[client] app: implement new overlay rendering framework

This change set implements a framework for overlays to be registered
that make use of ImGui. See `overlay/fps` for a simple implementation
example.

client/CMakeLists.txt

@@ -120,6 +120,9 @@ set(SOURCES
 	src/kb.c
 	src/egl_dynprocs.c
 	src/eglutil.c
+
+	src/overlay/fps.c
+	src/overlay/graphs.c
 )
 
 # Force cimgui to build as a static library.

client/include/app.h

@@ -27,6 +27,7 @@
 #include "common/ringbuffer.h"
 #include "common/types.h"
 #include "interface/displayserver.h"
+#include "interface/overlay.h"
 
 typedef enum LG_MsgAlert
 {
@@ -79,10 +80,15 @@ void app_glSetSwapInterval(int interval);
 void app_glSwapBuffers(void);
 #endif
 
-typedef struct ImGuiGraph * GraphHandle;
+void app_registerOverlay(const struct LG_OverlayOps * ops, void * params);
+int app_renderOverlay(struct Rect * rects, int maxRects);
+void app_freeOverlays(void);
+
+struct OverlayGraph;
+typedef struct OverlayGraph * GraphHandle;
+
 GraphHandle app_registerGraph(const char * name, RingBuffer buffer);
 void app_unregisterGraph(GraphHandle handle);
-bool app_renderImGui(void);
 
 void app_clipboardRelease(void);
 void app_clipboardNotifyTypes(const LG_ClipboardData types[], int count);

client/include/interface/overlay.h

@@ -22,6 +22,8 @@
 #define _H_I_OVERLAY_
 
 #include <stdbool.h>
+#include <assert.h>
+
 #include "common/types.h"
 
 enum LG_OverlayFlags
@@ -57,7 +59,8 @@ struct LG_OverlayOps
    * mode.
    *
    * The caller provides `windowRects` to be populated by the callee and is sized
-   * according to the return value of `getWindowCount`
+   * according to the return value of `getWindowCount`. Note, `windowRects` may
+   * be NULL if the caller does not want this information.
    */
   void (*render)(void * udata, bool interactive, struct Rect windowRects[]);
 

client/renderers/EGL/egl.c

@@ -1007,16 +1007,24 @@ bool egl_render(void * opaque, LG_RendererRotate rotate, const bool newFrame)
   hasOverlay |= egl_help_render(this->help, this->screenScaleX, this->screenScaleY);
   hasOverlay |= egl_damage_render(this->damage, newFrame ? desktopDamage : NULL);
 
-  if (app_renderImGui())
+  struct Rect damage[KVMFR_MAX_DAMAGE_RECTS + 2];
+  int damageIdx = app_renderOverlay(damage, KVMFR_MAX_DAMAGE_RECTS);
+
+  // if no overlay
+  if (damageIdx == -1)
+  {
+    damageIdx = 0;
+  }
+  else
   {
     ImGui_ImplOpenGL3_NewFrame();
     ImGui_ImplOpenGL3_RenderDrawData(igGetDrawData());
+
+    // if there were too many rects invalidate the entire window
+    if (damageIdx == 0)
       hasOverlay = true;
   }
 
-  struct Rect damage[KVMFR_MAX_DAMAGE_RECTS + 2];
-  int damageIdx = 0;
-
   if (!hasOverlay && !this->hadOverlay)
   {
     if (this->cursorLast.visible)

client/renderers/OpenGL/opengl.c

@@ -686,7 +686,7 @@ bool opengl_render(void * opaque, LG_RendererRotate rotate, const bool newFrame)
     break;
   }
 
-  if (app_renderImGui())
+  if (app_renderOverlay(NULL, 0) > -1)
   {
     ImGui_ImplOpenGL2_NewFrame();
     ImGui_ImplOpenGL2_RenderDrawData(igGetDrawData());

client/src/app.c

@@ -30,6 +30,8 @@
 
 #include "common/debug.h"
 #include "common/stringutils.h"
+#include "interface/overlay.h"
+#include "overlays.h"
 
 #include "cimgui.h"
 
@@ -612,143 +614,87 @@ void app_showHelp(bool show)
   free(help);
 }
 
-struct ImGuiGraph
-{
-  const char * name;
-  RingBuffer   buffer;
-  bool         enabled;
-};
-
 GraphHandle app_registerGraph(const char * name, RingBuffer buffer)
 {
-  struct ImGuiGraph * graph = malloc(sizeof(struct ImGuiGraph));
+  return overlayGraph_register(name, buffer);
-  graph->name    = name;
-  graph->buffer  = buffer;
-  graph->enabled = true;
-  ll_push(g_state.graphs, graph);
-  return graph;
 }
 
 void app_unregisterGraph(GraphHandle handle)
 {
-  handle->enabled = false;
+  overlayGraph_unregister(handle);
 }
 
