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LibAccelGfx+LibWeb: Implement draw_scaled_bitmap()

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Very basic implementation of command to paint bitmap. In the future we
should reuse loaded textures across repaints whenever it is possible.
This commit is contained in:
Aliaksandr Kalenik 2023-11-02 01:18:07 +01:00 • committed by Andreas Kling
parent b7f8d7e357
commit aa6c008450
3 changed files with 110 additions and 2 deletions
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83
Userland/Libraries/LibAccelGfx/Painter.cpp
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@ -57,6 +57,25 @@ void main() {
}
)";
char const* blit_vertex_shader_source = R"(
attribute vec4 aVertexPosition;
attribute vec2 aTextureCoord;
varying vec2 vTextureCoord;
void main() {
gl_Position = aVertexPosition;
vTextureCoord = aTextureCoord;
}
)";
char const* blit_fragment_shader_source = R"(
precision mediump float;
varying vec2 vTextureCoord;
uniform sampler2D uSampler;
void main() {
gl_FragColor = texture2D(uSampler, vTextureCoord);
}
)";
OwnPtr<Painter> Painter::create()
{
auto& context = Context::the();
@ -66,6 +85,7 @@ OwnPtr<Painter> Painter::create()
Painter::Painter(Context& context)
: m_context(context)
, m_rectangle_program(Program::create(vertex_shader_source, solid_color_fragment_shader_source))
, m_blit_program(Program::create(blit_vertex_shader_source, blit_fragment_shader_source))
{
m_state_stack.empend(State());
}
@ -125,6 +145,69 @@ void Painter::fill_rect(Gfx::FloatRect rect, Gfx::Color color)
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);
}
static Gfx::FloatRect to_texture_space(Gfx::FloatRect rect, Gfx::IntSize image_size)
{
auto x = rect.x() / image_size.width();
auto y = rect.y() / image_size.height();
auto width = rect.width() / image_size.width();
auto height = rect.height() / image_size.height();
return { x, y, width, height };
}
static GLenum to_gl_scaling_mode(Painter::ScalingMode scaling_mode)
{
switch (scaling_mode) {
case Painter::ScalingMode::NearestNeighbor:
return GL_NEAREST;
case Painter::ScalingMode::Bilinear:
return GL_LINEAR;
default:
VERIFY_NOT_REACHED();
}
}
void Painter::draw_scaled_bitmap(Gfx::FloatRect const& dst_rect, Gfx::Bitmap const& bitmap, Gfx::FloatRect const& src_rect, ScalingMode scaling_mode)
{
m_blit_program.use();
GLuint texture;
// FIXME: We should reuse textures across repaints if possible.
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bitmap.width(), bitmap.height(), 0, GL_BGRA, GL_UNSIGNED_BYTE, bitmap.scanline(0));
GLenum scaling_mode_gl = to_gl_scaling_mode(scaling_mode);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, scaling_mode_gl);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, scaling_mode_gl);
auto vertices = rect_to_vertices(to_clip_space(transform().map(dst_rect)));
auto texture_coordinates = rect_to_vertices(to_texture_space(src_rect, bitmap.size()));
GLuint vertex_position_attribute = m_blit_program.get_attribute_location("aVertexPosition");
glVertexAttribPointer(vertex_position_attribute, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), vertices.data());
glEnableVertexAttribArray(vertex_position_attribute);
GLuint texture_coord_attribute = m_blit_program.get_attribute_location("aTextureCoord");
glVertexAttribPointer(texture_coord_attribute, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), texture_coordinates.data());
glEnableVertexAttribArray(texture_coord_attribute);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
glDeleteTextures(1, &texture);
}
void Painter::save()
{
m_state_stack.append(state());