1 files changed, 107 insertions, 0 deletions
diff --git a/core/src/main/kotlin/ca/allanwang/kau/ui/views/MeasureSpecDelegate.kt b/core/src/main/kotlin/ca/allanwang/kau/ui/views/MeasureSpecDelegate.kt
new file mode 100644
index 0000000..edc1536
--- /dev/null
+++ b/core/src/main/kotlin/ca/allanwang/kau/ui/views/MeasureSpecDelegate.kt
@@ -0,0 +1,107 @@
+package ca.allanwang.kau.ui.views
+
+import android.content.Context
+import android.graphics.Rect
+import android.util.AttributeSet
+import android.view.View
+import ca.allanwang.kau.R
+import ca.allanwang.kau.utils.parentViewGroup
+
+/**
+ * Created by Allan Wang on 2017-07-14.
+ *
+ * Handles relative sizes for any view
+ */
+interface MeasureSpecContract {
+
+    /**
+     * Width will be calculated as a percentage of the parent
+     * This takes precedence over relativeWidth
+     */
+    var relativeWidthToParent: Float
+    /**
+     * Height will be calculated as a percentage of the parent
+     * This takes precedence over relativeHeight
+     */
+    var relativeHeightToParent: Float
+    /**
+     * Width will be calculated based on the measured height
+     */
+    var relativeWidth: Float
+    /**
+     * Height will be calculated based on the measure width
+     */
+    var relativeHeight: Float
+    /**
+     * Width will be once again calculated from the current measured height
+     * This is the last step
+     */
+    var postRelativeWidth: Float
+    /**
+     * Height will be once again calculated from the current measured width
+     * This is the last step
+     */
+    var postRelativeHeight: Float
+
+    /**
+     * Retrieves relative values from the [AttributeSet]
+     * Call this on init
+     */
+    fun initAttrs(context: Context, attrs: AttributeSet?)
+
+    /**
+     * Calculates the final measure specs
+     * Call this from [View.onMeasure] and send the Pair result as the specs
+     * The pair is of the format (width, height)
+     */
+    fun onMeasure(view: View, widthMeasureSpec: Int, heightMeasureSpec: Int): Pair<Int, Int>
+}
+
+class MeasureSpecDelegate : MeasureSpecContract {
+
+    override var relativeWidth = -1f
+    override var relativeHeight = -1f
+    override var relativeWidthToParent = -1f
+    override var relativeHeightToParent = -1f
+    override var postRelativeWidth: Float = -1f
+    override var postRelativeHeight: Float = -1f
+    private val parentFrame = Rect()
+
+    override fun initAttrs(context: Context, attrs: AttributeSet?) {
+        if (attrs == null) return
+        val styledAttrs = context.obtainStyledAttributes(attrs, R.styleable.MeasureSpecDelegate)
+        relativeWidth = styledAttrs.getFloat(R.styleable.MeasureSpecDelegate_relativeWidth, relativeWidth)
+        relativeHeight = styledAttrs.getFloat(R.styleable.MeasureSpecDelegate_relativeHeight, relativeHeight)
+        relativeWidthToParent = styledAttrs.getFloat(R.styleable.MeasureSpecDelegate_relativeWidthToParent, relativeWidthToParent)
+        relativeHeightToParent = styledAttrs.getFloat(R.styleable.MeasureSpecDelegate_relativeHeightToParent, relativeHeightToParent)
+        postRelativeWidth = styledAttrs.getFloat(R.styleable.MeasureSpecDelegate_postRelativeWidth, postRelativeWidth)
+        postRelativeHeight = styledAttrs.getFloat(R.styleable.MeasureSpecDelegate_postRelativeHeight, postRelativeHeight)
+        styledAttrs.recycle()
+    }
+
+    override fun onMeasure(view: View, widthMeasureSpec: Int, heightMeasureSpec: Int): Pair<Int, Int> {
+        view.parentViewGroup.getWindowVisibleDisplayFrame(parentFrame)
+        var width = View.MeasureSpec.getSize(widthMeasureSpec).toFloat()
+        var height = View.MeasureSpec.getSize(heightMeasureSpec).toFloat()
+        //first cycle - relative to parent
+        if (relativeHeightToParent > 0)
+            height = relativeHeightToParent * parentFrame.height()
+        if (relativeWidthToParent > 0)
+            width = relativeWidthToParent * parentFrame.width()
+        //second cycle - relative to each other
+        if (relativeHeight > 0)
+            height = relativeHeight * width
+        else if (relativeWidth > 0)
+            width = relativeWidth * height
+        //third cycle - relative to each other
+        if (postRelativeHeight > 0)
+            height = postRelativeHeight * width
+        else if (postRelativeWidth > 0)
+            width = postRelativeWidth * height
+        return Pair(width.measureSpec, height.measureSpec)
+    }
+
+    private val Float.measureSpec: Int
+        get() = View.MeasureSpec.makeMeasureSpec(this.toInt(), View.MeasureSpec.EXACTLY)
+
+}