[client] renderer/egl: implement support for rendering help text

The help text is rendered in the bottom left corner on a semi-transparent
background, very similar to how the FPS text is rendered.

client/renderers/EGL/CMakeLists.txt

@@ -22,6 +22,9 @@ make_object(
 	shader/fps.vert
 	shader/fps.frag
 	shader/fps_bg.frag
+	shader/help.vert
+	shader/help.frag
+	shader/help_bg.frag
 	shader/alert.vert
 	shader/alert.frag
 	shader/alert_bg.frag
@@ -40,6 +43,7 @@ add_library(renderer_EGL STATIC
 	desktop.c
 	cursor.c
 	fps.c
+	help.c
 	draw.c
 	splash.c
 	alert.c

client/renderers/EGL/egl.c

@@ -45,6 +45,7 @@ Place, Suite 330, Boston, MA 02111-1307 USA
 #include "fps.h"
 #include "splash.h"
 #include "alert.h"
+#include "help.h"
 
 #define SPLASH_FADE_TIME 1000000
 #define ALERT_TIMEOUT    2000000
@@ -72,6 +73,7 @@ struct Inst
   EGL_FPS         * fps;     // the fps display
   EGL_Splash      * splash;  // the splash screen
   EGL_Alert       * alert;   // the alert display
+  EGL_Help        * help;    // the help display
 
   LG_RendererFormat    format;
   bool                 formatValid;
@@ -221,6 +223,7 @@ void egl_deinitialize(void * opaque)
   egl_fps_free    (&this->fps   );
   egl_splash_free (&this->splash);
   egl_alert_free  (&this->alert );
+  egl_help_free   (&this->help);
 
   LG_LOCK_FREE(this->lock);
 
@@ -478,7 +481,8 @@ void egl_on_alert(void * opaque, const LG_MsgAlert alert, const char * message,
 
 void egl_on_help(void * opaque, const char * message)
 {
-  // TODO: Implement this.
+  struct Inst * this = (struct Inst *)opaque;
+  egl_help_set_text(this->help, message);
 }
 
 bool egl_render_startup(void * opaque)
@@ -637,6 +641,12 @@ bool egl_render_startup(void * opaque)
     return false;
   }
 
+  if (!egl_help_init(&this->help, this->font, this->fontObj))
+  {
+    DEBUG_ERROR("Failed to initialize the alert display");
+    return false;
+  }
+
   return true;
 }
 
@@ -706,6 +716,7 @@ bool egl_render(void * opaque, LG_RendererRotate rotate)
   }
 
   egl_fps_render(this->fps, this->screenScaleX, this->screenScaleY);
+  egl_help_render(this->help, this->screenScaleX, this->screenScaleY);
   app_eglSwapBuffers(this->display, this->surface);
   return true;
 }

