Drezil/imgui
1
0
Fork 0
mirror of https://github.com/Drezil/imgui.git synced 2025-07-07 05:28:47 +02:00
Code Issues Packages Projects Releases Wiki Activity

ImGuiListClipper new version, detect height automatically, fix compatibility with SetScrollPosHere (#662)

Browse Source
This commit is contained in:
ocornut
2016-05-16 19:22:51 +02:00
parent fa5ae60bce
commit 7a28f5bb81
3 changed files with 156 additions and 74 deletions
Download Patch File Download Diff File Expand all files Collapse all files

155
imgui.cpp
View File

@ -1607,6 +1607,88 @@ float ImGuiSimpleColumns::CalcExtraSpace(float avail_w)
return ImMax(0.0f, avail_w - Width);
}
//-----------------------------------------------------------------------------
// ImGuiListClipper
//-----------------------------------------------------------------------------
static void SetCursorPosYAndSetupDummyPrevLine(float pos_y, float line_height)
{
// Setting those fields so that SetScrollHere() can properly function after the end of our clipper usage.
// If we end up needing more accurate data (to e.g. use SameLine) we may as well make the clipper have a fourth step to let user process and display the last item in their list.
ImGui::SetCursorPosY(pos_y);
ImGuiWindow* window = ImGui::GetCurrentWindow();
window->DC.CursorPosPrevLine.y = window->DC.CursorPos.y - line_height;
window->DC.PrevLineHeight = (line_height - GImGui->Style.ItemSpacing.y);
}
// Use case A: Begin() called from constructor with items_height<0, then called again from Sync() in StepNo 1
// Use case B: Begin() called from constructor with items_height>0
// FIXME-LEGACY: Ideally we should remove the Begin/End functions but they are part of the legacy API we still support. This is why some of the code in Step() calling Begin() and reassign some fields, spaghetti style.
void ImGuiListClipper::Begin(int count, float items_height)
{
StartPosY = ImGui::GetCursorPosY();
ItemsHeight = items_height;
ItemsCount = count;
StepNo = 0;
DisplayEnd = DisplayStart = -1;
if (ItemsHeight > 0.0f)
{
ImGui::CalcListClipping(ItemsCount, ItemsHeight, &DisplayStart, &DisplayEnd); // calculate how many to clip/display
if (DisplayStart > 0)
SetCursorPosYAndSetupDummyPrevLine(StartPosY + DisplayStart * ItemsHeight, ItemsHeight); // advance cursor
StepNo = 2;
}
}
void ImGuiListClipper::End()
{
if (ItemsCount < 0)
return;
float cur_y = ImGui::GetCursorPosY(); (void)cur_y;
float expected_display_end_y = StartPosY + DisplayEnd * ItemsHeight;
IM_ASSERT(fabsf(cur_y - expected_display_end_y) < 1.0f); // if this triggers, it probably means your items have varying height (in which case you can't use this helper) or the explicit height you have passed was incorrect.
if (ItemsCount < INT_MAX)
SetCursorPosYAndSetupDummyPrevLine(StartPosY + ItemsCount * ItemsHeight, ItemsHeight); // advance cursor
ItemsCount = -1;
StepNo = 3;
}
bool ImGuiListClipper::Step()
{
if (ItemsCount == 0 || ImGui::GetCurrentWindowRead()->SkipItems)
{
ItemsCount = -1;
return false;
}
if (StepNo == 0) // Step 0: the clipper let you process the first element, regardless of it being visible or not, so we can measure the element height.
{
DisplayStart = 0;
DisplayEnd = 1;
StartPosY = ImGui::GetCursorPosY();
StepNo = 1;
return true;
}
if (StepNo == 1) // Step 1: the clipper infer height from first element, calculate the actual range of elements to display, and position the cursor before the first element.
{
if (ItemsCount == 1) { ItemsCount = -1; return false; }
float items_height = ImGui::GetCursorPosY() - StartPosY;
IM_ASSERT(items_height > 0.0f); // If this triggers, it means Item 0 hasn't moved the cursor vertically
ImGui::SetCursorPosY(StartPosY); // Rewind cursor so we can Begin() again, this time with a known height.
Begin(ItemsCount, items_height);
StepNo = 3;
return true;
}
if (StepNo == 2) // Step 2: dummy step only required if an explicit items_height was passed to constructor or Begin() and user still call Step(). Does nothing and switch to Step 3.
{
IM_ASSERT(DisplayStart >= 0 && DisplayEnd >= 0);
StepNo = 3;
return true;
}
if (StepNo == 3) // Step 3: the clipper validate that we have reached the expected Y position (corresponding to element DisplayEnd), advance the cursor to the end of the list and then returns 'false' to end the loop.
End();
return false;
}
//-----------------------------------------------------------------------------
// ImGuiWindow
//-----------------------------------------------------------------------------
