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RangeSelect/MultiSelect: Comments. Tweak demo.

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omar 2020-04-01 20:14:51 +02:00 committed by ocornut
parent 4c376cb3e5
commit f68e03d92e
3 changed files with 41 additions and 31 deletions
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35
imgui.h
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@ -2342,31 +2342,36 @@ struct ImGuiListClipper
};
// Abstract:
// - This system implements standard multi-selection idioms (CTRL+Click/Arrow, SHIFT+Click/Arrow, etc) in a way that allow items to be
// fully clipped (= not submitted at all) when not visible. Clipping is typically provided by ImGuiListClipper.
// - This system helps you implements standard multi-selection idioms (CTRL+Click/Arrow, SHIFT+Click/Arrow, etc) in a way that allow
// selectable items to be fully clipped (= not submitted at all) when not visible. Clipping is typically provided by ImGuiListClipper.
// Handling all of this in a single pass imgui is a little tricky, and this is why we provide those functionalities.
// Note however that if you don't need SHIFT+Click/Arrow range-select, you can handle a simpler form of multi-selection yourself,
// by reacting to click/presses on Selectable() items and checking keyboard modifiers.
// The complexity of this system here is mostly caused by the handling of range-select while optionally allowing to clip elements.
// Note however that if you don't need SHIFT+Click/Arrow range-select + clipping, you can handle a simpler form of multi-selection
// yourself, by reacting to click/presses on Selectable() items and checking keyboard modifiers.
// The unusual complexity of this system is mostly caused by supporting SHIFT+Click/Arrow range-select with clipped elements.
// - TreeNode() and Selectable() are supported.
// - The work involved to deal with multi-selection differs whether you want to only submit visible items (and clip others) or submit all items
// regardless of their visibility. Clipping items is more efficient and will allow you to deal with large lists (1k~100k items) with near zero
// performance penalty, but requires a little more work on the code. If you only have a few hundreds elements in your possible selection set,
// you may as well not bother with clipping, as the cost should be negligible (as least on imgui side).
// you may as well not bother with clipping, as the cost 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 more optimized version afterwards.
// - The void* Src/Dst value represent a selectable object. They are the values you pass to SetNextItemSelectionData().
// Storing an integer index is the easiest thing to do, as SetRange requests will give you two end points. But the code never assume that sortable integers are used.
// - In the spirit of imgui design, your code own the selection data. So this is designed to handle all kind of selection data: instructive (store a bool inside each object),
// external array (store an array aside from your objects), set (store only selected items in a hash/map/set), using intervals (store indices in an interval tree), etc.
// - The void* RangeSrc/RangeDst value represent a selectable object. They are the values you pass to SetNextItemSelectionData().
// 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 RangeSrc to RangeDst).
// - In the spirit of Dear ImGui design, your code own the selection data. So this is designed to handle all kind of selection data:
// e.g. instructive selection (store a bool inside each object), external array (store an array aside from your objects),
// hash/map/set (store only selected items in a hash/map/set), or other structures (store indices in an interval tree), etc.
// Usage flow:
// 1) Call BeginMultiSelect() with the last saved value of ->RangeSrc and its selection status. As a default value for the initial frame or when,
// resetting your selection state: you may use the value for your first item or a "null" value that matches the type stored in your void*.
// 1) Call BeginMultiSelect() with the last saved value of ->RangeSrc and its selection state.
// It is because you need to pass its selection state (and you own selection) that we don't store this value in Dear ImGui.
// (For the initial frame or when resetting your selection state: you may use the value for your first item or a "null" value that matches the type stored in your void*).
// 2) Honor Clear/SelectAll requests by updating your selection data. [Only required if you are using a clipper in step 4]
// 3) Set RangeSrcPassedBy=true if the RangeSrc item is part of the items clipped before the first submitted/visible item. [Only required if you are using a clipper in step 4]
// 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 everywhere, this is easy to compute: if (clipper.DisplayStart > (int)data->RangeSrc) { data->RangeSrcPassedBy = true; }
// 4) Submit your items with SetNextItemSelectionData() + Selectable()/TreeNode() calls.
// Call IsItemSelectionToggled() to query with the selection state has been toggled, in which you need the info immediately (before EndMultiSelect()) for your display.
