My test environment:
Cinema 4D version: CINEMA 4D R19.068
Renderer: Octane renderer 3.07 R2

This is my code:

# -*- coding: UTF-8 -*-
import c4d
from time import sleep


# Save path
save_path = "D:\\temp"  # It's my dir for test. Change it if you dont want to save your bmp at here.


class RenderThread(c4d.threading.C4DThread):
    global save_path
    
    # Override
    def __init__(self, doc, rd, bmp):
        self.break_flag = False
        self.doc = doc
        self.rd = rd
        self.bmp = bmp
        self.res = None
        
    # Override
    def Main(self):
        self.res = c4d.documents.RenderDocument(
            self.doc,
            self.rd,
            self.bmp,
            c4d.RENDERFLAGS_EXTERNAL
        )
        
        # Just a test for distinguish the result file is saved by which thread.
        # If i get this file, it indicates that the render thread has run completed.
        if self.res == c4d.RENDERRESULT_OK:
            self.bmp.Save(
                "{}\\RenderThread_SaveResult.jpg".format(save_path),
                c4d.FILTER_JPG
            )

    # Override
    def TestDBreak(self):
        return self.break_flag


# This method is main thread.
def main():
    global save_path
    
    doc = c4d.documents.GetActiveDocument()
    rd = doc.GetActiveRenderData().GetData()
    bmp = c4d.bitmaps.BaseBitmap()
    bmp.Init(rd[c4d.RDATA_XRES], rd[c4d.RDATA_YRES])
    
    th = RenderThread(doc, rd ,bmp)
    th.Start()

    count = 0  # When "count" equals 10, end render thread.
    while True:
        print "Current count ->", count

        # Show bmp to picture viewer
        c4d.CallCommand(430000740, 430000740) # Remove All Images --> Clear history, just show current bmp
        c4d.CallCommand(430000774, 430000774) # Auto Zoom Mode --> Zoom picture to fit the picture viewer
        c4d.bitmaps.ShowBitmap(bmp)

        # Listen for the running state of the render thread.
        is_run = th.IsRunning()
        print "Is render thread running ->", is_run
        
        if not is_run:
            print "End Render Thread"
            
            # If i get this file, it indicates that the render thread has run completed.
            if th.res == c4d.RENDERRESULT_OK:
                th.bmp.Save(
                    "{}\\MainThread_SaveResult.jpg".format(save_path),
                    c4d.FILTER_JPG
                )
            
            break

        # Test of break render thread
        if count == 10:
            print "Break Render Thread"

            th.break_flag = True
            break_res = th.TestBreak()

            print "TestBreak() result ->", break_res

            if break_res:
                th.End(False)  # It doesn't work... and the bottom of result image have a state bar... 
                print "Execute End()..."
            
            print "Is render thread still running ->", th.IsRunning()
            
            # If i get this file, it indicates that the render thread has break.
            th.bmp.Save(
                "{}\\Break_SaveResult.jpg".format(save_path),
                c4d.FILTER_JPG
            )

            break

        count += 1
        sleep(1)


if __name__ == "__main__":
    c4d.CallCommand(13957) # Clear Console
    main()

There has two questions:

1. In fact, render thread is not break... this is my c4d console log:
   After "End()" has executed, render thread is still running...
   Emmmm... how to really end render thread ?

2. I got a image after "End()", but the image has a state bar at bottom...
   So, can I get the image without state bar when I break render thread ?
   This is the image:

Finally, I will got two images, because render thread doesn't break:

@m_magalhaes
Thanks you very much !
It's very help !

How to control Picture Viewer by Python in C4D R19 ?

Such as "Stop Rendering" , "Save Image", "Clear History"......

I can't find useful info in python doc...

@m_adam Thank you for your advice.

If my renderer is Octane Render 3.07 R2
For example:

# -*- coding: utf-8 -*-
import c4d

def test():
    doc = c4d.documents.GetActiveDocument()
    rd = doc.GetActiveRenderData()

    current_renderer_id = rd[c4d.RDATA_RENDERENGINE]
    current_renderer_name = c4d.documents.BaseVideoPost(current_renderer_id ).GetName()\
        if currentRendererID else "Standard"
    
    print "Current Renderer ID:", current_renderer_id  # 1029525
    print "Current Renderer Name:", current_renderer_name  # Octane Render

if __name__ == "__main__":
    test()

Emmmmm......
So, I can get id and name about octane renderer, but how to get version number by python ?

Thanks !
It works !

I tried "GetAllAssets()" and "GetAllTextures()", but I can't get realpath...

this is my test code:

# -*- coding: utf-8 -*-
"""
该模块用于解析场景使用，
无论插件提交，还是客户端提交，
解析方面的工作都在这个模块实现
"""
import c4d


class Parse:
    # Override
    def __init__(self, doc):
        """
        parameters::
            doc ==> 当前C4D场景
        """
        self.doc = doc

    def assetParse(self):
        """
        资源解析，解析场景中所有资源，
        是否存在，路径等信息
        """
        assets = c4d.documents.GetAllAssets(self.doc, False, "")
        if not assets:
            assets = self.doc.GetAllTextures()
        
        self.assets = assets
    
    def test(self):
        self.doc.SendInfo(
            c4d.MSG_DOCUMENTINFO_TYPE_MAKEPROJECT,
            c4d.FORMAT_C4DEXPORT,
            self.doc.GetDocumentName()
        )
    

if __name__ == "__main__":
    c4d.CallCommand(13957) # Clear Console
    
    doc = c4d.documents.GetActiveDocument()
    doc_parsed = Parse(doc)
    doc_parsed.assetParse()
    
    # for i in doc_parsed.assets[0]:
    #     print i
        
    for i in doc_parsed.assets:
        print i