How can I render a large number of waveforms drawn using ImGui's drawList only once and then use it as a cached image for display to reduce drawing resource usage? Should I use a texture with DirectX 11 and Win32, or save it as an image?

[Caesar454905970]

Version/Branch of Dear ImGui:

Version 1.91.0

Back-ends:

imgui_impl_dx11.h+ imgui_impl_win32.cpp

Compiler, OS:

win10+dx11+win32

Full config/build information:

No response

Details:

How can I render a large number of waveforms drawn using ImGui's drawList only once and then use it as a cached image for display to reduce drawing resource usage? Should I use a texture with DirectX 11 and Win32, or save it as an image?

Screenshots/Video:

Minimal, Complete and Verifiable Example code:

void RenderEcgines(ImDrawList* drawList, ImVec2 windowPos, const std::vector<std::vector>& tmp_list) {
// 常量定义
constexpr double baselineOffset = 100.0;
constexpr double leadOffset = 75.0;
constexpr float lineThickness = 1.0f;
constexpr ImU32 lineColor = IM_COL32(0, 0, 0, 255); // 黑色
const double y_Translate_item = baselineOffset + InputScalar_y_line_offect;

// 计算各导联的基线平移距离
std::vector<double> leadTranslates(12);
for (int i = 0; i < 12; ++i) {
    leadTranslates[i] = leadOffset + i * y_Translate_item;
}
// 增益因子
double m_x_line_standard_gain = 1;
double m_y_line_standard_gain = 1;
// 增益因子
const double xGain = 0.25 * m_x_line_standard_gain;
const double yGain = (-1) * m_y_line_standard_gain * InputScalar_y_line_standard_gain;

// 计算窗口的高度的一部分
const float windowHeight = ImGui::GetWindowSize().y;

for (size_t i = 0; i < tmp_list.size() - 1; ++i) {
    double x1 = i * xGain;
    double x2 = (i + 1) * xGain;

    // 绘制12导联
    for (int lead = 0; lead < 12; ++lead) {
        double y1 = tmp_list[i][lead] * yGain + leadTranslates[lead];
        double y2 = tmp_list[i + 1][lead] * yGain + leadTranslates[lead];

        drawList->AddLine(
                ImVec2(static_cast<float>(x1) + windowPos.x, static_cast<float>(y1) + windowPos.y),
                ImVec2(static_cast<float>(x2) + windowPos.x, static_cast<float>(y2) + windowPos.y),
                lineColor, lineThickness);
    }

    // 绘制时间轴
    if ((i + SliderInt_model) % 500 == 0) {
        std::size_t timestamp = (i + SliderInt_model) * 2;
        std::string timestampText = convertFromTimestamp_hh_mm_ss(timestamp);

        ImFont* font = ImGui::GetFont();
        ImVec2 textSize = font->CalcTextSizeA(font->FontSize, FLT_MAX, 0.0f, timestampText.c_str());

        float lineX = static_cast<float>(x1) + windowPos.x;

        drawList->AddLine(
                ImVec2(lineX, windowPos.y + windowHeight - 5 - textSize.y),
                ImVec2(lineX, windowPos.y + windowHeight),
                lineColor, 1.0f);

        float textX = lineX - textSize.x / 2.0f;
        float textY = windowPos.y + windowHeight - 20 - textSize.y;

        drawList->AddText(ImVec2(textX + 5, textY), lineColor, timestampText.c_str());
    }
}

isSliderChanged = false;

}

[Caesar454905970]

i can't save drawList to dx11 Texture

this is my test code:
//2. 渲染波形到纹理
void RenderEcginesToTexture(ImDrawList* drawList, const ImVec2& windowPos, const std::vector<std::vector>& tmp_list) {
if (!pWaveRenderTargetView) {
spdlog::error("Render target view is null.");
return;
}

g_pd3dDeviceContext->OMSetRenderTargets(1, &pWaveRenderTargetView, nullptr);

float clearColor[4] = { 0.0f, 0.0f, 0.0f, 0.0f };
g_pd3dDeviceContext->ClearRenderTargetView(pWaveRenderTargetView, clearColor);

// Render ECG waveforms
RenderEcgines(drawList, windowPos, tmp_list);

// Reset render target
g_pd3dDeviceContext->OMSetRenderTargets(1, &g_mainRenderTargetView, nullptr);

// Save the texture to file
SaveTextureToFile(pWaveTexture, "waveform.png");

}

[ocornut]

Render to texture is going to be specific to your engine and backend.

This page has links about DX11 render to texture:
https://github.com/ocornut/imgui/wiki/Image-Loading-and-Displaying-Examples

If you want to use ImDrawList you will need to likely create your own ImDrawData, or create another Dear ImGui Context and capture its render. See #6406 #6892 #1878 for further references.

Also see #2948 and specifically #2948 (comment) which implements the the second approach and for OpenGL.

i can't save drawList to dx11 Texture

At this point we cannot be debugging your engine/rendering code. It is frequent in graphics programming to run into issue.
Maybe RenderDoc can help you debug something.