-struct BufferMetrics
+struct Overlay
 {
-  float min;
+  const struct LG_OverlayOps * ops;
-  float max;
+  void * udata;
-  float sum;
+  int windowCount;
-  float avg;
-  float freq;
 };
 
-static bool rbCalcMetrics(int index, void * value_, void * udata_)
+void app_registerOverlay(const struct LG_OverlayOps * ops, void * params)
 {
-  float * value = value_;
+  ASSERT_LG_OVERLAY_VALID(ops);
-  struct BufferMetrics * udata = udata_;
 
-  if (index == 0)
+  void * udata;
+  if (!ops->init(&udata, params))
   {
-    udata->min = *value;
+    DEBUG_ERROR("Overlay `%s` failed to initialize", ops->name);
-    udata->max = *value;
+    return;
-    udata->sum = *value;
-    return true;
   }
 
-  if (udata->min > *value)
+  struct Overlay * overlay = malloc(sizeof(struct Overlay));
-    udata->min = *value;
+  overlay->ops   = ops;
-
+  overlay->udata = udata;
-  if (udata->max < *value)
+  ll_push(g_state.overlays, overlay);
-    udata->max = *value;
-
-  udata->sum += *value;
-  return true;
 }
 
-bool app_renderImGui(void)
+int app_renderOverlay(struct Rect * rects, int maxRects)
 {
-  if (!g_state.showFPS &&
+  int windowCount = 0;
-      !g_state.showTiming)
+  struct Overlay * overlay;
-    return false;
 
-  igNewFrame();
+  // get the total window count
-
+  for (ll_reset(g_state.overlays);
-  ImGuiStyle * style = igGetStyle();
+      ll_walk(g_state.overlays, (void **)&overlay); )
-  style->WindowBorderSize = 0.0f;
-
-  if (g_state.showFPS)
   {
-    const ImVec2 pos = {0.0f, 0.0f};
+    overlay->windowCount = overlay->ops->getWindowCount(overlay->udata, false);
-    igSetNextWindowBgAlpha(0.6f);
+    windowCount += overlay->windowCount;
-    igSetNextWindowPos(pos, 0, pos);
-
-    igBegin(
-      "FPS",
-      NULL,
-      ImGuiWindowFlags_NoDecoration    | ImGuiWindowFlags_AlwaysAutoResize   |
-      ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoFocusOnAppearing |
-      ImGuiWindowFlags_NoNav           | ImGuiWindowFlags_NoTitleBar
-    );
-
-    igText("FPS:%4.2f UPS:%4.2f",
-        atomic_load_explicit(&g_state.fps, memory_order_relaxed),
-        atomic_load_explicit(&g_state.ups, memory_order_relaxed));
-
-    igEnd();
   }
 
-  if (g_state.showTiming)
+  // return -1 if there are no windows to render
-  {
+  if (windowCount == 0)
-    const ImVec2 pos = {0.0f, 0.0f};
+    return -1;
-    igSetNextWindowBgAlpha(0.4f);
-    igSetNextWindowPos(pos, 0, pos);
 
-    igBegin(
+  if (windowCount > maxRects)
-      "Performance Metrics",
-      NULL,
-      ImGuiWindowFlags_NoDecoration    | ImGuiWindowFlags_AlwaysAutoResize   |
-      ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoFocusOnAppearing |
-      ImGuiWindowFlags_NoNav           | ImGuiWindowFlags_NoTitleBar
-    );
-
-    GraphHandle graph;
-    for (ll_reset(g_state.graphs); ll_walk(g_state.graphs, (void **)&graph); )
   {
-      if (!graph->enabled)
+    rects = NULL;
+    windowCount = 0;
+  }
+
+  // render the overlays
+  igNewFrame();
+  for (ll_reset(g_state.overlays);
+      ll_walk(g_state.overlays, (void **)&overlay); )
+  {
+    if (overlay->windowCount == 0)
       continue;
 
-      struct BufferMetrics metrics = {};
+    overlay->ops->render(overlay->udata, false, rects);
-      ringbuffer_forEach(graph->buffer, rbCalcMetrics, &metrics);
+    if (rects)
-
+      rects += overlay->windowCount;
-      if (metrics.sum > 0.0f)
-      {
-        metrics.avg  = metrics.sum / ringbuffer_getCount(graph->buffer);
-        metrics.freq = 1000.0f / metrics.avg;
-      }
-
-      char  title[64];
-      const ImVec2 size = {400.0f, 100.0f};
-
-      snprintf(title, sizeof(title),
-          "%s: min:%4.2f max:%4.2f avg:%4.2f/%4.2fHz",
-          graph->name, metrics.min, metrics.max, metrics.avg, metrics.freq);
-
-      igPlotLinesFloatPtr(
-          "",
-          (float *)ringbuffer_getValues(graph->buffer),
-          ringbuffer_getLength(graph->buffer),
-          ringbuffer_getStart (graph->buffer),
-          title,
-          0.0f,
-          50.0f,
-          size,
-          sizeof(float));
-    }
-
-    igEnd();
   }
 
