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

15 files changed, 222 insertions, 204 deletions

diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 994a30981..24de70a3b 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -2310,6 +2310,8 @@ Version History
   * Allow dropdown indexing events
 * Formspec version 5 (5.5.0):
   * Added padding[] element
+* Formspec version 6 (5.6.0):
+  * Add nine-slice images, animated_images, and fgimg_middle
 
 Elements
 --------
@@ -2474,20 +2476,25 @@ Elements
 * `bgcolor` tooltip background color as `ColorString` (optional)
 * `fontcolor` tooltip font color as `ColorString` (optional)
 
-### `image[<X>,<Y>;<W>,<H>;<texture name>]`
+### `image[<X>,<Y>;<W>,<H>;<texture name>;<middle>]`
 
-* Show an image
+* Show an image.
+* `middle` (optional): Makes the image render in 9-sliced mode and defines the middle rect.
+    * Requires formspec version >= 6.
+    * See `background9[]` documentation for more information.
 
-### `animated_image[<X>,<Y>;<W>,<H>;<name>;<texture name>;<frame count>;<frame duration>;<frame start>]`
+### `animated_image[<X>,<Y>;<W>,<H>;<name>;<texture name>;<frame count>;<frame duration>;<frame start>;<middle>]`
 
 * Show an animated image. The image is drawn like a "vertical_frames" tile
-    animation (See [Tile animation definition]), but uses a frame count/duration
-    for simplicity
+  animation (See [Tile animation definition]), but uses a frame count/duration for simplicity
 * `name`: Element name to send when an event occurs. The event value is the index of the current frame.
 * `texture name`: The image to use.
 * `frame count`: The number of frames animating the image.
 * `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`.
+* `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 >= 6.
+    * See `background9[]` documentation for more information.
 
 ### `model[<X>,<Y>;<W>,<H>;<name>;<mesh>;<textures>;<rotation X,Y>;<continuous>;<mouse control>;<frame loop range>;<animation speed>]`
 
@@ -3101,6 +3108,8 @@ Some types may inherit styles from parent types.
         * This is deprecated, use states instead.
     * fgimg_pressed - image when pressed. Defaults to fgimg when not provided.
         * This is deprecated, use states instead.
+    * fgimg_middle - Makes the fgimg textures render in 9-sliced mode and defines the middle rect.
+                     See background9[] documentation for more details.
     * NOTE: The parameters of any given image_button will take precedence over fgimg/fgimg_pressed
     * sound - a sound to be played when triggered.
 * scrollbar
diff --git a/games/devtest/mods/testformspec/formspec.lua b/games/devtest/mods/testformspec/formspec.lua
index 9f867631f..5f1f8970e 100644
--- a/games/devtest/mods/testformspec/formspec.lua
+++ b/games/devtest/mods/testformspec/formspec.lua
@@ -195,8 +195,10 @@ local style_fs = [[
 	style[one_btn15;border=false;bgcolor=#1cc;bgimg=testformspec_bg.png;bgimg_hovered=testformspec_bg_hovered.png;bgimg_pressed=testformspec_bg_pressed.png]
 	item_image_button[1.25,9.6;1,1;testformspec:item;one_btn15;Bg]
 
-	style[one_btn16;border=false;bgimg=testformspec_bg_9slice.png;bgimg_hovered=testformspec_bg_9slice_hovered.png;bgimg_pressed=testformspec_bg_9slice_pressed.png;bgimg_middle=4,6]
-	button[2.5,9.6;2,1;one_btn16;9-Slice Bg]
+	style[one_btn16;border=false;bgimg=testformspec_bg_9slice.png;bgimg_middle=4,6;padding=5,7;fgimg=testformspec_bg.png;fgimg_middle=1]
+	style[one_btn16:hovered;bgimg=testformspec_bg_9slice_hovered.png;fgimg=testformspec_bg_hovered.png]
+	style[one_btn16:pressed;bgimg=testformspec_bg_9slice_pressed.png;fgimg=testformspec_bg_pressed.png]
+	image_button[2.5,9.6;2,1;;one_btn16;9-Slice Bg]
 
 
 
