walk

About Walk
==========

Walk is a "Windows Application Library Kit" for the Go Programming Language.

Its primarily useful for Desktop GUI development, but there is some more stuff.

Setup
=====

Make sure you have a working Go installation.
See [Getting Started](http://golang.org/doc/install.html)

##### Note
`Go 1.7.x` doesn't work with walk anymore, Make sure you use `Go 1.8.x` or later.

##### To Install
Now run `go get github.com/lxn/walk`

Using Walk
==========

The preferred way to create GUIs with Walk is to use its declarative sub package,
as illustrated in this small example:

##### `test.go`

```go
package main

import (
	"github.com/lxn/walk"
	. "github.com/lxn/walk/declarative"
	"strings"
)

func main() {
	var inTE, outTE *walk.TextEdit

	MainWindow{
		Title:   "SCREAMO",
		MinSize: Size{600, 400},
		Layout:  VBox{},
		Children: []Widget{
			HSplitter{
				Children: []Widget{
					TextEdit{AssignTo: &inTE},
					TextEdit{AssignTo: &outTE, ReadOnly: true},
				},
			},
			PushButton{
				Text: "SCREAM",
				OnClicked: func() {
					outTE.SetText(strings.ToUpper(inTE.Text()))
				},
			},
		},
	}.Run()
}
```

##### Create Manifest `test.manifest`

```xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
    <assemblyIdentity version="1.0.0.0" processorArchitecture="*" name="SomeFunkyNameHere" type="win32"/>
    <dependency>
        <dependentAssembly>
            <assemblyIdentity type="win32" name="Microsoft.Windows.Common-Controls" version="6.0.0.0" processorArchitecture="*" publicKeyToken="6595b64144ccf1df" language="*"/>
        </dependentAssembly>
    </dependency>
    <application xmlns="urn:schemas-microsoft-com:asm.v3">
        <windowsSettings>
            <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2, PerMonitor</dpiAwareness>
            <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">True</dpiAware>
        </windowsSettings>
    </application>
</assembly>
```

Then either compile the manifest using the [rsrc tool](https://github.com/akavel/rsrc), like this:

	go get github.com/akavel/rsrc
	rsrc -manifest test.manifest -o rsrc.syso

or rename the `test.manifest` file to `test.exe.manifest` and distribute it with the application instead.

##### Build app

In the directory containing `test.go` run

	go build
	
To get rid of the cmd window, instead run

	go build -ldflags="-H windowsgui"

##### Run app
	
	test.exe
	
##### Sample Output (Windows 7)

![alt tag](http://i.imgur.com/lUrgE2Q.png)

##### More Examples
There are some [examples](examples) that should get you started.

Application Manifest Files
==========================
Walk requires Common Controls 6. This means that you must put an appropriate
application manifest file either next to your executable or embedded as a
resource.

You can copy one of the application manifest files that come with the examples.

To embed a manifest file as a resource, you can use the [rsrc tool](https://github.com/akavel/rsrc).

IMPORTANT: If you don't embed a manifest as a resource, then you should not launch
your executable before the manifest file is in place.
If you do anyway, the program will not run properly. And worse, Windows will not
recognize a manifest file, you later drop next to the executable. To fix this,
rebuild your executable and only launch it with a manifest file in place.

Program Crashes
===============
By default Go uses os threads with small stack sizes of 128KB. If your walk app crashes, it may be due
to a stack overflow. Until a [better solution is found](https://github.com/golang/go/issues/20975),
you can work around this by adding

    import _ "runtime/cgo"

somewhere in your program. If you don't have `gcc` installed and on your `PATH`,
you can alternatively add `-linkmode internal` to the `-ldflags` of your `go build` command like so:

    go build -ldflags="-H windowsgui -linkmode internal"

CGo Optimizations
=================

The usual default message loop includes calls to win32 API functions, which incurs a decent amount
of runtime overhead coming from Go. As an alternative to this, you may compile Walk using an
optional C implementation of the main message loop, by passing the `walk_use_cgo` build tag:

   go build -tags walk_use_cgo