Make gleam optional for compositor, switch various names from glutin to winit

components/compositing/gl.rs

@@ -0,0 +1,97 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+use gleam::gl;
+use image::RgbImage;
+use servo_geometry::DeviceUintLength;
+
+
+#[derive(Default)]
+pub struct RenderTargetInfo {
+    framebuffer_ids: Vec<gl::GLuint>,
+    renderbuffer_ids: Vec<gl::GLuint>,
+    texture_ids: Vec<gl::GLuint>,
+}
+
+pub fn initialize_png(
+    gl: &gl::Gl, width: DeviceUintLength, height: DeviceUintLength
+) -> RenderTargetInfo {
+    let framebuffer_ids = gl.gen_framebuffers(1);
+    gl.bind_framebuffer(gl::FRAMEBUFFER, framebuffer_ids[0]);
+
+    let texture_ids = gl.gen_textures(1);
+    gl.bind_texture(gl::TEXTURE_2D, texture_ids[0]);
+
+    gl.tex_image_2d(gl::TEXTURE_2D, 0, gl::RGB as gl::GLint, width.get() as gl::GLsizei,
+                    height.get() as gl::GLsizei, 0, gl::RGB, gl::UNSIGNED_BYTE, None);
+    gl.tex_parameter_i(gl::TEXTURE_2D, gl::TEXTURE_MAG_FILTER, gl::NEAREST as gl::GLint);
+    gl.tex_parameter_i(gl::TEXTURE_2D, gl::TEXTURE_MIN_FILTER, gl::NEAREST as gl::GLint);
+
+    gl.framebuffer_texture_2d(gl::FRAMEBUFFER, gl::COLOR_ATTACHMENT0, gl::TEXTURE_2D,
+                              texture_ids[0], 0);
+
+    gl.bind_texture(gl::TEXTURE_2D, 0);
+
+    let renderbuffer_ids = gl.gen_renderbuffers(1);
+    let depth_rb = renderbuffer_ids[0];
+    gl.bind_renderbuffer(gl::RENDERBUFFER, depth_rb);
+    gl.renderbuffer_storage(gl::RENDERBUFFER,
+                            gl::DEPTH_COMPONENT24,
+                            width.get() as gl::GLsizei,
+                            height.get() as gl::GLsizei);
+    gl.framebuffer_renderbuffer(gl::FRAMEBUFFER,
+                                gl::DEPTH_ATTACHMENT,
+                                gl::RENDERBUFFER,
+                                depth_rb);
+
+    RenderTargetInfo {
+        framebuffer_ids,
+        renderbuffer_ids,
+        texture_ids,
+    }
+}
+
+pub fn draw_img(
+    gl: &gl::Gl,
+    render_target_info: RenderTargetInfo,
+    width: DeviceUintLength,
+    height: DeviceUintLength,
+) -> RgbImage {
+    let width = width.get() as usize;
+    let height = height.get() as usize;
+    // For some reason, OSMesa fails to render on the 3rd
+    // attempt in headless mode, under some conditions.
+    // I think this can only be some kind of synchronization
+    // bug in OSMesa, but explicitly un-binding any vertex
+    // array here seems to work around that bug.
+    // See https://github.com/servo/servo/issues/18606.
+    gl.bind_vertex_array(0);
+
+    let mut pixels = gl.read_pixels(
+        0, 0,
+        width as gl::GLsizei,
+        height as gl::GLsizei,
+        gl::RGB, gl::UNSIGNED_BYTE,
+    );
+
+    gl.bind_framebuffer(gl::FRAMEBUFFER, 0);
+
+    gl.delete_buffers(&render_target_info.texture_ids);
+    gl.delete_renderbuffers(&render_target_info.renderbuffer_ids);
+    gl.delete_framebuffers(&render_target_info.framebuffer_ids);
+
+    // flip image vertically (texture is upside down)
+    let orig_pixels = pixels.clone();
+    let stride = width * 3;
+    for y in 0..height {
+        let dst_start = y * stride;
+        let src_start = (height - y - 1) * stride;
+        let src_slice = &orig_pixels[src_start .. src_start + stride];
+        (&mut pixels[dst_start .. dst_start + stride]).clone_from_slice(&src_slice[..stride]);
+    }
+
+    RgbImage::from_raw(width as u32, height as u32, pixels)
+        .expect("Flipping image failed!")
+}