@@ -375,12 +377,16 @@ local pages = {
 
 	-- Animation
 		[[
-			formspec_version[3]
+			formspec_version[6]
 			size[12,13]
 			animated_image[0.5,0.5;1,1;;testformspec_animation.png;4;100]
 			animated_image[0.5,1.75;1,1;;testformspec_animation.jpg;4;100]
 			animated_image[1.75,0.5;1,1;;testformspec_animation.png;100;100]
 			animated_image[3,0.5;1,1;ani_img_1;testformspec_animation.png;4;1000]
+			image[0.5,3;1,1;testformspec_bg.png;1]
+			animated_image[0.5,4.25;1,1;;[combine:16x48:0,0=testformspec_bg.png:0,16=testformspec_bg_hovered.png:0,32=testformspec_bg_pressed.png;3;250;1;1]
+			image[0.5,5.5;2,1;testformspec_9slice.png;16,0,-16,-16]
+			animated_image[2.75,5.5;1.5,0.5;;[combine:300x140:0,0=testformspec_9slice.png:0,70=(testformspec_9slice.png^[transformFX);2;500;1;16,0,-16,-16]
 			button[4.25,0.5;1,1;ani_btn_1;Current
 Number]
 			animated_image[3,1.75;1,1;ani_img_2;testformspec_animation.png;4;1000;2]
diff --git a/games/devtest/mods/testformspec/textures/testformspec_9slice.png b/games/devtest/mods/testformspec/textures/testformspec_9slice.png
new file mode 100644
index 000000000..70b6412a4
--- /dev/null
+++ b/games/devtest/mods/testformspec/textures/testformspec_9slice.png
diff --git a/src/client/guiscalingfilter.cpp b/src/client/guiscalingfilter.cpp
index de122becf..42508259f 100644
--- a/src/client/guiscalingfilter.cpp
+++ b/src/client/guiscalingfilter.cpp
@@ -176,52 +176,61 @@ void draw2DImageFilterScaled(video::IVideoDriver *driver, video::ITexture *txr,
 }
 
 void draw2DImage9Slice(video::IVideoDriver *driver, video::ITexture *texture,
-		const core::rect<s32> &rect, const core::rect<s32> &middle,
-		const core::rect<s32> *cliprect, const video::SColor *const colors)
+		const core::rect<s32> &destrect, const core::rect<s32> &srcrect,
+		const core::rect<s32> &middlerect, const core::rect<s32> *cliprect,
+		const video::SColor *const colors)
 {
-	auto originalSize = texture->getOriginalSize();
-	core::vector2di lowerRightOffset = core::vector2di(originalSize.Width, originalSize.Height) - middle.LowerRightCorner;
+	// `-x` is interpreted as `w - x`
+	core::rect<s32> middle = middlerect;
+
+	if (middlerect.LowerRightCorner.X < 0)
+		middle.LowerRightCorner.X += srcrect.getWidth();
+	if (middlerect.LowerRightCorner.Y < 0)
+		middle.LowerRightCorner.Y += srcrect.getHeight();
+
+	core::vector2di lower_right_offset = core::vector2di(srcrect.getWidth(),
+			srcrect.getHeight()) - middle.LowerRightCorner;
 
 	for (int y = 0; y < 3; ++y) {
 		for (int x = 0; x < 3; ++x) {
-			core::rect<s32> src({0, 0}, originalSize);
-			core::rect<s32> dest = rect;
+			core::rect<s32> src = srcrect;
+			core::rect<s32> dest = destrect;
 
 			switch (x) {
 			case 0:
-				dest.LowerRightCorner.X = rect.UpperLeftCorner.X + middle.UpperLeftCorner.X;
-				src.LowerRightCorner.X = middle.UpperLeftCorner.X;
+				dest.LowerRightCorner.X = destrect.UpperLeftCorner.X + middle.UpperLeftCorner.X;
+				src.LowerRightCorner.X = srcrect.UpperLeftCorner.X + middle.UpperLeftCorner.X;
 				break;
 
 			case 1:
 				dest.UpperLeftCorner.X += middle.UpperLeftCorner.X;
-				dest.LowerRightCorner.X -= lowerRightOffset.X;
-				src.UpperLeftCorner.X = middle.UpperLeftCorner.X;
-				src.LowerRightCorner.X = middle.LowerRightCorner.X;
+				dest.LowerRightCorner.X -= lower_right_offset.X;
+				src.UpperLeftCorner.X += middle.UpperLeftCorner.X;
+				src.LowerRightCorner.X -= lower_right_offset.X;
 				break;
 
 			case 2:
-				dest.UpperLeftCorner.X = rect.LowerRightCorner.X - lowerRightOffset.X;
-				src.UpperLeftCorner.X = middle.LowerRightCorner.X;
+				dest.UpperLeftCorner.X = destrect.LowerRightCorner.X - lower_right_offset.X;
+				src.UpperLeftCorner.X = srcrect.LowerRightCorner.X - lower_right_offset.X;
 				break;
 			}
 