client/renderers/EGL/help.c

@@ -0,0 +1,207 @@
+/*
+Looking Glass - KVM FrameRelay (KVMFR) Client
+Copyright (C) 2021 Guanzhong Chen <quantum2048@gmail.com>
+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 "help.h"
+#include "common/debug.h"
+
+#include "texture.h"
+#include "shader.h"
+#include "model.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+// these headers are auto generated by cmake
+#include "help.vert.h"
+#include "help.frag.h"
+#include "help_bg.frag.h"
+
+struct EGL_Help
+{
+  const LG_Font * font;
+  LG_FontObj      fontObj;
+
+  EGL_Texture   * texture;
+  EGL_Shader    * shader;
+  EGL_Shader    * shaderBG;
+  EGL_Model     * model;
+  LG_FontBitmap * bmp;
+
+  bool  shouldRender;
+  int   iwidth, iheight;
+  float width, height;
+
+  // uniforms
+  GLint uScreen  , uSize;
+  GLint uScreenBG, uSizeBG;
+};
+
+bool egl_help_init(EGL_Help ** help, const LG_Font * font, LG_FontObj fontObj)
+{
+  *help = (EGL_Help *)malloc(sizeof(EGL_Help));
+  if (!*help)
+  {
+    DEBUG_ERROR("Failed to malloc EGL_Help");
+    return false;
+  }
+
+  memset(*help, 0, sizeof(EGL_Help));
+
+  (*help)->font    = font;
+  (*help)->fontObj = fontObj;
+
+  if (!egl_texture_init(&(*help)->texture, NULL))
+  {
+    DEBUG_ERROR("Failed to initialize the help texture");
+    return false;
+  }
+
+  if (!egl_shader_init(&(*help)->shader))
+  {
+    DEBUG_ERROR("Failed to initialize the help shader");
+    return false;
+  }
+
+  if (!egl_shader_init(&(*help)->shaderBG))
+  {
+    DEBUG_ERROR("Failed to initialize the help bg shader");
+    return false;
+  }
+
+
+  if (!egl_shader_compile((*help)->shader,
+        b_shader_help_vert, b_shader_help_vert_size,
+        b_shader_help_frag, b_shader_help_frag_size))
+  {
+    DEBUG_ERROR("Failed to compile the help shader");
+    return false;
+  }
+
+  if (!egl_shader_compile((*help)->shaderBG,
+        b_shader_help_vert   , b_shader_help_vert_size,
+        b_shader_help_bg_frag, b_shader_help_bg_frag_size))
+  {
+    DEBUG_ERROR("Failed to compile the help shader");
+    return false;
+  }
+
+
+  (*help)->uSize     = egl_shader_get_uniform_location((*help)->shader  , "size"  );
+  (*help)->uScreen   = egl_shader_get_uniform_location((*help)->shader  , "screen");
+  (*help)->uSizeBG   = egl_shader_get_uniform_location((*help)->shaderBG, "size"  );
+  (*help)->uScreenBG = egl_shader_get_uniform_location((*help)->shaderBG, "screen");
+
+  if (!egl_model_init(&(*help)->model))
+  {
+    DEBUG_ERROR("Failed to initialize the fps model");
+    return false;
+  }
+
+  egl_model_set_default((*help)->model);
+  egl_model_set_texture((*help)->model, (*help)->texture);
+
+  return true;
+}
+
+void egl_help_free(EGL_Help ** help)
+{
+  if (!*help)
+    return;
+
+  egl_texture_free(&(*help)->texture );
+  egl_shader_free (&(*help)->shader  );
+  egl_shader_free (&(*help)->shaderBG);
+  egl_model_free  (&(*help)->model   );
+
+  free(*help);
+  *help = NULL;
+}
+
+void egl_help_set_text(EGL_Help * help, const char * help_text)
+{
+  if (!help_text)
+  {
+    help->shouldRender = false;
+    return;
+  }
+
+  help->bmp = help->font->render(help->fontObj, 0xffffff00, help_text);
+  if (!help->bmp)
+  {
+    DEBUG_ERROR("Failed to render help text");
+    return;
+  }
+}
+
+void egl_help_render(EGL_Help * help, const float scaleX, const float scaleY)
+{
+  if (help->bmp)
+  {
+    if (help->iwidth != help->bmp->width || help->iheight != help->bmp->height)
+    {
+      help->iwidth  = help->bmp->width;
+      help->iheight = help->bmp->height;
+      help->width   = (float)help->bmp->width;
+      help->height  = (float)help->bmp->height;
+
+      egl_texture_setup(
+        help->texture,
+        EGL_PF_BGRA,
+        help->bmp->width ,
+        help->bmp->height,
+        help->bmp->width * help->bmp->bpp,
+        false,
+        false
+      );
+    }
+
+    egl_texture_update
+    (
+      help->texture,
+      help->bmp->pixels
+    );
+
+    help->shouldRender = true;
+    help->font->release(help->fontObj, help->bmp);
+    help->bmp = NULL;
+  }
+
+  if (!help->shouldRender)
+    return;
+
+  glEnable(GL_BLEND);
+  glBlendColor(0, 0, 0, 0.5);
+  glBlendFunc(GL_CONSTANT_ALPHA, GL_ONE_MINUS_CONSTANT_ALPHA);
+
+  // render the background first
+  egl_shader_use(help->shaderBG);
+  glUniform2f(help->uScreenBG, scaleX     , scaleY      );
+  glUniform2f(help->uSizeBG  , help->width, help->height);
+  egl_model_render(help->model);
+
+  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+  // render the texture over the background
+  egl_shader_use(help->shader);
+  glUniform2f(help->uScreen, scaleX     , scaleY      );
+  glUniform2f(help->uSize  , help->width, help->height);
+  egl_model_render(help->model);
+
+  glDisable(GL_BLEND);
+}

client/renderers/EGL/help.h

@@ -0,0 +1,32 @@
+/*
+Looking Glass - KVM FrameRelay (KVMFR) Client
+Copyright (C) 2021 Guanzhong Chen <quantum2048@gmail.com>
+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
+*/
+
+#pragma once
+
+#include <stdbool.h>
+
+#include "interface/font.h"
+
+typedef struct EGL_Help EGL_Help;
+
+bool egl_help_init(EGL_Help ** help, const LG_Font * font, LG_FontObj fontObj);
+void egl_help_free(EGL_Help ** help);
+
+void egl_help_set_text(EGL_Help * help, const char * help_text);
+void egl_help_render(EGL_Help * help, const float scaleX, const float scaleY);

client/renderers/EGL/shader/help.frag

@@ -0,0 +1,11 @@
+#version 300 es
+
+in  highp vec2 uv;
+out highp vec4 color;
+
+uniform sampler2D sampler1;
+
+void main()
+{
+  color = texture(sampler1, uv);
+}

client/renderers/EGL/shader/help.vert

@@ -0,0 +1,22 @@
+#version 300 es
+
+layout(location = 0) in vec3 vertexPosition_modelspace;
+layout(location = 1) in vec2 vertexUV;
+
+uniform vec2 screen;
+uniform vec2 size;
+
+out highp vec2 uv;
+
+void main()
+{
+  gl_Position.xyz = vertexPosition_modelspace;
+  gl_Position.w   = 1.0;
+  gl_Position.xy *= screen.xy * size.xy;
+  gl_Position.x  -= 1.0 - (screen.x * size.x);
+  gl_Position.y  -= 1.0 - (screen.y * size.y);
+  gl_Position.x  += screen.x * 10.0;
+  gl_Position.y  += screen.y * 10.0;
+
+  uv = vertexUV;
+}

client/renderers/EGL/shader/help_bg.frag

@@ -0,0 +1,8 @@
+#version 300 es
+
+out highp vec4 color;
+
+void main()
+{
+  color = vec4(0.0, 0.0, 1.0, 1.0);
+}