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Feat: Different types of legend icon #680

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130 changes: 129 additions & 1 deletion implot.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -661,6 +661,134 @@ int LegendSortingComp(const void* _a, const void* _b) {
return strcmp(label_a,label_b);
}

// Marker geometry (duplicated from implot_items.cpp for legend rendering)
static const ImVec2 MARKER_FILL_CIRCLE[10] = {ImVec2(1.0f, 0.0f), ImVec2(0.809017f, 0.58778524f),ImVec2(0.30901697f, 0.95105654f),ImVec2(-0.30901703f, 0.9510565f),ImVec2(-0.80901706f, 0.5877852f),ImVec2(-1.0f, 0.0f),ImVec2(-0.80901694f, -0.58778536f),ImVec2(-0.3090171f, -0.9510565f),ImVec2(0.30901712f, -0.9510565f),ImVec2(0.80901694f, -0.5877853f)};
static const ImVec2 MARKER_FILL_SQUARE[4] = {ImVec2(1.0f, 1.0f), ImVec2(1.0f, -1.0f), ImVec2(-1.0f, -1.0f), ImVec2(-1.0f, 1.0f)};
static const ImVec2 MARKER_FILL_DIAMOND[4] = {ImVec2(1.0f, 0.0f), ImVec2(0.0f, -1.0f), ImVec2(-1.0f, 0.0f), ImVec2(0.0f, 1.0f)};
static const ImVec2 MARKER_FILL_UP[3] = {ImVec2(0.0f, 1.0f), ImVec2(-1.0f, -1.0f), ImVec2(1.0f, -1.0f)};
static const ImVec2 MARKER_FILL_DOWN[3] = {ImVec2(0.0f, -1.0f), ImVec2(-1.0f, 1.0f), ImVec2(1.0f, 1.0f)};
static const ImVec2 MARKER_FILL_LEFT[3] = {ImVec2(-1.0f, 0.0f), ImVec2(1.0f, 1.0f), ImVec2(1.0f, -1.0f)};
static const ImVec2 MARKER_FILL_RIGHT[3] = {ImVec2(1.0f, 0.0f), ImVec2(-1.0f, -1.0f), ImVec2(-1.0f, 1.0f)};

void RenderMarkerGeneral(ImDrawList& DrawList, const ImVec2& c, float size, ImPlotMarker marker, bool rend_fill, ImU32 col_fill, bool rend_line, ImU32 col_line, float weight) {
ImVec2 points[10];
int count = 0;
const ImVec2* shape = nullptr;

// Get marker shape
switch (marker) {
case ImPlotMarker_Circle: shape = MARKER_FILL_CIRCLE; count = 10; break;
case ImPlotMarker_Square: shape = MARKER_FILL_SQUARE; count = 4; break;
case ImPlotMarker_Diamond: shape = MARKER_FILL_DIAMOND; count = 4; break;
case ImPlotMarker_Up: shape = MARKER_FILL_UP; count = 3; break;
case ImPlotMarker_Down: shape = MARKER_FILL_DOWN; count = 3; break;
case ImPlotMarker_Left: shape = MARKER_FILL_LEFT; count = 3; break;
case ImPlotMarker_Right: shape = MARKER_FILL_RIGHT; count = 3; break;
default: return; // Unknown marker
}

// Transform points
for (int i = 0; i < count; ++i) {
points[i].x = c.x + shape[i].x * size;
points[i].y = c.y + shape[i].y * size;
}

// Render fill
if (rend_fill && count > 0) {
DrawList.AddConvexPolyFilled(points, count, col_fill);
}

// Render outline
if (rend_line && count > 0) {
DrawList.AddPolyline(points, count, col_line, ImDrawFlags_Closed, weight);
}

// Special cases for line-only markers
if (rend_line) {
switch (marker) {
case ImPlotMarker_Plus: {
DrawList.AddLine(ImVec2(c.x - size, c.y), ImVec2(c.x + size, c.y), col_line, weight);
DrawList.AddLine(ImVec2(c.x, c.y - size), ImVec2(c.x, c.y + size), col_line, weight);
break;
}
case ImPlotMarker_Cross: {
DrawList.AddLine(ImVec2(c.x - size, c.y - size), ImVec2(c.x + size, c.y + size), col_line, weight);
DrawList.AddLine(ImVec2(c.x + size, c.y - size), ImVec2(c.x - size, c.y + size), col_line, weight);
break;
}
case ImPlotMarker_Asterisk: {
DrawList.AddLine(ImVec2(c.x - size, c.y), ImVec2(c.x + size, c.y), col_line, weight);
DrawList.AddLine(ImVec2(c.x, c.y - size), ImVec2(c.x, c.y + size), col_line, weight);
DrawList.AddLine(ImVec2(c.x - size, c.y - size), ImVec2(c.x + size, c.y + size), col_line, weight);
DrawList.AddLine(ImVec2(c.x + size, c.y - size), ImVec2(c.x - size, c.y + size), col_line, weight);
break;
}
}
}
}

