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MultiSelect: Demo: rework ExampleSelection with an ExampleSelectionAdapter layer, allowing to share more code accross examples using different storage systems. 

Not ideal way to showcase this demo but this is really more flexible.
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ocornut 2023-08-23 15:53:20 +02:00
parent 8fe6b31952
commit 8c1f659b3d
1 changed files with 74 additions and 27 deletions
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101
imgui_demo.cpp
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@ -2761,19 +2761,41 @@ static void ShowDemoWindowWidgets()
}
}
// [Advanced] Helper class to simulate storage of a multi-selection state, used by the BeginMultiSelect() demos.
// We use ImGuiStorage (simple key->value storage) to avoid external dependencies but it's probably not optimal.
// We use a little extra indirection layer here in order to use and demonstrate different ways to
// - identify items in the multi-selection system (using index? using identifiers? using pointers?)
// - store our persistent selection data (using index? using identifiers? using pointers?)
// Many combinations are possible depending on how you prefer to store your items and how you prefer to store your selection.
// WHEN YOUR APPLICATION SETTLES ON A CHOICE, YOU WILL PROBABLY PREFER TO GET RID OF THIS UNNECESSARY 'ExampleSelectionAdapter' INDIRECTION LOGIC.
// In theory we could add a IndexToUserData() function which would be used when calling SetNextItemSelectionUserData(), but omitting it makes things clearer.
struct ExampleSelectionAdapter
{
void* Data = NULL;
int (*UserDataToIndex)(ExampleSelectionAdapter* self, ImGuiSelectionUserData item_data); // Function to convert item ImGuiSelectionUserData to item index
ImGuiID (*IndexToStorage)(ExampleSelectionAdapter* self, int idx); // Function to convert item index to data stored in persistent selection
ExampleSelectionAdapter() { SetupForDirectIndexes(); }
// Example for the simplest case: UserData==Index==SelectionStorage (this adapter doesn't even need to use the item data field)
void SetupForDirectIndexes()
{
UserDataToIndex = [](ExampleSelectionAdapter*, ImGuiSelectionUserData item_data) { return (int)item_data; }; // No transform: Pass indices to SetNextItemSelectionUserData()
IndexToStorage = [](ExampleSelectionAdapter*, int idx) { return (ImGuiID)idx; }; // No transform: Store indices inside persistent selection storage
}
};
// [Advanced] Helper class to store multi-selection state, used by the BeginMultiSelect() demos.
// Provide an abstraction layer for the purpose of the demo showcasing different forms of underlying selection data.
// To store a single-selection:
// - You only need a single variable and don't need any of this!
// To store a multi-selection, in your real application you could:
// - Use external storage: e.g. unordered_set/set/hash/map/interval trees (storing indices, objects id, etc.)
// are generally appropriate. Even a large array of bool might work for you... This is what we are doing here.
// - Use intrusively stored selection (e.g. 'bool IsSelected' inside your object).
// - This is simple, but it means you cannot have multiple simultaneous views over your objects.
// - This is what many of the simpler demos in other sections of this file are using (so they are not using this class).
// - Some of our features requires you to provide the selection size, which with this specific strategy require additional work:
// - A) Use external storage: e.g. std::set<index>, std::set<MyObjectId>, std::vector<MyObjectId>, interval trees, etc.
// are generally appropriate. Even a large array of bool might work for you...
// This code here use ImGuiStorage (a simple key->value storage) as a std::set replacement to avoid external dependencies.
// - B) Or use intrusively stored selection (e.g. 'bool IsSelected' inside your object).
// - It is simple, but it means you cannot have multiple simultaneous views over your objects.
// - Some of our features requires you to provide the selection _size_, which with this specific strategy require additional work:
// either you maintain it (which requires storage outside of objects) either you recompute (which may be costly for large sets).
// - So I would suggest that using intrusive selection for multi-select is not the most adequate.
// - So we suggest using intrusive selection for multi-select is not really adequate.
struct ExampleSelection
{
// Data
@ -2784,6 +2806,7 @@ struct ExampleSelection
// Functions
ExampleSelection() { Clear(); }
void Clear() { Storage.Clear(); Size = 0; QueueDeletion = false; }
void Swap(ExampleSelection& rhs) { Storage.Data.swap(rhs.Storage.Data); }
bool Contains(int n) const { return Storage.GetInt((ImGuiID)n, 0) != 0; }
void AddItem(int n) { int* p_int = Storage.GetIntRef((ImGuiID)n, 0); if (*p_int != 0) return; *p_int = 1; Size++; }
void RemoveItem(int n) { int* p_int = Storage.GetIntRef((ImGuiID)n, 0); if (*p_int == 0) return; *p_int = 0; Size--; }
@ -2796,15 +2819,33 @@ struct ExampleSelection
// - Honoring RequestSetRange requires that you can iterate/interpolate between RangeFirstItem and RangeLastItem.
// - In this demo we often submit indices to SetNextItemSelectionUserData() + store the same indices in persistent selection.