 			switch (y) {
 			case 0:
-				dest.LowerRightCorner.Y = rect.UpperLeftCorner.Y + middle.UpperLeftCorner.Y;
-				src.LowerRightCorner.Y = middle.UpperLeftCorner.Y;
+				dest.LowerRightCorner.Y = destrect.UpperLeftCorner.Y + middle.UpperLeftCorner.Y;
+				src.LowerRightCorner.Y = srcrect.UpperLeftCorner.Y + middle.UpperLeftCorner.Y;
 				break;
 
 			case 1:
 				dest.UpperLeftCorner.Y += middle.UpperLeftCorner.Y;
-				dest.LowerRightCorner.Y -= lowerRightOffset.Y;
-				src.UpperLeftCorner.Y = middle.UpperLeftCorner.Y;
-				src.LowerRightCorner.Y = middle.LowerRightCorner.Y;
+				dest.LowerRightCorner.Y -= lower_right_offset.Y;
+				src.UpperLeftCorner.Y += middle.UpperLeftCorner.Y;
+				src.LowerRightCorner.Y -= lower_right_offset.Y;
 				break;
 
 			case 2:
-				dest.UpperLeftCorner.Y = rect.LowerRightCorner.Y - lowerRightOffset.Y;
-				src.UpperLeftCorner.Y = middle.LowerRightCorner.Y;
+				dest.UpperLeftCorner.Y = destrect.LowerRightCorner.Y - lower_right_offset.Y;
+				src.UpperLeftCorner.Y = srcrect.LowerRightCorner.Y - lower_right_offset.Y;
 				break;
 			}
 
diff --git a/src/client/guiscalingfilter.h b/src/client/guiscalingfilter.h
index 379a4bdb0..f2d2fce10 100644
--- a/src/client/guiscalingfilter.h
+++ b/src/client/guiscalingfilter.h
@@ -46,13 +46,13 @@ video::ITexture *guiScalingImageButton(video::IVideoDriver *driver, video::IText
  */
 void draw2DImageFilterScaled(video::IVideoDriver *driver, video::ITexture *txr,
 		const core::rect<s32> &destrect, const core::rect<s32> &srcrect,
-		const core::rect<s32> *cliprect = 0, const video::SColor *const colors = 0,
-		bool usealpha = false);
+		const core::rect<s32> *cliprect = nullptr,
+		const video::SColor *const colors = nullptr, bool usealpha = false);
 
 /*
  * 9-slice / segment drawing
  */
 void draw2DImage9Slice(video::IVideoDriver *driver, video::ITexture *texture,
-		const core::rect<s32> &rect, const core::rect<s32> &middle,
-		const core::rect<s32> *cliprect = nullptr,
+		const core::rect<s32> &destrect, const core::rect<s32> &srcrect,
+		const core::rect<s32> &middlerect, const core::rect<s32> *cliprect = nullptr,
 		const video::SColor *const colors = nullptr);
diff --git a/src/gui/StyleSpec.h b/src/gui/StyleSpec.h
index fc92a861b..7a45e07d1 100644
--- a/src/gui/StyleSpec.h
+++ b/src/gui/StyleSpec.h
@@ -45,6 +45,7 @@ public:
 		BGIMG_PRESSED, // Note: Deprecated property
 		FGIMG,
 		FGIMG_HOVERED, // Note: Deprecated property
+		FGIMG_MIDDLE,
 		FGIMG_PRESSED, // Note: Deprecated property
 		ALPHA,
 		CONTENT_OFFSET,
@@ -101,6 +102,8 @@ public:
 			return FGIMG;
 		} else if (name == "fgimg_hovered") {
 			return FGIMG_HOVERED;
+		} else if (name == "fgimg_middle") {
+			return FGIMG_MIDDLE;
 		} else if (name == "fgimg_pressed") {
 			return FGIMG_PRESSED;
 		} else if (name == "alpha") {
diff --git a/src/gui/guiAnimatedImage.cpp b/src/gui/guiAnimatedImage.cpp
index b1447c45f..890763e71 100644
--- a/src/gui/guiAnimatedImage.cpp
+++ b/src/gui/guiAnimatedImage.cpp
@@ -9,40 +9,37 @@
 #include <vector>
 
