1 files changed, 125 insertions, 0 deletions
diff --git a/library/main/src/com/android/setupwizardlib/view/FillContentLayout.java b/library/main/src/com/android/setupwizardlib/view/FillContentLayout.java
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+++ b/library/main/src/com/android/setupwizardlib/view/FillContentLayout.java
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+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.setupwizardlib.view;
+
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.FrameLayout;
+
+import com.android.setupwizardlib.R;
+
+/**
+ * A layout that will measure its children size based on the space it is given, by using its
+ * {@code android:minWidth}, {@code android:minHeight}, {@code android:maxWidth}, and
+ * {@code android:maxHeight} values.
+ *
+ * <p>Typically this is used to show an illustration image or video on the screen. For optimal UX,
+ * those assets typically want to occupy the remaining space available on screen within a certain
+ * range, and then stop scaling beyond the min/max size attributes. Therefore this view is typically
+ * used inside a ScrollView with {@code fillViewport} set to true, together with a linear layout
+ * weight or relative layout to fill the remaining space visible on screen.
+ *
+ * <p>When measuring, this view ignores its children and simply layout according to the minWidth /
+ * minHeight given. Therefore it is common for children of this layout to have width / height set to
+ * {@code match_parent}. The maxWidth / maxHeight values will then be applied to the children to
+ * make sure they are not too big.
+ */
+public class FillContentLayout extends FrameLayout {
+
+    private int mMaxWidth;
+    private int mMaxHeight;
+
+    public FillContentLayout(Context context) {
+        this(context, null);
+    }
+
+    public FillContentLayout(Context context, AttributeSet attrs) {
+        this(context, attrs, R.attr.suwFillContentLayoutStyle);
+    }
+
+    public FillContentLayout(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        init(context, attrs, defStyleAttr);
+    }
+
+    private void init(Context context, AttributeSet attrs, int defStyleAttr) {
+        TypedArray a = context.obtainStyledAttributes(
+                attrs,
+                R.styleable.SuwFillContentLayout,
+                defStyleAttr,
+                0);
+
+        mMaxHeight = a.getDimensionPixelSize(
+                R.styleable.SuwFillContentLayout_android_maxHeight, -1);
+        mMaxWidth = a.getDimensionPixelSize(R.styleable.SuwFillContentLayout_android_maxWidth, -1);
+
+        a.recycle();
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        // Measure this view with the minWidth and minHeight, without asking the children.
+        // (Children size is the drawable's intrinsic size, and we don't want that to influence
+        // the size of the illustration).
+        setMeasuredDimension(
+                getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
+                getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
+
+        int childCount = getChildCount();
+        for (int i = 0; i < childCount; i++) {
+            measureIllustrationChild(getChildAt(i), getMeasuredWidth(), getMeasuredHeight());
+        }
+    }
+
+    private void measureIllustrationChild(View child, int parentWidth, int parentHeight) {
+        // Modified from ViewGroup#measureChildWithMargins
+        final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
+
+        // Create measure specs that are no bigger than min(parentSize, maxSize)
+
+        int childWidthMeasureSpec = getMaxSizeMeasureSpec(
+                Math.min(mMaxWidth, parentWidth),
+                getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin,
+                lp.width);
+        int childHeightMeasureSpec = getMaxSizeMeasureSpec(
+                Math.min(mMaxHeight, parentHeight),
+                getPaddingTop() + getPaddingBottom() + lp.topMargin + lp.bottomMargin,
+                lp.height);
+
+        child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
+    }
+
+    private static int getMaxSizeMeasureSpec(int maxSize, int padding, int childDimension) {
+        // Modified from ViewGroup#getChildMeasureSpec
+        int size = Math.max(0, maxSize - padding);
+
+        if (childDimension >= 0) {
+            // Child wants a specific size... so be it
+            return MeasureSpec.makeMeasureSpec(childDimension, MeasureSpec.EXACTLY);
+        } else if (childDimension == LayoutParams.MATCH_PARENT) {
+            // Child wants to be our size. So be it.
+            return MeasureSpec.makeMeasureSpec(size, MeasureSpec.EXACTLY);
+        } else if (childDimension == LayoutParams.WRAP_CONTENT) {
+            // Child wants to determine its own size. It can't be
+            // bigger than us.
+            return MeasureSpec.makeMeasureSpec(size, MeasureSpec.AT_MOST);
+        }
+        return 0;
+    }
+}