// - Your code may do differently. If you store pointers or objects ID in ImGuiSelectionUserData you may need to perform
// a lookup and have some way to iterate between two values.
// - A full-featured application is likely to allow search/filtering which is likely to lead to using indices and
// constructing a view index <> object id/ptr data structure. (FIXME-MULTISELECT: Would be worth providing a demo of doing this).
// - (Our implementation is slightly inefficient because it doesn't take advantage of the fat that ImguiStorage stores sorted key)
void ApplyRequests(ImGuiMultiSelectIO* ms_io, int items_count)
// a lookup in order to have some way to iterate/interpolate between two items.
// - A full-featured application is likely to allow search/filtering which is likely to lead to using indices
// and constructing a view index <> object id/ptr data structure anyway.
// WHEN YOUR APPLICATION SETTLES ON A CHOICE, YOU WILL PROBABLY PREFER TO GET RID OF THIS UNNECESSARY 'ExampleSelectionAdapter' INDIRECTION LOGIC.
// Notice that with the simplest adapter (using indices everywhere), all functions return their parameters.
// The most simple implementation (using indices everywhere) would look like:
// if (ms_io->RequestClear) { Clear(); }
// if (ms_io->RequestSelectAll) { Clear(); for (int n = 0; n < items_count; n++) { AddItem(n); } }
// if (ms_io->RequestSetRange) { for (int n = (int)ms_io->RangeFirstItem; n <= (int)ms_io->RangeLastItem; n++) { UpdateItem(n, ms_io->RangeSelected); } }
void ApplyRequests(ImGuiMultiSelectIO* ms_io, ExampleSelectionAdapter* adapter, int items_count)
{
if (ms_io->RequestClear) { Clear(); }
if (ms_io->RequestSelectAll) { Clear(); for (int n = 0; n < items_count; n++) { AddItem(n); } }
if (ms_io->RequestSetRange) { for (int n = (int)ms_io->RangeFirstItem; n <= (int)ms_io->RangeLastItem; n++) { UpdateItem(n, ms_io->RangeSelected); } }
IM_ASSERT(adapter->UserDataToIndex != NULL && adapter->IndexToStorage != NULL);
if (ms_io->RequestClear || ms_io->RequestSelectAll)
Clear();
if (ms_io->RequestSelectAll)
for (int idx = 0; idx < items_count; idx++)
AddItem(adapter->IndexToStorage(adapter, idx));
if (ms_io->RequestSetRange)
{
int first_item_idx = adapter->UserDataToIndex(adapter, ms_io->RangeFirstItem);
int last_item_idx = adapter->UserDataToIndex(adapter, ms_io->RangeLastItem);
for (int idx = first_item_idx; idx <= last_item_idx; idx++)
UpdateItem(adapter->IndexToStorage(adapter, idx), ms_io->RangeSelected);
}
}
// Call after BeginMultiSelect().
@ -2924,6 +2965,7 @@ static void ShowDemoWindowMultiSelect()
if (ImGui::TreeNode("Multi-Select"))
{
static ExampleSelection selection;
ExampleSelectionAdapter selection_adapter; // Use default: Pass index to SetNextItemSelectionUserData(), store index in Selection
ImGui::Text("Tips: Use 'Debug Log->Selection' to see selection requests as they happen.");
@ -2940,7 +2982,7 @@ static void ShowDemoWindowMultiSelect()
{
ImGuiMultiSelectFlags flags = ImGuiMultiSelectFlags_ClearOnEscape;
ImGuiMultiSelectIO* ms_io = ImGui::BeginMultiSelect(flags);
selection.ApplyRequests(ms_io, ITEMS_COUNT);
selection.ApplyRequests(ms_io, &selection_adapter, ITEMS_COUNT);
for (int n = 0; n < ITEMS_COUNT; n++)
{
@ -2952,7 +2994,7 @@ static void ShowDemoWindowMultiSelect()
}
ms_io = ImGui::EndMultiSelect();
selection.ApplyRequests(ms_io, ITEMS_COUNT);
selection.ApplyRequests(ms_io, &selection_adapter, ITEMS_COUNT);
ImGui::EndListBox();
}
@ -2964,6 +3006,7 @@ static void ShowDemoWindowMultiSelect()
if (ImGui::TreeNode("Multi-Select (with clipper)"))
{
static ExampleSelection selection;
ExampleSelectionAdapter selection_adapter; // Use default: Pass index to SetNextItemSelectionUserData(), store index in Selection
ImGui::Text("Added features:");
ImGui::BulletText("Using ImGuiListClipper.");
@ -2974,7 +3017,7 @@ static void ShowDemoWindowMultiSelect()
{
ImGuiMultiSelectFlags flags = ImGuiMultiSelectFlags_ClearOnEscape;
ImGuiMultiSelectIO* ms_io = ImGui::BeginMultiSelect(flags);
selection.ApplyRequests(ms_io, ITEMS_COUNT);
selection.ApplyRequests(ms_io, &selection_adapter, ITEMS_COUNT);
ImGuiListClipper clipper;
clipper.Begin(ITEMS_COUNT);
@ -2993,7 +3036,7 @@ static void ShowDemoWindowMultiSelect()
}
ms_io = ImGui::EndMultiSelect();
selection.ApplyRequests(ms_io, ITEMS_COUNT);
selection.ApplyRequests(ms_io, &selection_adapter, ITEMS_COUNT);
ImGui::EndListBox();
}
@ -3015,6 +3058,8 @@ static void ShowDemoWindowMultiSelect()
// But you may decide to store selection data inside your item (aka intrusive storage).