@ -2878,18 +2960,8 @@ ImVec2 ImGui::CalcTextSize(const char* text, const char* text_end, bool hide_tex
}
// Helper to calculate coarse clipping of large list of evenly sized items.
// NB: Prefer using the ImGuiListClipper higher-level helper if you can!
// NB: Prefer using the ImGuiListClipper higher-level helper if you can! Read comments and instructions there on how those use this sort of pattern.
// NB: 'items_count' is only used to clamp the result, if you don't know your count you can use INT_MAX
// If you are displaying thousands of items and you have a random access to the list, you can perform clipping yourself to save on CPU.
// {
// float item_height = ImGui::GetTextLineHeightWithSpacing();
// int display_start, display_end;
// ImGui::CalcListClipping(count, item_height, &display_start, &display_end); // calculate how many to clip/display
// ImGui::SetCursorPosY(ImGui::GetCursorPosY() + (display_start) * item_height); // advance cursor
// for (int i = display_start; i < display_end; i++) // display only visible items
// // TODO: display visible item
// ImGui::SetCursorPosY(ImGui::GetCursorPosY() + (count - display_end) * item_height); // advance cursor
// }
void ImGui::CalcListClipping(int items_count, float items_height, int* out_items_display_start, int* out_items_display_end)
{
ImGuiContext& g = *GImGui;
@ -2901,6 +2973,11 @@ void ImGui::CalcListClipping(int items_count, float items_height, int* out_items
*out_items_display_end = items_count;
return;
}
if (window->SkipItems)
{
*out_items_display_start = *out_items_display_end = 0;
return;
}
const ImVec2 pos = window->DC.CursorPos;
int start = (int)((window->ClipRect.Min.y - pos.y) / items_height);
@ -8492,22 +8569,22 @@ bool ImGui::ListBox(const char* label, int* current_item, bool (*items_getter)(v
// 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.
bool value_changed = false;
ImGuiListClipper clipper(items_count, ImGui::GetTextLineHeightWithSpacing());
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*";
ImGui::PushID(i);
if (ImGui::Selectable(item_text, item_selected))
while (clipper.Step())
for (int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++)
{
*current_item = i;
value_changed = true;
const bool item_selected = (i == *current_item);
const char* item_text;
if (!items_getter(data, i, &item_text))
item_text = "*Unknown item*";
ImGui::PushID(i);
if (ImGui::Selectable(item_text, item_selected))
{
*current_item = i;
value_changed = true;
}
ImGui::PopID();
}
ImGui::PopID();
}
clipper.End();
ImGui::ListBoxFooter();
return value_changed;
}
@ -9520,22 +9597,22 @@ void ImGui::ShowMetricsWindow(bool* p_open)
}
if (!pcmd_node_open)
continue;
ImGuiListClipper clipper(pcmd->ElemCount/3, ImGui::GetTextLineHeight()*3 + ImGui::GetStyle().ItemSpacing.y); // Manually coarse clip our print out of individual vertices to save CPU, only items that may be visible.
for (int prim = clipper.DisplayStart, vtx_i = elem_offset + clipper.DisplayStart*3; prim < clipper.DisplayEnd; prim++)
{
char buf[300], *buf_p = buf;
ImVec2 triangles_pos[3];
for (int n = 0; n < 3; n++, vtx_i++)
ImGuiListClipper clipper(pcmd->ElemCount/3); // Manually coarse clip our print out of individual vertices to save CPU, only items that may be visible.
while (clipper.Step())
for (int prim = clipper.DisplayStart, vtx_i = elem_offset + clipper.DisplayStart*3; prim < clipper.DisplayEnd; prim++)
{
ImDrawVert& v = draw_list->VtxBuffer[idx_buffer ? idx_buffer[vtx_i] : vtx_i];
triangles_pos[n] = v.pos;
buf_p += sprintf(buf_p, "%s %04d { pos = (%8.2f,%8.2f), uv = (%.6f,%.6f), col = %08X }\n", (n == 0) ? "vtx" : " ", vtx_i, v.pos.x, v.pos.y, v.uv.x, v.uv.y, v.col);
char buf[300], *buf_p = buf;
ImVec2 triangles_pos[3];
for (int n = 0; n < 3; n++, vtx_i++)
{
ImDrawVert& v = draw_list->VtxBuffer[idx_buffer ? idx_buffer[vtx_i] : vtx_i];
triangles_pos[n] = v.pos;
buf_p += sprintf(buf_p, "%s %04d { pos = (%8.2f,%8.2f), uv = (%.6f,%.6f), col = %08X }\n", (n == 0) ? "vtx" : " ", vtx_i, v.pos.x, v.pos.y, v.uv.x, v.uv.y, v.col);
}
ImGui::Selectable(buf, false);
if (ImGui::IsItemHovered())
overlay_draw_list->AddPolyline(triangles_pos, 3, IM_COL32(255,255,0,255), true, 1.0f, false); // Add triangle without AA, more readable for large-thin triangle
}
ImGui::Selectable(buf, false);
if (ImGui::IsItemHovered())
overlay_draw_list->AddPolyline(triangles_pos, 3, IM_COL32(255,255,0,255), true, 1.0f, false); // Add triangle without AA, more readable for large-thin triangle
}
clipper.End();
ImGui::TreePop();
}
overlay_draw_list->PopClipRect();