GUI: prepare for a per-channel oscilloscope?

currently supported systems:
- Amiga
- AY-3-8910
- Dummy System
- OPLL
- SegaPCM

no trigger supported yet!

src/gui/chanOsc.cpp

@@ -0,0 +1,101 @@
+/**
+ * Furnace Tracker - multi-system chiptune tracker
+ * Copyright (C) 2021-2022 tildearrow and contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "gui.h"
+#include "imgui.h"
+#include "imgui_internal.h"
+
+void FurnaceGUI::drawChanOsc() {
+  if (nextWindow==GUI_WINDOW_CHAN_OSC) {
+    chanOscOpen=true;
+    ImGui::SetNextWindowFocus();
+    nextWindow=GUI_WINDOW_NOTHING;
+  }
+  if (!chanOscOpen) return;
+  ImGui::SetNextWindowSizeConstraints(ImVec2(64.0f*dpiScale,32.0f*dpiScale),ImVec2(scrW*dpiScale,scrH*dpiScale));
+  if (ImGui::Begin("Oscilloscope (per-channel)",&chanOscOpen)) {
+    if (ImGui::InputInt("Columns",&chanOscCols,1,1)) {
+      if (chanOscCols<1) chanOscCols=1;
+      if (chanOscCols>64) chanOscCols=64;
+    }
+
+    ImGui::PushStyleVar(ImGuiStyleVar_CellPadding,ImVec2(0.0f,0.0f));
+    float availY=ImGui::GetContentRegionAvail().y;
+    if (ImGui::BeginTable("ChanOsc",chanOscCols,ImGuiTableFlags_Borders)) {
+      int chans=e->getTotalChannelCount();
+      int rows=(chans+(chanOscCols-1))/chanOscCols;
+      ImDrawList* dl=ImGui::GetWindowDrawList();
+      ImGuiWindow* window=ImGui::GetCurrentWindow();
+      ImVec2 waveform[512];
+
+      ImGuiStyle& style=ImGui::GetStyle();
+      ImU32 color=ImGui::GetColorU32(uiColors[GUI_COLOR_OSC_WAVE]);
+
+      for (int i=0; i<chans; i++) {
+        if (i%chanOscCols==0) ImGui::TableNextRow();
+        ImGui::TableNextColumn();
+
+        DivDispatchOscBuffer* buf=e->getOscBuffer(i);
+        if (buf==NULL) {
+          ImGui::Text("Not Available");
+        } else {
+          ImVec2 size=ImGui::GetContentRegionAvail();
+          size.y=availY/rows;
+
+          int displaySize=(buf->rate)/30;
+
+          ImVec2 minArea=window->DC.CursorPos;
+          ImVec2 maxArea=ImVec2(
+            minArea.x+size.x,
+            minArea.y+size.y
+          );
+          ImRect rect=ImRect(minArea,maxArea);
+          ImRect inRect=rect;
+          inRect.Min.x+=dpiScale;
+          inRect.Min.y+=dpiScale;
+          inRect.Max.x-=dpiScale;
+          inRect.Max.y-=dpiScale;
+          ImGui::ItemSize(size,style.FramePadding.y);
+          if (ImGui::ItemAdd(rect,ImGui::GetID("chOscDisplay"))) {
+            if (!e->isPlaying()) {
+              for (unsigned short i=0; i<512; i++) {
+                float x=(float)i/512.0f;
+                waveform[i]=ImLerp(inRect.Min,inRect.Max,ImVec2(x,0.5f));
+              }
+            } else {
+              unsigned short needlePos=buf->needle-displaySize;
+              for (unsigned short i=0; i<512; i++) {
+                float x=(float)i/512.0f;
+                float y=(float)buf->data[(unsigned short)(needlePos+(i*displaySize/512))]/65536.0f;
+                if (y<-0.5f) y=-0.5f;
+                if (y>0.5f) y=0.5f;
+                waveform[i]=ImLerp(inRect.Min,inRect.Max,ImVec2(x,0.5f-y));
+              }
+            }
+            dl->AddPolyline(waveform,512,color,ImDrawFlags_None,dpiScale);
+          }
+        }
+      }
+      ImGui::EndTable();
+    }
+    ImGui::PopStyleVar();
+  }
+  if (ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows)) curWindow=GUI_WINDOW_CHAN_OSC;
+  ImGui::End();
+}