Function ImGuiListClipper_StepInternal

KBotExt/imgui/imgui.cpp:2864–2987

}

static bool ImGuiListClipper_StepInternal(ImGuiListClipper* clipper)
{
	ImGuiContext& g = *clipper->Ctx;
	ImGuiWindow* window = g.CurrentWindow;
	ImGuiListClipperData* data = (ImGuiListClipperData*)clipper->TempData;
	IM_ASSERT(data != NULL && "Called ImGuiListClipper::Step() too many times, or before ImGuiListClipper::Begin() ?");

	ImGuiTable* table = g.CurrentTable;
	if (table && table->IsInsideRow)
		ImGui::TableEndRow(table);

	// No items
	if (clipper->ItemsCount == 0 || GetSkipItemForListClipping())
		return false;

	// While we are in frozen row state, keep displaying items one by one, unclipped
	// FIXME: Could be stored as a table-agnostic state.
	if (data->StepNo == 0 && table != NULL && !table->IsUnfrozenRows)
	{
		clipper->DisplayStart = data->ItemsFrozen;
		clipper->DisplayEnd = ImMin(data->ItemsFrozen + 1, clipper->ItemsCount);
		if (clipper->DisplayStart < clipper->DisplayEnd)
			data->ItemsFrozen++;
		return true;
	}

	// Step 0: Let you process the first element (regardless of it being visible or not, so we can measure the element height)
	bool calc_clipping = false;
	if (data->StepNo == 0)
	{
		clipper->StartPosY = window->DC.CursorPos.y;
		if (clipper->ItemsHeight <= 0.0f)
		{
			// Submit the first item (or range) so we can measure its height (generally the first range is 0..1)
			data->Ranges.push_front(ImGuiListClipperRange::FromIndices(data->ItemsFrozen, data->ItemsFrozen + 1));
			clipper->DisplayStart = ImMax(data->Ranges[0].Min, data->ItemsFrozen);
			clipper->DisplayEnd = ImMin(data->Ranges[0].Max, clipper->ItemsCount);
			data->StepNo = 1;
			return true;
		}
		calc_clipping = true;   // If on the first step with known item height, calculate clipping.
	}

	// Step 1: Let the clipper infer height from first range
	if (clipper->ItemsHeight <= 0.0f)
	{
		IM_ASSERT(data->StepNo == 1);
		if (table)
			IM_ASSERT(table->RowPosY1 == clipper->StartPosY && table->RowPosY2 == window->DC.CursorPos.y);

		clipper->ItemsHeight = (window->DC.CursorPos.y - clipper->StartPosY) / (float)(clipper->DisplayEnd - clipper->DisplayStart);
		bool affected_by_floating_point_precision = ImIsFloatAboveGuaranteedIntegerPrecision(clipper->StartPosY) || ImIsFloatAboveGuaranteedIntegerPrecision(window->DC.CursorPos.y);
		if (affected_by_floating_point_precision)
			clipper->ItemsHeight = window->DC.PrevLineSize.y + g.Style.ItemSpacing.y; // FIXME: Technically wouldn't allow multi-line entries.

		IM_ASSERT(clipper->ItemsHeight > 0.0f && "Unable to calculate item height! First item hasn't moved the cursor vertically!");
		calc_clipping = true;   // If item height had to be calculated, calculate clipping afterwards.
	}