[PATCH] TextRenderer allocation and cache fix

[Jorma Rebane]

Currently the CGUI::DrawText and CTextRenderer is quite inefficient.

In CTextRenderer, for every [text+font] chunk, a temporary object and a copy of the string is made:

	struct SBatch
	{
		CMatrix3D transform;
		CColor color;
		shared_ptr<CFont> font;
		std::wstring text; // <--- bad!
	};

This results in a huge amount of temporary wstring objects that get deleted right after the small batch has been rendered. This is extremely inefficient.

In order to speed this up, two changes were made:

• Removed wstring from SBatch, replaced with text_index and text_length
• Added m_TextBuffer, m_VertexBuffer and m_IndexBuffer

Using this very basic buffering we can avoid a huge number of memory operations:

	struct SBatch
	{
		CMatrix3D transform;
		CColor color;
		CFont* font;
		int text_index;
		int text_length;
	};

In the actual CGUI::DrawText method CTextRenderer is just a temporary object, which is very bad, since the temporary font cache and buffers inside CTextRenderer is destroyed.

Fortunately the VFS cache system never releases the font handles. However if this is true, then why cache fonts EVERY DRAW CALL if you end up deleting them anyways? This makes no sense at all.

Solution: Since CTextRenderer is actually used a lot, the Singleton pattern makes sense here.

[Jorma Rebane]

Initial release, waiting for review.

[Jorma Rebane]

Further remarks:

• Breaks font hotloading - If we replace the current font system with FreeType fonts in the near future, will this really matter?

[alpha123]

I'd really like to get this in for Alpha 14. I tried it last night and it makes a really noticeable difference in scenario loading speed. I unfortunately don't have any hard numbers (well, I can load Gambia River in 36 seconds from a cold cache, but I don't know what it was without the patch) but apply it and it's hard not to notice.

[historic_bruno]

Closing these tickets as no further active development is expected. See Philip's megapatch-split git branch for an attempt at splitting megapatch into it's separate parts: ​http://git.wildfiregames.com/gitweb/?p=0ad.git;a=shortlog;h=refs/heads/projects/philip/megapatch-split