[TIMOB-20267] Android: fix slider track showing

[frankieandone]

Test Case:
Expect to see track to be visible beneath transparent thumbImage.

var win = Ti.UI.createWindow();
var sldr = Ti.UI.createSlider({
	min: 1,
	max: 51,
	value: 51,
	thumbImage: "thumb.png",
	splitTrack: false
});
win.add(sldr);
win.open();

JIRA: https://jira.appcelerator.org/browse/TIMOB-20267

[jquick-axway]

CR: Pass

[ssjsamir]

FR passed, was able to see the slider track beneath the transparent thumbImage.

Test Steps:

• Downloaded the SDK Build from this PR
• Created a new Titanium project
• Copied the the test case from description
• Added a transparent thumbimage and background
• Ran the application
• Was able to see the track bar under the transparent image

Test Environment
Appcelerator Command-Line Interface, version 6.2.2
Google Nexus 6P (7.1.1)
Nexus 6 (6.0)
Operating System Name: Mac OS X El Capitan
Operating System Version: 10.11.6
Node.js Version: 6.10.1
Xcode: 8.2
Appcelerator Studio: 4.9.0.201705251638

[ypbnv]

Can you guard this line to apply only for API 21 and above? It causes crashes on lower levels since it was added for Lollipop.

https://developer.android.com/reference/android/widget/AbsSeekBar.html#setSplitTrack(boolean)

[jquick-axway]

Good catch Yordan.

We also have to watch out in case the property value is not a boolean. So, the code should look something like this...

if (Build.VERSION.SDK_INT  >= 21) {
	ApiLevel21.setSplitTrack(this.seekBar, TiConvert.toBoolean([[value]], false));
}

private static class ApiLevel21
{
	private ApiLevel21() {}

	public void setSplitTrack(SeekBar seekBar, boolean enabled)
	{
		if (seekBar != null) {
			seekBar.setSplitTrack(enabled);
		}
	}
}

The static inner class above avoids the opcode warning on the lower API levels.

[ypbnv]

Also here:
https://github.com/fmerzadyan/titanium_mobile/blob/08f415de7f9d395a015618ea279ef2f586f51e14/android/modules/ui/src/java/ti/modules/titanium/ui/widget/TiUISlider.java#L272

[ypbnv]

Guarding for API level.