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◆ main openmsx / src / imgui / ImGuiPlot.cc
3.7 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
#include "ImGuiPlot.hh"
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#include "imgui.h"
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#include "imgui_internal.h" // for ImLerp
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#include "narrow.hh"
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#include <algorithm>
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#include <span>
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namespace openmsx {
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// Simplified/optimized version of ImGui::PlotLines()
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void plotLinesRaw(std::span<const float> values, float scale_min, float scale_max,
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                  gl::vec2 top_left, gl::vec2 bottom_right, uint32_t color)
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{
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	int num_values = narrow<int>(values.size());
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	if (num_values < 2) return;
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	int num_items = num_values - 1;
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	int inner_width = std::max(1, static_cast<int>(bottom_right.x - top_left.x));
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	int res_w = std::min(inner_width, num_items);
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	float t_step = 1.0f / (float)res_w;
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	float scale_range = scale_max - scale_min;
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	float inv_scale = (scale_range != 0.0f) ? (1.0f / scale_range) : 0.0f;
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	auto valueToY = [&](float v) {
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		return 1.0f - std::clamp((v - scale_min) * inv_scale, 0.0f, 1.0f);
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	};
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	float t = 0.0f;
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	auto tp0 = gl::vec2(t, valueToY(values[0]));
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	auto pos0 = ImLerp(top_left, bottom_right, tp0);
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	auto* drawList = ImGui::GetWindowDrawList();
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	for (int n = 0; n < res_w; n++) {
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		auto idx = static_cast<int>(t * float(num_items) + 0.5f);
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		assert(0 <= idx && idx < num_values);
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		float v = values[(idx + 1) % num_values];
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		t += t_step;
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		auto tp1 = gl::vec2(t, valueToY(v));
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		auto pos1 = ImLerp(top_left, bottom_right, tp1);
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		drawList->AddLine(pos0, pos1, color);
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		pos0 = pos1;
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	}
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}
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void plotLines(std::span<const float> values, float scale_min, float scale_max, gl::vec2 outer_size)
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{
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	const auto& style = ImGui::GetStyle();
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	gl::vec2 pos = ImGui::GetCursorScreenPos();
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	auto outer_tl = pos;              // top-left
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	auto outer_br = pos + outer_size; // bottom-right
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	auto inner_tl = outer_tl + gl::vec2(style.FramePadding);
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	auto inner_br = outer_br - gl::vec2(style.FramePadding);
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	ImGui::RenderFrame(outer_tl, outer_br, ImGui::GetColorU32(ImGuiCol_FrameBg),
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	                   true, style.FrameRounding);
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	auto color = ImGui::GetColorU32(ImGuiCol_PlotLines);
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	plotLinesRaw(values, scale_min, scale_max, inner_tl, inner_br, color);
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}
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// Simplified/optimized version of ImGui::PlotHistogram()
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void plotHistogram(std::span<const float> values, float scale_min, float scale_max, gl::vec2 outer_size)
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{
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	const auto& style = ImGui::GetStyle();
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	gl::vec2 pos = ImGui::GetCursorScreenPos();
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	auto outer_tl = pos;              // top-left
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	auto outer_br = pos + outer_size; // bottom-right
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	auto inner_tl = outer_tl + gl::vec2(style.FramePadding);
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	auto inner_br = outer_br - gl::vec2(style.FramePadding);
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	ImGui::RenderFrame(outer_tl, outer_br, ImGui::GetColorU32(ImGuiCol_FrameBg),
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	                   true, style.FrameRounding);
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	if (values.empty()) return;
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	int num_values = narrow<int>(values.size());
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	int inner_width = std::max(1, static_cast<int>(inner_br.x - inner_tl.x));
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	int res_w = std::min(inner_width, num_values);
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	float t_step = 1.0f / static_cast<float>(res_w);
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	float scale_range = scale_max - scale_min;
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	float inv_scale = (scale_range != 0.0f) ? (1.0f / scale_range) : 0.0f;
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	auto valueToY = [&](float v) {
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		return 1.0f - std::clamp((v - scale_min) * inv_scale, 0.0f, 1.0f);
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	};
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	float zero_line = (scale_min * scale_max < 0.0f)
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	                ? (1 + scale_min * inv_scale)
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	                : (scale_min < 0.0f ? 0.0f : 1.0f);
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	auto color = ImGui::GetColorU32(ImGuiCol_PlotHistogram);
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	float t0 = 0.0f;
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	auto* drawList = ImGui::GetWindowDrawList();
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	drawList->PrimReserve(6 * res_w, 4 * res_w);
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	for (int n = 0; n < res_w; n++) {
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		auto idx = static_cast<int>(t0 * float(num_values) + 0.5f);
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		assert(0 <= idx && idx < num_values);
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		float y0 = valueToY(values[idx]);
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		float t1 = t0 + t_step;
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		auto pos0 = ImLerp(inner_tl, inner_br, gl::vec2(t0, y0));
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		auto pos1 = ImLerp(inner_tl, inner_br, gl::vec2(t1, zero_line));
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		drawList->PrimRect(pos0, pos1, color);
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		t0 = t1;
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	}
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}
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} // namespace openmsx