feat(api): make FreeType a toggleable option which is disabled by default (#254)

* deps(build): bump FreeType from 2.12.1 to 2.13.3

* fix(generator): add missing ImGuiFreeTypeBuilderFlags

* feat(generator): add possibility to provide additional defines specifically for AST

* feat(api): make FreeType optional and disabled by default

FreeType renderer is still included in the final build.
Its usage is toggleable and DISABLED by default.

buildSrc/src/main/groovy/tool/generator/GenerateLibs.groovy

@@ -85,7 +85,15 @@ class GenerateLibs extends DefaultTask {
                 spec.from(project.rootProject.file('include/imgui/misc/freetype')) { CopySpec it -> it.include('*.h', '*.cpp') }
                 spec.into("$jniDir/misc/freetype")
             }
-            enableDefine('IMGUI_ENABLE_FREETYPE')
+
+            // Since we give a possibility to build library without enabled freetype - define should be set like that.
+            replaceSourceFileContent("imconfig.h", "//#define IMGUI_ENABLE_FREETYPE", "#define IMGUI_ENABLE_FREETYPE")
+
+            // Binding specific behavior to handle FreeType.
+            // By defining IMGUI_ENABLE_FREETYPE, Dear ImGui will default to using the FreeType font renderer.
+            // However, we modify the source code to ensure that, even with this, the STB_TrueType renderer is used instead.
+            // To use the FreeType font renderer, it must be explicitly forced on the atlas manually.
+            replaceSourceFileContent("imgui_draw.cpp", "ImGuiFreeType::GetBuilderForFreeType()", "ImFontAtlasGetBuilderForStbTruetype()")
         }
 
         // Copy dirent for ImGuiFileDialog
@@ -181,7 +189,13 @@ class GenerateLibs extends DefaultTask {
         target.libraries += ' -lfreetype'
     }
 
-    void enableDefine(String define) {
-        new File("$jniDir/imconfig.h").text += "#define $define"
+    void replaceSourceFileContent(String fileName, String replaceWhat, String replaceWith) {
+        def sourceFile = new File("$jniDir/$fileName")
+        def sourceTxt = sourceFile.text
+        def sourceTxtModified = sourceTxt.replace(replaceWhat, replaceWith)
+        if (sourceTxt == sourceTxtModified) {
+            throw new IllegalStateException("Unable to replace [$fileName] with content [$replaceWith]!")
+        }
+        sourceFile.text = sourceTxtModified
     }
 }

buildSrc/src/main/kotlin/tool/generator/ast/task/GenerateAst.kt

@@ -6,6 +6,7 @@ import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.SerializationFeature
 import com.lordcodes.turtle.shellRun
 import org.gradle.api.DefaultTask
+import org.gradle.api.tasks.Input
 import org.gradle.api.tasks.InputFiles
 import org.gradle.api.tasks.Internal
 import org.gradle.api.tasks.TaskAction
@@ -23,6 +24,8 @@ open class GenerateAst : DefaultTask() {
 
     @InputFiles
     lateinit var headerFiles: Collection<File>
+    @Input
+    var defines: Set<String> = emptySet()
 
     private val dstDir: File = File("${project.rootDir}/buildSrc/src/main/resources/${AstParser.RESOURCE_PATH}")
     private val objectMapper: ObjectMapper = ObjectMapper()
@@ -403,9 +406,21 @@ open class GenerateAst : DefaultTask() {
     }
 
     private fun callClangAstBump(scriptPath: String, srcHeader: File, dstJson: File) {
+        fun buildCommand(): List<String> {
+            val command = mutableListOf(
+                scriptPath,
+                srcHeader.absolutePath,
+                dstJson.absolutePath,
+            )
+            if (defines.isNotEmpty()) {
+                command += defines.map { "-D$it" }
+            }
+            return command
+        }
+
         dstJson.delete()
         val pb = ProcessBuilder()
-        pb.command(scriptPath, srcHeader.absolutePath, dstJson.absolutePath)
+        pb.command(buildCommand())
         pb.start().waitFor()
     }
 

buildSrc/src/main/resources/generator/api/ast/_gen_ast.sh

@@ -4,4 +4,22 @@
 # Java ProcessBuilder doesn't see command properly.
 # Also, running like that helps to ignore local clang++ warnings which can happen.
 