// When cannot reliably return a "IsItemSelected()" value because we need to consider clipped (unprocessed) item, this is why we return a toggle event instead.
// Call IsItemToggledSelection() to query if the selection state has been toggled, if you need the info immediately for your display (before EndMultiSelect()).
// When cannot return a "IsItemSelected()" value because we need to consider clipped/unprocessed items, this is why we return a "Toggle" event instead.
// 5) Call EndMultiSelect(). Save the value of ->RangeSrc for the next frame (you may convert the value in a format that is safe for persistance)
// 6) Honor Clear/SelectAll/SetRange requests by updating your selection data. Always process them in this order (as you will receive Clear+SetRange request simultaneously)
// If you submit all items (no clipper), Step 2 and 3 and will be handled by Selectable() on a per-item basis.
@ -2376,7 +2381,7 @@ struct ImGuiMultiSelectData
bool RequestClear; // Begin, End // Request user to clear selection
bool RequestSelectAll; // Begin, End // Request user to select all
bool RequestSetRange; // End // Request user to set or clear selection in the [RangeSrc..RangeDst] range
bool RangeSrcPassedBy; // After Begin // Need to be set by user is RangeSrc was part of the clipped set before submitting the visible items. Ignore if not clipping.
bool RangeSrcPassedBy; // In loop // (If clipping) Need to be set by user if RangeSrc was part of the clipped set before submitting the visible items. Ignore if not clipping.
bool RangeValue; // End // End: parameter from RequestSetRange request. True = Select Range, False = Unselect range.
void* RangeSrc; // Begin, End // End: parameter from RequestSetRange request + you need to save this value so you can pass it again next frame. / Begin: this is the value you passed to BeginMultiSelect()
void* RangeDst; // End // End: parameter from RequestSetRange request.

27
imgui_demo.cpp
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@ -566,12 +566,15 @@ void ImGui::ShowDemoWindow(bool* p_open)
// are generally appropriate. Even a large array of bool might work for you...
// - If you need to handle extremely large selections, it might be advantageous to support a "negative" mode in
// your storage, so "Select All" becomes "Negative=1, Clear" and then sparse unselect can add to the storage.
struct ExampleSelectionData
// About RefItem:
// - The MultiSelect API requires you to store information about the reference/pivot item (generally the last clicked item).
struct ExampleSelection
{
ImGuiStorage Storage;
int SelectionSize; // Number of selected items (== number of 1 in the Storage)
int SelectionSize; // Number of selected items (== number of 1 in the Storage, maintained by this class)
int RangeRef; // Reference/pivot item (generally last clicked item)
ExampleSelectionData() { Clear(); }
ExampleSelection() { RangeRef = 0; Clear(); }
void Clear() { Storage.Clear(); SelectionSize = 0; }
bool GetSelected(int n) const { return Storage.GetInt((ImGuiID)n, 0) != 0; }
void SetSelected(int n, bool v) { int* p_int = Storage.GetIntRef((ImGuiID)n, 0); if (*p_int == (int)v) return; if (v) SelectionSize++; else SelectionSize--; *p_int = (bool)v; }
@ -1252,8 +1255,7 @@ static void ShowDemoWindowWidgets()
if (ImGui::TreeNode("Selection State: Multiple Selection (Full)"))
{
// Demonstrate holding/updating multi-selection data and using the BeginMultiSelect/EndMultiSelect API to support range-selection and clipping.
