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1 /*
2 * Copyright 2017 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7 
8 #include "ImGuiLayer.h"
9 
10 #include "SkCanvas.h"
11 #include "SkImage.h"
12 #include "SkPixmap.h"
13 #include "SkSwizzle.h"
14 #include "SkVertices.h"
15 
16 #include "imgui.h"
17 
18 #include <stdlib.h>
19 #include <map>
20 
21 using namespace sk_app;
22 
ImGuiLayer()23 ImGuiLayer::ImGuiLayer() {
24     // ImGui initialization:
25     ImGuiIO& io = ImGui::GetIO();
26 
27     // Keymap...
28     io.KeyMap[ImGuiKey_Tab] = (int)Window::Key::kTab;
29     io.KeyMap[ImGuiKey_LeftArrow] = (int)Window::Key::kLeft;
30     io.KeyMap[ImGuiKey_RightArrow] = (int)Window::Key::kRight;
31     io.KeyMap[ImGuiKey_UpArrow] = (int)Window::Key::kUp;
32     io.KeyMap[ImGuiKey_DownArrow] = (int)Window::Key::kDown;
33     io.KeyMap[ImGuiKey_PageUp] = (int)Window::Key::kPageUp;
34     io.KeyMap[ImGuiKey_PageDown] = (int)Window::Key::kPageDown;
35     io.KeyMap[ImGuiKey_Home] = (int)Window::Key::kHome;
36     io.KeyMap[ImGuiKey_End] = (int)Window::Key::kEnd;
37     io.KeyMap[ImGuiKey_Delete] = (int)Window::Key::kDelete;
38     io.KeyMap[ImGuiKey_Backspace] = (int)Window::Key::kBack;
39     io.KeyMap[ImGuiKey_Enter] = (int)Window::Key::kOK;
40     io.KeyMap[ImGuiKey_Escape] = (int)Window::Key::kEscape;
41     io.KeyMap[ImGuiKey_A] = (int)Window::Key::kA;
42     io.KeyMap[ImGuiKey_C] = (int)Window::Key::kC;
43     io.KeyMap[ImGuiKey_V] = (int)Window::Key::kV;
44     io.KeyMap[ImGuiKey_X] = (int)Window::Key::kX;
45     io.KeyMap[ImGuiKey_Y] = (int)Window::Key::kY;
46     io.KeyMap[ImGuiKey_Z] = (int)Window::Key::kZ;
47 
48     int w, h;
49     unsigned char* pixels;
50     io.Fonts->GetTexDataAsAlpha8(&pixels, &w, &h);
51     SkImageInfo info = SkImageInfo::MakeA8(w, h);
52     SkPixmap pmap(info, pixels, info.minRowBytes());
53     SkMatrix localMatrix = SkMatrix::MakeScale(1.0f / w, 1.0f / h);
54     auto fontImage = SkImage::MakeFromRaster(pmap, nullptr, nullptr);
55     auto fontShader = fontImage->makeShader(&localMatrix);
56     fFontPaint.setShader(fontShader);
57     fFontPaint.setColor(SK_ColorWHITE);
58     fFontPaint.setFilterQuality(kLow_SkFilterQuality);
59     io.Fonts->TexID = &fFontPaint;
60 }
61 
onAttach(Window * window)62 void ImGuiLayer::onAttach(Window* window) {
63     fWindow = window;
64 }
65 
onMouse(int x,int y,Window::InputState state,uint32_t modifiers)66 bool ImGuiLayer::onMouse(int x, int y, Window::InputState state, uint32_t modifiers) {
67     ImGuiIO& io = ImGui::GetIO();
68     io.MousePos.x = static_cast<float>(x);
69     io.MousePos.y = static_cast<float>(y);
70     if (Window::kDown_InputState == state) {
71         io.MouseDown[0] = true;
72     } else if (Window::kUp_InputState == state) {
73         io.MouseDown[0] = false;
74     }
75     return io.WantCaptureMouse;
76 }
77 
onMouseWheel(float delta,uint32_t modifiers)78 bool ImGuiLayer::onMouseWheel(float delta, uint32_t modifiers) {
79     ImGuiIO& io = ImGui::GetIO();
80     io.MouseWheel += delta;
81     return true;
82 }
83 
skiaWidget(const ImVec2 & size,SkiaWidgetFunc func)84 void ImGuiLayer::skiaWidget(const ImVec2& size, SkiaWidgetFunc func) {
85     intptr_t funcIndex = fSkiaWidgetFuncs.count();
86     fSkiaWidgetFuncs.push_back(func);
87     ImGui::Image((ImTextureID)funcIndex, size);
88 }
89 
onPrePaint()90 void ImGuiLayer::onPrePaint() {
91     // Update ImGui input
92     ImGuiIO& io = ImGui::GetIO();
93     io.DeltaTime = 1.0f / 60.0f;
94     io.DisplaySize.x = static_cast<float>(fWindow->width());
95     io.DisplaySize.y = static_cast<float>(fWindow->height());
96 
97     io.KeyAlt = io.KeysDown[static_cast<int>(Window::Key::kOption)];
98     io.KeyCtrl = io.KeysDown[static_cast<int>(Window::Key::kCtrl)];
99     io.KeyShift = io.KeysDown[static_cast<int>(Window::Key::kShift)];
100 
101     ImGui::NewFrame();
102 }
103 
onPaint(SkCanvas * canvas)104 void ImGuiLayer::onPaint(SkCanvas* canvas) {
105     // This causes ImGui to rebuild vertex/index data based on all immediate-mode commands
106     // (widgets, etc...) that have been issued
