LibAccelGfx+LibWeb: Add basic line painting support

For now only solid line style is supported.
lanmonster · Nov 9, 2023 · 2811862 · 2811862
1 parent f1824a5
commit 2811862
Show file tree

Hide file tree

Showing 3 changed files with 42 additions and 2 deletions.
diff --git a/Userland/Libraries/LibAccelGfx/Painter.cpp b/Userland/Libraries/LibAccelGfx/Painter.cpp
@@ -150,6 +150,42 @@ void Painter::fill_rect(Gfx::FloatRect rect, Gfx::Color color)
  glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 }
 
+void Painter::draw_line(Gfx::IntPoint a, Gfx::IntPoint b, float thickness, Gfx::Color color)
+{
+ draw_line(a.to_type<float>(), b.to_type<float>(), thickness, color);
+}
+
+void Painter::draw_line(Gfx::FloatPoint a, Gfx::FloatPoint b, float thickness, Color color)
+{
+ auto midpoint = (a + b) / 2.0f;
+ auto length = a.distance_from(b);
+ auto angle = AK::atan2(b.y() - a.y(), b.x() - a.x());
+ auto offset = Gfx::FloatPoint {
+ (length / 2) * AK::cos(angle) - (thickness / 2) * AK::sin(angle),
+ (length / 2) * AK::sin(angle) + (thickness / 2) * AK::cos(angle),
+ };
+ auto rect = Gfx::FloatRect(midpoint - offset, { length, thickness });
+
+ auto vertices = rect_to_vertices(to_clip_space(transform().map(rect)));
+
+ auto [red, green, blue, alpha] = gfx_color_to_opengl_color(color);
+
+ m_rectangle_program.use();
+
+ GLuint position_attribute = m_rectangle_program.get_attribute_location("aVertexPosition");
+ GLuint color_uniform = m_rectangle_program.get_uniform_location("uColor");
+
+ glUniform4f(color_uniform, red, green, blue, alpha);
+
+ glVertexAttribPointer(position_attribute, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), vertices.data());
+ glEnableVertexAttribArray(position_attribute);
+
+ glEnable(GL_BLEND);
+ glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+ glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+}
+
 void Painter::draw_scaled_bitmap(Gfx::IntRect const& dest_rect, Gfx::Bitmap const& bitmap, Gfx::IntRect const& src_rect, ScalingMode scaling_mode)
 {
  draw_scaled_bitmap(dest_rect.to_type<float>(), bitmap, src_rect.to_type<float>(), scaling_mode);

diff --git a/Userland/Libraries/LibAccelGfx/Painter.h b/Userland/Libraries/LibAccelGfx/Painter.h
@@ -46,6 +46,9 @@ class Painter {
  Bilinear,
  };
 
+ void draw_line(Gfx::IntPoint a, Gfx::IntPoint b, float thickness, Gfx::Color color);
+ void draw_line(Gfx::FloatPoint a, Gfx::FloatPoint b, float thickness, Gfx::Color color);
+
  void draw_scaled_bitmap(Gfx::FloatRect const& dst_rect, Gfx::Bitmap const&, Gfx::FloatRect const& src_rect, ScalingMode = ScalingMode::NearestNeighbor);
  void draw_scaled_bitmap(Gfx::IntRect const& dst_rect, Gfx::Bitmap const&, Gfx::IntRect const& src_rect, ScalingMode = ScalingMode::NearestNeighbor);
 

diff --git a/Userland/Libraries/LibWeb/Painting/PaintingCommandExecutorGPU.cpp b/Userland/Libraries/LibWeb/Painting/PaintingCommandExecutorGPU.cpp
@@ -166,9 +166,10 @@ CommandResult PaintingCommandExecutorGPU::fill_ellipse(Gfx::IntRect const&, Colo
  return CommandResult::Continue;
 }
 
-CommandResult PaintingCommandExecutorGPU::draw_line(Color const&, Gfx::IntPoint const&, Gfx::IntPoint const&, int, Gfx::Painter::LineStyle, Color const&)
+CommandResult PaintingCommandExecutorGPU::draw_line(Color const& color, Gfx::IntPoint const& a, Gfx::IntPoint const& b, int thickness, Gfx::Painter::LineStyle, Color const&)
 {
- // FIXME
+ // FIXME: Pass line style and alternate color once AccelGfx::Painter supports it
+ painter().draw_line(a, b, thickness, color);
  return CommandResult::Continue;
 }