[Remoting Android] Cursor & Cursor Feedback for OpenGL Renderer

remoting/client/gl_canvas.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/client/gl_canvas.h"
 
 #include "base/logging.h"
 #include "remoting/client/gl_helpers.h"
 
 namespace {
@@ skipping 26 matching lines @@
        // projection component 1.
     "  gl_Position = vec4(tex_to_view * trans_position, 1.0);\n"
     "}";
 
 const char kDrawTexFrag[] =
     "precision mediump float;\n"
 
     // Region on the texture to be used (normally the whole texture).
     "varying vec2 v_texCoord;\n"
     "uniform sampler2D u_texture;\n"
+    "uniform float u_alpha_multiplier;\n"
     "void main() {\n"
     "  gl_FragColor = texture2D(u_texture, v_texCoord);\n"
+    "  gl_FragColor.a *= u_alpha_multiplier;\n"
     "}";
 
 }  // namespace
 
 namespace remoting {
 
 GlCanvas::GlCanvas(int gl_version) : gl_version_(gl_version) {
   vertex_shader_ = CompileShader(GL_VERTEX_SHADER, kTexCoordToViewVert);
   fragment_shader_ = CompileShader(GL_FRAGMENT_SHADER, kDrawTexFrag);
   program_ = CreateProgram(vertex_shader_, fragment_shader_);
   glUseProgram(program_);
 
   transform_location_ = glGetUniformLocation(program_, "u_transform");
   texture_location_ = glGetUniformLocation(program_, "u_texture");
+  alpha_multiplier_location_ =
+      glGetUniformLocation(program_, "u_alpha_multiplier");
   position_location_ = glGetAttribLocation(program_, "a_position");
   tex_cord_location_ = glGetAttribLocation(program_, "a_texCoord");
   glEnableVertexAttribArray(position_location_);
   glEnableVertexAttribArray(tex_cord_location_);
   glEnable(GL_BLEND);
   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 }
 
 GlCanvas::~GlCanvas() {
   DCHECK(thread_checker_.CalledOnValidThread());
   glDisable(GL_BLEND);
   glDisableVertexAttribArray(tex_cord_location_);
   glDisableVertexAttribArray(position_location_);
   glDeleteProgram(program_);
   glDeleteShader(vertex_shader_);
   glDeleteShader(fragment_shader_);
 }
 
 void GlCanvas::SetNormalizedTransformation(const std::array<float, 9>& matrix) {
   DCHECK(thread_checker_.CalledOnValidThread());
   glUniformMatrix3fv(transform_location_, 1, GL_TRUE, matrix.data());
   transformation_set_ = true;
 }
 
 void GlCanvas::DrawTexture(int texture_id,
                            GLuint texture_handle,
-                           GLuint vertex_buffer) {
+                           GLuint vertex_buffer,
+                           float alpha_multiplier) {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!transformation_set_) {
     return;
   }
   glActiveTexture(GL_TEXTURE0 + texture_id);
   glBindTexture(GL_TEXTURE_2D, texture_handle);
   glUniform1i(texture_location_, texture_id);
+  glUniform1f(alpha_multiplier_location_, alpha_multiplier);
   glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
 
   glVertexAttribPointer(position_location_, kVertexSize, GL_FLOAT, GL_FALSE, 0,
                         0);
   glVertexAttribPointer(tex_cord_location_, kVertexSize, GL_FLOAT, GL_FALSE, 0,
                         static_cast<float*>(0) + kVertexSize * kVertexCount);
 
   glDrawArrays(GL_TRIANGLE_STRIP, 0, kVertexCount);
   glBindBuffer(GL_ARRAY_BUFFER, 0);
   glBindTexture(GL_TEXTURE_2D, 0);
 }
 
 int GlCanvas::GetGlVersion() const {
   return gl_version_;
 }
 
 }  // namespace remoting