hudly/app/app.go

package main

import (
	"github.com/haleyrom/skia-go"
	"image/color"
	"log"
	"runtime"

	"github.com/go-gl/gl/v3.3-core/gl"
	"github.com/go-gl/glfw/v3.3/glfw"
)

func init() {
	// GLFW event handling must run on the main OS thread
	runtime.LockOSThread()
}

func main() {
	// Initialize GLFW
	if err := glfw.Init(); err != nil {
		log.Fatalf("failed to initialize GLFW: %v", err)
	}
	defer glfw.Terminate()

	// Create GLFW window
	glfw.WindowHint(glfw.ContextVersionMajor, 3)
	glfw.WindowHint(glfw.ContextVersionMinor, 3)
	glfw.WindowHint(glfw.OpenGLProfile, glfw.OpenGLCoreProfile)
	glfw.WindowHint(glfw.OpenGLForwardCompatible, glfw.True)

	window, err := glfw.CreateWindow(800, 600, "GLFW + Skia Demo", nil, nil)
	if err != nil {
		log.Fatalf("failed to create GLFW window: %v", err)
	}
	window.MakeContextCurrent()

	// Initialize OpenGL
	if err := gl.Init(); err != nil {
		log.Fatalf("failed to initialize OpenGL: %v", err)
	}

	// Set up Skia surface
	glInterface := skia.NewNativeGrGlinterface()
	if glInterface == nil {
		log.Fatalf("failed to create Skia OpenGL interface")
	}
	grContext := skia.NewGLGrContext(glInterface)
	if grContext == nil {
		log.Fatalf("failed to create Skia GrContext")
	}

	// Get framebuffer info
	var framebufferInfo skia.GrGlFramebufferinfo
	var fboID int32
	gl.GetIntegerv(gl.FRAMEBUFFER_BINDING, &fboID)
	framebufferInfo.FFBOID = uint32(fboID)
	framebufferInfo.FFormat = gl.RGBA8

	width, height := window.GetSize()
	renderTarget := skia.NewGlGrBackendrendertarget(int32(width), int32(height), 1, 8, &framebufferInfo)
	if renderTarget == nil {
		log.Fatalf("failed to create Skia render target")
	}

	surface := skia.NewSurfaceBackendRenderTarget(grContext, renderTarget, skia.GR_SURFACE_ORIGIN_BOTTOM_LEFT, skia.SK_COLORTYPE_RGBA_8888, nil, nil)
	if surface == nil {
		log.Fatalf("failed to create Skia surface")
	}
	defer surface.Unref()

	c := color.RGBA{R: 255, G: 100, B: 50, A: 255}
	f := skia.NewColor4f(c)
	colorWhite := f.ToColor()

	for !window.ShouldClose() {
		gl.ClearColor(0.3, 0.3, 0.3, 1.0)
		gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)

		canvas := surface.GetCanvas()

		paint := skia.NewPaint()
		paint.SetColor(0xffff0000)

		// Clear the canvas with white color
		canvas.Clear(colorWhite)

		// Create a rectangle and draw it
		rect := skia.Rect{
			Left:   100,
			Top:    100,
			Right:  300,
			Bottom: 300,
		}
		canvas.DrawRect(&rect, paint)
		grContext.Flush()

		// Swap OpenGL buffers
		window.SwapBuffers()

		// Poll for GLFW events
		glfw.PollEvents()
	}

	// Cleanup
	surface.Unref()
	grContext.Unref()
}