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Scrollbar: clicking above or below the grab scrolls by one page, hold…
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…ing mouse button repeats scrolling. (#7328, #150)

Remove absolute seeking entirely. Amend f021080.
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@ocornut
ocornut committed May 28, 2024
1 parent 479c5f6 commit 5cbc34a
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Showing 3 changed files with 34 additions and 20 deletions.
2 changes: 2 additions & 0 deletions docs/CHANGELOG.txt
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Expand Up @@ -45,6 +45,8 @@ Other changes:

- Windows: fixed altering FramePadding mid-frame not correctly affecting logic
responsible for honoring io.ConfigWindowsMoveFromTitleBarOnly. (#7576, #899)
- Scrollbar: made scrolling logic more standard: clicking above or below the
grab scrolls by one page, holding mouse button repeats scrolling. (#7328, #150)


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8 changes: 5 additions & 3 deletions imgui_internal.h
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Expand Up @@ -472,7 +472,7 @@ template<typename T> static inline T ImSubClampOverflow(T a, T b, T mn, T mx)
// - Misc maths helpers
static inline ImVec2 ImMin(const ImVec2& lhs, const ImVec2& rhs) { return ImVec2(lhs.x < rhs.x ? lhs.x : rhs.x, lhs.y < rhs.y ? lhs.y : rhs.y); }
static inline ImVec2 ImMax(const ImVec2& lhs, const ImVec2& rhs) { return ImVec2(lhs.x >= rhs.x ? lhs.x : rhs.x, lhs.y >= rhs.y ? lhs.y : rhs.y); }
static inline ImVec2 ImClamp(const ImVec2& v, const ImVec2& mn, ImVec2 mx) { return ImVec2((v.x < mn.x) ? mn.x : (v.x > mx.x) ? mx.x : v.x, (v.y < mn.y) ? mn.y : (v.y > mx.y) ? mx.y : v.y); }
static inline ImVec2 ImClamp(const ImVec2& v, const ImVec2&mn, const ImVec2&mx) { return ImVec2((v.x < mn.x) ? mn.x : (v.x > mx.x) ? mx.x : v.x, (v.y < mn.y) ? mn.y : (v.y > mx.y) ? mx.y : v.y); }
static inline ImVec2 ImLerp(const ImVec2& a, const ImVec2& b, float t) { return ImVec2(a.x + (b.x - a.x) * t, a.y + (b.y - a.y) * t); }
static inline ImVec2 ImLerp(const ImVec2& a, const ImVec2& b, const ImVec2& t) { return ImVec2(a.x + (b.x - a.x) * t.x, a.y + (b.y - a.y) * t.y); }
static inline ImVec4 ImLerp(const ImVec4& a, const ImVec4& b, float t) { return ImVec4(a.x + (b.x - a.x) * t, a.y + (b.y - a.y) * t, a.z + (b.z - a.z) * t, a.w + (b.w - a.w) * t); }
Expand Down Expand Up @@ -2162,13 +2162,14 @@ struct ImGuiContext
ImGuiComboPreviewData ComboPreviewData;
ImRect WindowResizeBorderExpectedRect; // Expected border rect, switch to relative edit if moving
bool WindowResizeRelativeMode;
short ScrollbarSeekMode; // 0: relative, -1/+1: prev/next page.
float ScrollbarClickDeltaToGrabCenter; // Distance between mouse and center of grab box, normalized in parent space. Use storage?
float SliderGrabClickOffset;
float SliderCurrentAccum; // Accumulated slider delta when using navigation controls.
bool SliderCurrentAccumDirty; // Has the accumulated slider delta changed since last time we tried to apply it?
bool DragCurrentAccumDirty;
float DragCurrentAccum; // Accumulator for dragging modification. Always high-precision, not rounded by end-user precision settings
float DragSpeedDefaultRatio; // If speed == 0.0f, uses (max-min) * DragSpeedDefaultRatio
float ScrollbarClickDeltaToGrabCenter; // Distance between mouse and center of grab box, normalized in parent space. Use storage?
float DisabledAlphaBackup; // Backup for style.Alpha for BeginDisabled()
short DisabledStackSize;
short LockMarkEdited;
Expand Down Expand Up @@ -2376,13 +2377,14 @@ struct ImGuiContext
ColorEditSavedHue = ColorEditSavedSat = 0.0f;
ColorEditSavedColor = 0;
WindowResizeRelativeMode = false;
ScrollbarSeekMode = 0;
ScrollbarClickDeltaToGrabCenter = 0.0f;
SliderGrabClickOffset = 0.0f;
SliderCurrentAccum = 0.0f;
SliderCurrentAccumDirty = false;
DragCurrentAccumDirty = false;
DragCurrentAccum = 0.0f;
DragSpeedDefaultRatio = 1.0f / 100.0f;
ScrollbarClickDeltaToGrabCenter = 0.0f;
DisabledAlphaBackup = 0.0f;
DisabledStackSize = 0;
LockMarkEdited = 0;
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44 changes: 27 additions & 17 deletions imgui_widgets.cpp
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Expand Up @@ -916,10 +916,10 @@ void ImGui::Scrollbar(ImGuiAxis axis)
if (!window->ScrollbarX)
rounding_corners |= ImDrawFlags_RoundCornersBottomRight;
}
float size_avail = window->InnerRect.Max[axis] - window->InnerRect.Min[axis];
float size_visible = window->InnerRect.Max[axis] - window->InnerRect.Min[axis];
float size_contents = window->ContentSize[axis] + window->WindowPadding[axis] * 2.0f;
ImS64 scroll = (ImS64)window->Scroll[axis];
ScrollbarEx(bb, id, axis, &scroll, (ImS64)size_avail, (ImS64)size_contents, rounding_corners);
ScrollbarEx(bb, id, axis, &scroll, (ImS64)size_visible, (ImS64)size_contents, rounding_corners);
window->Scroll[axis] = (float)scroll;
}