-clang++ -Xclang -ast-dump=json -fsyntax-only -fparse-all-comments -fmerge-all-constants "$1" >> "$2"
+# Assign the first argument to 'input_file' (the C++ file to analyze).
+input_file="$1"
+
+# Assign the second argument to 'output_file' (where to save the AST JSON).
+output_file="$2"
+
+# 'shift 2' shifts the positional parameters to the left by two positions.
+# This means "$@" will now contain any additional arguments (like macro definitions).
+shift 2
+
+# Run clang++ with the specified options.
+# -Xclang -ast-dump=json: Dumps the AST in JSON format.
+# -fsyntax-only: Only checks the syntax, does not compile.
+# -fparse-all-comments: Includes comments in the AST.
+# -fmerge-all-constants: Merges identical constants.
+# "$@" passes any additional arguments (like -D for macro definitions).
+# "$input_file" is the C++ source file to process.
+# The output is redirected and appended to the specified output file.
+clang++ -Xclang -ast-dump=json -fsyntax-only -fparse-all-comments -fmerge-all-constants "$@" "$input_file" >> "$output_file"

buildSrc/src/main/resources/generator/api/ast/ast-imgui_freetype.json

@@ -0,0 +1,186 @@
+{
+  "info" : {
+    "source" : "include/imgui/misc/freetype/imgui_freetype.h",
+    "hash" : "5976473c3ad2fbe2f0386eaa9019d4e0",
+    "url" : "https://github.com/ocornut/imgui",
+    "revision" : "1ee252772ae9c0a971d06257bb5c89f628fa696a"
+  },
+  "decls" : [ {
+    "@type" : "AstRecordDecl",
+    "name" : "ImFontAtlas",
+    "decls" : [ {
+      "@type" : "AstFullComment",
+      "decls" : [ {
+        "@type" : "AstParagraphComment",
+        "decls" : [ {
+          "@type" : "AstTextComment",
+          "text" : " Forward declarations"
+        } ]
+      } ]
+    } ]
+  }, {
+    "@type" : "AstEnumDecl",
+    "name" : "ImGuiFreeTypeBuilderFlags",
+    "decls" : [ {
+      "@type" : "AstFullComment",
+      "decls" : [ {
+        "@type" : "AstParagraphComment",
+        "decls" : [ {
+          "@type" : "AstTextComment",
+          "text" : " Hinting greatly impacts visuals (and glyph sizes)."
+        }, {
+          "@type" : "AstTextComment",
+          "text" : " - By default, hinting is enabled and the font's native hinter is preferred over the auto-hinter."
+        }, {
+          "@type" : "AstTextComment",
+          "text" : " - When disabled, FreeType generates blurrier glyphs, more or less matches the stb_truetype.h"
+        }, {
+          "@type" : "AstTextComment",
+          "text" : " - The Default hinting mode usually looks good, but may distort glyphs in an unusual way."
+        }, {
+          "@type" : "AstTextComment",
+          "text" : " - The Light hinting mode generates fuzzier glyphs but better matches Microsoft's rasterizer."
+        }, {
+          "@type" : "AstTextComment",
+          "text" : " You can set those flags globaly in ImFontAtlas::FontBuilderFlags"
+        }, {
+          "@type" : "AstTextComment",
+          "text" : " You can set those flags on a per font basis in ImFontConfig::FontBuilderFlags"
+        } ]
+      } ]
+    }, {
+      "@type" : "AstEnumConstantDecl",
+      "name" : "ImGuiFreeTypeBuilderFlags_NoHinting",
+      "docComment" : "Disable hinting. This generally generates 'blurrier' bitmap glyphs when the glyph are rendered in any of the anti-aliased modes.",
+      "qualType" : "ImGuiFreeTypeBuilderFlags",
+      "order" : 0,
+      "value" : "1 << 0",
+      "evaluatedValue" : 1
+    }, {
+      "@type" : "AstEnumConstantDecl",
+      "name" : "ImGuiFreeTypeBuilderFlags_NoAutoHint",
+      "docComment" : "Disable auto-hinter.",
+      "qualType" : "ImGuiFreeTypeBuilderFlags",
+      "order" : 1,
+      "value" : "1 << 1",
+      "evaluatedValue" : 2
+    }, {
+      "@type" : "AstEnumConstantDecl",
+      "name" : "ImGuiFreeTypeBuilderFlags_ForceAutoHint",
+      "docComment" : "Indicates that the auto-hinter is preferred over the font's native hinter.",
+      "qualType" : "ImGuiFreeTypeBuilderFlags",
+      "order" : 2,
+      "value" : "1 << 2",
