gl: GL canvas targeting across SDL platforms (macOS/EGL/Win32/X11)

meson_options.txt

@@ -0,0 +1,5 @@
+option('gl_backend',
+  type: 'combo',
+  choices: ['gl', 'gles'],
+  value: 'gl',
+  description: 'Select GL backend for examples (gl, gles)')

src/Example.h

@@ -30,6 +30,9 @@
 #include <thorvg-1/thorvg.h>
 #include <SDL2/SDL.h>
 #include <SDL2/SDL_syswm.h>
+#ifdef TVGEXAMPLE_GLES_SUPPORTED
+    #include <EGL/egl.h>
+#endif
 #ifdef _WIN32
     #include <windows.h>
     #ifndef PATH_MAX
@@ -395,8 +398,23 @@ struct GlWindow : Window
 
     void resize() override
     {
-        //Set the canvas target and draw on it.
-        verify(static_cast<tvg::GlCanvas*>(canvas)->target(context, 0, width, height, tvg::ColorSpace::ABGR8888S));
+        // Set the canvas target and draw on it.
+        SDL_GL_MakeCurrent(window, context);
+
+#if defined(TVGEXAMPLE_GLES_SUPPORTED)
+        // OpenGL ES via EGL
+        auto eglDisplay = eglGetCurrentDisplay();
+        auto eglSurface = eglGetCurrentSurface(EGL_DRAW);
+        verify(static_cast<tvg::GlCanvas*>(canvas)->target(eglDisplay, eglSurface, context, 0, width, height, tvg::ColorSpace::ABGR8888S));
+#elif defined(_WIN32)
+        SDL_SysWMinfo wmInfo;
+        SDL_VERSION(&wmInfo.version);
+        SDL_GetWindowWMInfo(window, &wmInfo);
+        auto hdc = GetDC(wmInfo.info.win.window);
+        verify(static_cast<tvg::GlCanvas*>(canvas)->target(hdc, wmInfo.info.win.window, context, 0, width, height, tvg::ColorSpace::ABGR8888S));
+#else
+        verify(static_cast<tvg::GlCanvas*>(canvas)->target(nullptr, nullptr, context, 0, width, height, tvg::ColorSpace::ABGR8888S));
+#endif
     }
 
     void refresh() override

src/MultiCanvas.cpp

@@ -175,7 +175,8 @@ void runGl()
 {
 #ifdef THORVG_GL_RASTER_SUPPORT
 
-#ifdef THORVG_GL_TARGET_GLES
+#ifdef TVGEXAMPLE_GLES_SUPPORTED
+        SDL_SetHint(SDL_HINT_OPENGL_ES_DRIVER, "1");
         SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
         SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
         SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
@@ -187,6 +188,7 @@ void runGl()
 
     auto window = SDL_CreateWindow("ThorVG Example (OpenGL)", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, WIDTH, HEIGHT, SDL_WINDOW_OPENGL | SDL_WINDOW_HIDDEN);
     auto context = SDL_GL_CreateContext(window);
+    SDL_GL_MakeCurrent(window, context);
 
     fglBindTexture = (PFNGLBINDTEXTUREEXTPROC)SDL_GL_GetProcAddress("glBindTexture");
     fglDeleteTextures = (PFNGLDELETETEXTURESEXTPROC)SDL_GL_GetProcAddress("glDeleteTextures");
@@ -208,7 +210,19 @@ void runGl()
         auto canvas = unique_ptr<tvg::GlCanvas>(tvg::GlCanvas::gen());
 
         // Pass the framebuffer id to the GlCanvas
-        tvgexam::verify(canvas->target(context, glFbo.fbo, SIZE, SIZE, tvg::ColorSpace::ABGR8888S));
+#if defined(TVGEXAMPLE_GLES_SUPPORTED)
+        auto eglDisplay = eglGetCurrentDisplay();
+        auto eglSurface = eglGetCurrentSurface(EGL_DRAW);
+        tvgexam::verify(canvas->target(eglDisplay, eglSurface, context, glFbo.fbo, SIZE, SIZE, tvg::ColorSpace::ABGR8888S));
+#elif defined(_WIN32)
+        SDL_SysWMinfo wmInfo;
+        SDL_VERSION(&wmInfo.version);
+        SDL_GetWindowWMInfo(window, &wmInfo);
+        auto hdc = GetDC(wmInfo.info.win.window);
+        tvgexam::verify(canvas->target(hdc, wmInfo.info.win.window, context, glFbo.fbo, SIZE, SIZE, tvg::ColorSpace::ABGR8888S));
+#else
+        tvgexam::verify(canvas->target(nullptr, nullptr, context, glFbo.fbo, SIZE, SIZE, tvg::ColorSpace::ABGR8888S));
+#endif
 
