From 7f556038b00b9cee9efe290ce79c2f99071463cd Mon Sep 17 00:00:00 2001
From: Marten Gajda <marten@dmfs.org>
Date: Fri, 7 Apr 2017 14:24:19 +0200
Subject: [PATCH] Add "autoAnimate" attribute to configure how scrim and title
 behave when collapsing the toolbar.

none - nothing will be auto-animated, i.e. values change gradually as you scroll
title - the title blending will be auto-animated when the scrim height has been reached
scrim - scrim will be auto-animated when the scrim height has been reached (this is the default)
all - title and scrim will be auto-animated when the scrim height as been reached

Note there is another value "children" which requires the changes of another branch to work
---
 demo/src/main/res/layout/activity_demo.xml    |  5 +++
 .../CollapsingTextHelper.java                 | 40 +++++++++++++----
 .../CollapsingToolbarLayout.java              | 45 ++++++++++++++++---
 .../res/values/collapsing_toolbar_attrs.xml   |  7 +++
 4 files changed, 81 insertions(+), 16 deletions(-)

diff --git a/demo/src/main/res/layout/activity_demo.xml b/demo/src/main/res/layout/activity_demo.xml
index ab78bfd..249095e 100644
--- a/demo/src/main/res/layout/activity_demo.xml
+++ b/demo/src/main/res/layout/activity_demo.xml
@@ -21,8 +21,13 @@
             app:layout_scrollFlags="scroll|exitUntilCollapsed"
             app:title="@string/title"
             app:expandedTitleTextAppearance="@style/TextAppearance.ExpandedTitle"
+            app:autoAnimate="all"
+            app:contentScrim="#ff00ff"
             app:maxLines="3">
 
+            <ImageView
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"/>
             <android.support.v7.widget.Toolbar
                 android:id="@+id/toolbar"
                 android:layout_width="match_parent"
diff --git a/multiline-collapsingtoolbar/src/main/java/net/opacapp/multilinecollapsingtoolbar/CollapsingTextHelper.java b/multiline-collapsingtoolbar/src/main/java/net/opacapp/multilinecollapsingtoolbar/CollapsingTextHelper.java
index dd009d2..c8b18bb 100644
--- a/multiline-collapsingtoolbar/src/main/java/net/opacapp/multilinecollapsingtoolbar/CollapsingTextHelper.java
+++ b/multiline-collapsingtoolbar/src/main/java/net/opacapp/multilinecollapsingtoolbar/CollapsingTextHelper.java
@@ -119,6 +119,7 @@ final class CollapsingTextHelper {
     private float mExpandedTextBlend;
     private float mExpandedFirstLineDrawX;
     private int maxLines = 3;
+    private float mBlendRatio;
     // END MODIFICATION
 
     public CollapsingTextHelper(View view) {
@@ -341,6 +342,25 @@ void setExpansionFraction(float fraction) {
         }
     }
 
+    // BEGIN MODIFICATION by dmfs: setter method for blend ratio
+    /**
+     * Set the value indicating the current scroll value. This decides how much of the
+     * background will be displayed, as well as the title metrics/positioning.
+     *
+     * A value of {@code 0.0} indicates that the expanded title is fully opaque.
+     * A value of {@code 1.0} indicates that the collapsed title is fully opaque.
+     */
+    void setBlendRatio(float ratio) {
+        ratio = MathUtils.constrain(ratio, 0f, 1f);
+
+        if (ratio != mBlendRatio) {
+            mBlendRatio = ratio;
+            calculateCurrentOffsets();
+        }
+    }
+    // END MODIFICATION by dmfs
+
+
     final boolean setState(final int[] state) {
         mState = state;
 
@@ -371,10 +391,10 @@ float getExpandedTextSize() {
     }
 
     private void calculateCurrentOffsets() {
-        calculateOffsets(mExpandedFraction);
+        calculateOffsets(mExpandedFraction, mBlendRatio);
     }
 
-    private void calculateOffsets(final float fraction) {
+    private void calculateOffsets(final float fraction, final float blendRatio) {
         interpolateBounds(fraction);
         mCurrentDrawX = lerp(mExpandedDrawX, mCollapsedDrawX, fraction,
                 mPositionInterpolator);
@@ -384,18 +404,20 @@ private void calculateOffsets(final float fraction) {
         setInterpolatedTextSize(lerp(mExpandedTextSize, mCollapsedTextSize,
                 fraction, mTextSizeInterpolator));
 