void RenderLegendIcon(ImDrawList& DrawList, const ImRect& icon_bb, const ImPlotItem* item, ImU32 col_icon) {
const float icon_center_x = (icon_bb.Min.x + icon_bb.Max.x) * 0.5f;
const float icon_center_y = (icon_bb.Min.y + icon_bb.Max.y) * 0.5f;
const ImVec2 icon_center(icon_center_x, icon_center_y);

// Extract alpha from col_icon to apply same modulation to stored colors
float alpha = ((col_icon >> IM_COL32_A_SHIFT) & 0xFF) / 255.0f;

ImU32 line_col = ImAlphaU32(item->LineColor, alpha);
ImU32 fill_col = ImAlphaU32(item->FillColor, alpha);
ImU32 marker_line_col = ImAlphaU32(item->MarkerLineColor, alpha);
ImU32 marker_fill_col = ImAlphaU32(item->MarkerFillColor, alpha);

// Render based on icon type
switch (item->LegendIconType) {
case ImPlotLegendIconType_Line: {
// Horizontal line only
ImVec2 line_start(icon_bb.Min.x, icon_center_y);
ImVec2 line_end(icon_bb.Max.x, icon_center_y);
DrawList.AddLine(line_start, line_end, line_col, item->LegendLineWeight);
break;
}
case ImPlotLegendIconType_LineMarkers: {
// Horizontal line with marker at center
ImVec2 line_start(icon_bb.Min.x, icon_center_y);
ImVec2 line_end(icon_bb.Max.x, icon_center_y);
DrawList.AddLine(line_start, line_end, line_col, item->LegendLineWeight);
const float marker_size = icon_bb.GetWidth() * 0.25f;
const bool rend_marker_fill = (item->MarkerFillColor & IM_COL32_A_MASK) != 0;
const bool rend_marker_line = (item->MarkerLineColor & IM_COL32_A_MASK) != 0;
RenderMarkerGeneral(DrawList, icon_center, marker_size, item->Marker,
rend_marker_fill, marker_fill_col, rend_marker_line, marker_line_col, item->LegendLineWeight);
break;
}
case ImPlotLegendIconType_Markers: {
// Single marker at center
const float marker_size = icon_bb.GetWidth() * 0.5f;
const bool rend_marker_fill = (item->MarkerFillColor & IM_COL32_A_MASK) != 0;
const bool rend_marker_line = (item->MarkerLineColor & IM_COL32_A_MASK) != 0;
RenderMarkerGeneral(DrawList, icon_center, marker_size, item->Marker,
rend_marker_fill, marker_fill_col, rend_marker_line, marker_line_col, item->LegendLineWeight);
break;
}
case ImPlotLegendIconType_Fill: {
// Filled square
DrawList.AddRectFilled(icon_bb.Min, icon_bb.Max, fill_col);
break;
}
case ImPlotLegendIconType_FillLine: {
// Filled square with outline
DrawList.AddRectFilled(icon_bb.Min, icon_bb.Max, fill_col);
DrawList.AddRect(icon_bb.Min, icon_bb.Max, line_col, 0.0f, 0, item->LegendLineWeight);
break;
}
default: {
// Fallback: solid square
DrawList.AddRectFilled(icon_bb.Min, icon_bb.Max, col_icon);
break;
}
}
}

bool ShowLegendEntries(ImPlotItemGroup& items, const ImRect& legend_bb, bool hovered, const ImVec2& pad, const ImVec2& spacing, bool vertical, ImDrawList& DrawList) {
// vars
const float txt_ht = ImGui::GetTextLineHeight();
Expand Down Expand Up @@ -740,7 +868,7 @@ bool ShowLegendEntries(ImPlotItemGroup& items, const ImRect& legend_bb, bool hov
else
col_icon = item->Show ? col_item : col_txt_dis;

DrawList.AddRectFilled(icon_bb.Min, icon_bb.Max, col_icon);
RenderLegendIcon(DrawList, icon_bb, item, col_icon);
const char* text_display_end = ImGui::FindRenderedTextEnd(label, nullptr);
if (label != text_display_end)
DrawList.AddText(top_left + ImVec2(icon_size, 0), item->Show ? col_txt_hl : col_txt_dis, label, text_display_end);
Expand Down
2 changes: 1 addition & 1 deletion implot_demo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2596,7 +2596,7 @@ void PlotCandlestick(const char* label_id, const double* xs, const double* opens
}