         content(canvas.get());
         if (tvgexam::verify(canvas->draw())) {
@@ -416,4 +430,4 @@ int main(int argc, char **argv)
     }
 
     return 0;
-}
+}

src/context.cpp

@@ -0,0 +1,130 @@
+#include "Example.h"
+#ifdef TVGEXAMPLE_GLES_SUPPORTED
+#include <SDL2/SDL_opengles2.h>
+#else
+#include <SDL2/SDL_opengl.h>
+#endif
+#if defined(_WIN32) && !defined(__CYGWIN__) && !defined(__SCITECH_SNAP__)
+#include <windows.h>
+static HDC gHdc = nullptr;
+#endif
+
+static SDL_GLContext getCurrentContext() {
+#if defined(TVGEXAMPLE_GLES_SUPPORTED)
+  auto fn = (SDL_GLContext(*)())SDL_GL_GetProcAddress("eglGetCurrentContext");
+  return fn ? fn() : SDL_GL_GetCurrentContext();
+#elif defined(_WIN32) && !defined(__CYGWIN__) && !defined(__SCITECH_SNAP__)
+  return (SDL_GLContext)wglGetCurrentContext();
+#else
+  return SDL_GL_GetCurrentContext();
+#endif
+}
+
+static bool makeCurrent(SDL_Window* win, SDL_GLContext ctx) {
+#if defined(_WIN32) && !defined(__CYGWIN__) && !defined(__SCITECH_SNAP__) && !defined(TVGEXAMPLE_GLES_SUPPORTED)
+  if (!gHdc) {
+    SDL_SysWMinfo info; SDL_VERSION(&info.version);
+    if (SDL_GetWindowWMInfo(win, &info)) gHdc = GetDC(info.info.win.window);
+  }
+  return wglMakeCurrent(gHdc, (HGLRC)ctx);
+#else
+  return SDL_GL_MakeCurrent(win, ctx) == 0;
+#endif
+}
+
+int main(int argc, char** argv) {
+  (void)argc; (void)argv;
+  if (!tvgexam::verify(tvg::Initializer::init(0))) return 0;
+  if (SDL_Init(SDL_INIT_VIDEO) != 0) { tvg::Initializer::term(); return 0; }
+
+  uint32_t w = 800, h = 800;
+#ifdef TVGEXAMPLE_GLES_SUPPORTED
+  SDL_SetHint(SDL_HINT_OPENGL_ES_DRIVER, "1");
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
+#else
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
+#endif
+  SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+
+  auto window = SDL_CreateWindow("Context", SDL_WINDOWPOS_UNDEFINED,
+      SDL_WINDOWPOS_UNDEFINED, w, h, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
+  auto tvgCtx = window ? SDL_GL_CreateContext(window) : nullptr;
+  auto otherCtx = tvgCtx ? SDL_GL_CreateContext(window) : nullptr;
+  if (!otherCtx || !makeCurrent(window, tvgCtx)) {
+    if (otherCtx) SDL_GL_DeleteContext(otherCtx);
+    if (tvgCtx) SDL_GL_DeleteContext(tvgCtx);
+    if (window) SDL_DestroyWindow(window);
+    SDL_Quit(); tvg::Initializer::term();
+    return 0;
+  }
+
+#if defined(TVGEXAMPLE_GLES_SUPPORTED)
+  auto targetCtx = getCurrentContext();
+  void* display = eglGetCurrentDisplay();
+  void* surface = eglGetCurrentSurface(EGL_DRAW);
+#elif defined(_WIN32) && !defined(__CYGWIN__) && !defined(__SCITECH_SNAP__)
+  auto targetCtx = getCurrentContext();
+  void* display = nullptr;
+  void* surface = gHdc;
+#else
+  auto targetCtx = getCurrentContext();
+  void* display = nullptr;
+  void* surface = nullptr;
+#endif
+  auto canvas = tvg::GlCanvas::gen();
+  if (!canvas || !tvgexam::verify(canvas->target(display, surface, targetCtx, 0, w, h, tvg::ColorSpace::ABGR8888S))) {
+    delete canvas;
+    SDL_GL_DeleteContext(otherCtx); SDL_GL_DeleteContext(tvgCtx);
+    SDL_DestroyWindow(window); SDL_Quit(); tvg::Initializer::term();
+    return 0;
+  }
+
+  auto ring = tvg::Shape::gen();
+  ring->appendCircle(0, 0, 260, 260);
+  ring->fill(0, 0, 0, 0);
+  ring->strokeFill(255, 255, 255, 255);
+  ring->strokeWidth(8);
+  ring->translate(w * 0.5f, h * 0.5f);
+  canvas->push(ring);
+
+  auto needle = tvg::Shape::gen();
+  needle->appendRect(-8, -200, 16, 140);
+  needle->fill(255, 140, 0, 220);
+  needle->translate(w * 0.5f, h * 0.5f);
+  canvas->push(needle);
+
+  canvas->draw(); canvas->sync();
+  SDL_GL_SwapWindow(window);
+  makeCurrent(window, otherCtx);
+
+  SDL_Event ev;
+  bool running = true;
+  auto t0 = SDL_GetTicks();
+  while (running) {
+    while (SDL_PollEvent(&ev)) {
+      if (ev.type == SDL_QUIT) running = false;
+      if (ev.type == SDL_KEYUP && ev.key.keysym.sym == SDLK_ESCAPE) running = false;
+    }
+    makeCurrent(window, otherCtx);
+    float t = (SDL_GetTicks() - t0) * 0.001f;
+    glViewport(0, 0, w, h);
+    glDisable(GL_SCISSOR_TEST);
+    glClearColor(0.15f + 0.1f*sinf(t*0.9f), 0.18f + 0.1f*sinf(t*1.1f+2), 0.22f + 0.1f*sinf(t*1.3f+4), 1);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    needle->rotate(t * 90);
+    canvas->update(); canvas->draw(false); canvas->sync();
+
+    if (getCurrentContext() != targetCtx) break;
+    SDL_GL_SwapWindow(window);
+  }
+
+  delete canvas;
+  SDL_GL_DeleteContext(otherCtx); SDL_GL_DeleteContext(tvgCtx);
+  SDL_DestroyWindow(window); SDL_Quit(); tvg::Initializer::term();
+  return 0;
+}

