imgui_freetype: Documentation, tweaks. (#618)

misc/fonts/README.txt

@@ -120,9 +120,7 @@ In this document:
 
  Dear Imgui uses stb_truetype.h to rasterize fonts (with optional oversampling).
  This technique and implementation are not ideal for fonts rendered at _small sizes_, which may appear a little blurry.
- There is an implementation of the ImFontAtlas builder using FreeType that you can use:
-
-   https://github.com/ocornut/imgui_club
+ There is an implementation of the ImFontAtlas builder using FreeType that you can use in the misc/freetype/ folder.
 
  FreeType supports auto-hinting which tends to improve the readability of small fonts.
  Note that this code currently creates textures that are unoptimally too large (could be fixed with some work)

misc/freetype/README.md

@@ -0,0 +1,126 @@
+# imgui_freetype
+
+This is an attempt to replace stb_truetype (the default imgui's font rasterizer) with FreeType. 
+Currently not optimal and probably has some limitations or bugs.
+By [Vuhdo](https://github.com/Vuhdo) (Aleksei Skriabin). Improvements by @mikesart. Maintained by @ocornut.
+
+**Usage**
+1. Get latest FreeType binaries or build yourself.
+2. Add imgui_freetype.h/cpp alongside your imgui sources.
+3. Include imgui_freetype.h after imgui.h.
+4. Call ImGuiFreeType::BuildFontAtlas() *BEFORE* calling ImFontAtlas::GetTexDataAsRGBA32() or ImFontAtlas::Build() (so normal Build() won't be called):
+
+```cpp
+// See ImGuiFreeType::RasterizationFlags
+unsigned int flags = ImGuiFreeType::DisableHinting;
+ImGuiFreeType::BuildFontAtlas(io.Fonts, flags);
+io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);
+```
+
+**Test code Usage**
+```cpp
+#include "misc/freetype/imgui_freetype.h"
+#include "misc/freetype/imgui_freetype.cpp"
+
+// Load various small fonts
+ImGuiIO& io = ImGui::GetIO();
+io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 13.0f);
+io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 13.0f);
+io.Fonts->AddFontDefault();
+
+FreeTypeTest freetype_test;
+
+// Main Loop
+while (true)
+{
+   if (freetype_test.UpdateRebuild())
+   {
+      // REUPLOAD FONT TEXTURE TO GPU
+      // e.g ImGui_ImplGlfwGL3_InvalidateDeviceObjects() + ImGui_ImplGlfwGL3_CreateDeviceObjects()
+   }
+   ImGui::NewFrame();
+   freetype_test.ShowFreetypeOptionsWindow();
+   ...
+   }
+}
+```
+
+**Test code**
+```cpp
+#include "misc/freetype/imgui_freetype.h"
+#include "misc/freetype/imgui_freetype.cpp"
+
+struct FreeTypeTest
+{
+    enum FontBuildMode
+    {
+        FontBuildMode_FreeType,
+        FontBuildMode_Stb,
+    };
+
+    FontBuildMode BuildMode;
+    bool          WantRebuild;
+    float         FontsMultiply;
+    unsigned int  FontsFlags;
+
+    FreeTypeTest()
+    {
+        BuildMode = FontBuildMode_FreeType;
+        WantRebuild = true;
+        FontsMultiply = 1.0f;
+        FontsFlags = 0;
+    }
+
+    // Call _BEFORE_ NewFrame()
+    bool UpdateRebuild()
+    {
+        if (!WantRebuild)
+            return false;
+        ImGuiIO& io = ImGui::GetIO();
+        for (int n = 0; n < io.Fonts->Fonts.Size; n++)
+        {
+            io.Fonts->Fonts[n]->ConfigData->RasterizerMultiply = FontsMultiply;
+            io.Fonts->Fonts[n]->ConfigData->RasterizerFlags = (BuildMode == FontBuildMode_FreeType) ? FontsFlags : 0x00;
+        }
+        if (BuildMode == FontBuildMode_FreeType)
+            ImGuiFreeType::BuildFontAtlas(io.Fonts, FontsFlags);
+        else if (BuildMode == FontBuildMode_Stb)
+            io.Fonts->Build();
+        WantRebuild = false;
+        return true;
+    }
+
+    // Call to draw interface
+    void ShowFreetypeOptionsWindow()
+    {
+        ImGui::Begin("FreeType Options");
+        ImGui::ShowFontSelector("Fonts");
+        WantRebuild |= ImGui::RadioButton("FreeType", (int*)&BuildMode, FontBuildMode_FreeType);
+        ImGui::SameLine();
+        WantRebuild |= ImGui::RadioButton("Stb (Default)", (int*)&BuildMode, FontBuildMode_Stb);
+        WantRebuild |= ImGui::DragFloat("Multiply", &FontsMultiply, 0.001f, 0.0f, 2.0f);
+        if (BuildMode == FontBuildMode_FreeType)
+        {
+            WantRebuild |= ImGui::CheckboxFlags("NoHinting",     &FontsFlags, ImGuiFreeType::NoHinting);
+            WantRebuild |= ImGui::CheckboxFlags("NoAutoHint",    &FontsFlags, ImGuiFreeType::NoAutoHint);
+            WantRebuild |= ImGui::CheckboxFlags("ForceAutoHint", &FontsFlags, ImGuiFreeType::ForceAutoHint);
+            WantRebuild |= ImGui::CheckboxFlags("LightHinting",  &FontsFlags, ImGuiFreeType::LightHinting);
+            WantRebuild |= ImGui::CheckboxFlags("MonoHinting",   &FontsFlags, ImGuiFreeType::MonoHinting);
+            WantRebuild |= ImGui::CheckboxFlags("Bold",          &FontsFlags, ImGuiFreeType::Bold);
+            WantRebuild |= ImGui::CheckboxFlags("Oblique",       &FontsFlags, ImGuiFreeType::Oblique);
+        }
+        ImGui::End();
+    }
+};
+```
+
+**Known issues**
+- Output texture has excessive resolution (lots of vertical waste)
+- FreeType's memory allocator is not overridden.
+
+**Obligatory comparison screenshots**
+
+Using Windows built-in segoeui.ttf font. Open in new browser tabs, view at 1080p+.
+
+![freetype rasterizer](https://raw.githubusercontent.com/wiki/ocornut/imgui_club/images/freetype_20170817.png)
+