static int selection_ref = 0; // Selection pivot (last clicked item, we need to preserve this to handle range-select)
static ExampleSelectionData selection;
static ExampleSelection selection;
const char* random_names[] =
{
"Artichoke", "Arugula", "Asparagus", "Avocado", "Bamboo Shoots", "Bean Sprouts", "Beans", "Beet", "Belgian Endive", "Bell Pepper",
@ -1281,7 +1283,7 @@ static void ShowDemoWindowWidgets()
if (widget_type == WidgetType_TreeNode)
ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(ImGui::GetStyle().ItemSpacing.x, 0.0f));
ImGuiMultiSelectData* multi_select_data = ImGui::BeginMultiSelect(ImGuiMultiSelectFlags_None, (void*)(intptr_t)selection_ref, selection.GetSelected(selection_ref));
ImGuiMultiSelectData* multi_select_data = ImGui::BeginMultiSelect(ImGuiMultiSelectFlags_None, (void*)(intptr_t)selection.RangeRef, selection.GetSelected(selection.RangeRef));
if (multi_select_data->RequestClear) { selection.Clear(); }
if (multi_select_data->RequestSelectAll) { selection.SelectAll(ITEMS_COUNT); }
@ -1295,7 +1297,7 @@ static void ShowDemoWindowWidgets()
clipper.Begin(ITEMS_COUNT);
while (clipper.Step())
{
if (clipper.DisplayStart > (int)selection_ref)
if (clipper.DisplayStart > selection.RangeRef)
multi_select_data->RangeSrcPassedBy = true;
for (int n = clipper.DisplayStart; n < clipper.DisplayEnd; n++)
{
@ -1319,12 +1321,15 @@ static void ShowDemoWindowWidgets()
}
else if (widget_type == WidgetType_TreeNode)
{
ImGuiTreeNodeFlags tree_node_flags = ImGuiTreeNodeFlags_NoTreePushOnOpen | ImGuiTreeNodeFlags_SpanAvailWidth | ImGuiTreeNodeFlags_OpenOnDoubleClick;
ImGuiTreeNodeFlags tree_node_flags = ImGuiTreeNodeFlags_SpanAvailWidth;
tree_node_flags |= ImGuiTreeNodeFlags_OpenOnArrow | ImGuiTreeNodeFlags_OpenOnDoubleClick;
if (item_is_selected)
tree_node_flags |= ImGuiTreeNodeFlags_Selected;
ImGui::TreeNodeEx(label, tree_node_flags);
bool open = ImGui::TreeNodeEx(label, tree_node_flags);
if (ImGui::IsItemToggledSelection())
selection.SetSelected(n, !item_is_selected);
if (open)
ImGui::TreePop();
}
if (use_columns)
@ -1332,7 +1337,7 @@ static void ShowDemoWindowWidgets()
ImGui::NextColumn();
ImGui::SetNextItemWidth(-FLT_MIN);
ImGui::PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(0, 0));
ImGui::InputText("###NoLabel", (char*)category, strlen(category), ImGuiInputTextFlags_ReadOnly);
ImGui::InputText("###NoLabel", (char*)(void*)category, strlen(category), ImGuiInputTextFlags_ReadOnly);
ImGui::PopStyleVar();
ImGui::NextColumn();
}
@ -1346,7 +1351,7 @@ static void ShowDemoWindowWidgets()
// Apply multi-select requests
multi_select_data = ImGui::EndMultiSelect();
selection_ref = (int)(intptr_t)multi_select_data->RangeSrc;
selection.RangeRef = (int)(intptr_t)multi_select_data->RangeSrc;
if (multi_select_data->RequestClear) { selection.Clear(); }
if (multi_select_data->RequestSelectAll) { selection.SelectAll(ITEMS_COUNT); }
if (multi_select_data->RequestSetRange) { selection.SetRange((int)(intptr_t)multi_select_data->RangeSrc, (int)(intptr_t)multi_select_data->RangeDst, multi_select_data->RangeValue ? 1 : 0); }

2
imgui_widgets.cpp
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@ -5932,7 +5932,7 @@ bool ImGui::TreeNodeBehavior(ImGuiID id, ImGuiTreeNodeFlags flags, const char* l
flags |= ImGuiTreeNodeFlags_OpenOnArrow;
// To handle drag and drop of multiple items we need to avoid clearing selection on click.
// Enabling this test makes actions using CTRL+SHIFT delay their effect on the mouse release which is annoying, but it allows drag and drop of multiple items.
// Enabling this test makes actions using CTRL+SHIFT delay their effect on MouseUp which is annoying, but it allows drag and drop of multiple items.
// FIXME-MULTISELECT: Consider opt-in for drag and drop behavior in ImGuiMultiSelectFlags?
if (!selected || (g.ActiveId == id && g.ActiveIdHasBeenPressedBefore))
button_flags |= ImGuiButtonFlags_PressedOnClick;