107     ImGui::Render();
108 
109     // Then we fetch the most recent data, and convert it so we can render with Skia
110     const ImDrawData* drawData = ImGui::GetDrawData();
111     SkTDArray<SkPoint> pos;
112     SkTDArray<SkPoint> uv;
113     SkTDArray<SkColor> color;
114 
115     for (int i = 0; i < drawData->CmdListsCount; ++i) {
116         const ImDrawList* drawList = drawData->CmdLists[i];
117 
118         // De-interleave all vertex data (sigh), convert to Skia types
119         pos.rewind(); uv.rewind(); color.rewind();
120         for (int i = 0; i < drawList->VtxBuffer.size(); ++i) {
121             const ImDrawVert& vert = drawList->VtxBuffer[i];
122             pos.push(SkPoint::Make(vert.pos.x, vert.pos.y));
123             uv.push(SkPoint::Make(vert.uv.x, vert.uv.y));
124             color.push(vert.col);
125         }
126         // ImGui colors are RGBA
127         SkSwapRB(color.begin(), color.begin(), color.count());
128 
129         int indexOffset = 0;
130 
131         // Draw everything with canvas.drawVertices...
132         for (int j = 0; j < drawList->CmdBuffer.size(); ++j) {
133             const ImDrawCmd* drawCmd = &drawList->CmdBuffer[j];
134 
135             SkAutoCanvasRestore acr(canvas, true);
136 
137             // TODO: Find min/max index for each draw, so we know how many vertices (sigh)
138             if (drawCmd->UserCallback) {
139                 drawCmd->UserCallback(drawList, drawCmd);
140             } else {
141                 intptr_t idIndex = (intptr_t)drawCmd->TextureId;
142                 if (idIndex < fSkiaWidgetFuncs.count()) {
143                     // Small image IDs are actually indices into a list of callbacks. We directly
144                     // examing the vertex data to deduce the image rectangle, then reconfigure the
145                     // canvas to be clipped and translated so that the callback code gets to use
146                     // Skia to render a widget in the middle of an ImGui panel.
147                     ImDrawIdx rectIndex = drawList->IdxBuffer[indexOffset];
148                     SkPoint tl = pos[rectIndex], br = pos[rectIndex + 2];
149                     canvas->clipRect(SkRect::MakeLTRB(tl.fX, tl.fY, br.fX, br.fY));
150                     canvas->translate(tl.fX, tl.fY);
151                     fSkiaWidgetFuncs[idIndex](canvas);
152                 } else {
153                     SkPaint* paint = static_cast<SkPaint*>(drawCmd->TextureId);
154                     SkASSERT(paint);
155 
156                     canvas->clipRect(SkRect::MakeLTRB(drawCmd->ClipRect.x, drawCmd->ClipRect.y,
157                                                       drawCmd->ClipRect.z, drawCmd->ClipRect.w));
158                     auto vertices = SkVertices::MakeCopy(SkVertices::kTriangles_VertexMode,
159                                                          drawList->VtxBuffer.size(),
160                                                          pos.begin(), uv.begin(), color.begin(),
161                                                          drawCmd->ElemCount,
162                                                          drawList->IdxBuffer.begin() + indexOffset);
163                     canvas->drawVertices(vertices, SkBlendMode::kModulate, *paint);
164                     indexOffset += drawCmd->ElemCount;
165                 }
166             }
167         }
168     }
169 
170     fSkiaWidgetFuncs.reset();
171 }
172 
onKey(sk_app::Window::Key key,sk_app::Window::InputState state,uint32_t modifiers)173 bool ImGuiLayer::onKey(sk_app::Window::Key key, sk_app::Window::InputState state, uint32_t modifiers) {
174     ImGuiIO& io = ImGui::GetIO();
175     io.KeysDown[static_cast<int>(key)] = (Window::kDown_InputState == state);
176     return io.WantCaptureKeyboard;
177 }
178 
onChar(SkUnichar c,uint32_t modifiers)179 bool ImGuiLayer::onChar(SkUnichar c, uint32_t modifiers) {
180     ImGuiIO& io = ImGui::GetIO();
181     if (io.WantTextInput) {
182         if (c > 0 && c < 0x10000) {
183             io.AddInputCharacter(c);
184         }
185         return true;
186     }
187     return false;
188 }
189