Backport (II): "FormSpec: 9-slice images, animated_images, and fgimg_middle (#12453)"

* FormSpec: 9-slice images and animated_images

* Add fgimg_middle; clean up code

* Address issues, add tests

* Fix stupid error; bump formspec version

* Re-add image[] elements without a size

doc/lua_api.txt

@@ -2288,7 +2288,8 @@ Elements
 
 * Show an image.
 * `middle` (optional): Makes the image render in 9-sliced mode and defines the middle rect.
-  Requires formspec version >= 4. See `background9[]` documentation for more information.
+    * Requires formspec version >= 4.
+    * See `background9[]` documentation for more information.
 
 ### `animated_image[<X>,<Y>;<W>,<H>;<name>;<texture name>;<frame count>;<frame duration>;<frame start>;<middle>]`
 
@@ -2300,7 +2301,8 @@ Elements
 * `frame duration`: Milliseconds between each frame. `0` means the frames don't advance.
 * `frame start` (optional): The index of the frame to start on. Default `1`.
 * `middle` (optional): Makes the image render in 9-sliced mode and defines the middle rect.
-  Requires formspec version >= 4. See `background9[]` documentation for more information.
+    * Requires formspec version >= 4.
+    * See `background9[]` documentation for more information.
 
 ### `model[<X>,<Y>;<W>,<H>;<name>;<mesh>;<textures>;<rotation X,Y>;<continuous>;<mouse control>;<frame loop range>]`
 

src/gui/guiFormSpecMenu.cpp

@@ -802,31 +802,51 @@ void GUIFormSpecMenu::parseImage(parserData* data, const std::string &element)
 {
 	std::vector<std::string> parts = split(element,';');
 
-	if (parts.size() == 3 || parts.size() == 4 ||
+	if ((parts.size() >= 2 && parts.size() <= 4) ||
 		(parts.size() > 4 && m_formspec_version > FORMSPEC_API_VERSION))
 	{
-		std::vector<std::string> v_pos = split(parts[0],',');
-		std::vector<std::string> v_geom = split(parts[1],',');
-		std::string name = unescape_string(parts[2]);
 
+		size_t offset = parts.size() >= 3;
+
+		std::vector<std::string> v_pos = split(parts[0],',');
 		MY_CHECKPOS("image", 0);
-		MY_CHECKGEOM("image", 1);
+
+		std::vector<std::string> v_geom;
+		if (parts.size() >= 3) {
+			v_geom = split(parts[1],',');
+			MY_CHECKGEOM("image", 1);
+		}
+
+		std::string name = unescape_string(parts[1 + offset]);
+		video::ITexture *texture = m_tsrc->getTexture(name);
 
 		v2s32 pos;
 		v2s32 geom;
 
+		if (parts.size() < 3) {
+			if (texture != nullptr) {
+				core::dimension2du dim = texture->getOriginalSize();
+				geom.X = dim.Width;
+				geom.Y = dim.Height;
+			} else {
+				geom = v2s32(0);
+			}
+		}
+
 		if (data->real_coordinates) {
 			pos = getRealCoordinateBasePos(v_pos);
-			geom = getRealCoordinateGeometry(v_geom);
+			if (parts.size() >= 3)
+				geom = getRealCoordinateGeometry(v_geom);
 		} else {
 			pos = getElementBasePos(&v_pos);
-			geom.X = stof(v_geom[0]) * (float)imgsize.X;
-			geom.Y = stof(v_geom[1]) * (float)imgsize.Y;
+			if (parts.size() >= 3) {
+				geom.X = stof(v_geom[0]) * (float)imgsize.X;
+				geom.Y = stof(v_geom[1]) * (float)imgsize.Y;
+			}
 		}
 
 		if (!data->explicit_size)
-			warningstream << "Invalid use of image without a size[] element"
-					<< std::endl;
+			warningstream << "Invalid use of image without a size[] element" << std::endl;
 
 		FieldSpec spec(
 			name,
@@ -845,7 +865,7 @@ void GUIFormSpecMenu::parseImage(parserData* data, const std::string &element)
 		GUIAnimatedImage *e = new GUIAnimatedImage(Environment, data->current_parent,
 			spec.fid, rect);
 
-		e->setTexture(m_tsrc->getTexture(name));
+		e->setTexture(texture);
 		e->setMiddleRect(middle);
 
 		auto style = getDefaultStyleForElement("image", spec.fname);

src/network/networkprotocol.h

@@ -227,7 +227,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #define PASSWORD_SIZE 28       // Maximum password length. Allows for
                                // base64-encoded SHA-1 (27+\0).
 
-// See also: Formspec Version History in doc/lua_api.txt
+// See also formspec [Version History] in doc/lua_api.txt
 #define FORMSPEC_API_VERSION 4
 
 #define TEXTURENAME_ALLOWED_CHARS "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.-"