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ListBox: tweaked default height calculation. simplifying code internally (rework passing of full rect). Should have no visible side-effects + misc comments.

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This commit is contained in:
ocornut
2021-02-03 14:16:08 +01:00
parent 90a518c501
commit e5cbf60def
5 changed files with 35 additions and 35 deletions
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47
imgui_widgets.cpp
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@ -6129,12 +6129,12 @@ bool ImGui::Selectable(const char* label, bool* p_selected, ImGuiSelectableFlags
// - ListBoxFooter()
//-------------------------------------------------------------------------
// FIXME: This is an old API. We should redesign some of it, rename ListBoxHeader->BeginListBox, ListBoxFooter->EndListBox
// and promote using them over existing ListBox() functions, similarly to change with combo boxes.
// and promote using them over existing ListBox() functions, similarly to how we now use combo boxes.
//-------------------------------------------------------------------------
// FIXME: In principle this function should be called BeginListBox(). We should rename it after re-evaluating if we want to keep the same signature.
// Helper to calculate the size of a listbox and display a label on the right.
// Tip: To have a list filling the entire window width, PushItemWidth(-1) and pass an non-visible label e.g. "##empty"
// Tip: To have a list filling the entire window width, use size.x = -FLT_MIN and pass an non-visible label e.g. "##empty"
// Tip: If your vertical size is calculated from an item count (e.g. 10 * item_height) consider adding a fractional part to facilitate seeing scrolling boundaries (e.g. 10.25 * item_height).
bool ImGui::ListBoxHeader(const char* label, const ImVec2& size_arg)
{
ImGuiContext& g = *GImGui;
@ -6146,12 +6146,12 @@ bool ImGui::ListBoxHeader(const char* label, const ImVec2& size_arg)
const ImGuiID id = GetID(label);
const ImVec2 label_size = CalcTextSize(label, NULL, true);
// Size default to hold ~7 items. Fractional number of items helps seeing that we can scroll down/up without looking at scrollbar.
ImVec2 size = CalcItemSize(size_arg, CalcItemWidth(), GetTextLineHeightWithSpacing() * 7.4f + style.ItemSpacing.y);
// Size default to hold ~7.25 items.
// Fractional number of items helps seeing that we can scroll down/up without looking at scrollbar.
ImVec2 size = ImFloor(CalcItemSize(size_arg, CalcItemWidth(), GetTextLineHeightWithSpacing() * 7.25f + style.FramePadding.y * 2.0f));
ImVec2 frame_size = ImVec2(size.x, ImMax(size.y, label_size.y));
ImRect frame_bb(window->DC.CursorPos, window->DC.CursorPos + frame_size);
ImRect bb(frame_bb.Min, frame_bb.Max + ImVec2(label_size.x > 0.0f ? style.ItemInnerSpacing.x + label_size.x : 0.0f, 0.0f));
window->DC.LastItemRect = bb; // Forward storage for ListBoxFooter.. dodgy.
g.NextItemData.ClearFlags();
if (!IsRectVisible(bb.Min, bb.Max))
@ -6161,50 +6161,46 @@ bool ImGui::ListBoxHeader(const char* label, const ImVec2& size_arg)
return false;
}
// FIXME-OPT: We could omit the BeginGroup() if label_size.x but would need to omit the EndGroup() as well.
BeginGroup();
if (label_size.x > 0)
RenderText(ImVec2(frame_bb.Max.x + style.ItemInnerSpacing.x, frame_bb.Min.y + style.FramePadding.y), label);
if (label_size.x > 0.0f)
{
ImVec2 label_pos = ImVec2(frame_bb.Max.x + style.ItemInnerSpacing.x, frame_bb.Min.y + style.FramePadding.y);
RenderText(label_pos, label);
window->DC.CursorMaxPos = ImMax(window->DC.CursorMaxPos, label_pos + label_size);
}
BeginChildFrame(id, frame_bb.GetSize());
return true;
}
// FIXME: In principle this function should be called EndListBox(). We should rename it after re-evaluating if we want to keep the same signature.
// FIXME: In principle this function should be called BeginListBox(). We should rename it after re-evaluating if we want to keep the same signature.
bool ImGui::ListBoxHeader(const char* label, int items_count, int height_in_items)
{
// Size default to hold ~7.25 items.
// We add +25% worth of item height to allow the user to see at a glance if there are more items up/down, without looking at the scrollbar.
// We don't add this extra bit if items_count <= height_in_items. It is slightly dodgy, because it means a dynamic list of items will make the widget resize occasionally when it crosses that size.
// I am expecting that someone will come and complain about this behavior in a remote future, then we can advise on a better solution.
ImGuiContext& g = *GImGui;
if (height_in_items < 0)
height_in_items = ImMin(items_count, 7);
const ImGuiStyle& style = GetStyle();
float height_in_items_f = (height_in_items < items_count) ? (height_in_items + 0.25f) : (height_in_items + 0.00f);
// We include ItemSpacing.y so that a list sized for the exact number of items doesn't make a scrollbar appears. We could also enforce that by passing a flag to BeginChild().
ImVec2 size;
size.x = 0.0f;
size.y = ImFloor(GetTextLineHeightWithSpacing() * height_in_items_f + style.FramePadding.y * 2.0f);
size.y = GetTextLineHeightWithSpacing() * height_in_items_f + g.Style.FramePadding.y * 2.0f;
return ListBoxHeader(label, size);
}
// FIXME: In principle this function should be called EndListBox(). We should rename it after re-evaluating if we want to keep the same signature.
void ImGui::ListBoxFooter()
{
ImGuiWindow * window = GetCurrentWindow();
ImGuiContext& g = *GImGui;
ImGuiWindow* window = g.CurrentWindow;
IM_ASSERT((window->Flags & ImGuiWindowFlags_ChildWindow) && "Mismatched ListBoxHeader/ListBoxFooter calls. Did you test the return value of ListBoxHeader()?");
ImGuiWindow* parent_window = window->ParentWindow;
const ImRect bb = parent_window->DC.LastItemRect;
const ImGuiStyle& style = GetStyle();
EndChildFrame();
// Redeclare item size so that it includes the label (we have stored the full size in LastItemRect)
// We call SameLine() to restore DC.CurrentLine* data
SameLine();
parent_window->DC.CursorPos = bb.Min;
ItemSize(bb, style.FramePadding.y);
EndGroup();
EndGroup(); // This is only required to be able to do IsItemXXX query on the whole ListBox including label
}
bool ImGui::ListBox(const char* label, int* current_item, const char* const items[], int items_count, int height_items)
@ -6218,7 +6214,8 @@ bool ImGui::ListBox(const char* label, int* current_item, bool (*items_getter)(v
if (!ListBoxHeader(label, items_count, height_in_items))
return false;
// Assume all items have even height (= 1 line of text). If you need items of different or variable sizes you can create a custom version of ListBox() in your code without using the clipper.
// Assume all items have even height (= 1 line of text). If you need items of different height,
// you can create a custom version of ListBox() in your code without using the clipper.
ImGuiContext& g = *GImGui;
bool value_changed = false;
ImGuiListClipper clipper;
@ -6226,12 +6223,12 @@ bool ImGui::ListBox(const char* label, int* current_item, bool (*items_getter)(v
while (clipper.Step())
for (int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++)
{
const bool item_selected = (i == *current_item);
const char* item_text;
if (!items_getter(data, i, &item_text))
item_text = "*Unknown item*";
PushID(i);
const bool item_selected = (i == *current_item);
if (Selectable(item_text, item_selected))
{
*current_item = i;