Render font outlines using TTF_SetFontOutlineHEADmaster

Rather than rendering the same texture 4 additional times, render a
specific outline version of the text. While reducing the number of times
the text is drawn, it does increase font texture use.

Result is a generally prettier outline due to rendering it properly at
sharp corners of the characters. The shadow for outlined text is now
also thicker, as appropriate.

As part of this change, the `TextRenderer` class was merged into the
`Graphics` and `TrueTypeFont` classes. There seemed to be little point
in having a separate function for this, apart from needing more static
casts to `Graphics*`.

Also fixed an issue where the font style was not being restored after
adjusting the font scale, when using an older SDL_ttf than 2.0.18.

Closes #87

10 files changed, 197 insertions, 136 deletions

diff --git a/src/gui/truetypefont.cpp b/src/gui/truetypefont.cpp
index 444641b5..c85d08c0 100644
--- a/src/gui/truetypefont.cpp
+++ b/src/gui/truetypefont.cpp
@@ -53,6 +53,7 @@ bool operator==(SDL_Color lhs, SDL_Color rhs)
             lhs.a == rhs.a);
 }
 
+
 class TextChunk
 {
 public:
@@ -60,24 +61,49 @@ public:
         : text(text)
     {}
 
-    void generate(TTF_Font *font)
+    void render(Graphics *graphics,
+                int x, int y,
+                TTF_Font *font,
+                std::unique_ptr<Image> &img,
+                float scale);
+
+    const std::string text;
+    std::unique_ptr<Image> regular;
+    std::unique_ptr<Image> outlined;
+};
+
+void TextChunk::render(Graphics *graphics,
+                       int x, int y,
+                       TTF_Font *font,
+                       std::unique_ptr<Image> &img,
+                       float scale)
+{
+    if (!img)
     {
         // Always render in white, we'll use color modulation when rendering
+        constexpr SDL_Color white = { 255, 255, 255, 255 };
         SDL_Surface *surface = TTF_RenderUTF8_Blended(font,
                                                       getSafeUtf8String(text),
-                                                      SDL_Color { 255, 255, 255, 255 });
+                                                      white);
 
-        if (!surface)
-            return;
+        if (surface)
+        {
+            img.reset(Image::load(surface));
+            SDL_FreeSurface(surface);
+        }
+    }
 
-        img.reset(Image::load(surface));
+    if (img)
+    {
+        graphics->drawRescaledImageF(img.get(), 0, 0, x, y,
+                                     img->getWidth(),
+                                     img->getHeight(),
+                                     img->getWidth() / scale,
+                                     img->getHeight() / scale, true);
 
-        SDL_FreeSurface(surface);
     }
+}
 
-    std::unique_ptr<Image> img;
-    const std::string text;
-};
 
 std::list<TrueTypeFont*> TrueTypeFont::mFonts;
 float TrueTypeFont::mScale = 1.0f;
@@ -85,6 +111,7 @@ float TrueTypeFont::mScale = 1.0f;
 TrueTypeFont::TrueTypeFont(const std::string &filename, int size, int style)
     : mFilename(filename)
     , mPointSize(size)
+    , mStyle(style)
 {
     if (TTF_Init() == -1)
     {
@@ -93,14 +120,18 @@ TrueTypeFont::TrueTypeFont(const std::string &filename, int size, int style)
     }
 
     mFont = TTF_OpenFont(filename.c_str(), size * mScale);
+    mFontOutline = TTF_OpenFont(filename.c_str(), size * mScale);
 
-    if (!mFont)
+    if (!mFont || !mFontOutline)
     {
         throw GCN_EXCEPTION("SDLTrueTypeFont::SDLTrueTypeFont: " +
             std::string(TTF_GetError()));
     }
 
     TTF_SetFontStyle(mFont, style);
+    TTF_SetFontStyle(mFontOutline, style);
+
+    TTF_SetFontOutline(mFontOutline, static_cast<int>(mScale));
 
     mFonts.push_back(this);
 }
@@ -112,6 +143,9 @@ TrueTypeFont::~TrueTypeFont()
     if (mFont)
         TTF_CloseFont(mFont);
 