src/meson.build

@@ -4,16 +4,26 @@ examples_dep = [thorvg_dep, dependency('sdl2', required: true)]
 compiler_flags = ['-DSDL_MAIN_HANDLED']
 
 # GL or GLES
+gl_backend = get_option('gl_backend')
 gl_dep = dependency('gl', required: false)
 gles_dep = dependency('glesv2', required: false)
+egl_dep = dependency('egl', required: false)
 
-if gl_dep.found()
-    examples_dep += gl_dep
-elif gles_dep.found()
-    examples_dep += gles_dep
-    compiler_flags += ['-DTVGEXAMPLE_GLES_SUPPORTED']
-else
-    message('Neither OpenGL nor OpenGL ES was found. Skipping GL examples.')
+if gl_backend == 'gl'
+    if gl_dep.found()
+        examples_dep += gl_dep
+        compiler_flags += ['-DTHORVG_GL_RASTER_SUPPORT']
+    else
+        message('Requested OpenGL but it was not found. Skipping GL examples.')
+    endif
+elif gl_backend == 'gles'
+    if gles_dep.found() and egl_dep.found()
+        examples_dep += [gles_dep, egl_dep]
+        compiler_flags += ['-DTHORVG_GL_RASTER_SUPPORT']
+        compiler_flags += ['-DTVGEXAMPLE_GLES_SUPPORTED']
+    else
+        message('Requested OpenGL ES but it was not found. Skipping GL examples.')
+    endif
 endif
 
 # WebGPU
@@ -37,6 +47,7 @@ source_file = [
     'Blending.cpp',
     'BoundingBox.cpp',
     'Clipping.cpp',
+    'context.cpp',
     'CustomTransform.cpp',
     'DataLoad.cpp',
     'DirectUpdate.cpp',