// begin plot item
if (ImPlot::BeginItem(label_id)) {
if (ImPlot::BeginItem(label_id, ImPlotLegendIconType_FillLine)) {
// override legend icon color
ImPlot::GetCurrentItem()->Color = IM_COL32(64,64,64,255);
// fit data if requested
Expand Down
65 changes: 47 additions & 18 deletions implot_internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -967,26 +967,55 @@ struct ImPlotAlignmentData {
void Reset() { PadA = PadB = PadAMax = PadBMax = 0; }
};

// Legend icon types
enum ImPlotLegendIconType_ {
ImPlotLegendIconType_Line, // Horizontal line (line plots)
ImPlotLegendIconType_LineMarkers, // Horizontal line with marker (line plots with markers)
ImPlotLegendIconType_Markers, // Single marker (scatter plots)
ImPlotLegendIconType_Fill, // Filled square (shaded plots, pie charts)
ImPlotLegendIconType_FillLine // Filled square with outline (bars, histograms)
};

// State information for Plot items
struct ImPlotItem
{
ImGuiID ID;
ImU32 Color;
ImPlotMarker Marker;
ImRect LegendHoverRect;
int NameOffset;
bool Show;
bool LegendHovered;
bool SeenThisFrame;
ImGuiID ID;
ImU32 Color;
ImU32 LineColor;
ImU32 FillColor;
ImU32 MarkerLineColor;
ImU32 MarkerFillColor;
ImPlotMarker Marker;
ImPlotItemFlags LegendFlags;
ImPlotLegendIconType_ LegendIconType;
ImRect LegendHoverRect;
int NameOffset;
bool Show;
bool LegendHovered;
bool SeenThisFrame;
bool LegendRenderLine;
bool LegendRenderFill;
bool LegendRenderMarkers;
float LegendLineWeight;

ImPlotItem() {
ID = 0;
Color = IM_COL32_WHITE;
Marker = ImPlotMarker_None;
NameOffset = -1;
Show = true;
SeenThisFrame = false;
LegendHovered = false;
ID = 0;
Color = IM_COL32_WHITE;
LineColor = IM_COL32_WHITE;
FillColor = IM_COL32_WHITE;
MarkerLineColor = IM_COL32_WHITE;
MarkerFillColor = IM_COL32_WHITE;
Marker = ImPlotMarker_None;
LegendFlags = ImPlotItemFlags_None;
LegendIconType = ImPlotLegendIconType_Line;
NameOffset = -1;
Show = true;
SeenThisFrame = false;
LegendHovered = false;
LegendRenderLine = false;
LegendRenderFill = false;
LegendRenderMarkers = false;
LegendLineWeight = 1.0f;
}

~ImPlotItem() { ID = 0; }
Expand Down Expand Up @@ -1333,12 +1362,12 @@ IMPLOT_API void ShowSubplotsContextMenu(ImPlotSubplot& subplot);
//-----------------------------------------------------------------------------

// Begins a new item. Returns false if the item should not be plotted. Pushes PlotClipRect.
IMPLOT_API bool BeginItem(const char* label_id, const ImPlotSpec& spec = ImPlotSpec(), const ImVec4& item_col = IMPLOT_AUTO_COL, ImPlotMarker item_mkr = ImPlotMarker_Invalid);
IMPLOT_API bool BeginItem(const char* label_id, ImPlotLegendIconType_ icon_type, const ImPlotSpec& spec = ImPlotSpec(), const ImVec4& item_col = IMPLOT_AUTO_COL, ImPlotMarker item_mkr = ImPlotMarker_Invalid);

// Same as above but with fitting functionality.
template <typename _Fitter>
bool BeginItemEx(const char* label_id, const _Fitter& fitter, const ImPlotSpec& spec, const ImVec4& item_col = IMPLOT_AUTO_COL, ImPlotMarker item_mkr = ImPlotMarker_Invalid) {
if (BeginItem(label_id, spec, item_col, item_mkr)) {
bool BeginItemEx(const char* label_id, ImPlotLegendIconType_ icon_type, const _Fitter& fitter, const ImPlotSpec& spec, const ImVec4& item_col = IMPLOT_AUTO_COL, ImPlotMarker item_mkr = ImPlotMarker_Invalid) {
if (BeginItem(label_id, icon_type, spec, item_col, item_mkr)) {
ImPlotPlot& plot = *GetCurrentPlot();
if (plot.FitThisFrame && !ImHasFlag(spec.Flags, ImPlotItemFlags_NoFit))
fitter.Fit(plot.Axes[plot.CurrentX], plot.Axes[plot.CurrentY]);
Expand Down
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