+    if (mFontOutline)
+        TTF_CloseFont(mFontOutline);
+
     TTF_Quit();
 }
 
@@ -123,37 +157,41 @@ void TrueTypeFont::drawString(gcn::Graphics *graphics,
         return;
 
     auto *g = static_cast<Graphics *>(graphics);
+    TextChunk &chunk = getChunk(text);
 
-    bool found = false;
+    chunk.render(g, x, y, mFont, chunk.regular, mScale);
+}
 
-    for (auto i = mCache.begin(); i != mCache.end(); ++i)
-    {
-        auto &chunk = *i;
-        if (chunk.text == text)
-        {
-            // Raise priority: move it to front
-            mCache.splice(mCache.begin(), mCache, i);
-            found = true;
-            break;
-        }
-    }
+void TrueTypeFont::drawString(Graphics *graphics,
+                              const std::string &text,
+                              int x, int y,
+                              const std::optional<gcn::Color> &outlineColor,
+                              const std::optional<gcn::Color> &shadowColor)
+{
+    if (text.empty())
+        return;
+
+    auto *g = static_cast<Graphics *>(graphics);
+    auto color = graphics->getColor();
+    TextChunk &chunk = getChunk(text);
 
-    if (!found)
+    if (shadowColor)
     {
-        if (mCache.size() >= CACHE_SIZE)
-            mCache.pop_back();
-        mCache.emplace_front(text);
-        mCache.front().generate(mFont);
+        g->setColor(*shadowColor);
+        if (outlineColor)
+            chunk.render(g, x, y, mFontOutline, chunk.outlined, mScale);
+        else
+            chunk.render(g, x + 1, y + 1, mFont, chunk.regular, mScale);
     }
 
-    if (auto img = mCache.front().img.get())
+    if (outlineColor)
     {
-        g->drawRescaledImageF(img, 0, 0, x, y,
-                              img->getWidth(),
-                              img->getHeight(),
-                              img->getWidth() / mScale,
-                              img->getHeight() / mScale, true);
+        g->setColor(*outlineColor);
+        chunk.render(g, x - 1, y - 1, mFontOutline, chunk.outlined, mScale);
     }
+
+    g->setColor(color);
+    chunk.render(g, x, y, mFont, chunk.regular, mScale);
 }
 
 void TrueTypeFont::updateFontScale(float scale)
@@ -167,9 +205,16 @@ void TrueTypeFont::updateFontScale(float scale)
     {
 #if SDL_TTF_VERSION_ATLEAST(2, 0, 18)
         TTF_SetFontSize(font->mFont, font->mPointSize * mScale);
+        TTF_SetFontSize(font->mFontOutline, font->mPointSize * mScale);
+        TTF_SetFontOutline(font->mFontOutline, mScale);
 #else
         TTF_CloseFont(font->mFont);
+        TTF_CloseFont(font->mFontOutline);
         font->mFont = TTF_OpenFont(font->mFilename.c_str(), font->mPointSize * mScale);
+        font->mFontOutline = TTF_OpenFont(font->mFilename.c_str(), font->mPointSize * mScale);
+        TTF_SetFontStyle(font->mFont, font->mStyle);
+        TTF_SetFontStyle(font->mFontOutline, font->mStyle);
+        TTF_SetFontOutline(font->mFontOutline, mScale);
 #endif
 
         font->mCache.clear();
@@ -178,19 +223,11 @@ void TrueTypeFont::updateFontScale(float scale)
 
 int TrueTypeFont::getWidth(const std::string &text) const
 {
-    for (auto i = mCache.begin(); i != mCache.end(); i++)
-    {
-        if (i->text == text)
-        {
-            // Raise priority: move it to front
-            // Assumption is that TTF::draw will be called next
-            mCache.splice(mCache.begin(), mCache, i);
-            if (i->img)
-                return std::ceil(i->img->getWidth() / mScale);
-            return 0;
-        }
-    }
+    TextChunk &chunk = getChunk(text);
+    if (auto img = chunk.regular.get())
+        return std::ceil(img->getWidth() / mScale);
 