   igRender();
-  return true;
+
+  return windowCount;
+}
+
+void app_freeOverlays(void)
+{
+  struct Overlay * overlay;
+  while(ll_shift(g_state.overlays, (void **)&overlay))
+  {
+    overlay->ops->free(overlay->udata);
+    free(overlay);
+  }
 }

client/src/main.c

@@ -55,6 +55,7 @@
 #include "clipboard.h"
 #include "ll.h"
 #include "egl_dynprocs.h"
+#include "overlays.h"
 
 // forwards
 static int cursorThread(void * unused);
@@ -758,14 +759,15 @@ static int lg_run(void)
   ImFontAtlas_GetTexDataAsRGBA32(g_state.io->Fonts, &text_pixels,
       &text_w, &text_h, NULL);
 
-  g_state.graphs = ll_new();
+  g_state.overlays = ll_new();
+  app_registerOverlay(&LGOverlayFPS   , NULL);
+  app_registerOverlay(&LGOverlayGraphs, NULL);
 
   // initialize metrics ringbuffers
   g_state.renderTimings = ringbuffer_new(256, sizeof(float));
   g_state.frameTimings  = ringbuffer_new(256, sizeof(float));
-
+  overlayGraph_register("RENDER", g_state.renderTimings);
-  app_registerGraph("RENDER", g_state.renderTimings);
+  overlayGraph_register("UPLOAD", g_state.frameTimings );
-  app_registerGraph("UPLOAD", g_state.frameTimings);
 
   // search for the best displayserver ops to use
   for(int i = 0; i < LG_DISPLAYSERVER_COUNT; ++i)
@@ -1091,6 +1093,13 @@ static void lg_shutdown(void)
 
   lgmpClientFree(&g_state.lgmp);
 
+  if (g_state.overlays)
+  {
+    app_freeOverlays();
+    ll_free(g_state.overlays);
+    g_state.overlays = NULL;
+  }
+
   if (e_frame)
   {
     lgFreeEvent(e_frame);

client/src/main.h

@@ -48,7 +48,7 @@ struct AppState
   enum RunState state;
 
   ImGuiIO   * io;
-  struct ll * graphs;
+  struct ll * overlays;
 
   struct LG_DisplayServerOps * ds;
   bool                         dsInitialized;

client/src/overlay/fps.c

@@ -0,0 +1,79 @@
+/**
+ * Looking Glass
+ * Copyright (C) 2017-2021 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * 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., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "interface/overlay.h"
+#include "cimgui.h"
+
+#include "../main.h"
+
+static bool fps_init(void ** udata, void * params)
+{
+  return true;
+}
+
+static void fps_free(void * udata)
+{
+}
+
+static int fps_getWindowCount(void * udata, bool interactive)
+{
+  return g_state.showFPS ? 1 : 0;
+}
+
+static void fps_render(void * udata, bool interactive, struct Rect * windowRects)
+{
+  const ImVec2 pos = {0.0f, 0.0f};
+  igSetNextWindowBgAlpha(0.6f);
+  igSetNextWindowPos(pos, 0, pos);
+
+  igBegin(
+    "FPS",
+    NULL,
+    ImGuiWindowFlags_NoDecoration    | ImGuiWindowFlags_AlwaysAutoResize   |
+    ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoFocusOnAppearing |
+    ImGuiWindowFlags_NoNav           | ImGuiWindowFlags_NoTitleBar
+  );
+
+  igText("FPS:%4.2f UPS:%4.2f",
+      atomic_load_explicit(&g_state.fps, memory_order_relaxed),
+      atomic_load_explicit(&g_state.ups, memory_order_relaxed));
+
+  if (windowRects)
+  {
+    ImVec2 pos, size;
+    igGetWindowPos(&pos);
+    igGetWindowSize(&size);
+    windowRects[0].x = pos.x;
+    windowRects[0].y = pos.y;
+    windowRects[0].w = size.x;
+    windowRects[0].h = size.y;
+  }
+
+  igEnd();
+}
+
+struct LG_OverlayOps LGOverlayFPS =
+{
+  .name           = "FPS",
+  .init           = fps_init,
+  .free           = fps_free,
+  .getWindowCount = fps_getWindowCount,
+  .render         = fps_render
+};

