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MultiSelect: (Breaking) Use ImGuiSelectionUserData (= ImS64) instead of void* for selection user data.

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Less confusing for most users, less casting.
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ocornut 2023-08-07 12:38:24 +02:00
parent 140a2f0565
commit e82b49d2d4
4 changed files with 53 additions and 45 deletions
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38
imgui.h
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@ -265,8 +265,9 @@ typedef ImWchar32 ImWchar;
typedef ImWchar16 ImWchar;
#endif
// Multi-Selection item index or identifier when using SetNextItemSelectionUserData()/BeginMultiSelect()
// (Most users are likely to use this store an item INDEX but this may be used to store a POINTER as well.)
// Multi-Selection item index or identifier when using BeginMultiSelect()
// - Used by SetNextItemSelectionUserData() + and inside ImGuiMultiSelectIO structure.
// - Most users are likely to use this store an item INDEX but this may be used to store a POINTER as well. Read comments near ImGuiMultiSelectIO for details.
typedef ImS64 ImGuiSelectionUserData;
// Callback and functions types
@ -670,7 +671,7 @@ namespace ImGui
// Multi-selection system for Selectable() and TreeNode() functions.
// - This enables standard multi-selection/range-selection idioms (CTRL+Mouse/Keyboard, SHIFT+Mouse/Keyboard, etc.) in a way that also allow a clipper to be used.
// - Read comments near ImGuiMultiSelectIO for details.
// - ImGuiSelectionUserData is often used to store your item index. Read comments near ImGuiMultiSelectIO for details.
IMGUI_API ImGuiMultiSelectIO* BeginMultiSelect(ImGuiMultiSelectFlags flags);
IMGUI_API ImGuiMultiSelectIO* EndMultiSelect();
IMGUI_API void SetNextItemSelectionUserData(ImGuiSelectionUserData selection_user_data);
@ -2754,18 +2755,25 @@ enum ImGuiMultiSelectFlags_
// For small selection set (<100 items), you might want to not bother with using the clipper, as the cost you should
// be negligible (as least on Dear ImGui side).
// If you are not sure, always start without clipping and you can work your way to the optimized version afterwards.
// - The void* RangeSrcItem/RangeDstItem value represent a selectable object. They are the value you pass to SetNextItemSelectionUserData().
// Most likely you will want to store an index here.
// Storing an integer index is the easiest thing to do, as SetRange requests will give you two end points and you will need to interpolate
// between them to honor range selection. But the code never assume that sortable integers are used (you may store pointers to your object,
// and then from the pointer have your own way of iterating from RangeSrcItem to RangeDstItem).
// About ImGuiSelectionUserData:
// - This is your application-defined identifier in a selection set:
// - For each item is submitted by your calls to SetNextItemSelectionUserData().
// - In return we store them into RangeSrcItem/RangeDstItem and other fields ImGuiMultiSelectIO.
// - Most applications will store an object INDEX, hence the chosen name and type.
// Storing an integer index is the easiest thing to do, as SetRange requests will give you two end points
// and you will need to interpolate between them to honor range selection.
// - However it is perfectly possible to store a POINTER inside this value! The multi-selection system never assume
// that you identify items by indices, and never attempt to interpolate between two ImGuiSelectionUserData values.
// - As most users will want to cast this to integer, for convenience and to reduce confusion we use ImS64 instead
// of void*, being syntactically easier to downcast. But feel free to reinterpret_cast a pointer into this.
// - If you need to wrap this API for another language/framework, feel free to expose this as 'int' if simpler.
// Usage flow:
// BEGIN - (1) Call BeginMultiSelect() and retrieve the ImGuiMultiSelectIO* result.
// - (2) [If using clipper] Honor Clear/SelectAll/SetRange requests by updating your selection data. Same code as Step 6.
// LOOP - (3) [If using clipper] Set RangeSrcPassedBy=true if the RangeSrcItem item is part of the items clipped before the first submitted/visible item.
// This is because for range-selection we need to know if we are currently "inside" or "outside" the range.
// - If you are using integer indices, this is easy to compute: if (clipper.DisplayStart > data->RangeSrcItem) { data->RangeSrcPassedBy = true; }
// - If you are using pointers, you may need additional processing in each clipper step to tell if current DisplayStart comes after RangeSrcItem..
