BPicture: fix BeOS flattened format compatibility

- BeOS store strings with `int32` size prefix.

- Corrected `B_PIC_DRAW_STRING` field order to match BeOS.

Part of #1133.

Change-Id: I354fbf3e8a093ee21a87a6400a036751b442955b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/9307
Reviewed-by: Adrien Destugues <[email protected]>
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: Stephan Aßmus <[email protected]>

src/kits/interface/PictureDataWriter.cpp

@@ -496,12 +496,10 @@ PictureDataWriter::WriteDrawString(const BPoint& where, const char* string,
 		EndOp();
 
 		BeginOp(B_PIC_DRAW_STRING);
+		Write<int32>(length);
+		WriteData(string, length);
 		Write<float>(escapement.space);
 		Write<float>(escapement.nonspace);
-		//WriteData(string, length + 1);
-			// TODO: is string 0 terminated? why is length given?
-		WriteData(string, length);
-		Write<uint8>(0);
 		EndOp();
 	} catch (status_t& status) {
 		return status;
@@ -521,8 +519,8 @@ PictureDataWriter::WriteDrawString(const char* string,
 		for (int32 i = 0; i < locationCount; i++) {
 			Write<BPoint>(locations[i]);
 		}
+		Write<int32>(length);
 		WriteData(string, length);
-		Write<uint8>(0);
 		EndOp();
 	} catch (status_t& status) {
 		return status;
@@ -734,8 +732,10 @@ PictureDataWriter::WriteSetFontFamily(const font_family family)
 {
 	try {
 		BeginOp(B_PIC_SET_FONT_FAMILY);
-		WriteData(family, strlen(family));
+		// BeOS writes string size including terminating null character for some reason.
-		Write<uint8>(0);
+		uint32 length = strlen(family) + 1;
+		Write<uint32>(length);
+		WriteData(family, length);
 		EndOp();
 	} catch (status_t& status) {
 		return status;
@@ -750,8 +750,10 @@ PictureDataWriter::WriteSetFontStyle(const font_style style)
 {
 	try {
 		BeginOp(B_PIC_SET_FONT_STYLE);
-		WriteData(style, strlen(style));
+		// BeOS writes string size including terminating null character for some reason.
-		Write<uint8>(0);
+		uint32 length = strlen(style) + 1;
+		Write<uint32>(length);
+		WriteData(style, length);
 		EndOp();
 	} catch (status_t& status) {
 		return status;

src/kits/interface/PicturePlayer.cpp

@@ -1202,18 +1202,19 @@ PicturePlayer::_Play(const picture_player_callbacks& callbacks, void* userData,
 
 			case B_PIC_DRAW_STRING:
 			{
+				const int32* length;
+				const char* string;
 				const float* escapementSpace;
 				const float* escapementNonSpace;
-				const char* string;
-				size_t length;
 				if (callbacks.draw_string == NULL
+					|| !reader.Get(length)
+					|| !reader.Get(string, *length)
 					|| !reader.Get(escapementSpace)
-					|| !reader.Get(escapementNonSpace)
+					|| !reader.Get(escapementNonSpace)) {
-					|| !reader.GetRemaining(string, length)) {
 					break;
 				}
 
-				callbacks.draw_string(userData, string, length,
+				callbacks.draw_string(userData, string, *length,
 					*escapementSpace, *escapementNonSpace);
 				break;
 			}
@@ -1222,16 +1223,17 @@ PicturePlayer::_Play(const picture_player_callbacks& callbacks, void* userData,
 			{
 				const uint32* pointCount;
 				const BPoint* pointList;
+				const int32* length;
 				const char* string;
-				size_t length;
 				if (callbacks.draw_string_locations == NULL
 					|| !reader.Get(pointCount)
 					|| !reader.Get(pointList, *pointCount)
-					|| !reader.GetRemaining(string, length)) {
+					|| !reader.Get(length)
+					|| !reader.Get(string, *length)) {
 					break;
 				}
 
-				callbacks.draw_string_locations(userData, string, length,
+				callbacks.draw_string_locations(userData, string, *length,
 					pointList, *pointCount);
 				break;
 			}
@@ -1454,27 +1456,29 @@ PicturePlayer::_Play(const picture_player_callbacks& callbacks, void* userData,
 
 			case B_PIC_SET_FONT_FAMILY:
 			{
+				const int32* length;
 				const char* family;
-				size_t length;
 				if (callbacks.set_font_family == NULL
-					|| !reader.GetRemaining(family, length)) {
+					|| !reader.Get(length)
+					|| !reader.Get(family, *length)) {
 					break;
 				}
 
-				callbacks.set_font_family(userData, family, length);
+				callbacks.set_font_family(userData, family, *length);
 				break;
 			}
 
 			case B_PIC_SET_FONT_STYLE:
 			{
+				const int32* length;
 				const char* style;
-				size_t length;
 				if (callbacks.set_font_style == NULL
-					|| !reader.GetRemaining(style, length)) {
+					|| !reader.Get(length)
+					|| !reader.Get(style, *length)) {
 					break;
 				}
 
-				callbacks.set_font_style(userData, style, length);
+				callbacks.set_font_style(userData, style, *length);
 				break;
 			}