 GUIAnimatedImage::GUIAnimatedImage(gui::IGUIEnvironment *env, gui::IGUIElement *parent,
-	s32 id, const core::rect<s32> &rectangle, const std::string &texture_name,
-	s32 frame_count, s32 frame_duration, ISimpleTextureSource *tsrc) :
-	gui::IGUIElement(gui::EGUIET_ELEMENT, env, parent, id, rectangle), m_tsrc(tsrc)
+	s32 id, const core::rect<s32> &rectangle) :
+	gui::IGUIElement(gui::EGUIET_ELEMENT, env, parent, id, rectangle)
 {
-	m_texture = m_tsrc->getTexture(texture_name);
-
-	m_frame_count    = std::max(frame_count,    1);
-	m_frame_duration = std::max(frame_duration, 0);
-
-	if (m_texture != nullptr) {
-		core::dimension2d<u32> size = m_texture->getOriginalSize();
-		if (size.Height < (u64)m_frame_count)
-			m_frame_count = size.Height;
-	} else {
-		// No need to step an animation if we have nothing to draw
-		m_frame_count = 1;
-	}
 }
 
 void GUIAnimatedImage::draw()
 {
-	// Render the current frame
-	if (m_texture != nullptr) {
-		video::IVideoDriver *driver = Environment->getVideoDriver();
+	if (m_texture == nullptr)
+		return;
 
-		const video::SColor color(255, 255, 255, 255);
-		const video::SColor colors[] = {color, color, color, color};
+	video::IVideoDriver *driver = Environment->getVideoDriver();
+
+	core::dimension2d<u32> size = m_texture->getOriginalSize();
+
+	if ((u32)m_frame_count > size.Height)
+		m_frame_count = size.Height;
+	if (m_frame_idx >= m_frame_count)
+		m_frame_idx = m_frame_count - 1;
 
-		core::dimension2d<u32> size = m_texture->getOriginalSize();
-		size.Height /= m_frame_count;
+	size.Height /= m_frame_count;
 
-		draw2DImageFilterScaled(driver, m_texture, AbsoluteRect,
-			core::rect<s32>(core::position2d<s32>(0, size.Height * m_frame_idx), size),
-			NoClip ? nullptr : &AbsoluteClippingRect, colors, true);
+	core::rect<s32> rect(core::position2d<s32>(0, size.Height * m_frame_idx), size);
+	core::rect<s32> *cliprect = NoClip ? nullptr : &AbsoluteClippingRect;
+
+	if (m_middle.getArea() == 0) {
+		const video::SColor color(255, 255, 255, 255);
+		const video::SColor colors[] = {color, color, color, color};
+		draw2DImageFilterScaled(driver, m_texture, AbsoluteRect, rect, cliprect,
+			colors, true);
+	} else {
+		draw2DImage9Slice(driver, m_texture, AbsoluteRect, rect, m_middle, cliprect);
 	}
 
 	// Step the animation
@@ -55,7 +52,7 @@ void GUIAnimatedImage::draw()
 		m_global_time = new_global_time;
 
 		// Advance by the number of elapsed frames, looping if necessary
-		m_frame_idx += u32(m_frame_time / m_frame_duration);
+		m_frame_idx += (u32)(m_frame_time / m_frame_duration);
 		m_frame_idx %= m_frame_count;
 
 		// If 1 or more frames have elapsed, reset the frame time counter with
@@ -63,11 +60,3 @@ void GUIAnimatedImage::draw()
 		m_frame_time %= m_frame_duration;
 	}
 }
-
-
-void GUIAnimatedImage::setFrameIndex(s32 frame)
-{
-	s32 idx = std::max(frame, 0);
-	if (idx > 0 && idx < m_frame_count)
-		m_frame_idx = idx;
-}
diff --git a/src/gui/guiAnimatedImage.h b/src/gui/guiAnimatedImage.h
index f8e6a506e..885aedece 100644
--- a/src/gui/guiAnimatedImage.h
+++ b/src/gui/guiAnimatedImage.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "irrlichttypes_extrabloated.h"
+#include <algorithm>
 #include <string>
 
 class ISimpleTextureSource;
@@ -8,21 +9,33 @@ class ISimpleTextureSource;
 class GUIAnimatedImage : public gui::IGUIElement {
 public:
 	GUIAnimatedImage(gui::IGUIEnvironment *env, gui::IGUIElement *parent,
-		s32 id, const core::rect<s32> &rectangle, const std::string &texture_name,
-		s32 frame_count, s32 frame_duration, ISimpleTextureSource *tsrc);
+		s32 id, const core::rect<s32> &rectangle);
 
 	virtual void draw() override;
 