Expand All @@ -929,7 +929,7 @@ void ImGui::Scrollbar(ImGuiAxis axis)
// - We store values as normalized ratio and in a form that allows the window content to change while we are holding on a scrollbar
// - We handle both horizontal and vertical scrollbars, which makes the terminology not ideal.
// Still, the code should probably be made simpler..
bool ImGui::ScrollbarEx(const ImRect& bb_frame, ImGuiID id, ImGuiAxis axis, ImS64* p_scroll_v, ImS64 size_avail_v, ImS64 size_contents_v, ImDrawFlags flags)
bool ImGui::ScrollbarEx(const ImRect& bb_frame, ImGuiID id, ImGuiAxis axis, ImS64* p_scroll_v, ImS64 size_visible_v, ImS64 size_contents_v, ImDrawFlags flags)
{
ImGuiContext& g = *GImGui;
ImGuiWindow* window = g.CurrentWindow;
Expand Down Expand Up @@ -959,9 +959,9 @@ bool ImGui::ScrollbarEx(const ImRect& bb_frame, ImGuiID id, ImGuiAxis axis, ImS6

// Calculate the height of our grabbable box. It generally represent the amount visible (vs the total scrollable amount)
// But we maintain a minimum size in pixel to allow for the user to still aim inside.
IM_ASSERT(ImMax(size_contents_v, size_avail_v) > 0.0f); // Adding this assert to check if the ImMax(XXX,1.0f) is still needed. PLEASE CONTACT ME if this triggers.
const ImS64 win_size_v = ImMax(ImMax(size_contents_v, size_avail_v), (ImS64)1);
const float grab_h_pixels = ImClamp(scrollbar_size_v * ((float)size_avail_v / (float)win_size_v), style.GrabMinSize, scrollbar_size_v);
IM_ASSERT(ImMax(size_contents_v, size_visible_v) > 0.0f); // Adding this assert to check if the ImMax(XXX,1.0f) is still needed. PLEASE CONTACT ME if this triggers.
const ImS64 win_size_v = ImMax(ImMax(size_contents_v, size_visible_v), (ImS64)1);
const float grab_h_pixels = ImClamp(scrollbar_size_v * ((float)size_visible_v / (float)win_size_v), style.GrabMinSize, scrollbar_size_v);
const float grab_h_norm = grab_h_pixels / scrollbar_size_v;

