From 5c77e641e9a592787d484fcad1ebb653825ad159 Mon Sep 17 00:00:00 2001
From: Benau <Benau@users.noreply.github.com>
Date: Fri, 1 May 2020 09:45:22 +0800
Subject: [PATCH] Add batch drawing for list box widget

---
 src/font/font_drawer.cpp                 | 24 ++++++++++++++++++++++++
 src/font/font_drawer.hpp                 |  6 ++++++
 src/guiengine/CGUISpriteBank.cpp         | 19 ++++++++++++++++---
 src/guiengine/widgets/CGUISTKListBox.cpp |  8 +++++---
 4 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/src/font/font_drawer.cpp b/src/font/font_drawer.cpp
index 9e0fce3bc..5ea260d02 100644
--- a/src/font/font_drawer.cpp
+++ b/src/font/font_drawer.cpp
@@ -57,6 +57,27 @@ public:
 std::unique_ptr<core::rect<s32> > g_clip;
 // ============================================================================
 std::map<video::ITexture*, std::vector<uint8_t> > g_glyphs;
+// ============================================================================
+bool g_batching = false;
+// ----------------------------------------------------------------------------
+void FontDrawer::startBatching()
+{
+    g_batching = true;
+}   // startBatching
+
+// ----------------------------------------------------------------------------
+bool FontDrawer::isBatching()
+{
+    return g_batching;
+}   // isBatching
+
+// ----------------------------------------------------------------------------
+void FontDrawer::endBatching()
+{
+    g_batching = false;
+    draw();
+}   // endBatching
+
 // ----------------------------------------------------------------------------
 void FontDrawer::addGlyph(video::ITexture* texture,
                           const core::rect<float>& dest_rect,
@@ -119,6 +140,9 @@ void FontDrawer::addGlyph(video::ITexture* texture,
 // ----------------------------------------------------------------------------
 void FontDrawer::draw()
 {
+    if (g_batching || g_glyphs.empty())
+        return;
+
     if (g_clip && !g_clip->isValid())
     {
         for (auto it = g_glyphs.begin(); it != g_glyphs.end();)
diff --git a/src/font/font_drawer.hpp b/src/font/font_drawer.hpp
index 64cf4d6b7..1900e8a8a 100644
--- a/src/font/font_drawer.hpp
+++ b/src/font/font_drawer.hpp
@@ -31,6 +31,12 @@ using namespace irr;
 
 namespace FontDrawer
 {
+    // ------------------------------------------------------------------------
+    void startBatching();
+    // ------------------------------------------------------------------------
+    bool isBatching();
+    // ------------------------------------------------------------------------
+    void endBatching();
     // ------------------------------------------------------------------------
     void addGlyph(video::ITexture* texture,
                   const core::rect<float>& dest_rect,
diff --git a/src/guiengine/CGUISpriteBank.cpp b/src/guiengine/CGUISpriteBank.cpp
index c7cf908ba..1edfe4650 100644
--- a/src/guiengine/CGUISpriteBank.cpp
+++ b/src/guiengine/CGUISpriteBank.cpp
@@ -9,6 +9,7 @@
 #include "IVideoDriver.h"
 #include "ITexture.h"
 #include <cassert>
+#include "font/font_drawer.hpp"
 #include "graphics/2dutils.hpp"
 
 namespace irr
@@ -202,7 +203,7 @@ void STKModifiedSpriteBank::draw2DSprite(u32 index,
                   ? Sprites[index].Frames.size()-1 : f;
     }
 
-    const video::ITexture* tex =
+    video::ITexture* tex =
         Textures[Sprites[index].Frames[frame].textureNumber];
     if (!tex)
         return;
@@ -242,8 +243,20 @@ void STKModifiedSpriteBank::draw2DSprite(u32 index,
                       const video::SColor  *const colors=0,
                       bool useAlphaChannelOfTexture=false)=0
      */
-    draw2DImage(tex, dest, r /* source rect */, clip,
-                        NULL /* colors */, true);
+    if (FontDrawer::isBatching())
+    {
+        // FontDrawing is batching when stk list box widget is drawing text,
+        // so we combine the images to them to make it faster (for example in
+        // server list when there are all green tick icons)
+        FontDrawer::addGlyph(tex, core::rect<f32>(dest.UpperLeftCorner.X,
+            dest.UpperLeftCorner.Y, dest.LowerRightCorner.X,
+            dest.LowerRightCorner.Y), r, clip, video::SColor(-1));
+    }
+    else
+    {
+        draw2DImage(tex, dest, r /* source rect */, clip, NULL /* colors */,
+            true);
+    }
 #endif
 }   // draw2DSprite
 
diff --git a/src/guiengine/widgets/CGUISTKListBox.cpp b/src/guiengine/widgets/CGUISTKListBox.cpp
index a4dcbb634..3e795ec57 100644
--- a/src/guiengine/widgets/CGUISTKListBox.cpp
+++ b/src/guiengine/widgets/CGUISTKListBox.cpp
@@ -5,6 +5,7 @@
 
 #include "guiengine/widgets/CGUISTKListBox.hpp"
 
+#include "font/font_drawer.hpp"
 #include "graphics/2dutils.hpp"
 #include "IGUISkin.h"
 #include "IGUIEnvironment.h"
@@ -467,6 +468,7 @@ void CGUISTKListBox::updateAbsolutePosition()
 //! draws the element and its children
 void CGUISTKListBox::draw()
 {
+#ifndef SERVER_ONLY
     if (!IsVisible)
         return;
 
@@ -505,19 +507,18 @@ void CGUISTKListBox::draw()
 
     bool hl = (HighlightWhenNotFocused || Environment->hasFocus(this) || Environment->hasFocus(ScrollBar));
 
+    FontDrawer::startBatching();
     for (s32 i=0; i<(s32)Items.size(); ++i)
     {
         if (frameRect.LowerRightCorner.Y >= AbsoluteRect.UpperLeftCorner.Y &&
             frameRect.UpperLeftCorner.Y <= AbsoluteRect.LowerRightCorner.Y)
         {
-#ifndef SERVER_ONLY
             if (m_alternating_darkness && i % 2 != 0)
             {
                 video::SColor color(0);
                 color.setAlpha(30);
                 GL32_draw2DRectangle(color, frameRect, &clientClip);
             }
-#endif
             if (i == Selected && hl)
                 skin->draw2DRectangle(this, skin->getColor(EGDC_HIGH_LIGHT), frameRect, &clientClip);
 
@@ -614,7 +615,8 @@ void CGUISTKListBox::draw()
         frameRect.UpperLeftCorner.Y += ItemHeight;
         frameRect.LowerRightCorner.Y += ItemHeight;
     }
-
+    FontDrawer::endBatching();
+#endif
     IGUIElement::draw();
 }