-	void setFrameIndex(s32 frame);
+	void setTexture(video::ITexture *texture) { m_texture = texture; };
+	video::ITexture *getTexture() const { return m_texture; };
+
+	void setMiddleRect(const core::rect<s32> &middle) { m_middle = middle; };
+	core::rect<s32> getMiddleRect() const { return m_middle; };
+
+	void setFrameDuration(u64 duration) { m_frame_duration = duration; };
+	u64 getFrameDuration() const { return m_frame_duration; };
+
+	void setFrameCount(s32 count) { m_frame_count = std::max(count, 1); };
+	s32 getFrameCount() const { return m_frame_count; };
+
+	void setFrameIndex(s32 frame) { m_frame_idx = std::max(frame, 0); };
 	s32 getFrameIndex() const { return m_frame_idx; };
 
 private:
-	ISimpleTextureSource *m_tsrc;
-
 	video::ITexture *m_texture = nullptr;
+
 	u64 m_global_time = 0;
 	s32 m_frame_idx = 0;
 	s32 m_frame_count = 1;
-	u64 m_frame_duration = 1;
+	u64 m_frame_duration = 0;
 	u64 m_frame_time = 0;
+
+	core::rect<s32> m_middle;
 };
diff --git a/src/gui/guiBackgroundImage.cpp b/src/gui/guiBackgroundImage.cpp
index 85e870771..8d0d1c010 100644
--- a/src/gui/guiBackgroundImage.cpp
+++ b/src/gui/guiBackgroundImage.cpp
@@ -48,21 +48,15 @@ void GUIBackgroundImage::draw()
 
 	video::IVideoDriver *driver = Environment->getVideoDriver();
 
+	core::rect<s32> srcrect(core::position2d<s32>(0, 0),
+			core::dimension2di(texture->getOriginalSize()));
+
 	if (m_middle.getArea() == 0) {
 		const video::SColor color(255, 255, 255, 255);
 		const video::SColor colors[] = {color, color, color, color};
-		draw2DImageFilterScaled(driver, texture, rect,
-				core::rect<s32>(core::position2d<s32>(0, 0),
-						core::dimension2di(texture->getOriginalSize())),
-				nullptr, colors, true);
+		draw2DImageFilterScaled(driver, texture, rect, srcrect, nullptr, colors, true);
 	} else {
-		core::rect<s32> middle = m_middle;
-		// `-x` is interpreted as `w - x`
-		if (middle.LowerRightCorner.X < 0)
-			middle.LowerRightCorner.X += texture->getOriginalSize().Width;
-		if (middle.LowerRightCorner.Y < 0)
-			middle.LowerRightCorner.Y += texture->getOriginalSize().Height;
-		draw2DImage9Slice(driver, texture, rect, middle);
+		draw2DImage9Slice(driver, texture, rect, srcrect, m_middle);
 	}
 
 	IGUIElement::draw();
diff --git a/src/gui/guiButton.cpp b/src/gui/guiButton.cpp
index ba95b81c3..c38d901c4 100644
--- a/src/gui/guiButton.cpp
+++ b/src/gui/guiButton.cpp
@@ -320,15 +320,9 @@ void GUIButton::draw()
 					sourceRect, &AbsoluteClippingRect,

 					image_colors, UseAlphaChannel);

 		} else {

-			core::rect<s32> middle = BgMiddle;

-			// `-x` is interpreted as `w - x`

-			if (middle.LowerRightCorner.X < 0)

-				middle.LowerRightCorner.X += texture->getOriginalSize().Width;

-			if (middle.LowerRightCorner.Y < 0)

-				middle.LowerRightCorner.Y += texture->getOriginalSize().Height;

 			draw2DImage9Slice(driver, texture,

 					ScaleImage ? AbsoluteRect : core::rect<s32>(pos, sourceRect.getSize()),

-					middle, &AbsoluteClippingRect, image_colors);

+					sourceRect, BgMiddle, &AbsoluteClippingRect, image_colors);

 		}

 		// END PATCH

 	}

diff --git a/src/gui/guiButtonImage.cpp b/src/gui/guiButtonImage.cpp
index b507ffece..4ab770a99 100644
--- a/src/gui/guiButtonImage.cpp
+++ b/src/gui/guiButtonImage.cpp
@@ -32,15 +32,15 @@ using namespace gui;
 GUIButtonImage::GUIButtonImage(gui::IGUIEnvironment *environment,
 		gui::IGUIElement *parent, s32 id, core::rect<s32> rectangle,
 		ISimpleTextureSource *tsrc, bool noclip)
-	: GUIButton (environment, parent, id, rectangle, tsrc, noclip)
+	: GUIButton(environment, parent, id, rectangle, tsrc, noclip)
 {
-	m_image = Environment->addImage(
-			core::rect<s32>(0,0,rectangle.getWidth(),rectangle.getHeight()), this);
-	m_image->setScaleImage(isScalingImage());
+	GUIButton::setScaleImage(true);
+	m_image = new GUIAnimatedImage(environment, this, id, rectangle);
 	sendToBack(m_image);
 }
 
