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Scrolling: Fixed edge snapping being applied prior to knowing ContentSize. (#3452)

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Fix 473a01adb.
This commit is contained in:
ocornut 2020-09-03 17:38:51 +02:00
parent 8db94cd992
commit 70289ab42c
2 changed files with 30 additions and 25 deletions
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54
imgui.cpp
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@ -7363,6 +7363,19 @@ void ImGui::EndGroup()
// [SECTION] SCROLLING
//-----------------------------------------------------------------------------
// Helper to snap on edges when aiming at an item very close to the edge,
// So the difference between WindowPadding and ItemSpacing will be in the visible area after scrolling.
// When we refactor the scrolling API this may be configurable with a flag?
// Note that the effect for this won't be visible on X axis with default Style settings as WindowPadding.x == ItemSpacing.x by default.
static float CalcScrollEdgeSnap(float target, float snap_min, float snap_max, float snap_threshold, float center_ratio)
{
if (target <= snap_min + snap_threshold)
return ImLerp(snap_min, target, center_ratio);
if (target >= snap_max - snap_threshold)
return ImLerp(target, snap_max, center_ratio);
return target;
}
static ImVec2 CalcNextScrollFromScrollTargetAndClamp(ImGuiWindow* window)
{
ImVec2 scroll = window->Scroll;
@ -7370,6 +7383,10 @@ static ImVec2 CalcNextScrollFromScrollTargetAndClamp(ImGuiWindow* window)
{
float center_x_ratio = window->ScrollTargetCenterRatio.x;
float scroll_target_x = window->ScrollTarget.x;
float snap_x_min = 0.0f;
float snap_x_max = window->ScrollMax.x + window->Size.x;
if (window->ScrollTargetEdgeSnapDist.x > 0.0f)
scroll_target_x = CalcScrollEdgeSnap(scroll_target_x, snap_x_min, snap_x_max, window->ScrollTargetEdgeSnapDist.x, center_x_ratio);
scroll.x = scroll_target_x - center_x_ratio * (window->SizeFull.x - window->ScrollbarSizes.x);
}
if (window->ScrollTarget.y < FLT_MAX)
@ -7377,6 +7394,10 @@ static ImVec2 CalcNextScrollFromScrollTargetAndClamp(ImGuiWindow* window)
float decoration_up_height = window->TitleBarHeight() + window->MenuBarHeight();
float center_y_ratio = window->ScrollTargetCenterRatio.y;
float scroll_target_y = window->ScrollTarget.y;
float snap_y_min = 0.0f;
float snap_y_max = window->ScrollMax.y + window->Size.y - decoration_up_height;
if (window->ScrollTargetEdgeSnapDist.y > 0.0f)
scroll_target_y = CalcScrollEdgeSnap(scroll_target_y, snap_y_min, snap_y_max, window->ScrollTargetEdgeSnapDist.y, center_y_ratio);
scroll.y = scroll_target_y - center_y_ratio * (window->SizeFull.y - window->ScrollbarSizes.y - decoration_up_height);
}
scroll.x = IM_FLOOR(ImMax(scroll.x, 0.0f));
@ -7447,12 +7468,14 @@ void ImGui::SetScrollX(ImGuiWindow* window, float scroll_x)
{
window->ScrollTarget.x = scroll_x;
window->ScrollTargetCenterRatio.x = 0.0f;
window->ScrollTargetEdgeSnapDist.x = 0.0f;
}
void ImGui::SetScrollY(ImGuiWindow* window, float scroll_y)
{
window->ScrollTarget.y = scroll_y;
window->ScrollTargetCenterRatio.y = 0.0f;
window->ScrollTargetEdgeSnapDist.y = 0.0f;
}
void ImGui::SetScrollX(float scroll_x)
@ -7482,6 +7505,7 @@ void ImGui::SetScrollFromPosX(ImGuiWindow* window, float local_x, float center_x
IM_ASSERT(center_x_ratio >= 0.0f && center_x_ratio <= 1.0f);
window->ScrollTarget.x = IM_FLOOR(local_x + window->Scroll.x); // Convert local position to scroll offset
window->ScrollTargetCenterRatio.x = center_x_ratio;
window->ScrollTargetEdgeSnapDist.x = 0.0f;
}
void ImGui::SetScrollFromPosY(ImGuiWindow* window, float local_y, float center_y_ratio)
@ -7490,6 +7514,7 @@ void ImGui::SetScrollFromPosY(ImGuiWindow* window, float local_y, float center_y
local_y -= window->TitleBarHeight() + window->MenuBarHeight(); // FIXME: Would be nice to have a more standardized access to our scrollable/client rect
window->ScrollTarget.y = IM_FLOOR(local_y + window->Scroll.y); // Convert local position to scroll offset
window->ScrollTargetCenterRatio.y = center_y_ratio;
window->ScrollTargetEdgeSnapDist.y = 0.0f;
}
