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imgui_freetype: Documentation, tweaks. (#618)

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omar 2018-02-04 12:44:31 +01:00
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4 changed files with 140 additions and 15 deletions
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4
misc/fonts/README.txt
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@ -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)

126
misc/freetype/README.md Normal file
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@ -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)

11
misc/freetype/imgui_freetype.cpp
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@ -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"

14
misc/freetype/imgui_freetype.h
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@ -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);