-void GUIButtonImage::setForegroundImage(video::ITexture *image)
+void GUIButtonImage::setForegroundImage(video::ITexture *image,
+		const core::rect<s32> &middle)
 {
 	if (image == m_foreground_image)
 		return;
@@ -52,11 +52,12 @@ void GUIButtonImage::setForegroundImage(video::ITexture *image)
 		m_foreground_image->drop();
 
 	m_foreground_image = image;
-	m_image->setImage(image);
+	m_image->setTexture(image);
+	m_image->setMiddleRect(middle);
 }
 
 //! Set element properties from a StyleSpec
-void GUIButtonImage::setFromStyle(const StyleSpec& style)
+void GUIButtonImage::setFromStyle(const StyleSpec &style)
 {
 	GUIButton::setFromStyle(style);
 
@@ -67,19 +68,13 @@ void GUIButtonImage::setFromStyle(const StyleSpec& style)
 				getTextureSource());
 
 		setForegroundImage(guiScalingImageButton(driver, texture,
-			AbsoluteRect.getWidth(), AbsoluteRect.getHeight()));
-		setScaleImage(true);
+				AbsoluteRect.getWidth(), AbsoluteRect.getHeight()),
+				style.getRect(StyleSpec::FGIMG_MIDDLE, m_image->getMiddleRect()));
 	} else {
-		setForegroundImage(nullptr);
+		setForegroundImage();
 	}
 }
 
-void GUIButtonImage::setScaleImage(bool scaleImage)
-{
-	GUIButton::setScaleImage(scaleImage);
-	m_image->setScaleImage(scaleImage);
-}
-
 GUIButtonImage *GUIButtonImage::addButton(IGUIEnvironment *environment,
 		const core::rect<s32> &rectangle, ISimpleTextureSource *tsrc,
 		IGUIElement *parent, s32 id, const wchar_t *text,
diff --git a/src/gui/guiButtonImage.h b/src/gui/guiButtonImage.h
index 59a25b4f0..554934518 100644
--- a/src/gui/guiButtonImage.h
+++ b/src/gui/guiButtonImage.h
@@ -21,6 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "guiButton.h"
 #include "IGUIButton.h"
+#include "guiAnimatedImage.h"
 
 using namespace irr;
 
@@ -32,12 +33,11 @@ public:
 			s32 id, core::rect<s32> rectangle, ISimpleTextureSource *tsrc,
 			bool noclip = false);
 
-	void setForegroundImage(video::ITexture *image = nullptr);
+	void setForegroundImage(video::ITexture *image = nullptr,
+			const core::rect<s32> &middle = core::rect<s32>());
 
 	//! Set element properties from a StyleSpec
-	virtual void setFromStyle(const StyleSpec& style) override;
-
-	virtual void setScaleImage(bool scaleImage=true) override;
+	virtual void setFromStyle(const StyleSpec &style) override;
 
 	//! Do not drop returned handle
 	static GUIButtonImage *addButton(gui::IGUIEnvironment *environment,
@@ -47,5 +47,5 @@ public:
 
 private:
 	video::ITexture *m_foreground_image = nullptr;
-	gui::IGUIImage *m_image;
+	GUIAnimatedImage *m_image;
 };
diff --git a/src/gui/guiFormSpecMenu.cpp b/src/gui/guiFormSpecMenu.cpp
index 422d6da16..e01a5347a 100644
--- a/src/gui/guiFormSpecMenu.cpp
+++ b/src/gui/guiFormSpecMenu.cpp
@@ -767,101 +767,84 @@ void GUIFormSpecMenu::parseScrollBarOptions(parserData* data, const std::string
 void GUIFormSpecMenu::parseImage(parserData* data, const std::string &element)
 {
 	std::vector<std::string> parts;
-	if (!precheckElement("image", element, 2, 3, parts))
+	if (!precheckElement("image", element, 2, 4, parts))
 		return;
 
-	if (parts.size() >= 3) {
-		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_CHECKPOS("image", 0);
+	std::vector<std::string> v_geom;
+	if (parts.size() >= 3) {
+		v_geom = split(parts[1],',');
 		MY_CHECKGEOM("image", 1);
+	}
 
-		v2s32 pos;
-		v2s32 geom;
+	std::string name = unescape_string(parts[1 + offset]);
+	video::ITexture *texture = m_tsrc->getTexture(name);
 
-		if (data->real_coordinates) {
-			pos = getRealCoordinateBasePos(v_pos);
-			geom = getRealCoordinateGeometry(v_geom);
+	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 {
-			pos = getElementBasePos(&v_pos);
-			geom.X = stof(v_geom[0]) * (float)imgsize.X;
-			geom.Y = stof(v_geom[1]) * (float)imgsize.Y;
+			geom = v2s32(0);
 		}
+	}
 
