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Hashing: handling of "###" operator to reset to seed within a string identifier doesn't include the "###" characters in the output hash anymore.

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This has various simplifying properties.
Need a test engine update too.
+ Demo: removed misleading/unnecessary usage of ###.
This commit is contained in:
omar
2019-12-26 21:40:58 +01:00
committed by ocornut
parent 1e7d2adc29
commit fc89c61089
4 changed files with 23 additions and 9 deletions
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8
docs/CHANGELOG.txt
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@@ -41,6 +41,14 @@ HOW TO UPDATE?
Breaking Changes:
- Hashing: handling of "###" operator to reset to seed within a string identifier
doesn't include the "###" characters in the output hash anymore:
Before: GetID("Hello###World") == GetID("###World") != GetID("World");
Now: GetID("Hello###World") == GetID("###World") == GetID("World");
- This has the property of facilitating concatenating and manipulating
identifers using "###", and will allow fixing other dangling issues.
- This will invalidate hashes (stored in .ini data) for Tables and Windows
that are using the "###" operators. (#713, #1698)
- Fonts: Fixed handling of `ImFontConfig::FontDataOwnedByAtlas = false` which
did erroneously make a copy of the font data, essentially defeating the purpose
of this flag and wasting memory (undetected since July 2015 and now spotted

20
imgui.cpp
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@@ -2368,11 +2368,8 @@ ImGuiID ImHashData(const void* data_p, size_t data_size, ImGuiID seed)
#endif
}
// Zero-terminated string hash, with support for ### to reset back to seed value
// We support a syntax of "label###id" where only "###id" is included in the hash, and only "label" gets displayed.
// Because this syntax is rarely used we are optimizing for the common case.
// - If we reach ### in the string we discard the hash so far and reset to the seed.
// - We don't do 'current += 2; continue;' after handling ### to keep the code smaller/faster (measured ~10% diff in Debug build)
// Zero-terminated string hash, with support for ### to reset back to seed value.
// e.g. "label###id" outputs the same hash as "id" (and "label" is generally displayed by the UI functions)
// FIXME-OPT: Replace with e.g. FNV1a hash? CRC32 pretty much randomly access 1KB. Need to do proper measurements.
ImGuiID ImHashStr(const char* data_p, size_t data_size, ImGuiID seed)
{
@@ -2384,11 +2381,16 @@ ImGuiID ImHashStr(const char* data_p, size_t data_size, ImGuiID seed)
#endif
if (data_size != 0)
{
while (data_size-- != 0)
while (data_size-- > 0)
{
unsigned char c = *data++;
if (c == '#' && data_size >= 2 && data[0] == '#' && data[1] == '#')
{
crc = seed;
data += 2;
data_size -= 2;
continue;
}
#ifndef IMGUI_ENABLE_SSE4_2_CRC
crc = (crc >> 8) ^ crc32_lut[(crc & 0xFF) ^ c];
#else
@@ -2401,7 +2403,11 @@ ImGuiID ImHashStr(const char* data_p, size_t data_size, ImGuiID seed)
while (unsigned char c = *data++)
{
if (c == '#' && data[0] == '#' && data[1] == '#')
{
crc = seed;
data += 2;
continue;
}
#ifndef IMGUI_ENABLE_SSE4_2_CRC
crc = (crc >> 8) ^ crc32_lut[(crc & 0xFF) ^ c];
#else
@@ -2419,7 +2425,7 @@ const char* ImHashSkipUncontributingPrefix(const char* label)
const char* result = label;
while (unsigned char c = *label++)
if (c == '#' && label[0] == '#' && label[1] == '#')
result = label - 1;
result = label + 2;
return result;
}

2
imgui.h
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@@ -30,7 +30,7 @@
// Library Version
// (Integer encoded as XYYZZ for use in #if preprocessor conditionals, e.g. '#if IMGUI_VERSION_NUM >= 12345')
#define IMGUI_VERSION "1.92.6 WIP"
#define IMGUI_VERSION_NUM 19254
#define IMGUI_VERSION_NUM 19255
#define IMGUI_HAS_TABLE // Added BeginTable() - from IMGUI_VERSION_NUM >= 18000
#define IMGUI_HAS_TEXTURES // Added ImGuiBackendFlags_RendererHasTextures - from IMGUI_VERSION_NUM >= 19198

2
imgui_demo.cpp
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@@ -3358,7 +3358,7 @@ static void DemoWindowWidgetsSelectionAndMultiSelect(ImGuiDemoWindowData* demo_d
ImGui::TableNextColumn();
ImGui::SetNextItemWidth(-FLT_MIN);
ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(0, 0));
ImGui::InputText("###NoLabel", (char*)(void*)item_category, strlen(item_category), ImGuiInputTextFlags_ReadOnly);
ImGui::InputText("##NoLabel", (char*)(void*)item_category, strlen(item_category), ImGuiInputTextFlags_ReadOnly);
ImGui::PopStyleVar();
}