ZVISION: Convert subtitles to UTF-32 before rendering them (bug #6772)

Because we use Common::String to store UTF-8 data, the font
renderer will draw the wrong glyphs for non-ASCII characters,
unless we first convert the string to UTF-32. (I thought the same
change would have to be made for the ZGI game over screens, but
apparently they work anyway. At least the German version, I'm told.)

I've discussed this change with [md5], and while it would probably
be more correct to make the engine use UTF-32 throughout, that is
also rather painful.

2 files changed, 37 insertions, 3 deletions

diff --git a/engines/zvision/text/truetype_font.cpp b/engines/zvision/text/truetype_font.cpp
index 9f4fbe797b..f7580fb553 100644
--- a/engines/zvision/text/truetype_font.cpp
+++ b/engines/zvision/text/truetype_font.cpp
@@ -26,6 +26,7 @@
 #include "common/file.h"
 #include "common/system.h"
 #include "common/unzip.h"
+#include "common/ustr.h"
 #include "graphics/font.h"
 #include "graphics/fonts/ttf.h"
 #include "graphics/surface.h"
@@ -168,6 +169,36 @@ int StyledTTFont::getKerningOffset(byte left, byte right) {
 	return 0;
 }
 
+Common::U32String StyledTTFont::convertUtf8ToUtf32(const Common::String &str) {
+	// The String class, and therefore the Font class as well, assume one
+	// character is one byte, but in this case it's actually an UTF-8
+	// string with up to 4 bytes per character. To work around this,
+	// convert it to an U32String before drawing it, because our Font class
+	// can handle that.
+	Common::U32String u32str;
+	uint i = 0;
+	while (i < str.size()) {
+		uint32 chr = 0;
+		if ((str[i] & 0xF8) == 0xF0) {
+			chr |= (str[i++] & 0x07) << 18;
+			chr |= (str[i++] & 0x3F) << 12;
+			chr |= (str[i++] & 0x3F) << 6;
+			chr |= (str[i++] & 0x3F);
+		} else if ((str[i] & 0xF0) == 0xE0) {
+			chr |= (str[i++] & 0x0F) << 12;
+			chr |= (str[i++] & 0x3F) << 6;
+			chr |= (str[i++] & 0x3F);
+		} else if ((str[i] & 0xE0) == 0xC0) {
+			chr |= (str[i++] & 0x1F) << 6;
+			chr |= (str[i++] & 0x3F);
+		} else {
+			chr = (str[i++] & 0x7F);
+		}
+		u32str += chr;
+	}
+	return u32str;
+}
+
 void StyledTTFont::drawChar(Graphics::Surface *dst, byte chr, int x, int y, uint32 color) {
 	if (_font) {
 		_font->drawChar(dst, chr, x, y, color);
@@ -186,10 +217,11 @@ void StyledTTFont::drawChar(Graphics::Surface *dst, byte chr, int x, int y, uint
 
 void StyledTTFont::drawString(Graphics::Surface *dst, const Common::String &str, int x, int y, int w, uint32 color, Graphics::TextAlign align) {
 	if (_font) {
-		_font->drawString(dst, str, x, y, w, color, align);
+		Common::U32String u32str = convertUtf8ToUtf32(str);
+		_font->drawString(dst, u32str, x, y, w, color, align);
 		if (_style & STTF_UNDERLINE) {
 			int16 pos = floor(_font->getFontHeight() * 0.87);
-			int16 wd = MIN(_font->getStringWidth(str), w);
+			int16 wd = MIN(_font->getStringWidth(u32str), w);
 			int16 stX = x;
 			if (align == Graphics::kTextAlignCenter)
 				stX += (w - wd) / 2;
@@ -202,7 +234,7 @@ void StyledTTFont::drawString(Graphics::Surface *dst, const Common::String &str,
 		}
 		if (_style & STTF_STRIKEOUT) {
 			int16 pos = floor(_font->getFontHeight() * 0.60);
-			int16 wd = MIN(_font->getStringWidth(str), w);
+			int16 wd = MIN(_font->getStringWidth(u32str), w);
 			int16 stX = x;
 			if (align == Graphics::kTextAlignCenter)
 				stX += (w - wd) / 2;
diff --git a/engines/zvision/text/truetype_font.h b/engines/zvision/text/truetype_font.h
index 6fbb1f0504..caa9c09a76 100644
--- a/engines/zvision/text/truetype_font.h
+++ b/engines/zvision/text/truetype_font.h
@@ -77,6 +77,8 @@ public:
 	int getCharWidth(byte chr);
 	int getKerningOffset(byte left, byte right);
 
+	Common::U32String convertUtf8ToUtf32(const Common::String &str);
+
 	void drawChar(Graphics::Surface *dst, byte chr, int x, int y, uint32 color);
 
 	void drawString(Graphics::Surface *dst, const Common::String &str, int x, int y, int w, uint32 color, Graphics::TextAlign align = Graphics::kTextAlignLeft);