Unable to set property with integer value

[brucekim]

Hi,

SetProperty() strictly checks property type and the type of value given so that it cannot set several property with integer value.

gobject.go

fakevideosrc, err := gst.NewElementWithName("videotestsrc", "vtestsrc")
	err = fakevideosrc.SetProperty("pattern", 2)
	if err != nil {
		logger.Infof("err %v", err)
	}

> log output
[main.go][func1] => err Invalid type gint for property pattern

I think, It is convenient for properties to allow integer value to be set with integer. In addition, gstreamer does like that.

In order to do this, I simply added following function, SetPropertyWithInteger().

I would like to hear your opinion.

func (v *Object) SetPropertyWithInteger(name string, value int) error {
	prop, err := ValueInit(TYPE_INT)
	if err != nil {
		return err
	}
	prop.SetInt(value)
	if err != nil {
		return fmt.Errorf("Unable to perform type conversion: %s", err.Error())
	}
	cstr := C.CString(name)
	defer C.free(unsafe.Pointer(cstr))
	C.g_object_set_property(v.GObject, (*C.gchar)(cstr), prop.native())
	return nil
}

[tinyzimmer]

If SetProperty doesn't work, use SetArg from the go-gst bindings instead. It will handle type conversion on the fly.

[tinyzimmer]

That being said, it's weird the integer isn't working. I thought I had examples doing that, but I can't seem to find them at the moment.

[brucekim]

testsrc, err := gst.NewElementWithName("videotestsrc", "vtestsrc")
testsrc.SetArg("pattern", "ball")
getProp, err := testsrc.GetProperty("pattern")
logger.Infof("videosrc pattern %v %v", getProp, err)

> log out
=> videosrc pattern 18 <nil>

Yeah, I checked SetArgs works well. It takes value as string.

I think integer type of value would be necessary to set property in some cases.

In the following example, giving to integer value to SetProperty returns error message.
I think it is because "pattern" property is type of C.G_TYPE_ENUM against C.G_TYPE_INT.

fakevideosrc, err := gst.NewElementWithName("videotestsrc", "vtestsrc")
	err = fakevideosrc.SetProperty("pattern", 2)
	if err != nil {
		logger.Infof("err %v", err)
	}

> log output
[main.go][func1] => err Invalid type gint for property pattern

[tinyzimmer]

Ah yep, that makes sense. Enum properties are not handled at all. And I think it was me stumbling on an enum myself than eventually led to binding SetArg downstream.

[brucekim]

I have an idea. What if an enum type of property accepts interger type of value as well in SetPropertyValue()?
Gstreamer is capable of this so making go-gst binding capable this would be nice I think.

In order to make this,
I found that enum type of properties belong to an element has a hierarchy unlike other fundamental types.
For example, pattern property of videotestsrc element has a hierarchy such as GEnum -> GstVideoTestSrcPattern in which .Depth() is two. Thus, it was necessary for searching GEum type to go upstream of propType
I would like to hear your opinion.

I share test code below.

Related PR: #3

import (
	"fmt"
	"github.com/tinyzimmer/go-glib/glib"
	"github.com/tinyzimmer/go-gst/gst"
	"testing"
)

func TestSetProperty_TypeCheck (t *testing.T) {
	//INT
	value := 10
	name := "pattern"
	//name := "timestamp-offset"
	gst.Init(nil)
	elem, err := gst.NewElement("videotestsrc")
	if err != nil {
		t.Errorf(err.Error())
	}
	gValue, err := glib.GValue(value)
	if err != nil {
		t.Errorf(err.Error())
	}
	propType, err := elem.GetPropertyType(name)
	if err != nil {
		t.Errorf(err.Error())
	}
	valType, _, err := gValue.Type()
	if err != nil {
		t.Errorf(err.Error())
	}

	fmt.Printf("propType name %v depth %v parent %v parent name %v\n",
		propType.Name(),
		propType.Depth(),
		propType.Parent(),
		propType.Parent().Name(),
		)
	fmt.Printf("valType name %v depth %v parent %v parent name %v\n",
		valType.Name(),
		valType.Depth(),
		valType.Parent(),
		valType.Parent().Name(),
		)

	switch valType {
	case glib.TYPE_INT:
		for ; propType.Depth() > 1; propType = propType.Parent() {
		}
		fmt.Printf("propType name %v depth %v parent %v parent name %v\n",
			propType.Name(),
			propType.Depth(),
			propType.Parent(),
			propType.Parent().Name(),
		)

		if propType == glib.TYPE_ENUM {
			break
		}
		fallthrough
	default:
		if valType != propType {
			fmt.Errorf("Invalid type %s for property %s", gValue.TypeName(), name)
			return
		}
	}
	fmt.Println("set property here")
}

> execution result
=== RUN   TestSetProperty_TypeCheck
propType name GstVideoTestSrcPattern depth 2 parent 48 parent name GEnum
valType name gint depth 1 parent 0 parent name 
propType name GEnum depth 1 parent 0 parent name 
set property here
--- PASS: TestSetProperty_TypeCheck (0.02s)