-		if (!data->explicit_size)
-			warningstream<<"invalid use of image without a size[] element"<<std::endl;
-
-		video::ITexture *texture = m_tsrc->getTexture(name);
-		if (!texture) {
-			errorstream << "GUIFormSpecMenu::parseImage() Unable to load texture:"
-					<< std::endl << "\t" << name << std::endl;
-			return;
+	if (data->real_coordinates) {
+		pos = getRealCoordinateBasePos(v_pos);
+		if (parts.size() >= 3)
+			geom = getRealCoordinateGeometry(v_geom);
+	} else {
+		pos = getElementBasePos(&v_pos);
+		if (parts.size() >= 3) {
+			geom.X = stof(v_geom[0]) * (float)imgsize.X;
+			geom.Y = stof(v_geom[1]) * (float)imgsize.Y;
 		}
-
-		FieldSpec spec(
-			name,
-			L"",
-			L"",
-			258 + m_fields.size(),
-			1
-		);
-		core::rect<s32> rect(pos, pos + geom);
-		gui::IGUIImage *e = Environment->addImage(rect, data->current_parent,
-				spec.fid, 0, true);
-		e->setImage(texture);
-		e->setScaleImage(true);
-		auto style = getDefaultStyleForElement("image", spec.fname);
-		e->setNotClipped(style.getBool(StyleSpec::NOCLIP, m_formspec_version < 3));
-		m_fields.push_back(spec);
-
-		// images should let events through
-		e->grab();
-		m_clickthrough_elements.push_back(e);
-		return;
 	}
 
-	// Else: 2 arguments in "parts"
-
-	std::vector<std::string> v_pos = split(parts[0],',');
-	std::string name = unescape_string(parts[1]);
-
-	MY_CHECKPOS("image", 0);
-
-	v2s32 pos = getElementBasePos(&v_pos);
-
 	if (!data->explicit_size)
-		warningstream<<"invalid use of image without a size[] element"<<std::endl;
-
-	video::ITexture *texture = m_tsrc->getTexture(name);
-	if (!texture) {
-		errorstream << "GUIFormSpecMenu::parseImage() Unable to load texture:"
-				<< std::endl << "\t" << name << std::endl;
-		return;
-	}
+		warningstream << "Invalid use of image without a size[] element" << std::endl;
 
 	FieldSpec spec(
 		name,
 		L"",
 		L"",
-		258 + m_fields.size()
+		258 + m_fields.size(),
+		1
 	);
-	gui::IGUIImage *e = Environment->addImage(texture, pos, true,
-			data->current_parent, spec.fid, 0);
+
+	core::rect<s32> rect = core::rect<s32>(pos, pos + geom);
+
+	core::rect<s32> middle;
+	if (parts.size() >= 4)
+		parseMiddleRect(parts[3], &middle);
+
+	GUIAnimatedImage *e = new GUIAnimatedImage(Environment, data->current_parent,
+		spec.fid, rect);
+
+	e->setTexture(texture);
+	e->setMiddleRect(middle);
+
 	auto style = getDefaultStyleForElement("image", spec.fname);
 	e->setNotClipped(style.getBool(StyleSpec::NOCLIP, m_formspec_version < 3));
-	m_fields.push_back(spec);
 
-	// images should let events through
-	e->grab();
+	// Animated images should let events through
 	m_clickthrough_elements.push_back(e);
+
+	m_fields.push_back(spec);
 }
 
 void GUIFormSpecMenu::parseAnimatedImage(parserData *data, const std::string &element)
 {
 	std::vector<std::string> parts;
-	if (!precheckElement("animated_image", element, 6, 7, parts))
+	if (!precheckElement("animated_image", element, 6, 8, parts))
 		return;
 
 	std::vector<std::string> v_pos  = split(parts[0], ',');
@@ -887,7 +870,8 @@ void GUIFormSpecMenu::parseAnimatedImage(parserData *data, const std::string &el
 	}
 
 	if (!data->explicit_size)
-		warningstream << "Invalid use of animated_image without a size[] element" << std::endl;
+		warningstream << "Invalid use of animated_image without a size[] element"
+				<< std::endl;
 
 	FieldSpec spec(
 		name,
@@ -900,9 +884,17 @@ void GUIFormSpecMenu::parseAnimatedImage(parserData *data, const std::string &el
 
 	core::rect<s32> rect = core::rect<s32>(pos, pos + geom);
 
-	GUIAnimatedImage *e = new GUIAnimatedImage(Environment, data->current_parent, spec.fid,
-		rect, texture_name, frame_count, frame_duration, m_tsrc);
+	core::rect<s32> middle;
+	if (parts.size() >= 8)
+		parseMiddleRect(parts[7], &middle);
+
+	GUIAnimatedImage *e = new GUIAnimatedImage(Environment, data->current_parent,
+		spec.fid, rect);
 
