qt.go

package main

import (
	"bytes"
	"fmt"
	"image/png"
	"os"

	"github.com/therecipe/qt/core"
	"github.com/therecipe/qt/gui"
	"github.com/therecipe/qt/widgets"
)

func main() {
	widgets.NewQApplication(len(os.Args), os.Args)

	var btn = widgets.NewQPushButton2("Hello World", nil)
	var btn2 = widgets.NewQPushButton2("Hello World", nil)
	var btn3 = widgets.NewQPushButton2("Hello World", nil)

	// icon from filesystem is loaded and shown
	icon := gui.NewQIcon5("images/refresh.png")

	// this is data from bindata.go (go-bindata images/refresh.png)
	// file is checked with pngfix refresh.png
	// IDAT OK  maximum 15 15 616 2730 refresh.png
	data, err := Asset("images/refresh.png")
	if err != nil {
		fmt.Println("Asset:", err)
	}

	fmt.Println("len(data):", len(data))

	// png decode works with data
	im, err := png.Decode(bytes.NewReader(data))
	if err != nil {
		fmt.Println("png.Decode:", err)
	}

	// data2, bytes from png.Encode
	buf := new(bytes.Buffer)
	err = png.Encode(buf, im)
	data2 := buf.Bytes()

	fmt.Println("len(data2):", len(data2))

	// try to load pixmap from data
	pixmap := gui.NewQPixmap()
	fmt.Println("pixmap.LoadFromData2")

	// returns libpng error: Read Error
	ok := pixmap.LoadFromData2(string(data), "PNG", core.Qt__AutoColor)
	if !ok {
		ok = pixmap.LoadFromData2(string(data[:]), "PNG", core.Qt__AutoColor)
		if !ok {
			pixmap.LoadFromData2(string(data[:clen(data)]), "PNG", core.Qt__AutoColor)
		}
	}

	icon2 := gui.NewQIcon()
	icon2.AddPixmap(pixmap, gui.QIcon__Normal, gui.QIcon__Off)

	fmt.Println("len(data):", len(data))
	fmt.Println("len(data2):", len(data2))

	// try to load pixmap from data2 (png.Encoded)
	pixmap = gui.NewQPixmap()
	fmt.Println("pixmap.LoadFromData2")

	// returns libpng error: Read Error
	ok = pixmap.LoadFromData2(string(data2), "PNG", core.Qt__AutoColor)
	if !ok {
		ok = pixmap.LoadFromData2(string(data2[:]), "PNG", core.Qt__AutoColor)
		if !ok {
			pixmap.LoadFromData2(string(data2[:clen(data2)]), "PNG", core.Qt__AutoColor)
		}
	}

	icon3 := gui.NewQIcon()
	icon3.AddPixmap(pixmap, gui.QIcon__Normal, gui.QIcon__Off)

	btn.SetIcon(icon)
	btn2.SetIcon(icon2)
	btn3.SetIcon(icon3)

	var window = widgets.NewQWidget(nil, 0)
	var layout = widgets.NewQVBoxLayout()

	layout.AddWidget(btn, 0, 0)
	layout.AddWidget(btn2, 0, 0)
	layout.AddWidget(btn3, 0, 0)

	window.SetLayout(layout)
	window.SetWindowTitle("Hello World Example")
	window.Show()

	widgets.QApplication_Exec()
}

// Finds first null byte and returns the length
func clen(n []byte) int {
	for i := 0; i < len(n); i++ {
		if n[i] == 0 {
			return i
		}
	}
	return len(n)
}