are supported. The [b]Video RAM[/b] compression mode can't be used for custom cursors.
+				[b]Note:[/b] The [b]Lossless[/b], [b]Lossy[/b] or [b]Uncompressed[/b] compression modes are recommended. The [b]Video RAM[/b] compression mode can be used, but it will be decompressed on the CPU, which means loading times are slowed down and no memory is saved compared to lossless modes.
 				[b]Note:[/b] On the web platform, the maximum allowed cursor image size is 128×128. Cursor images larger than 32×32 will also only be displayed if the mouse cursor image is entirely located within the page for [url=https://chromestatus.com/feature/5825971391299584]security reasons[/url].
 			</description>
 		</method>

platform/linuxbsd/x11/display_server_x11.cpp

@@ -2671,6 +2671,11 @@ void DisplayServerX11::cursor_set_custom_image(const Ref<Resource> &p_cursor, Cu
 		Ref<Image> image = texture->get_image();
 
 		ERR_FAIL_COND(!image.is_valid());
+		if (image->is_compressed()) {
+			image = image->duplicate(true);
+			Error err = image->decompress();
+			ERR_FAIL_COND_MSG(err != OK, "Couldn't decompress VRAM-compressed custom mouse cursor image. Switch to a lossless compression mode in the Import dock.");
+		}
 
 		// Create the cursor structure
 		XcursorImage *cursor_image = XcursorImageCreate(texture_size.width, texture_size.height);

platform/macos/display_server_macos.mm

@@ -3300,6 +3300,11 @@ void DisplayServerMacOS::cursor_set_custom_image(const Ref<Resource> &p_cursor,
 		Ref<Image> image = texture->get_image();
 
 		ERR_FAIL_COND(!image.is_valid());
+		if (image->is_compressed()) {
+			image = image->duplicate(true);
+			Error err = image->decompress();
+			ERR_FAIL_COND_MSG(err != OK, "Couldn't decompress VRAM-compressed custom mouse cursor image. Switch to a lossless compression mode in the Import dock.");
+		}
 
 		NSBitmapImageRep *imgrep = [[NSBitmapImageRep alloc]
 				initWithBitmapDataPlanes:nullptr

platform/web/display_server_web.cpp

@@ -426,7 +426,12 @@ void DisplayServerWeb::cursor_set_custom_image(const Ref<Resource> &p_cursor, Cu
 
 		ERR_FAIL_COND(!image.is_valid());
 
-		image = image->duplicate();
+		image = image->duplicate(true);
+
+		if (image->is_compressed()) {
+			Error err = image->decompress();
+			ERR_FAIL_COND_MSG(err != OK, "Couldn't decompress VRAM-compressed custom mouse cursor image. Switch to a lossless compression mode in the Import dock.");
+		}
 
 		if (atlas_texture.is_valid()) {
 			image->crop_from_point(

platform/windows/display_server_windows.cpp

@@ -1742,6 +1742,11 @@ void DisplayServerWindows::cursor_set_custom_image(const Ref<Resource> &p_cursor
 		Ref<Image> image = texture->get_image();
 
 		ERR_FAIL_COND(!image.is_valid());
+		if (image->is_compressed()) {
+			image = image->duplicate(true);
+			Error err = image->decompress();
+			ERR_FAIL_COND_MSG(err != OK, "Couldn't decompress VRAM-compressed custom mouse cursor image. Switch to a lossless compression mode in the Import dock.");
+		}
 
 		UINT image_size = texture_size.width * texture_size.height;