+    // If the image wasn't created yet, just calculate the width of the text
     int w, h;
     TTF_SizeUTF8(mFont, getSafeUtf8String(text), &w, &h);
     return std::ceil(w / mScale);
@@ -205,3 +242,21 @@ int TrueTypeFont::getLineHeight() const
 {
     return std::ceil(TTF_FontLineSkip(mFont) / mScale);
 }
+
+TextChunk &TrueTypeFont::getChunk(const std::string &text) const
+{
+    for (auto i = mCache.begin(); i != mCache.end(); i++)
+    {
+        if (i->text == text)
+        {
+            // Raise priority: move it to front
+            mCache.splice(mCache.begin(), mCache, i);
+            return *i;
+        }
+    }
+
+    if (mCache.size() >= CACHE_SIZE)
+        mCache.pop_back();
+
+    return mCache.emplace_front(text);
+}
diff --git a/src/gui/truetypefont.h b/src/gui/truetypefont.h
index a479537d..f88938ff 100644
--- a/src/gui/truetypefont.h
+++ b/src/gui/truetypefont.h
@@ -22,13 +22,16 @@
 
 #pragma once
 
+#include <guichan/color.hpp>
 #include <guichan/font.hpp>
 
 #include <SDL_ttf.h>
 
 #include <list>
+#include <optional>
 #include <string>
 
+class Graphics;
 class TextChunk;
 
 /**
@@ -46,11 +49,13 @@ class TrueTypeFont : public gcn::Font
          * @param size      Font size.
          */
         TrueTypeFont(const std::string &filename, int size, int style = 0);
-
         ~TrueTypeFont() override;
 
-        int getWidth(const std::string &text) const override;
+        const std::string &filename() const { return mFilename; }
+        int pointSize() const { return mPointSize; }
+        int style() const { return mStyle; }
 
+        int getWidth(const std::string &text) const override;
         int getHeight() const override;
 
         /**
@@ -67,13 +72,27 @@ class TrueTypeFont : public gcn::Font
                         const std::string &text,
                         int x, int y) override;
 
+        /**
+         * Extended version of drawString that allows for rendering text with
+         * outline and/or shadow.
+         */
+        void drawString(Graphics *graphics,
+                        const std::string &text,
+                        int x, int y,
+                        const std::optional<gcn::Color> &outlineColor,
+                        const std::optional<gcn::Color> &shadowColor);
+
         static void updateFontScale(float scale);
 
     private:
+        TextChunk &getChunk(const std::string &text) const;
+
         const std::string mFilename;
-        TTF_Font *mFont;
+        TTF_Font *mFont = nullptr;
+        TTF_Font *mFontOutline = nullptr;
 
         const int mPointSize;
+        const int mStyle;
 
         // Word surfaces cache
         mutable std::list<TextChunk> mCache;
diff --git a/src/gui/widgets/browserbox.cpp b/src/gui/widgets/browserbox.cpp
index 1deea30b..bf337a0f 100644
--- a/src/gui/widgets/browserbox.cpp
+++ b/src/gui/widgets/browserbox.cpp
@@ -23,7 +23,6 @@
 #include "gui/widgets/browserbox.h"
 
 #include "keyboardconfig.h"
-#include "textrenderer.h"
 
 #include "gui/gui.h"
 #include "gui/truetypefont.h"
@@ -292,6 +291,8 @@ void BrowserBox::draw(gcn::Graphics *graphics)
         }
     }
 
+    auto g = static_cast<Graphics*>(graphics);
+
     for (const auto &row : mTextRows)
     {
         for (const auto &part : row.parts)
@@ -301,16 +302,15 @@ void BrowserBox::draw(gcn::Graphics *graphics)
             if (part.y > yEnd)
                 return;
 
