imgui

Class ImGuiListClipper

java.lang.Object

imgui.binding.ImGuiStruct

imgui.binding.ImGuiStructDestroyable

imgui.ImGuiListClipper

public final class ImGuiListClipper
extends ImGuiStructDestroyable

Helper: Manually clip large list of items. If you have lots evenly spaced items and you have random access to the list, you can perform coarse clipping based on visibility to only submit items that are in view. The clipper calculates the range of visible items and advance the cursor to compensate for the non-visible items we have skipped. (Dear ImGui already clip items based on their bounds but: it needs to first layout the item to do so, and generally fetching/submitting your own data incurs additional cost. Coarse clipping using ImGuiListClipper allows you to easily scale using lists with tens of thousands of items without a problem) Usage:

  ImGuiListClipper clipper;
  clipper.Begin(1000);         // We have 1000 elements, evenly spaced.
  while (clipper.Step())
  for (int i = clipper.DisplayStart; i  < clipper.DisplayEnd; i++)
  ImGui::Text("line number %d", i);
 

Generally what happens is: - Clipper lets you process the first element (DisplayStart = 0, DisplayEnd = 1) regardless of it being visible or not. - User code submit that one element. - Clipper can measure the height of the first element - Clipper calculate the actual range of elements to display based on the current clipping rectangle, position the cursor before the first visible element. - User code submit visible elements. - The clipper also handles various subtleties related to keyboard/gamepad navigation, wrapping etc.

Field Summary

Fields inherited from class imgui.binding.ImGuiStruct

ptr

Constructor Summary

Constructors

Constructor and Description
ImGuiListClipper()
ImGuiListClipper(long ptr)

Method Summary

Modifier and Type	Method and Description
void	begin(int itemsCount)
void	begin(int itemsCount, float itemsHeight)
protected long	create()
void	end() Automatically called on the last call of Step() that returns false.
static void	forEach(java.util.function.Consumer<ImGuiListClipper> clipAction) Shortcut to use ImGuiListClipper instance.
static void	forEach(int itemsCount, ImListClipperCallback callback)
static void	forEach(int itemsCount, int itemsHeight, ImListClipperCallback callback)
ImGuiContext	getCtx() Parent UI context
int	getDisplayEnd()
int	getDisplayStart()
int	getItemsCount()
float	getItemsHeight()
float	getStartPosY()
void	includeItemByIndex(int itemIndex) Call IncludeItemByIndex() or IncludeItemsByIndex() *BEFORE* first call to Step() if you need a range of items to not be clipped, regardless of their visibility.
void	includeItemsByIndex(int itemBegin, int itemEnd) Call IncludeItemByIndex() or IncludeItemsByIndex() *BEFORE* first call to Step() if you need a range of items to not be clipped, regardless of their visibility.
void	setCtx(ImGuiContext value) Parent UI context
void	setDisplayEnd(int value)
void	setDisplayStart(int value)
boolean	step() Call until it returns false.

Methods inherited from class imgui.binding.ImGuiStructDestroyable

destroy

Methods inherited from class imgui.binding.ImGuiStruct

isNotValidPtr, isValidPtr

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ImGuiListClipper

public ImGuiListClipper()

ImGuiListClipper

public ImGuiListClipper(long ptr)

Method Detail

create

protected long create()

Specified by:

create in class ImGuiStructDestroyable

getCtx

public ImGuiContext getCtx()

Parent UI context

setCtx

public void setCtx(ImGuiContext value)

Parent UI context

getDisplayStart

public int getDisplayStart()

setDisplayStart

public void setDisplayStart(int value)

getDisplayEnd

public int getDisplayEnd()

setDisplayEnd

public void setDisplayEnd(int value)

getItemsCount

public int getItemsCount()

getItemsHeight

public float getItemsHeight()

getStartPosY

public float getStartPosY()

begin

public void begin(int itemsCount)

begin

public void begin(int itemsCount,
                  float itemsHeight)

end

public void end()

Automatically called on the last call of Step() that returns false.

step

public boolean step()

Call until it returns false. The DisplayStart/DisplayEnd fields will be set and you can process/draw those items.

includeItemByIndex

public void includeItemByIndex(int itemIndex)

Call IncludeItemByIndex() or IncludeItemsByIndex() *BEFORE* first call to Step() if you need a range of items to not be clipped, regardless of their visibility. (Due to alignment / padding of certain items it is possible that an extra item may be included on either end of the display range).

includeItemsByIndex

public void includeItemsByIndex(int itemBegin,
                                int itemEnd)

Call IncludeItemByIndex() or IncludeItemsByIndex() *BEFORE* first call to Step() if you need a range of items to not be clipped, regardless of their visibility. (Due to alignment / padding of certain items it is possible that an extra item may be included on either end of the display range).

Parameters:

itemEnd - is exclusive e.g. use (42, 42+1) to make item 42 never clipped.

forEach

public static void forEach(java.util.function.Consumer<ImGuiListClipper> clipAction)

Shortcut to use ImGuiListClipper instance.

Parameters:

clipAction - action to use inside the ImGuiListClipper instance

forEach

public static void forEach(int itemsCount,
                           ImListClipperCallback callback)

Parameters:

itemsCount - Use -1 to ignore (you can call Begin later). Use INT_MAX if you don't know how many items you have (in which case the cursor won't be advanced in the final step).

callback - action to do in iterations

forEach

public static void forEach(int itemsCount,
                           int itemsHeight,
                           ImListClipperCallback callback)

Parameters:

itemsCount - Use -1 to ignore (you can call Begin later). Use INT_MAX if you don't know how many items you have (in which case the cursor won't be advanced in the final step).

itemsHeight - Use -1.0f to be calculated automatically on first step. Otherwise, pass in the distance between your items, typically GetTextLineHeightWithSpacing() or GetFrameHeightWithSpacing().

callback - action to do in iterations