void ImGui::SetScrollFromPosX(float local_x, float center_x_ratio)
@ -7504,19 +7529,6 @@ void ImGui::SetScrollFromPosY(float local_y, float center_y_ratio)
SetScrollFromPosY(g.CurrentWindow, local_y, center_y_ratio);
}
// Tweak: snap on edges when aiming at an item very close to the edge,
// So the difference between WindowPadding and ItemSpacing will be in the visible area after scrolling.
// When we refactor the scrolling API this may be configurable with a flag?
// Note that the effect for this won't be visible on X axis with default Style settings as WindowPadding.x == ItemSpacing.x by default.
static float CalcScrollSnap(float target, float snap_min, float snap_max, float snap_threshold, float center_ratio)
{
if (target <= snap_min + snap_threshold)
return ImLerp(snap_min, target, center_ratio);
if (target >= snap_max - snap_threshold)
return ImLerp(target, snap_max, center_ratio);
return target;
}
// center_x_ratio: 0.0f left of last item, 0.5f horizontal center of last item, 1.0f right of last item.
void ImGui::SetScrollHereX(float center_x_ratio)
{
@ -7524,14 +7536,10 @@ void ImGui::SetScrollHereX(float center_x_ratio)
ImGuiWindow* window = g.CurrentWindow;
float spacing_x = g.Style.ItemSpacing.x;
float target_pos_x = ImLerp(window->DC.LastItemRect.Min.x - spacing_x, window->DC.LastItemRect.Max.x + spacing_x, center_x_ratio);
SetScrollFromPosX(window, target_pos_x - window->Pos.x, center_x_ratio); // Convert from absolute to local pos
// Tweak: snap on edges when aiming at an item very close to the edge
const float snap_x_threshold = ImMax(0.0f, window->WindowPadding.x - spacing_x);
const float snap_x_min = window->DC.CursorStartPos.x - window->WindowPadding.x;
const float snap_x_max = window->DC.CursorStartPos.x + window->ContentSize.x + window->WindowPadding.x;
target_pos_x = CalcScrollSnap(target_pos_x, snap_x_min, snap_x_max, snap_x_threshold, center_x_ratio);
SetScrollFromPosX(window, target_pos_x - window->Pos.x, center_x_ratio); // Convert from absolute to local pos
window->ScrollTargetEdgeSnapDist.x = ImMax(0.0f, window->WindowPadding.x - spacing_x);
}
// center_y_ratio: 0.0f top of last item, 0.5f vertical center of last item, 1.0f bottom of last item.
@ -7541,14 +7549,10 @@ void ImGui::SetScrollHereY(float center_y_ratio)
ImGuiWindow* window = g.CurrentWindow;
float spacing_y = g.Style.ItemSpacing.y;
float target_pos_y = ImLerp(window->DC.CursorPosPrevLine.y - spacing_y, window->DC.CursorPosPrevLine.y + window->DC.PrevLineSize.y + spacing_y, center_y_ratio);
SetScrollFromPosY(window, target_pos_y - window->Pos.y, center_y_ratio); // Convert from absolute to local pos
// Tweak: snap on edges when aiming at an item very close to the edge
const float snap_y_threshold = ImMax(0.0f, window->WindowPadding.y - spacing_y);
const float snap_y_min = window->DC.CursorStartPos.y - window->WindowPadding.y;
const float snap_y_max = window->DC.CursorStartPos.y + window->ContentSize.y + window->WindowPadding.y;
target_pos_y = CalcScrollSnap(target_pos_y, snap_y_min, snap_y_max, snap_y_threshold, center_y_ratio);
SetScrollFromPosY(window, target_pos_y - window->Pos.y, center_y_ratio); // Convert from absolute to local pos
window->ScrollTargetEdgeSnapDist.y = ImMax(0.0f, window->WindowPadding.y - spacing_y);
}
//-----------------------------------------------------------------------------

1
imgui_internal.h
View File

@ -1585,6 +1585,7 @@ struct IMGUI_API ImGuiWindow
ImVec2 ScrollMax;
ImVec2 ScrollTarget; // target scroll position. stored as cursor position with scrolling canceled out, so the highest point is always 0.0f. (FLT_MAX for no change)
ImVec2 ScrollTargetCenterRatio; // 0.0f = scroll so that target position is at top, 0.5f = scroll so that target position is centered
ImVec2 ScrollTargetEdgeSnapDist; // 0.0f = no snapping, >0.0f snapping threshold
ImVec2 ScrollbarSizes; // Size taken by each scrollbars on their smaller axis. Pay attention! ScrollbarSizes.x == width of the vertical scrollbar, ScrollbarSizes.y = height of the horizontal scrollbar.
bool ScrollbarX, ScrollbarY; // Are scrollbars visible?
bool Active; // Set to true on Begin(), unless Collapsed