Instance Management API

MinecraftInstance and PackProfile for managing Minecraft instances

MinecraftInstance

Concrete implementation of BaseInstance for Minecraft instances.

Class: MinecraftInstance
Header: launcher/minecraft/MinecraftInstance.h
Inherits: BaseInstance

Constructor

MinecraftInstance(
    SettingsObject* globalSettings,
    std::unique_ptr<SettingsObject> settings,
    const QString& rootDir
);

Directory Structure

gameRoot() · QString

Returns the Minecraft game directory (.minecraft).

binRoot() · QString

Returns the binary directory for Minecraft executables.

modsRoot() · QString

Returns the mods root directory.

jarModsDir() · QString

Returns the jar mods directory.

resourcePacksDir() · QString

Returns the resource packs directory.

texturePacksDir() · QString

Returns the texture packs directory.

shaderPacksDir() · QString

Returns the shader packs directory.

dataPacksDir() · QString

Returns the data packs directory.

worldDir() · QString

Returns the saves/worlds directory.

libDir() · QString

Returns the libraries directory.

resourcesDir() · QString

Returns the resources directory.

Path Helpers

QDir jarmodsPath() const;
QDir librariesPath() const;
QDir versionsPath() const;
QString instanceConfigFolder() const override;
QString getNativePath() const;
QString getLocalLibraryPath() const;

Resource Management

Access various resource folder models:

loaderModList() · ModFolderModel*

Returns the loader mods folder model.

coreModList() · ModFolderModel*

Returns the core mods folder model.

nilModList() · ModFolderModel*

Returns the nil mods folder model.

resourcePackList() · ResourcePackFolderModel*

Returns the resource packs folder model.

texturePackList() · TexturePackFolderModel*

Returns the texture packs folder model.

shaderPackList() · ShaderPackFolderModel*

Returns the shader packs folder model.

dataPackList() · DataPackFolderModel*

Returns the data packs folder model.

worldList() · WorldList*

Returns the worlds list.

resourceLists() · QList<ResourceFolderModel*>

Returns all resource folder models.

Profile Management

getPackProfile() · PackProfile*

Returns the component/version profile for this instance.

Launch Configuration

Create Tasks

QList<Task::Ptr> createUpdateTask() override;

Creates update tasks for the instance (downloads libraries, assets, etc.).

LaunchTask* createLaunchTask(
    AuthSessionPtr account,
    MinecraftTarget::Ptr targetToJoin
) override;

Creates a launch task for starting the game.

Arguments

QStringList extraArguments() override;
QStringList javaArguments();

Returns additional JVM and game arguments.

QStringList processMinecraftArgs(
    AuthSessionPtr account,
    MinecraftTarget::Ptr targetToJoin
) const;

Processes Minecraft arguments with variable substitution.

Environment

QProcessEnvironment createEnvironment() override;
QProcessEnvironment createLaunchEnvironment() override;

Creates environment variables for launching processes.

QMap<QString, QString> getVariables() override;

Returns variables for launch command substitution.

Java Configuration

getJavaVersion() · JavaVersion

Returns the Java version required by this instance.

QStringList getClassPath();
QStringList getNativeJars();
QString getMainClass() const;

Utility Methods

supportsDemo() · bool

Returns true if the instance supports Minecraft demo mode.

getJarMods() · QList<Mod*>

Returns list of jar mods in the instance.

getLauncher() · QString

Returns the launcher type/wrapper to use.

shouldApplyOnlineFixes() · bool

Returns true if online fixes should be applied.

Example Usage

#include "minecraft/MinecraftInstance.h"
#include "Application.h"

// Get a Minecraft instance
BaseInstance* base = APPLICATION->instances()->getInstanceById("my_instance");
MinecraftInstance* inst = dynamic_cast<MinecraftInstance*>(base);

if (inst) {
    // Access resource lists
    ModFolderModel* mods = inst->loaderModList();
    qDebug() << "Mods:" << mods->size();
    
    // Get directories
    qDebug() << "Mods dir:" << inst->modsRoot();
    qDebug() << "World dir:" << inst->worldDir();
    qDebug() << "Resource packs:" << inst->resourcePacksDir();
    
    // Work with pack profile
    PackProfile* profile = inst->getPackProfile();
    qDebug() << "Minecraft version:" << profile->getComponentVersion("net.minecraft");
    
    // Create launch task
    AuthSessionPtr session = /* get account session */;
    LaunchTask* task = inst->createLaunchTask(session, nullptr);
    connect(task, &Task::finished, [task]() {
        qDebug() << "Launch task finished";
    });
    task->start();
}

---

PackProfile

Manages the component profile for a Minecraft instance (versions, mods, loaders).

