Use glBlitFramebuffer when rendering

shell/platform/linux/fl_renderer.cc

@@ -12,26 +12,6 @@
 #include "flutter/shell/platform/linux/fl_engine_private.h"
 #include "flutter/shell/platform/linux/fl_view_private.h"
 
-// Vertex shader to draw Flutter window contents.
-static const char* vertex_shader_src =
-    "attribute vec2 position;\n"
-    "attribute vec2 in_texcoord;\n"
-    "varying vec2 texcoord;\n"
-    "\n"
-    "void main() {\n"
-    "  gl_Position = vec4(position, 0, 1);\n"
-    "  texcoord = in_texcoord;\n"
-    "}\n";
-
-// Fragment shader to draw Flutter window contents.
-static const char* fragment_shader_src =
-    "uniform sampler2D texture;\n"
-    "varying vec2 texcoord;\n"
-    "\n"
-    "void main() {\n"
-    "  gl_FragColor = texture2D(texture, texcoord);\n"
-    "}\n";
-
 G_DEFINE_QUARK(fl_renderer_error_quark, fl_renderer_error)
 
 typedef struct {
@@ -48,46 +28,12 @@ typedef struct {
   // was rendered
   bool had_first_frame;
 
-  // Shader program.
-  GLuint program;
-
   // Textures to render.
   GPtrArray* textures;
 } FlRendererPrivate;
 
 G_DEFINE_TYPE_WITH_PRIVATE(FlRenderer, fl_renderer, G_TYPE_OBJECT)
 
-// Returns the log for the given OpenGL shader. Must be freed by the caller.
-static gchar* get_shader_log(GLuint shader) {
-  int log_length;
-  gchar* log;
-
-  glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &log_length);
-
-  log = static_cast<gchar*>(g_malloc(log_length + 1));
-  glGetShaderInfoLog(shader, log_length, nullptr, log);
-
-  return log;
-}
-
-// Returns the log for the given OpenGL program. Must be freed by the caller.
-static gchar* get_program_log(GLuint program) {
-  int log_length;
-  gchar* log;
-
-  glGetProgramiv(program, GL_INFO_LOG_LENGTH, &log_length);
-
-  log = static_cast<gchar*>(g_malloc(log_length + 1));
-  glGetProgramInfoLog(program, log_length, nullptr, log);
-
-  return log;
-}
-
-/// Converts a pixel co-ordinate from 0..pixels to OpenGL -1..1.
-static GLfloat pixels_to_gl_coords(GLfloat position, GLfloat pixels) {
-  return (2.0 * position / pixels) - 1.0;
-}
-
 static void fl_renderer_unblock_main_thread(FlRenderer* self) {
   FlRendererPrivate* priv = reinterpret_cast<FlRendererPrivate*>(
       fl_renderer_get_instance_private(self));
@@ -271,125 +217,29 @@ gboolean fl_renderer_present_layers(FlRenderer* self,
   return TRUE;
 }
 
-void fl_renderer_setup(FlRenderer* self) {
-  FlRendererPrivate* priv = reinterpret_cast<FlRendererPrivate*>(
-      fl_renderer_get_instance_private(self));
-
-  g_return_if_fail(FL_IS_RENDERER(self));
-
-  GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
-  glShaderSource(vertex_shader, 1, &vertex_shader_src, nullptr);
-  glCompileShader(vertex_shader);
-  int vertex_compile_status;
-  glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &vertex_compile_status);
-  if (vertex_compile_status == GL_FALSE) {
-    g_autofree gchar* shader_log = get_shader_log(vertex_shader);
-    g_warning("Failed to compile vertex shader: %s", shader_log);
-  }
-
-  GLuint fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
-  glShaderSource(fragment_shader, 1, &fragment_shader_src, nullptr);
-  glCompileShader(fragment_shader);
-  int fragment_compile_status;
-  glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &fragment_compile_status);
-  if (fragment_compile_status == GL_FALSE) {
-    g_autofree gchar* shader_log = get_shader_log(fragment_shader);
-    g_warning("Failed to compile fragment shader: %s", shader_log);
-  }
-
-  priv->program = glCreateProgram();
-  glAttachShader(priv->program, vertex_shader);
-  glAttachShader(priv->program, fragment_shader);
-  glLinkProgram(priv->program);
-
-  int link_status;
-  glGetProgramiv(priv->program, GL_LINK_STATUS, &link_status);
-  if (link_status == GL_FALSE) {
-    g_autofree gchar* program_log = get_program_log(priv->program);
-    g_warning("Failed to link program: %s", program_log);
-  }
-
-  glDeleteShader(vertex_shader);
-  glDeleteShader(fragment_shader);
-}
-
 void fl_renderer_render(FlRenderer* self, int width, int height) {
   FlRendererPrivate* priv = reinterpret_cast<FlRendererPrivate*>(
       fl_renderer_get_instance_private(self));
 