+	e->setTexture(m_tsrc->getTexture(texture_name));
+	e->setMiddleRect(middle);
+	e->setFrameDuration(frame_duration);
+	e->setFrameCount(frame_count);
 	if (parts.size() >= 7)
 		e->setFrameIndex(stoi(parts[6]) - 1);
 
@@ -1027,6 +1019,35 @@ void GUIFormSpecMenu::parseButton(parserData* data, const std::string &element,
 	m_fields.push_back(spec);
 }
 
+bool GUIFormSpecMenu::parseMiddleRect(const std::string &value, core::rect<s32> *parsed_rect)
+{
+	core::rect<s32> rect;
+	std::vector<std::string> v_rect = split(value, ',');
+
+	if (v_rect.size() == 1) {
+		s32 x = stoi(v_rect[0]);
+		rect.UpperLeftCorner = core::vector2di(x, x);
+		rect.LowerRightCorner = core::vector2di(-x, -x);
+	} else if (v_rect.size() == 2) {
+		s32 x = stoi(v_rect[0]);
+		s32 y =	stoi(v_rect[1]);
+		rect.UpperLeftCorner = core::vector2di(x, y);
+		rect.LowerRightCorner = core::vector2di(-x, -y);
+		// `-x` is interpreted as `w - x`
+	} else if (v_rect.size() == 4) {
+		rect.UpperLeftCorner = core::vector2di(stoi(v_rect[0]), stoi(v_rect[1]));
+		rect.LowerRightCorner = core::vector2di(stoi(v_rect[2]), stoi(v_rect[3]));
+	} else {
+		warningstream << "Invalid rectangle string format: \"" << value
+				<< "\"" << std::endl;
+		return false;
+	}
+
+	*parsed_rect = rect;
+
+	return true;
+}
+
 void GUIFormSpecMenu::parseBackground(parserData* data, const std::string &element)
 {
 	std::vector<std::string> parts;
@@ -1068,25 +1089,8 @@ void GUIFormSpecMenu::parseBackground(parserData* data, const std::string &eleme
 	}
 
 	core::rect<s32> middle;
-	if (parts.size() >= 5) {
-		std::vector<std::string> v_middle = split(parts[4], ',');
-		if (v_middle.size() == 1) {
-			s32 x = stoi(v_middle[0]);
-			middle.UpperLeftCorner = core::vector2di(x, x);
-			middle.LowerRightCorner = core::vector2di(-x, -x);
-		} else if (v_middle.size() == 2) {
-			s32 x = stoi(v_middle[0]);
-			s32 y =	stoi(v_middle[1]);
-			middle.UpperLeftCorner = core::vector2di(x, y);
-			middle.LowerRightCorner = core::vector2di(-x, -y);
-			// `-x` is interpreted as `w - x`
-		} else if (v_middle.size() == 4) {
-			middle.UpperLeftCorner = core::vector2di(stoi(v_middle[0]), stoi(v_middle[1]));
-			middle.LowerRightCorner = core::vector2di(stoi(v_middle[2]), stoi(v_middle[3]));
-		} else {
-			warningstream << "Invalid rectangle given to middle param of background[] element" << std::endl;
-		}
-	}
+	if (parts.size() >= 5)
+		parseMiddleRect(parts[4], &middle);
 
 	if (!data->explicit_size && !clip)
 		warningstream << "invalid use of unclipped background without a size[] element" << std::endl;
diff --git a/src/gui/guiFormSpecMenu.h b/src/gui/guiFormSpecMenu.h
index a584456db..c01ff817b 100644
--- a/src/gui/guiFormSpecMenu.h
+++ b/src/gui/guiFormSpecMenu.h
@@ -457,6 +457,8 @@ private:
 	void parseSetFocus(const std::string &element);
 	void parseModel(parserData *data, const std::string &element);
 
+	bool parseMiddleRect(const std::string &value, core::rect<s32> *parsed_rect);
+
 	void tryClose();
 
 	void showTooltip(const std::wstring &text, const irr::video::SColor &color,
diff --git a/src/network/networkprotocol.h b/src/network/networkprotocol.h
index 7c5b2e3fe..33e49afa4 100644
--- a/src/network/networkprotocol.h
+++ b/src/network/networkprotocol.h
@@ -228,8 +228,8 @@ 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
-#define FORMSPEC_API_VERSION 5
+// See also formspec [Version History] in doc/lua_api.txt
+#define FORMSPEC_API_VERSION 6
 
 #define TEXTURENAME_ALLOWED_CHARS "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.-"