Class: PackProfile
Header: launcher/minecraft/PackProfile.h
Inherits: QAbstractListModel

Constructor

explicit PackProfile(MinecraftInstance* instance);

Component Management

getComponent(const QString& id) · ComponentPtr

Returns a component by its unique ID (e.g., “net.minecraft”, “net.fabricmc.fabric-loader”).

getComponent(size_t index) · ComponentPtr

Returns a component by its index in the profile.

appendComponent(ComponentPtr component) · void

Adds a component to the profile.

Version Management

getComponentVersion(const QString& uid) · QString

Returns the version string for a component.

setComponentVersion(const QString& uid, const QString& version, bool important) · bool

Sets the version for a component. Returns true on success.

void setOldConfigVersion(const QString& uid, const QString& version);

Sets legacy version mapping from instance config.

Installation

Jar Mods

void installJarMods(QStringList selectedFiles);

Installs jar mods to the instance.

void installCustomJar(QString selectedFile);

Installs a custom jar as the main game jar.

Components

bool installComponents(QStringList selectedFiles);

Installs Prism/MultiMC component files.

bool installEmpty(const QString& uid, const QString& name);

Creates an empty component with the given UID.

Agents

void installAgents(QStringList selectedFiles);

Installs Java agent files to the instance.

Component Operations

enum MoveDirection { MoveUp, MoveDown };

move(int index, MoveDirection direction) · void

Moves a component up or down in the load order.

remove(int index) · bool

Removes a component by index. Returns true on success.

remove(const QString& id) · bool

Removes a component by ID. Returns true on success.

customize(int index) · bool

Customizes a component (creates editable patch). Returns true on success.

revertToBase(int index) · bool

Reverts a customized component to its base version. Returns true on success.

Profile Operations

Show Result Type

struct Result {
    bool success;
    QString error;
    
    operator bool() const { return success; }
    
    static Result Success() { return { true, "" }; }
    static Result Error(const QString& errorMessage) { return { false, errorMessage }; }
};

reload(Net::Mode netmode) · Result

Reloads the component list and resolves dependencies.

resolve(Net::Mode netmode) · void

Resolves component dependencies without reloading.

saveNow() · void

Saves the profile immediately (normally saves are scheduled).

Launch Profile

getProfile() · std::shared_ptr<LaunchProfile>

Returns the computed launch profile after resolving all components.

invalidateLaunchProfile() · void

Marks the launch profile as invalid, requiring recomputation.

Mod Loader Detection

getModLoaders() · std::optional<ModPlatform::ModLoaderTypes>

Returns the active mod loader types (Forge, Fabric, Quilt, NeoForge).

getSupportedModLoaders() · std::optional<ModPlatform::ModLoaderTypes>

Returns supported mod loaders including compatible ones (e.g., Quilt supports Fabric).

getModLoadersList() · QList<ModPlatform::ModLoaderType>

Returns list of individual mod loader types.

Model Columns

enum Columns {
    NameColumn = 0,
    VersionColumn,
    NUM_COLUMNS
};

Signals

signals:
    void minecraftChanged();

Example Usage

#include "minecraft/PackProfile.h"
#include "minecraft/MinecraftInstance.h"

MinecraftInstance* inst = /* ... */;
PackProfile* profile = inst->getPackProfile();

// Get Minecraft version
QString mcVersion = profile->getComponentVersion("net.minecraft");
qDebug() << "Minecraft version:" << mcVersion;

// Change Minecraft version
if (profile->setComponentVersion("net.minecraft", "1.20.1", true)) {
    qDebug() << "Version changed successfully";
}

// Install Fabric
if (profile->installEmpty("net.fabricmc.fabric-loader", "Fabric Loader")) {
    profile->setComponentVersion("net.fabricmc.fabric-loader", "0.15.0");
}

// Check mod loaders
auto loaders = profile->getModLoaders();
if (loaders.has_value()) {
    qDebug() << "Has mod loader installed";
}

// Reload profile with network access
auto result = profile->reload(Net::Mode::Online);
if (result) {
    qDebug() << "Profile reloaded successfully";
} else {
    qDebug() << "Error:" << result.error;
}

// Get component by ID
ComponentPtr mc = profile->getComponent("net.minecraft");
if (mc) {
    qDebug() << "Component name:" << mc->getName();
}