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Tables: comments about skipping access to table data in coarse clipping path.

This commit is contained in:
ocornut 2024-05-21 11:34:58 +02:00
parent 28a283b460
commit cd48059dc5
2 changed files with 12 additions and 5 deletions
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4
imgui_internal.h
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@ -2822,8 +2822,7 @@ struct ImGuiTableInstanceData
ImGuiTableInstanceData() { TableInstanceID = 0; LastOuterHeight = LastTopHeadersRowHeight = LastFrozenHeight = 0.0f; HoveredRowLast = HoveredRowNext = -1; }
};
// FIXME-TABLE: more transient data could be stored in a stacked ImGuiTableTempData: e.g. SortSpecs, incoming RowData
// sizeof() ~ 580 bytes + heap allocs described in TableBeginInitMemory()
// sizeof() ~ 592 bytes + heap allocs described in TableBeginInitMemory()
struct IMGUI_API ImGuiTable
{
ImGuiID ID;
@ -2946,6 +2945,7 @@ struct IMGUI_API ImGuiTable
// Transient data that are only needed between BeginTable() and EndTable(), those buffers are shared (1 per level of stacked table).
// - Accessing those requires chasing an extra pointer so for very frequently used data we leave them in the main table structure.
// - We also leave out of this structure data that tend to be particularly useful for debugging/metrics.
// FIXME-TABLE: more transient data could be stored in a stacked ImGuiTableTempData: e.g. SortSpecs.
// sizeof() ~ 136 bytes.
struct IMGUI_API ImGuiTableTempData
{

13
imgui_tables.cpp
View File

@ -320,6 +320,12 @@ bool ImGui::BeginTableEx(const char* name, ImGuiID id, int columns_count, ImG
IM_ASSERT(inner_width >= 0.0f);
// If an outer size is specified ahead we will be able to early out when not visible. Exact clipping criteria may evolve.
// FIXME: coarse clipping because access to table data causes two issues:
// - instance numbers varying/unstable. may not be a direct problem for users, but could make outside access broken or confusing, e.g. TestEngine.
// - can't implement support for ImGuiChildFlags_ResizeY as we need to somehow pull the height data from somewhere. this also needs stable instance numbers.
// The side-effects of accessing table data on coarse clip would be:
// - always reserving the pooled ImGuiTable data ahead for a fully clipped table (minor IMHO). Also the 'outer_window_is_measuring_size' criteria may already be defeating this in some situations.
// - always performing the GetOrAddByKey() O(log N) query in g.Tables.Map[].
const bool use_child_window = (flags & (ImGuiTableFlags_ScrollX | ImGuiTableFlags_ScrollY)) != 0;
const ImVec2 avail_size = GetContentRegionAvail();
const ImVec2 actual_outer_size = CalcItemSize(outer_size, ImMax(avail_size.x, 1.0f), use_child_window ? ImMax(avail_size.y, 1.0f) : 0.0f);
@ -338,7 +344,6 @@ bool ImGui::BeginTableEx(const char* name, ImGuiID id, int columns_count, ImG
// Acquire storage for the table
ImGuiTable* table = g.Tables.GetOrAddByKey(id);
const ImGuiTableFlags table_last_flags = table->Flags;
// Acquire temporary buffers
const int table_idx = g.Tables.GetIndex(table);
@ -356,6 +361,7 @@ bool ImGui::BeginTableEx(const char* name, ImGuiID id, int columns_count, ImG
// Initialize
const int previous_frame_active = table->LastFrameActive;
const int instance_no = (previous_frame_active != g.FrameCount) ? 0 : table->InstanceCurrent + 1;
const ImGuiTableFlags previous_flags = table->Flags;
table->ID = id;
table->Flags = flags;
table->LastFrameActive = g.FrameCount;
@ -402,7 +408,7 @@ bool ImGui::BeginTableEx(const char* name, ImGuiID id, int columns_count, ImG
SetNextWindowContentSize(ImVec2(override_content_size.x != FLT_MAX ? override_content_size.x : 0.0f, override_content_size.y != FLT_MAX ? override_content_size.y : 0.0f));
// Reset scroll if we are reactivating it
if ((table_last_flags & (ImGuiTableFlags_ScrollX | ImGuiTableFlags_ScrollY)) == 0)
if ((previous_flags & (ImGuiTableFlags_ScrollX | ImGuiTableFlags_ScrollY)) == 0)
SetNextWindowScroll(ImVec2(0.0f, 0.0f));
// Create scrolling region (without border and zero window padding)
@ -515,7 +521,7 @@ bool ImGui::BeginTableEx(const char* name, ImGuiID id, int columns_count, ImG
if (inner_window != outer_window) // So EndChild() within the inner window can restore the table properly.
inner_window->DC.CurrentTableIdx = table_idx;
if ((table_last_flags & ImGuiTableFlags_Reorderable) && (flags & ImGuiTableFlags_Reorderable) == 0)
if ((previous_flags & ImGuiTableFlags_Reorderable) && (flags & ImGuiTableFlags_Reorderable) == 0)
table->IsResetDisplayOrderRequest = true;
// Mark as used to avoid GC
@ -2928,6 +2934,7 @@ void ImGui::TableSortSpecsBuild(ImGuiTable* table)
}
// Write output
// May be able to move all SortSpecs data from table (48 bytes) to ImGuiTableTempData if we decide to write it back on every BeginTable()
ImGuiTableColumnSortSpecs* sort_specs = (table->SortSpecsCount == 0) ? NULL : (table->SortSpecsCount == 1) ? &table->SortSpecsSingle : table->SortSpecsMulti.Data;
if (dirty && sort_specs != NULL)
for (int column_n = 0; column_n < table->ColumnsCount; column_n++)