misc/freetype/imgui_freetype.cpp

@@ -1,16 +1,17 @@
 // Wrapper to use Freetype (instead of stb_truetype) for Dear ImGui
-// Get latest version at http://www.github.com/ocornut/imgui_club
-// Original code by @Vuhdo (Aleksei Skriabin)
+// Get latest version at https://github.com/ocornut/imgui/tree/master/misc/freetype
+// Original code by @Vuhdo (Aleksei Skriabin). Improvements by @mikesart. Maintained by @ocornut
 
 // Changelog:
-// - v0.50: (2017/08/16) imported from https://github.com/Vuhdo/imgui_freetype, updated for latest changes in ImFontAtlas, minor tweaks.
+// - v0.50: (2017/08/16) imported from https://github.com/Vuhdo/imgui_freetype into http://www.github.com/ocornut/imgui_club, updated for latest changes in ImFontAtlas, minor tweaks.
 // - v0.51: (2017/08/26) cleanup, optimizations, support for ImFontConfig::RasterizerFlags, ImFontConfig::RasterizerMultiply.
 // - v0.52: (2017/09/26) fixes for imgui internal changes
 // - v0.53: (2017/10/22) minor inconsequential change to match change in master (removed an unnecessary statement)
 // - v0.54: (2018/01/22) fix for addition of ImFontAtlas::TexUvscale member
+// - v0.55: (2018/02/04) moved to main imgui repository (away from http://www.github.com/ocornut/imgui_club)
 
-// Todo/Bugs:
-// - Font size has lots of waste.
+// TODO:
+// - Output texture has excessive resolution (lots of vertical waste)
 // - FreeType's memory allocator is not overridden.
 
 #include "imgui_freetype.h"

misc/freetype/imgui_freetype.h

@@ -1,6 +1,6 @@
 // Wrapper to use Freetype (instead of stb_truetype) for Dear ImGui
-// Original code by @Vuhdo
-// Get latest version at http://www.github.com/ocornut/imgui_club
+// Get latest version at https://github.com/ocornut/imgui/tree/master/misc/freetype
+// Original code by @Vuhdo (Aleksei Skriabin), maintained by @ocornut
 
 #pragma once
 
@@ -8,10 +8,10 @@
 
 namespace ImGuiFreeType
 {
-    //  Hinting greatly impacts visuals (and glyph sizes).
-    //  When disabled, FreeType generates blurrier glyphs, more or less matches the stb's output.
-    //  The Default hinting mode usually looks good, but may distort glyphs in an unusual way.
-    //  The Light hinting mode generates fuzzier glyphs but better matches Microsoft's rasterizer.
+    // Hinting greatly impacts visuals (and glyph sizes).
+    // When disabled, FreeType generates blurrier glyphs, more or less matches the stb's output.
+    // The Default hinting mode usually looks good, but may distort glyphs in an unusual way.
+    // The Light hinting mode generates fuzzier glyphs but better matches Microsoft's rasterizer.
     
     // You can set those flags on a per font basis in ImFontConfig::RasterizerFlags.
     // Use the 'extra_flags' parameter of BuildFontAtlas() to force a flag on all your fonts.
@@ -24,7 +24,7 @@ namespace ImGuiFreeType
         LightHinting    = 1 << 3,   // A lighter hinting algorithm for gray-level modes. Many generated glyphs are fuzzier but better resemble their original shape. This is achieved by snapping glyphs to the pixel grid only vertically (Y-axis), as is done by Microsoft's ClearType and Adobe's proprietary font renderer. This preserves inter-glyph spacing in horizontal text.
         MonoHinting     = 1 << 4,   // Strong hinting algorithm that should only be used for monochrome output.
         Bold            = 1 << 5,   // Styling: Should we artificially embolden the font?
-        Oblique         = 1 << 6,   // Styling: Should we slant the font, emulating italic style?
+        Oblique         = 1 << 6    // Styling: Should we slant the font, emulating italic style?
     };
 
     IMGUI_API bool BuildFontAtlas(ImFontAtlas* atlas, unsigned int extra_flags = 0);