client/src/overlay/graphs.c

@@ -0,0 +1,175 @@
+/**
+ * Looking Glass
+ * Copyright (C) 2017-2021 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * 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., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "interface/overlay.h"
+#include "cimgui.h"
+
+#include "../main.h"
+
+#include "ll.h"
+#include "common/debug.h"
+
+struct GraphState
+{
+  struct ll * graphs;
+};
+
+static struct GraphState gs = {0};
+
+struct OverlayGraph
+{
+  const char * name;
+  RingBuffer   buffer;
+  bool         enabled;
+};
+
+static bool graphs_init(void ** udata, void * params)
+{
+  gs.graphs = ll_new();
+  return true;
+}
+
+static void graphs_free(void * udata)
+{
+  ll_free(gs.graphs);
+}
+
+static int graphs_getWindowCount(void * udata, bool interactive)
+{
+  return g_state.showTiming ? 1 : 0;
+}
+
+struct BufferMetrics
+{
+  float min;
+  float max;
+  float sum;
+  float avg;
+  float freq;
+};
+
+static bool rbCalcMetrics(int index, void * value_, void * udata_)
+{
+  float * value = value_;
+  struct BufferMetrics * udata = udata_;
+
+  if (index == 0)
+  {
+    udata->min = *value;
+    udata->max = *value;
+    udata->sum = *value;
+    return true;
+  }
+
+  if (udata->min > *value)
+    udata->min = *value;
+
+  if (udata->max < *value)
+    udata->max = *value;
+
+  udata->sum += *value;
+  return true;
+}
+
+static void graphs_render(void * udata, bool interactive, struct Rect * windowRects)
+{
+  const ImVec2 pos = {0.0f, 0.0f};
+  igSetNextWindowBgAlpha(0.4f);
+  igSetNextWindowPos(pos, 0, pos);
+
+  igBegin(
+    "Performance Metrics",
+    NULL,
+    ImGuiWindowFlags_NoDecoration    | ImGuiWindowFlags_AlwaysAutoResize   |
+    ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoFocusOnAppearing |
+    ImGuiWindowFlags_NoNav           | ImGuiWindowFlags_NoTitleBar
+  );
+
+  GraphHandle graph;
+  for (ll_reset(gs.graphs); ll_walk(gs.graphs, (void **)&graph); )
+  {
+    if (!graph->enabled)
+      continue;
+
+    struct BufferMetrics metrics = {};
+    ringbuffer_forEach(graph->buffer, rbCalcMetrics, &metrics);
+
+    if (metrics.sum > 0.0f)
+    {
+      metrics.avg  = metrics.sum / ringbuffer_getCount(graph->buffer);
+      metrics.freq = 1000.0f / metrics.avg;
+    }
+
+    char  title[64];
+    const ImVec2 size = {400.0f, 100.0f};
+
+    snprintf(title, sizeof(title),
+        "%s: min:%4.2f max:%4.2f avg:%4.2f/%4.2fHz",
+        graph->name, metrics.min, metrics.max, metrics.avg, metrics.freq);
+
+    igPlotLinesFloatPtr(
+        "",
+        (float *)ringbuffer_getValues(graph->buffer),
+        ringbuffer_getLength(graph->buffer),
+        ringbuffer_getStart (graph->buffer),
+        title,
+        0.0f,
+        50.0f,
+        size,
+        sizeof(float));
+  };
+
+  if (windowRects)
+  {
+    ImVec2 pos, size;
+    igGetWindowPos(&pos);
+    igGetWindowSize(&size);
+    windowRects[0].x = pos.x;
+    windowRects[0].y = pos.y;
+    windowRects[0].w = size.x;
+    windowRects[0].h = size.y;
+  }
+
+  igEnd();
+}
+
+struct LG_OverlayOps LGOverlayGraphs =
+{
+  .name           = "Graphs",
+  .init           = graphs_init,
+  .free           = graphs_free,
+  .getWindowCount = graphs_getWindowCount,
+  .render         = graphs_render
+};
+
+GraphHandle overlayGraph_register(const char * name, RingBuffer buffer)
+{
+  struct OverlayGraph * graph = malloc(sizeof(struct OverlayGraph));
+  graph->name    = name;
+  graph->buffer  = buffer;
+  graph->enabled = true;
+  ll_push(gs.graphs, graph);
+  return graph;
+}
+
+void overlayGraph_unregister(GraphHandle handle)
+{
+  handle->enabled = false;
+}

client/src/overlays.h

@@ -0,0 +1,32 @@
+/**
+ * Looking Glass
+ * Copyright (C) 2017-2021 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * 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., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _H_OVERLAYS_H
+#define _H_OVERLAYS_H
+
+#include "interface/overlay.h"
+
+extern struct LG_OverlayOps LGOverlayFPS;
+extern struct LG_OverlayOps LGOverlayGraphs;
+
+GraphHandle overlayGraph_register(const char * name, RingBuffer buffer);
+void overlayGraph_unregister();
+
+#endif