static ImVector<int> items;
static ExampleSelection selection;
ExampleSelectionAdapter selection_adapter;
selection_adapter.SetupForDirectIndexes(); // Pass index to SetNextItemSelectionUserData(), store index in Selection
ImGui::Text("Adding features:");
ImGui::BulletText("Dynamic list with Delete key support.");
@ -3039,7 +3084,7 @@ static void ShowDemoWindowMultiSelect()
{
ImGuiMultiSelectFlags flags = ImGuiMultiSelectFlags_ClearOnEscape;
ImGuiMultiSelectIO* ms_io = ImGui::BeginMultiSelect(flags);
selection.ApplyRequests(ms_io, items.Size);
selection.ApplyRequests(ms_io, &selection_adapter, items.Size);
// FIXME-MULTISELECT: Shortcut(). Hard to demo this? May be helpful to send a helper/optional "delete" signal.
// FIXME-MULTISELECT: may turn into 'ms_io->RequestDelete' -> need HasSelection passed.
@ -3064,7 +3109,7 @@ static void ShowDemoWindowMultiSelect()
// Apply multi-select requests
ms_io = ImGui::EndMultiSelect();
selection.ApplyRequests(ms_io, items.Size);
selection.ApplyRequests(ms_io, &selection_adapter, items.Size);
if (want_delete)
selection.ApplyDeletionPostLoop(ms_io, items);
@ -3080,6 +3125,7 @@ static void ShowDemoWindowMultiSelect()
const int SCOPES_COUNT = 3;
const int ITEMS_COUNT = 8; // Per scope
static ExampleSelection selections_data[SCOPES_COUNT];
ExampleSelectionAdapter selection_adapter; // Use default: Pass index to SetNextItemSelectionUserData(), store index in Selection
for (int selection_scope_n = 0; selection_scope_n < SCOPES_COUNT; selection_scope_n++)
{
@ -3090,7 +3136,7 @@ static void ShowDemoWindowMultiSelect()
ImGuiMultiSelectFlags flags = ImGuiMultiSelectFlags_ClearOnEscape; // | ImGuiMultiSelectFlags_ClearOnClickRectVoid
ImGuiMultiSelectIO* ms_io = ImGui::BeginMultiSelect(flags);
selection->ApplyRequests(ms_io, ITEMS_COUNT);
selection->ApplyRequests(ms_io, &selection_adapter, ITEMS_COUNT);
for (int n = 0; n < ITEMS_COUNT; n++)
{
@ -3103,7 +3149,7 @@ static void ShowDemoWindowMultiSelect()
// Apply multi-select requests
ms_io = ImGui::EndMultiSelect();
selection->ApplyRequests(ms_io, ITEMS_COUNT);
selection->ApplyRequests(ms_io, &selection_adapter, ITEMS_COUNT);
ImGui::PopID();
}
ImGui::TreePop();
@ -3147,6 +3193,7 @@ static void ShowDemoWindowMultiSelect()
static int items_next_id = 0;
if (items_next_id == 0) { for (int n = 0; n < 1000; n++) { items.push_back(items_next_id++); } }
static ExampleSelection selection;
ExampleSelectionAdapter selection_adapter; // Use default: Pass index to SetNextItemSelectionUserData(), store index in Selection
ImGui::Text("Selection size: %d/%d", selection.GetSize(), items.Size);
@ -3159,7 +3206,7 @@ static void ShowDemoWindowMultiSelect()
ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(ImGui::GetStyle().ItemSpacing.x, 0.0f));
ImGuiMultiSelectIO* ms_io = ImGui::BeginMultiSelect(flags);
selection.ApplyRequests(ms_io, items.Size);
selection.ApplyRequests(ms_io, &selection_adapter, items.Size);
// FIXME-MULTISELECT: Shortcut(). Hard to demo this? May be helpful to send a helper/optional "delete" signal.
// FIXME-MULTISELECT: may turn into 'ms_io->RequestDelete' -> need HasSelection passed.
@ -3285,7 +3332,7 @@ static void ShowDemoWindowMultiSelect()
// Apply multi-select requests
ms_io = ImGui::EndMultiSelect();
selection.ApplyRequests(ms_io, items.Size);
selection.ApplyRequests(ms_io, &selection_adapter, items.Size);
if (want_delete)
selection.ApplyDeletionPostLoop(ms_io, items);