From 16b0cde5fba7b16ff412710942e95ca91f87cecb Mon Sep 17 00:00:00 2001
From: Eugene Sandulenko
Date: Tue, 20 Dec 2016 21:07:54 +0100
Subject: GRAPHICS: Implemented partial MacText drawing

---
 graphics/macgui/mactext.cpp | 32 ++++++++++++++++++++++----------
 graphics/macgui/mactext.h   |  1 +
 2 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/graphics/macgui/mactext.cpp b/graphics/macgui/mactext.cpp
index 2dc1fc8e2c..389fca4872 100644
--- a/graphics/macgui/mactext.cpp
+++ b/graphics/macgui/mactext.cpp
@@ -74,12 +74,12 @@ void MacText::splitString(Common::String &str) {
 }
 
 void MacText::reallocSurface() {
-	int lineHeight = _font->getFontHeight() + _interLinear;
-	int requiredHeight = (_text.size() + (_text.size() * 10 + 9) / 10) * lineHeight;
+	int lineH = _font->getFontHeight() + _interLinear;
+	int requiredH = (_text.size() + (_text.size() * 10 + 9) / 10) * lineH;
 
-	if (_surface.w < requiredHeight) {
+	if (_surface.w < requiredH) {
 		// realloc surface
-		_surface.create(_maxWidth == -1 ? _textMaxWidth : _maxWidth, requiredHeight);
+		_surface.create(_maxWidth == -1 ? _textMaxWidth : _maxWidth, requiredH);
 	}
 }
 
@@ -89,16 +89,28 @@ void MacText::render() {
 
 		_surface.clear(_bgcolor);
 
-		int y = 0;
+		render(0, _text.size());
 
-		for (uint i = 0; i < _text.size(); i++) {
-			_font->drawString(&_surface, _text[i], 0, y, _textMaxWidth, _fgcolor);
+		_fullRefresh = false;
+	}
+}
 
-			y += _font->getFontHeight() + _interLinear;
-		}
+void MacText::render(int from, int to) {
+	from = MAX<int>(0, from);
+	to = MIN<int>(to, _text.size());
 
-		_fullRefresh = false;
+	int lineH = _font->getFontHeight() + _interLinear;
+	int y = from * lineH;
+
+	// Clear the screen
+	_surface.fillRect(Common::Rect(0, y, _surface.w, to * lineH), _bgcolor);
+
+	for (uint i = from; i < to; i++) {
+		_font->drawString(&_surface, _text[i], 0, y, _textMaxWidth, _fgcolor);
+
+		y += _font->getFontHeight() + _interLinear;
 	}
+
 }
 
 void MacText::draw(ManagedSurface *g, int x, int y, int w, int h, int xoff, int yoff) {
diff --git a/graphics/macgui/mactext.h b/graphics/macgui/mactext.h
index 65e93ca5c3..a133c5c24b 100644
--- a/graphics/macgui/mactext.h
+++ b/graphics/macgui/mactext.h
@@ -41,6 +41,7 @@ public:
 private:
 	void splitString(Common::String &s);
 	void render();
+	void render(int from, int to);
 	void calcMaxWidth();
 	void reallocSurface();
 
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