Drag and Drop: can use BeginDragDropSource() for other than the left mouse button (#1637, #3885)

As long as the item has an ID (for ID-less items will add new functionalities later.
Amend 2c3c5125
This commit is contained in:
ocornut
2021-03-08 15:44:56 +01:00
parent e842b196df
commit 954b06afe2
4 changed files with 37 additions and 17 deletions

View File

@ -3024,6 +3024,7 @@ void ImGui::SetActiveID(ImGuiID id, ImGuiWindow* window)
g.ActiveIdTimer = 0.0f;
g.ActiveIdHasBeenPressedBefore = false;
g.ActiveIdHasBeenEditedBefore = false;
g.ActiveIdMouseButton = -1;
if (id != 0)
{
g.LastActiveId = id;
@ -9643,27 +9644,45 @@ void ImGui::ClearDragDrop()
memset(&g.DragDropPayloadBufLocal, 0, sizeof(g.DragDropPayloadBufLocal));
}
// Call when current ID is active.
// When this returns true you need to: a) call SetDragDropPayload() exactly once, b) you may render the payload visual/description, c) call EndDragDropSource()
// If the item has an identifier:
// - This assume/require the item to be activated (typically via ButtonBehavior).
// - Therefore if you want to use this with a mouse button other than left mouse button, it is up to the item itself to activate with another button.
// - We then pull and use the mouse button that was used to activate the item and use it to carry on the drag.
// If the item has no identifier:
// - Currently always assume left mouse button.
bool ImGui::BeginDragDropSource(ImGuiDragDropFlags flags)
{
ImGuiContext& g = *GImGui;
ImGuiWindow* window = g.CurrentWindow;
// FIXME-DRAGDROP: While in the common-most "drag from non-zero active id" case we can tell the mouse button,
// in both SourceExtern and id==0 cases we may requires something else (explicit flags or some heuristic).
ImGuiMouseButton mouse_button = ImGuiMouseButton_Left;
bool source_drag_active = false;
ImGuiID source_id = 0;
ImGuiID source_parent_id = 0;
ImGuiMouseButton mouse_button = ImGuiMouseButton_Left;
if (!(flags & ImGuiDragDropFlags_SourceExtern))
{
source_id = window->DC.LastItemId;
if (source_id != 0 && g.ActiveId != source_id) // Early out for most common case
return false;
if (g.IO.MouseDown[mouse_button] == false)
return false;
if (source_id == 0)
if (source_id != 0)
{
// Common path: items with ID
if (g.ActiveId != source_id)
return false;
if (g.ActiveIdMouseButton != -1)
mouse_button = g.ActiveIdMouseButton;
if (g.IO.MouseDown[mouse_button] == false)
return false;
g.ActiveIdAllowOverlap = false;
}
else
{
// Uncommon path: items without ID
if (g.IO.MouseDown[mouse_button] == false)
return false;
// If you want to use BeginDragDropSource() on an item with no unique identifier for interaction, such as Text() or Image(), you need to:
// A) Read the explanation below, B) Use the ImGuiDragDropFlags_SourceAllowNullID flag, C) Swallow your programmer pride.
if (!(flags & ImGuiDragDropFlags_SourceAllowNullID))
@ -9690,10 +9709,6 @@ bool ImGui::BeginDragDropSource(ImGuiDragDropFlags flags)
if (g.ActiveId == source_id) // Allow the underlying widget to display/return hovered during the mouse release frame, else we would get a flicker.
g.ActiveIdAllowOverlap = is_hovered;
}
else
{
g.ActiveIdAllowOverlap = false;
}
if (g.ActiveId != source_id)
return false;
source_parent_id = window->IDStack.back();
@ -9896,7 +9911,7 @@ const ImGuiPayload* ImGui::AcceptDragDropPayload(const char* type, ImGuiDragDrop
flags |= (g.DragDropSourceFlags & ImGuiDragDropFlags_AcceptNoDrawDefaultRect); // Source can also inhibit the preview (useful for external sources that lives for 1 frame)
if (!(flags & ImGuiDragDropFlags_AcceptNoDrawDefaultRect) && payload.Preview)
{
// FIXME-DRAG: Settle on a proper default visuals for drop target.
// FIXME-DRAGDROP: Settle on a proper default visuals for drop target.
r.Expand(3.5f);
bool push_clip_rect = !window->ClipRect.Contains(r);
if (push_clip_rect) window->DrawList->PushClipRect(r.Min - ImVec2(1, 1), r.Max + ImVec2(1, 1));