-            TextRenderer::renderText(graphics,
-                                     part.text,
-                                     part.x,
-                                     part.y,
-                                     Graphics::LEFT,
-                                     part.color,
-                                     part.font,
-                                     part.outlineColor.has_value() || mOutline,
-                                     mShadows,
-                                     part.outlineColor);
+            g->drawText(part.text,
+                        part.x,
+                        part.y,
+                        Graphics::LEFT,
+                        part.color,
+                        part.font,
+                        part.outlineColor.has_value() || mOutline,
+                        mShadows,
+                        part.outlineColor);
         }
     }
 }
diff --git a/src/gui/widgets/button.cpp b/src/gui/widgets/button.cpp
index 31c3a677..604f5dc8 100644
--- a/src/gui/widgets/button.cpp
+++ b/src/gui/widgets/button.cpp
@@ -28,7 +28,6 @@
 
 #include "resources/image.h"
 #include "resources/theme.h"
-#include "textrenderer.h"
 
 #include <guichan/exception.hpp>
 #include <guichan/font.hpp>
@@ -132,8 +131,9 @@ void Button::draw(gcn::Graphics *graphics)
     if (isPressed())
         widgetState.flags |= STATE_SELECTED;
 
+    auto g = static_cast<Graphics *>(graphics);
     auto &skin = gui->getTheme()->getSkin(SkinType::Button);
-    skin.draw(static_cast<Graphics *>(graphics), widgetState);
+    skin.draw(g, widgetState);
 
     auto skinState = skin.getState(widgetState.flags);
     auto font = (skinState && skinState->textFormat.bold) ? boldFont : getFont();
@@ -196,18 +196,16 @@ void Button::draw(gcn::Graphics *graphics)
     }
 
     if (btnIconWidth)
-        static_cast<Graphics *>(graphics)->drawImage(icon, btnIconX, btnIconY);
+        g->drawImage(icon, btnIconX, btnIconY);
 
     if (auto skinState = skin.getState(widgetState.flags))
     {
-        auto &textFormat = skinState->textFormat;
-        TextRenderer::renderText(static_cast<Graphics *>(graphics),
-                                 getCaption(),
-                                 textX,
-                                 textY,
-                                 getAlignment(),
-                                 font,
-                                 textFormat);
+        g->drawText(getCaption(),
+                    textX,
+                    textY,
+                    getAlignment(),
+                    font,
+                    skinState->textFormat);
     }
 }
 
diff --git a/src/gui/widgets/checkbox.cpp b/src/gui/widgets/checkbox.cpp
index e6079f2f..4bb0bb72 100644
--- a/src/gui/widgets/checkbox.cpp
+++ b/src/gui/widgets/checkbox.cpp
@@ -21,8 +21,6 @@
 
 #include "gui/widgets/checkbox.h"
 
-#include "textrenderer.h"
-
 #include "gui/gui.h"
 #include "resources/theme.h"
 
@@ -44,19 +42,19 @@ void CheckBox::draw(gcn::Graphics* graphics)
     if (isSelected())
         widgetState.flags |= STATE_SELECTED;
 
+    auto g = static_cast<Graphics *>(graphics);
     auto &skin = gui->getTheme()->getSkin(SkinType::CheckBox);
-    skin.draw(static_cast<Graphics *>(graphics), widgetState);
+    skin.draw(g, widgetState);
 
     if (auto skinState = skin.getState(widgetState.flags))
     {
         auto &textFormat = skinState->textFormat;
-        TextRenderer::renderText(static_cast<Graphics *>(graphics),
-                                 getCaption(),
-                                 skin.getMinWidth() + skin.padding + skin.spacing,
-                                 skin.padding,
-                                 Graphics::LEFT,
-                                 textFormat.bold ? boldFont : getFont(),
-                                 textFormat);
+        g->drawText(getCaption(),
+                    skin.getMinWidth() + skin.padding + skin.spacing,
+                    skin.padding,
+                    Graphics::LEFT,
+                    textFormat.bold ? boldFont : getFont(),
+                    textFormat);
     }
 }
 
diff --git a/src/gui/widgets/label.cpp b/src/gui/widgets/label.cpp
index a2ed8820..9c0fd3cd 100644
--- a/src/gui/widgets/label.cpp
+++ b/src/gui/widgets/label.cpp
@@ -21,8 +21,6 @@
 
