Android 5.0: apply tint color

Without this change checkboxes, radio buttons, slider handle etc.
are black on Android 5.0. This change applies the tint color so
that the controls become green/cyan as appropriate.

Task-number: QTBUG-42520
Change-Id: Ib8bd9d279f34e0f7951b311f398bc1fb11f7b1ba
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@theqtcompany.com>

src/controls/Styles/Android/drawables/ImageDrawable.qml

@@ -52,5 +52,33 @@ Drawable {
         anchors.fill: parent
         fillMode: Image.TileHorizontally
         source: AndroidStyle.filePath(styleDef.path)
+
+        layer.enabled: !!styleDef && !!styleDef.tintList
+        layer.effect: ShaderEffect {
+            property variant source: image
+            property color color: AndroidStyle.colorValue(styleDef.tintList[state])
+            state: {
+                var states = []
+                if (pressed) states.push("PRESSED")
+                if (enabled) states.push("ENABLED")
+                if (focused) states.push("FOCUSED")
+                if (selected) states.push("SELECTED")
+                if (window_focused) states.push("WINDOW_FOCUSED")
+                if (!states.length)
+                    states.push("EMPTY")
+                return states.join("_") + "_STATE_SET"
+            }
+            // QtGraphicalEffects/ColorOverlay:
+            fragmentShader: "
+                varying mediump vec2 qt_TexCoord0;
+                uniform highp float qt_Opacity;
+                uniform lowp sampler2D source;
+                uniform highp vec4 color;
+                void main() {
+                    highp vec4 pixelColor = texture2D(source, qt_TexCoord0);
+                    gl_FragColor = vec4(mix(pixelColor.rgb/max(pixelColor.a, 0.00390625), color.rgb/max(color.a, 0.00390625), color.a) * pixelColor.a, pixelColor.a) * qt_Opacity;
+                }
+            "
+        }
     }
 }