89 lines
2.4 KiB
C++
89 lines
2.4 KiB
C++
#include <cstdint>
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#include "./imgui.h"
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#include "./imgui_internal.h"
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class Histogram {
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public:
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unsigned int count[4][256] = {0};
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int width;
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int height;
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int channels;
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Histogram(int width, int height, int channels) {
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this->width = width;
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this->height = height;
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this->channels = channels;
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}
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void Load(uint8_t * image) {
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for (int l = 0; l < height * width; l++)
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{
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count[0][*image++]++;
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count[1][*image++]++;
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count[2][*image++]++;
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count[3][*image++]++;
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}
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};
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void Draw() {
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ImGui::InvisibleButton("histogram", ImVec2(512, 256));
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unsigned int maxv = count[0][0];
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unsigned int* pCount = &count[0][0];
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for (int i = 0; i < 3 * 256; i++, pCount++)
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{
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maxv = (maxv > *pCount) ? maxv : *pCount;
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}
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ImDrawList* drawList = ImGui::GetWindowDrawList();
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const ImVec2 rmin = ImGui::GetItemRectMin();
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const ImVec2 rmax = ImGui::GetItemRectMax();
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const ImVec2 size = ImGui::GetItemRectSize();
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const float hFactor = size.y / float(maxv);
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for (int i = 0; i <= 10; i++)
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{
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float ax = rmin.x + (size.x / 10.f) * float(i);
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float ay = rmin.y + (size.y / 10.f) * float(i);
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drawList->AddLine(ImVec2(rmin.x, ay), ImVec2(rmax.x, ay), 0x80808080);
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drawList->AddLine(ImVec2(ax, rmin.y), ImVec2(ax, rmax.y), 0x80808080);
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}
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const float barWidth = (size.x / 256.f);
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for (int j = 0; j < 256; j++)
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{
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// pixel count << 2 + color index(on 2 bits)
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uint32_t cols[3] = {(count[0][j] << 2), (count[1][j] << 2) + 1, (count[2][j] << 2) + 2};
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if (cols[0] > cols[1])
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ImSwap(cols[0], cols[1]);
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if (cols[1] > cols[2])
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ImSwap(cols[1], cols[2]);
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if (cols[0] > cols[1])
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ImSwap(cols[0], cols[1]);
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float heights[3];
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uint32_t colors[3];
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uint32_t currentColor = 0xFFFFFFFF;
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for (int i = 0; i < 3; i++)
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{
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heights[i] = rmax.y - (cols[i] >> 2) * hFactor;
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colors[i] = currentColor;
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currentColor -= 0xFF << ((cols[i] & 3) * 8);
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}
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float currentHeight = rmax.y;
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const float left = rmin.x + barWidth * float(j);
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const float right = left + barWidth;
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for (int i = 0; i < 3; i++)
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{
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if (heights[i] >= currentHeight)
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{
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continue;
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}
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drawList->AddRectFilled(ImVec2(left, currentHeight), ImVec2(right, heights[i]), colors[i]);
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currentHeight = heights[i];
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}
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}
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};
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};
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