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DrawString: Stop allocating

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Switch to a state-machine UTF-8 decoder from the branchless one.
This allows us to avoid copying the string on every `DrawString` call.
This commit is contained in:
Gleb Mazovetskiy 2021-11-07 02:59:55 +00:00 • committed by Anders Jenbo
commit e9a9daa794
10 changed files with 173 additions and 120 deletions
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49
Source/engine/render/text_render.cpp
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@ -20,7 +20,7 @@
#include "palette.h"
#include "utils/display.h"
#include "utils/sdl_compat.h"
#include "utils/utf8.h"
#include "utils/utf8.hpp"
namespace devilution {
@ -196,20 +196,13 @@ int GetLineWidth(string_view text, GameFontTables size, int spacing, int *charac
{
int lineWidth = 0;
std::string textBuffer;
textBuffer.reserve(textBuffer.size() + 3); // Buffer must be padded before calling utf8_decode()
textBuffer.append(text.data(), text.size());
textBuffer.resize(textBuffer.size() + 3);
const char *textData = textBuffer.data();
uint32_t codepoints = 0;
uint32_t currentUnicodeRow = 0;
std::array<uint8_t, 256> *kerning = nullptr;
char32_t next;
int error;
while (*textData != '\0') {
textData = utf8_decode(textData, &next, &error);
if (error)
while (!text.empty()) {
next = ConsumeFirstUtf8CodePoint(&text);
if (next == Utf8DecodeError)
break;
if (next == ZWSP)
continue;
@ -249,13 +242,11 @@ std::string WordWrapString(string_view text, size_t width, GameFontTables size,
int lastBreakableLen;
char32_t lastBreakableCodePoint;
std::string input;
std::string input { text };
std::string output;
input.reserve(input.size() + 3); // Buffer must be padded before calling utf8_decode()
input.append(text.data(), text.size());
input.resize(input.size() + 3);
output.reserve(text.size());
const char *begin = input.data();
const char *end = input.data() + input.size();
const char *cur = begin;
const char *processedEnd = cur;
@ -263,10 +254,11 @@ std::string WordWrapString(string_view text, size_t width, GameFontTables size,
size_t lineWidth = 0;
std::array<uint8_t, 256> *kerning = nullptr;
char32_t next;
int error;
while (*cur != '\0') {
cur = utf8_decode(cur, &next, &error);
if (error != 0)
while (cur != end && *cur != '\0') {
uint8_t codepointLen;
next = DecodeFirstUtf8CodePoint(cur, &codepointLen);
cur += codepointLen;
if (next == Utf8DecodeError)
break;
if (next == U'\n') { // Existing line break, scan next line
@ -361,17 +353,12 @@ uint32_t DrawString(const Surface &out, string_view text, const Rectangle &rect,
Art *font = nullptr;
std::array<uint8_t, 256> *kerning = nullptr;
std::string textBuffer(text);
textBuffer.resize(textBuffer.size() + 4); // Buffer must be padded before calling utf8_decode()
const char *textData = textBuffer.data();
const char *previousPosition = textData;
char32_t next;
uint32_t currentUnicodeRow = 0;
int error;
for (; *textData != '\0'; previousPosition = textData) {
textData = utf8_decode(textData, &next, &error);
if (error)
string_view remaining = text;
while (!remaining.empty() && remaining[0] != '\0') {
next = ConsumeFirstUtf8CodePoint(&remaining);
if (next == Utf8DecodeError)
break;
if (next == ZWSP)
continue;
@ -392,8 +379,8 @@ uint32_t DrawString(const Surface &out, string_view text, const Rectangle &rect,
if (HasAnyOf(flags, (UiFlags::AlignCenter | UiFlags::AlignRight))) {
lineWidth = (*kerning)[frame];
if (*textData != '\0')
lineWidth += spacing + GetLineWidth(textData, size, spacing);
if (text[0] != '\0')
lineWidth += spacing + GetLineWidth(text, size, spacing);
}
if (HasAnyOf(flags, UiFlags::AlignCenter))
@ -415,7 +402,7 @@ uint32_t DrawString(const Surface &out, string_view text, const Rectangle &rect,
DrawArt(out, characterPosition, LoadFont(size, color, 0), '|');
}
return previousPosition - textBuffer.data();
return text.data() - remaining.data();
}
uint8_t PentSpn2Spin()