 #include "gui/widgets/label.h"
 
-#include "textrenderer.h"
-
 #include "resources/theme.h"
 
 #include <guichan/exception.hpp>
@@ -59,15 +57,15 @@ void Label::draw(gcn::Graphics *graphics)
         throw GCN_EXCEPTION("Unknown alignment.");
     }
 
-    TextRenderer::renderText(static_cast<Graphics *>(graphics),
-                             getCaption(),
-                             textX,
-                             textY,
-                             getAlignment(),
-                             getForegroundColor(),
-                             getFont(),
-                             mOutlineColor.has_value(),
-                             mShadowColor.has_value(),
-                             mOutlineColor,
-                             mShadowColor);
+    auto g = static_cast<Graphics *>(graphics);
+    g->drawText(getCaption(),
+                textX,
+                textY,
+                getAlignment(),
+                getForegroundColor(),
+                getFont(),
+                mOutlineColor.has_value(),
+                mShadowColor.has_value(),
+                mOutlineColor,
+                mShadowColor);
 }
diff --git a/src/gui/widgets/radiobutton.cpp b/src/gui/widgets/radiobutton.cpp
index ceba78eb..3474bbd8 100644
--- a/src/gui/widgets/radiobutton.cpp
+++ b/src/gui/widgets/radiobutton.cpp
@@ -21,11 +21,11 @@
 
 #include "gui/widgets/radiobutton.h"
 
-#include "textrenderer.h"
-
 #include "gui/gui.h"
 #include "resources/theme.h"
 
+#include <guichan/font.hpp>
+
 RadioButton::RadioButton(const std::string &caption,
                          const std::string &group,
                          bool marked)
@@ -44,19 +44,19 @@ void RadioButton::draw(gcn::Graphics* graphics)
     if (isSelected())
         widgetState.flags |= STATE_SELECTED;
 
+    auto g = static_cast<Graphics *>(graphics);
     auto &skin = gui->getTheme()->getSkin(SkinType::RadioButton);
-    skin.draw(static_cast<Graphics *>(graphics), widgetState);
+    skin.draw(g, widgetState);
 
     if (auto skinState = skin.getState(widgetState.flags))
     {
         auto &textFormat = skinState->textFormat;
-        TextRenderer::renderText(static_cast<Graphics *>(graphics),
-                                 getCaption(),
-                                 skin.getMinWidth() + skin.padding + skin.spacing,
-                                 skin.padding,
-                                 Graphics::LEFT,
-                                 textFormat.bold ? boldFont : getFont(),
-                                 textFormat);
+        g->drawText(getCaption(),
+                    skin.getMinWidth() + skin.padding + skin.spacing,
+                    skin.padding,
+                    Graphics::LEFT,
+                    textFormat.bold ? boldFont : getFont(),
+                    textFormat);
     }
 }
 
diff --git a/src/gui/widgets/textbox.cpp b/src/gui/widgets/textbox.cpp
index 6cc514fe..7fd7d626 100644
--- a/src/gui/widgets/textbox.cpp
+++ b/src/gui/widgets/textbox.cpp
@@ -23,7 +23,6 @@
 
 #include "gui/gui.h"
 #include "resources/theme.h"
-#include "textrenderer.h"
 