+      "evaluatedValue" : 4
+    }, {
+      "@type" : "AstEnumConstantDecl",
+      "name" : "ImGuiFreeTypeBuilderFlags_LightHinting",
+      "docComment" : "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.",
+      "qualType" : "ImGuiFreeTypeBuilderFlags",
+      "order" : 3,
+      "value" : "1 << 3",
+      "evaluatedValue" : 8
+    }, {
+      "@type" : "AstEnumConstantDecl",
+      "name" : "ImGuiFreeTypeBuilderFlags_MonoHinting",
+      "docComment" : "Strong hinting algorithm that should only be used for monochrome output.",
+      "qualType" : "ImGuiFreeTypeBuilderFlags",
+      "order" : 4,
+      "value" : "1 << 4",
+      "evaluatedValue" : 16
+    }, {
+      "@type" : "AstEnumConstantDecl",
+      "name" : "ImGuiFreeTypeBuilderFlags_Bold",
+      "docComment" : "Styling: Should we artificially embolden the font?",
+      "qualType" : "ImGuiFreeTypeBuilderFlags",
+      "order" : 5,
+      "value" : "1 << 5",
+      "evaluatedValue" : 32
+    }, {
+      "@type" : "AstEnumConstantDecl",
+      "name" : "ImGuiFreeTypeBuilderFlags_Oblique",
+      "docComment" : "Styling: Should we slant the font, emulating italic style?",
+      "qualType" : "ImGuiFreeTypeBuilderFlags",
+      "order" : 6,
+      "value" : "1 << 6",
+      "evaluatedValue" : 64
+    }, {
+      "@type" : "AstEnumConstantDecl",
+      "name" : "ImGuiFreeTypeBuilderFlags_Monochrome",
+      "docComment" : "Disable anti-aliasing. Combine this with MonoHinting for best results!",
+      "qualType" : "ImGuiFreeTypeBuilderFlags",
+      "order" : 7,
+      "value" : "1 << 7",
+      "evaluatedValue" : 128
+    }, {
+      "@type" : "AstEnumConstantDecl",
+      "name" : "ImGuiFreeTypeBuilderFlags_LoadColor",
+      "docComment" : "Enable FreeType color-layered glyphs",
+      "qualType" : "ImGuiFreeTypeBuilderFlags",
+      "order" : 8,
+      "value" : "1 << 8",
+      "evaluatedValue" : 256
+    }, {
+      "@type" : "AstEnumConstantDecl",
+      "name" : "ImGuiFreeTypeBuilderFlags_Bitmap",
+      "docComment" : "Enable FreeType bitmap glyphs",
+      "qualType" : "ImGuiFreeTypeBuilderFlags",
+      "order" : 9,
+      "value" : "1 << 9",
+      "evaluatedValue" : 512
+    } ]
+  }, {
+    "@type" : "AstNamespaceDecl",
+    "name" : "ImGuiFreeType",
+    "decls" : [ {
+      "@type" : "AstFunctionDecl",
+      "name" : "SetAllocatorFunctions",
+      "resultType" : "int",
+      "decls" : [ {
+        "@type" : "AstParmVarDecl",
+        "name" : "alloc_func",
+        "qualType" : "void *(*)(int, void *)",
+        "desugaredQualType" : "void *(*)(int, void *)"
+      }, {
+        "@type" : "AstParmVarDecl",
+        "name" : "free_func",
+        "qualType" : "void (*)(void *, void *)",
+        "desugaredQualType" : "void (*)(void *, void *)"
+      }, {
+        "@type" : "AstParmVarDecl",
+        "name" : "user_data",
+        "qualType" : "void *",
+        "desugaredQualType" : "void *",
+        "defaultValue" : "="
+      }, {
+        "@type" : "AstFullComment",
+        "decls" : [ {
+          "@type" : "AstParagraphComment",
+          "decls" : [ {
+            "@type" : "AstTextComment",
+            "text" : " Override allocators. By default ImGuiFreeType will use IM_ALLOC()/IM_FREE()"
+          }, {
+            "@type" : "AstTextComment",
+            "text" : " However, as FreeType does lots of allocations we provide a way for the user to redirect it to a separate memory heap if desired."
+          } ]
+        } ]
+      } ]
+    }, {
+      "@type" : "AstFunctionDecl",
+      "name" : "BuildFontAtlas",
+      "resultType" : "bool",
+      "decls" : [ {
+        "@type" : "AstParmVarDecl",
+        "name" : "atlas",
+        "qualType" : "ImFontAtlas *",
+        "desugaredQualType" : "ImFontAtlas *"
+      }, {
+        "@type" : "AstParmVarDecl",
+        "name" : "flags",
+        "qualType" : "unsigned int",
+        "desugaredQualType" : "unsigned int",
+        "defaultValue" : "0"
+      } ]
+    } ]
+  } ]
+}