   g_return_if_fail(FL_IS_RENDERER(self));
 
-  // Save bindings that are set by this function.  All bindings must be restored
-  // to their original values because Skia expects that its bindings have not
-  // been altered.
-  GLint saved_texture_binding;
-  glGetIntegerv(GL_TEXTURE_BINDING_2D, &saved_texture_binding);
-  GLint saved_vao_binding;
-  glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &saved_vao_binding);
-  GLint saved_array_buffer_binding;
-  glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &saved_array_buffer_binding);
-
   glClearColor(0.0, 0.0, 0.0, 1.0);
   glClear(GL_COLOR_BUFFER_BIT);
 
-  glUseProgram(priv->program);
-
   for (guint i = 0; i < priv->textures->len; i++) {
     FlBackingStoreProvider* texture =
         FL_BACKING_STORE_PROVIDER(g_ptr_array_index(priv->textures, i));
 
-    uint32_t texture_id = fl_backing_store_provider_get_gl_texture_id(texture);
-    glBindTexture(GL_TEXTURE_2D, texture_id);
-
-    // Translate into OpenGL co-ordinates
-    GdkRectangle texture_geometry =
-        fl_backing_store_provider_get_geometry(texture);
-    GLfloat texture_x = texture_geometry.x;
-    GLfloat texture_y = texture_geometry.y;
-    GLfloat texture_width = texture_geometry.width;
-    GLfloat texture_height = texture_geometry.height;
-    GLfloat x0 = pixels_to_gl_coords(texture_x, width);
-    GLfloat y0 =
-        pixels_to_gl_coords(height - (texture_y + texture_height), height);
-    GLfloat x1 = pixels_to_gl_coords(texture_x + texture_width, width);
-    GLfloat y1 = pixels_to_gl_coords(height - texture_y, height);
-    GLfloat vertex_data[] = {x0, y0, 0, 0, x1, y1, 1, 1, x0, y1, 0, 1,
-                             x0, y0, 0, 0, x1, y0, 1, 0, x1, y1, 1, 1};
-
-    GLuint vao, vertex_buffer;
-    glGenVertexArrays(1, &vao);
-    glBindVertexArray(vao);
-    glGenBuffers(1, &vertex_buffer);
-    glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
-    glBufferData(GL_ARRAY_BUFFER, sizeof(vertex_data), vertex_data,
-                 GL_STATIC_DRAW);
-    GLint position_index = glGetAttribLocation(priv->program, "position");
-    glEnableVertexAttribArray(position_index);
-    glVertexAttribPointer(position_index, 2, GL_FLOAT, GL_FALSE,
-                          sizeof(GLfloat) * 4, 0);
-    GLint texcoord_index = glGetAttribLocation(priv->program, "in_texcoord");
-    glEnableVertexAttribArray(texcoord_index);
-    glVertexAttribPointer(texcoord_index, 2, GL_FLOAT, GL_FALSE,
-                          sizeof(GLfloat) * 4, (void*)(sizeof(GLfloat) * 2));
-
-    glDrawArrays(GL_TRIANGLES, 0, 6);
-
-    glDeleteVertexArrays(1, &vao);
-    glDeleteBuffers(1, &vertex_buffer);
+    uint32_t framebuffer_id =
+        fl_backing_store_provider_get_gl_framebuffer_id(texture);
+    glBindFramebuffer(GL_READ_FRAMEBUFFER, framebuffer_id);
+    GdkRectangle geometry = fl_backing_store_provider_get_geometry(texture);
+    glBlitFramebuffer(0, 0, geometry.width, geometry.height, geometry.x,
+                      geometry.y, geometry.x + geometry.width,
+                      geometry.x + geometry.height, GL_COLOR_BUFFER_BIT,
+                      GL_NEAREST);
   }
+  glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
 