 #include <guichan/font.hpp>
 
@@ -96,7 +95,7 @@ void TextBox::setTextWrapped(const std::string &text, int minDimension)
                 xpos = width;
                 wrappedStream << word;
             }
-            else if (xpos != 0 && xpos + getFont()->getWidth(" ") + width <= 
+            else if (xpos != 0 && xpos + getFont()->getWidth(" ") + width <=
                      mMinWidth)
             {
                 xpos += getFont()->getWidth(" ") + width;
@@ -176,18 +175,19 @@ void TextBox::draw(gcn::Graphics *graphics)
     graphics->setColor(*mTextColor);
     graphics->setFont(getFont());
 
+    auto g = static_cast<Graphics*>(graphics);
+
     for (i = 0; i < mTextRows.size(); i++)
     {
         // Move the text one pixel so we can have a caret before a letter.
-        TextRenderer::renderText(graphics,
-                                 mTextRows[i],
-                                 1,
-                                 i * getFont()->getHeight(),
-                                 gcn::Graphics::LEFT,
-                                 *mTextColor,
-                                 getFont(),
-                                 mOutlineColor.has_value(),
-                                 false,
-                                 mOutlineColor);
+        g->drawText(mTextRows[i],
+                    1,
+                    i * getFont()->getHeight(),
+                    gcn::Graphics::LEFT,
+                    *mTextColor,
+                    getFont(),
+                    mOutlineColor.has_value(),
+                    false,
+                    mOutlineColor);
     }
 }
diff --git a/src/gui/widgets/textpreview.cpp b/src/gui/widgets/textpreview.cpp
index 2f80bd23..aed04853 100644
--- a/src/gui/widgets/textpreview.cpp
+++ b/src/gui/widgets/textpreview.cpp
@@ -21,13 +21,7 @@
 
 #include "gui/widgets/textpreview.h"
 
-#include "configuration.h"
-#include "textrenderer.h"
-
 #include "gui/gui.h"
-#include "gui/truetypefont.h"
-
-#include <typeinfo>
 
 TextPreview::TextPreview(const std::string &text)
     : mText(text)
@@ -36,12 +30,13 @@ TextPreview::TextPreview(const std::string &text)
     mTextColor = &Theme::getThemeColor(Theme::TEXT);
 }
 
-void TextPreview::draw(gcn::Graphics* graphics)
+void TextPreview::draw(gcn::Graphics *graphics)
 {
-    TextRenderer::renderText(graphics, mText, 2, 2,  gcn::Graphics::LEFT,
-                             gcn::Color(mTextColor->r,
-                                        mTextColor->g,
-                                        mTextColor->b,
-                                        255),
-                             mFont, mOutline, mShadow);
+    auto g = static_cast<Graphics*>(graphics);
+    g->drawText(mText, 2, 2, gcn::Graphics::LEFT,
+                gcn::Color(mTextColor->r,
+                           mTextColor->g,
+                           mTextColor->b,
+                           255),
+                mFont, mOutline, mShadow);
 }
diff --git a/src/gui/widgets/window.cpp b/src/gui/widgets/window.cpp
index bf496bd8..14d91af1 100644
--- a/src/gui/widgets/window.cpp
+++ b/src/gui/widgets/window.cpp
@@ -23,7 +23,6 @@
 
 #include "configuration.h"
 #include "log.h"
-#include "textrenderer.h"
 
 #include "gui/gui.h"
 #include "gui/viewport.h"
@@ -139,13 +138,12 @@ void Window::drawFrame(gcn::Graphics *graphics)
         if (auto skinState = skin.getState(widgetState.flags))
         {
             auto &textFormat = skinState->textFormat;
-            TextRenderer::renderText(g,
-                                     getCaption(),
-                                     getFrameSize() + skin.titleOffsetX,
-                                     getFrameSize() + skin.titleOffsetY,
-                                     gcn::Graphics::LEFT,
-                                     textFormat.bold ? boldFont : getFont(),
-                                     textFormat);
+            g->drawText(getCaption(),
+                        getFrameSize() + skin.titleOffsetX,
+                        getFrameSize() + skin.titleOffsetY,
+                        gcn::Graphics::LEFT,
+                        textFormat.bold ? boldFont : getFont(),
+                        textFormat);
         }
     }
 }