// - If you are using integer indices in ImGuiSelectionUserData, this is easy to compute: if (clipper.DisplayStart > data->RangeSrcItem) { data->RangeSrcPassedBy = true; }
// - If you are using pointers in ImGuiSelectionUserData, you may need additional processing in each clipper step to tell if current DisplayStart comes after RangeSrcItem..
// - (4) Submit your items with SetNextItemSelectionUserData() + Selectable()/TreeNode() calls. (optionally call IsItemToggledSelection() if you need that info immediately for displaying your item, before EndMultiSelect())
// END - (5) Call EndMultiSelect() and retrieve the ImGuiMultiSelectIO* result.
// - (6) Honor Clear/SelectAll/SetRange requests by updating your selection data. Same code as Step 2.
@ -2780,19 +2788,19 @@ struct ImGuiMultiSelectIO
bool RequestClear; // ms:w, app:r / / ms:w, app:r // 1. Request app/user to clear selection.
bool RequestSelectAll; // ms:w, app:r / / ms:w, app:r // 2. Request app/user to select all.
bool RequestSetRange; // / / ms:w, app:r // 3. Request app/user to select/unselect [RangeSrcItem..RangeDstItem] items, based on RangeSelected. In practice, only EndMultiSelect() request this, app code can read after BeginMultiSelect() and it will always be false.
void* RequestFocusItem; // app:w / app:r / app:r // (If using deletion) 4. Request user to focus item. This is actually only manipulated in user-space, but we provide storage to facilitate implementing a deletion idiom (see demo).
ImGuiSelectionUserData RequestFocusItem; // app:w / app:r / app:r // (If using deletion) 4. Request user to focus item. This is actually only manipulated in user-space, but we provide storage to facilitate implementing a deletion idiom (see demo).
// STATE/ARGUMENTS -------------------------// BEGIN / LOOP / END
void* RangeSrcItem; // ms:w / app:r / ms:w, app:r // Begin: Last known SetNextItemSelectionUserData() value for RangeSrcItem. End: parameter from RequestSetRange request.
void* RangeDstItem; // / / ms:w, app:r // End: parameter from RequestSetRange request.
ImGuiSelectionUserData RangeSrcItem; // ms:w / app:r / ms:w, app:r // Begin: Last known SetNextItemSelectionUserData() value for RangeSrcItem. End: parameter from RequestSetRange request.
ImGuiSelectionUserData RangeDstItem; // / / ms:w, app:r // End: parameter from RequestSetRange request.
ImS8 RangeDirection; // / / ms:w, app:r // End: parameter from RequestSetRange request. +1 if RangeSrcItem came before RangeDstItem, -1 otherwise. Available as an indicator in case you cannot infer order from the void* values. If your void* values are storing indices you will never need this.
bool RangeSelected; // / / ms:w, app:r // End: parameter from RequestSetRange request. true = Select Range, false = Unselect Range.
bool RangeSrcPassedBy; // / ms:rw app:w / ms:r // (If using clipper) Need to be set by app/user if RangeSrcItem was part of the clipped set before submitting the visible items. Ignore if not clipping.
bool RangeSrcReset; // app:w / app:w / ms:r // (If using deletion) Set before EndMultiSelect() to reset ResetSrcItem (e.g. if deleted selection).
bool NavIdSelected; // ms:w, app:r / / // (If using deletion) Last known selection state for NavId (if part of submitted items).
void* NavIdItem; // ms:w, app:r / / // (If using deletion) Last known SetNextItemSelectionUserData() value for NavId (if part of submitted items).
ImGuiSelectionUserData NavIdItem; // ms:w, app:r / / // (If using deletion) Last known SetNextItemSelectionUserData() value for NavId (if part of submitted items).
ImGuiMultiSelectIO() { Clear(); }
void Clear() { memset(this, 0, sizeof(*this)); RequestFocusItem = NavIdItem = RangeSrcItem = RangeDstItem = (void*)-1; }
void Clear() { memset(this, 0, sizeof(*this)); RequestFocusItem = NavIdItem = RangeSrcItem = RangeDstItem = (ImGuiSelectionUserData)-1; }
};
//-----------------------------------------------------------------------------