change android icon, move code so .cpp and implement stroke preview using Stroke class for accurate preview.

engine/canvas.cpp

@@ -3,3 +3,119 @@
 
 
 
+void ui::Canvas::clear()
+{
+    m_fb.bindFramebuffer();
+
+    GLint vp[4];
+    GLfloat cc[4];
+    glGetIntegerv(GL_VIEWPORT, vp);
+    glGetFloatv(GL_COLOR_CLEAR_VALUE, cc);
+
+    glClearColor(1, 1, 1, 1);
+    glClear(GL_COLOR_BUFFER_BIT);
+    glViewport(0, 0, m_width, m_height);
+
+    //
+
+    glViewport(vp[0], vp[1], vp[2], vp[3]);
+    glClearColor(cc[0], cc[1], cc[2], cc[3]);
+
+    m_fb.unbindFramebuffer();
+}
+void ui::Canvas::stroke_end()
+{
+    m_current_stroke = nullptr;
+}
+void ui::Canvas::stroke_draw()
+{
+    if (!(m_current_stroke && m_current_stroke->has_sample()))
+        return;
+
+    m_fb.bindFramebuffer();
+
+    GLint vp[4];
+    GLfloat cc[4];
+    glGetIntegerv(GL_VIEWPORT, vp);
+    glGetFloatv(GL_COLOR_CLEAR_VALUE, cc);
+
+    glViewport(0, 0, m_width, m_height);
+    glEnable(GL_BLEND);
+
+    auto proj = glm::ortho(0.f, (float)m_width, (float)m_height, 0.f, -1.f, 1.f);
+    auto m_brush = m_current_stroke->m_brush;
+    auto samples = m_current_stroke->compute_samples();
+    auto& tex = TextureManager::get(m_brush.m_tex_id);
+    tex.bind();
+    m_sampler.bind(0);
+
+    if (m_use_instanced)
+    {
+        m_mesh.shader.use();
+        m_mesh.shader.u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
+        m_mesh.shader.u_int(kShaderUniform::Tex, 0);
+        m_mesh.draw(samples, proj);
+    }
+    else
+    {
+        ShaderManager::use("stroke");
+        ShaderManager::u_vec4(kShaderUniform::Col, m_brush.m_tip_color);
+        ShaderManager::u_int(kShaderUniform::Tex, 0);
+        for (const auto& s : samples)
+        {
+            auto mvp = proj *
+                glm::translate(glm::vec3(s.pos, 0)) *
+                glm::scale(glm::vec3(s.size, s.size, 1)) *
+                glm::eulerAngleZ(s.angle);
+
+            ShaderManager::u_mat4(kShaderUniform::MVP, mvp);
+            ShaderManager::u_float(kShaderUniform::Alpha, s.flow);
+            m_plane.draw_fill();
+        }
+    }
+
+    m_sampler.unbind();
+    tex.unbind();
+
+    glDisable(GL_BLEND);
+
+    glViewport(vp[0], vp[1], vp[2], vp[3]);
+    glClearColor(cc[0], cc[1], cc[2], cc[3]);
+
+    m_fb.unbindFramebuffer();
+}
+void ui::Canvas::stroke_update(glm::vec2 point, float pressure)
+{
+    m_current_stroke->add_point(point, pressure);
+}
+void ui::Canvas::stroke_start(glm::vec2 point, float pressure, const ui::Brush& brush)
+{
+    m_strokes.emplace_back();
+    m_strokes.back().start(brush);
+    m_strokes.back().add_point(point, pressure);
+    m_current_stroke = &m_strokes.back();
+}
+void ui::Canvas::layer_add(std::string name)
+{
+    m_layers.emplace_back();
+    m_layers.back().create(m_width, m_height, name);
+}
+void ui::Canvas::resize(int width, int height)
+{
+    m_width = width;
+    m_height = height;
+    m_tmp->create(width, height, "tmp");
+    m_fb.create(width, height);
+}
+bool ui::Canvas::create(int width, int height)
+{
+    m_width = width;
+    m_height = height;
+    m_tmp = std::make_unique<Layer>();
+    m_tmp->create(width, height, "tmp");
+    m_fb.create(width, height);
+    m_sampler.create();
+    m_plane.create<1>(1, 1);
+    m_mesh.create();
+    return true;
+}