Custom Cinder logger for use with ImGui

example.cpp

#include "UILogger.h"

MyApp::MyApp()
{
    ci::log::makeLogger< ui::Logger >();
}

void MyApp::update() {
    for ( auto & log : log::manager()->getLoggers< ui::Logger >() ) {
        log->draw( "Log" );
    }
}

UILogger.h

#pragma once

#include "cinder/Log.h"
#include "CinderImGui.h"

namespace ImGui {
class Logger : public ci::log::Logger {
private:
    ImGuiTextBuffer     m_buffer;
    ImGuiTextFilter     m_filter;
    ImVector<int>       m_lineOffsets;        // Index to lines offset
    bool                m_shouldScrollToBottom;

public:

    void clear() { m_buffer.clear(); m_lineOffsets.clear(); }

    void write( const ci::log::Metadata &meta, const std::string &text ) override
    {
        int old_size = m_buffer.size();

        std::ostringstream stream;
        writeDefault( stream, meta, text );
        m_buffer.append( stream.str().c_str() );

        for ( int new_size = m_buffer.size(); old_size < new_size; old_size++ )
            if ( m_buffer[ old_size ] == '\n' )
                m_lineOffsets.push_back( old_size );
        m_shouldScrollToBottom = true;
    }

    void draw( const char* title, bool* p_opened = NULL )
    {
        ui::SetNextWindowSize( ImVec2( 500, 400 ), ImGuiSetCond_FirstUseEver );
        ui::Begin( title, p_opened );
        if ( ui::Button( "Clear" ) ) clear();
        ui::SameLine();
        bool copy = ui::Button( "Copy" );
        ui::SameLine();
        m_filter.Draw( "Filter", -100.0f );
        ui::Separator();
        ui::BeginChild( "scrolling" );
        ui::PushStyleVar( ImGuiStyleVar_ItemSpacing, ImVec2( 0, 1 ) );
        if ( copy ) ui::LogToClipboard();

        if ( m_filter.IsActive() )
        {
            const char* buf_begin = m_buffer.begin();
            const char* line = buf_begin;
            for ( int line_no = 0; line != NULL; line_no++ )
            {
                const char* line_end = ( line_no < m_lineOffsets.Size ) ? buf_begin + m_lineOffsets[ line_no ] : NULL;
                if ( m_filter.PassFilter( line, line_end ) )
                    ui::TextUnformatted( line, line_end );
                line = line_end && line_end[ 1 ] ? line_end + 1 : NULL;
            }
        }
        else
        {
            ui::TextUnformatted( m_buffer.begin() );
        }

        if ( m_shouldScrollToBottom )
            ui::SetScrollHere( 1.0f );
        m_shouldScrollToBottom = false;
        ui::PopStyleVar();
        ui::EndChild();
        ui::End();
    }
};
}

Based on ocornut/imgui#300