   glFlush();
-
-  glBindTexture(GL_TEXTURE_2D, saved_texture_binding);
-  glBindVertexArray(saved_vao_binding);
-  glBindBuffer(GL_ARRAY_BUFFER, saved_array_buffer_binding);
-}
-
-void fl_renderer_cleanup(FlRenderer* self) {
-  FlRendererPrivate* priv = reinterpret_cast<FlRendererPrivate*>(
-      fl_renderer_get_instance_private(self));
-
-  g_return_if_fail(FL_IS_RENDERER(self));
-
-  glDeleteProgram(priv->program);
 }

shell/platform/linux/fl_renderer.h

@@ -206,15 +206,6 @@ void fl_renderer_wait_for_frame(FlRenderer* renderer,
                                 int target_width,
                                 int target_height);
 
-/**
- * fl_renderer_setup:
- * @renderer: an #FlRenderer.
- *
- * Creates OpenGL resources required before rendering. Requires an active OpenGL
- * context.
- */
-void fl_renderer_setup(FlRenderer* renderer);
-
 /**
  * fl_renderer_render:
  * @renderer: an #FlRenderer.
@@ -225,14 +216,6 @@ void fl_renderer_setup(FlRenderer* renderer);
  */
 void fl_renderer_render(FlRenderer* renderer, int width, int height);
 
-/**
- * fl_renderer_cleanup:
- *
- * Removes OpenGL resources used for rendering. Requires an active OpenGL
- * context.
- */
-void fl_renderer_cleanup(FlRenderer* renderer);
-
 /**
  * fl_renderer_get_refresh_rate:
  * @renderer: an #FlRenderer.

shell/platform/linux/fl_view.cc

@@ -567,8 +567,6 @@ static void realize_cb(FlView* self) {
     return;
   }
 
-  fl_renderer_setup(FL_RENDERER(self->renderer));
-
   // Handle requests by the user to close the application.
   GtkWidget* toplevel_window = gtk_widget_get_toplevel(GTK_WIDGET(self));
 
@@ -613,20 +611,6 @@ static gboolean render_cb(FlView* self, GdkGLContext* context) {
   return TRUE;
 }
 
-static void unrealize_cb(FlView* self) {
-  g_autoptr(GError) error = nullptr;
-
-  fl_renderer_make_current(FL_RENDERER(self->renderer));
-
-  GError* gl_error = gtk_gl_area_get_error(self->gl_area);
-  if (gl_error != NULL) {
-    g_warning("Failed to uninitialize GLArea: %s", gl_error->message);
-    return;
-  }
-
-  fl_renderer_cleanup(FL_RENDERER(self->renderer));
-}
-
 static void size_allocate_cb(FlView* self) {
   handle_geometry_changed(self);
 }
@@ -797,8 +781,6 @@ static void fl_view_init(FlView* self) {
                            self);
   g_signal_connect_swapped(self->gl_area, "render", G_CALLBACK(render_cb),
                            self);
-  g_signal_connect_swapped(self->gl_area, "unrealize", G_CALLBACK(unrealize_cb),
-                           self);
 
   g_signal_connect_swapped(self, "size-allocate", G_CALLBACK(size_allocate_cb),
                            self);