// Handle input right away. None of the code of Begin() is relying on scrolling position before calling Scrollbar().
Expand All @@ -970,7 +970,7 @@ bool ImGui::ScrollbarEx(const ImRect& bb_frame, ImGuiID id, ImGuiAxis axis, ImS6
ItemAdd(bb_frame, id, NULL, ImGuiItemFlags_NoNav);
ButtonBehavior(bb, id, &hovered, &held, ImGuiButtonFlags_NoNavFocus);

const ImS64 scroll_max = ImMax((ImS64)1, size_contents_v - size_avail_v);
const ImS64 scroll_max = ImMax((ImS64)1, size_contents_v - size_visible_v);
float scroll_ratio = ImSaturate((float)*p_scroll_v / (float)scroll_max);
float grab_v_norm = scroll_ratio * (scrollbar_size_v - grab_h_pixels) / scrollbar_size_v; // Grab position in normalized space
if (held && allow_interaction && grab_h_norm < 1.0f)
Expand All @@ -981,29 +981,39 @@ bool ImGui::ScrollbarEx(const ImRect& bb_frame, ImGuiID id, ImGuiAxis axis, ImS6
// Click position in scrollbar normalized space (0.0f->1.0f)
const float clicked_v_norm = ImSaturate((mouse_pos_v - scrollbar_pos_v) / scrollbar_size_v);

bool seek_absolute = false;
const int held_dir = (clicked_v_norm < grab_v_norm) ? -1 : (clicked_v_norm > grab_v_norm + grab_h_norm) ? +1 : 0;
if (g.ActiveIdIsJustActivated)
{
// On initial click calculate the distance between mouse and the center of the grab
seek_absolute = (clicked_v_norm < grab_v_norm || clicked_v_norm > grab_v_norm + grab_h_norm);
if (seek_absolute)
g.ScrollbarClickDeltaToGrabCenter = 0.0f;
else
g.ScrollbarClickDeltaToGrabCenter = clicked_v_norm - grab_v_norm - grab_h_norm * 0.5f;
g.ScrollbarSeekMode = (short)held_dir;
g.ScrollbarClickDeltaToGrabCenter = (g.ScrollbarSeekMode == 0.0f) ? clicked_v_norm - grab_v_norm - grab_h_norm * 0.5f : 0.0f;
}

// Apply scroll (p_scroll_v will generally point on one member of window->Scroll)
// It is ok to modify Scroll here because we are being called in Begin() after the calculation of ContentSize and before setting up our starting position
const float scroll_v_norm = ImSaturate((clicked_v_norm - g.ScrollbarClickDeltaToGrabCenter - grab_h_norm * 0.5f) / (1.0f - grab_h_norm));
*p_scroll_v = (ImS64)(scroll_v_norm * scroll_max);
if (g.ScrollbarSeekMode == 0)
{
// Absolute seeking
const float scroll_v_norm = ImSaturate((clicked_v_norm - g.ScrollbarClickDeltaToGrabCenter - grab_h_norm * 0.5f) / (1.0f - grab_h_norm));
*p_scroll_v = (ImS64)(scroll_v_norm * scroll_max);
}
else
{
// Page by page
if (IsMouseClicked(ImGuiMouseButton_Left, ImGuiInputFlags_Repeat) && held_dir == g.ScrollbarSeekMode)
{
float page_dir = (g.ScrollbarSeekMode > 0.0f) ? +1.0f : -1.0f;
*p_scroll_v = ImClamp(*p_scroll_v + (ImS64)(page_dir * size_visible_v), (ImS64)0, scroll_max);
}
}

// Update values for rendering
scroll_ratio = ImSaturate((float)*p_scroll_v / (float)scroll_max);
grab_v_norm = scroll_ratio * (scrollbar_size_v - grab_h_pixels) / scrollbar_size_v;

// Update distance to grab now that we have seek'ed and saturated
if (seek_absolute)
g.ScrollbarClickDeltaToGrabCenter = clicked_v_norm - grab_v_norm - grab_h_norm * 0.5f;
//if (seek_absolute)
// g.ScrollbarClickDeltaToGrabCenter = clicked_v_norm - grab_v_norm - grab_h_norm * 0.5f;
}

// Render
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