-        // BEGIN MODIFICATION: set text blending
-        setCollapsedTextBlend(1 - lerp(0, 1, 1 - fraction, AnimationUtils
+        // BEGIN MODIFICATION: set text blending, using the blend ratio
+        setCollapsedTextBlend(1 - lerp(0, 1, 1 - blendRatio, AnimationUtils
                 .FAST_OUT_SLOW_IN_INTERPOLATOR));
-        setExpandedTextBlend(lerp(1, 0, fraction, AnimationUtils
+        setExpandedTextBlend(lerp(1, 0, blendRatio, AnimationUtils
                 .FAST_OUT_SLOW_IN_INTERPOLATOR));
         // END MODIFICATION
 
         if (mCollapsedTextColor != mExpandedTextColor) {
             // If the collapsed and expanded text colors are different, blend them based on the
             // fraction
+            // BEGIN MODIFICATION by dmfs: apply blend ratio
             mTextPaint.setColor(blendColors(
-                    getCurrentExpandedTextColor(), getCurrentCollapsedTextColor(), fraction));
+                    getCurrentExpandedTextColor(), getCurrentCollapsedTextColor(), blendRatio));
+            // END MODIFICATION by dmfs
         } else {
             mTextPaint.setColor(getCurrentCollapsedTextColor());
         }
@@ -756,7 +778,7 @@ private void ensureExpandedTexture() {
                 || TextUtils.isEmpty(mTextToDraw)) {
             return;
         }
-        calculateOffsets(0f);
+        calculateOffsets(0f, 0f);
 
         // BEGIN MODIFICATION: Calculate width and height using mTextLayout and remove
         // mTextureAscent and mTextureDescent assignment
@@ -785,7 +807,7 @@ private void ensureCollapsedTexture() {
                 || TextUtils.isEmpty(mTextToDraw)) {
             return;
         }
-        calculateOffsets(0f);
+        calculateOffsets(0f, 0f);
         final int w = Math.round(mTextPaint.measureText(mTextToDraw, 0, mTextToDraw.length()));
         final int h = Math.round(mTextPaint.descent() - mTextPaint.ascent());
         if (w <= 0 && h <= 0) {
@@ -806,7 +828,7 @@ private void ensureCrossSectionTexture() {
                 || TextUtils.isEmpty(mTextToDraw)) {
             return;
         }
-        calculateOffsets(0f);
+        calculateOffsets(0f, 0f);
         final int w = Math.round(mTextPaint.measureText(mTextToDraw, mTextLayout.getLineStart(0),
                 mTextLayout.getLineEnd(0)));
         final int h = Math.round(mTextPaint.descent() - mTextPaint.ascent());
diff --git a/multiline-collapsingtoolbar/src/main/java/net/opacapp/multilinecollapsingtoolbar/CollapsingToolbarLayout.java b/multiline-collapsingtoolbar/src/main/java/net/opacapp/multilinecollapsingtoolbar/CollapsingToolbarLayout.java
index fce3b39..bb359ea 100644
--- a/multiline-collapsingtoolbar/src/main/java/net/opacapp/multilinecollapsingtoolbar/CollapsingToolbarLayout.java
+++ b/multiline-collapsingtoolbar/src/main/java/net/opacapp/multilinecollapsingtoolbar/CollapsingToolbarLayout.java
@@ -104,6 +104,12 @@ public class CollapsingToolbarLayout extends FrameLayout {
 
     private static final int DEFAULT_SCRIM_ANIMATION_DURATION = 600;
 
+    public static final int AUTO_ANIMATE_SCRIM = 1;
+    public static final int AUTO_ANIMATE_TITLE = 2;
+    public static final int AUTO_ANIMATE_CHILDREN = 4;
+    public static final int AUTO_ANIMATE_ALL = AUTO_ANIMATE_SCRIM | AUTO_ANIMATE_TITLE | AUTO_ANIMATE_CHILDREN;
+    public static final int AUTO_ANIMATE_DEFAULT = AUTO_ANIMATE_SCRIM;
+
     private boolean mRefreshToolbar = true;
     private int mToolbarId;
     private Toolbar mToolbar;
@@ -135,6 +141,8 @@ public class CollapsingToolbarLayout extends FrameLayout {
 
     WindowInsetsCompat mLastInsets;
 
+    private int mAutoAnimate = AUTO_ANIMATE_DEFAULT;
+
     public CollapsingToolbarLayout(Context context) {
         this(context, null);
     }
@@ -236,6 +244,9 @@ public WindowInsetsCompat onApplyWindowInsets(View v,
         // BEGIN MODIFICATION: set the value of maxNumberOfLines attribute to the mCollapsingTextHelper
         TypedArray typedArray = context.obtainStyledAttributes(attrs, net.opacapp.multilinecollapsingtoolbar.R.styleable.CollapsingToolbarLayoutExtension, defStyleAttr, 0);
         mCollapsingTextHelper.setMaxLines(typedArray.getInteger(net.opacapp.multilinecollapsingtoolbar.R.styleable.CollapsingToolbarLayoutExtension_maxLines, 3));
+        // load auto animation setting
+        mAutoAnimate = typedArray.getInt(net.opacapp.multilinecollapsingtoolbar.R.styleable.CollapsingToolbarLayoutExtension_autoAnimate, AUTO_ANIMATE_DEFAULT);
+        typedArray.recycle();
         // END MODIFICATION
     }
 
@@ -633,7 +644,14 @@ private void animateScrim(int targetAlpha) {
             mScrimAnimator.addUpdateListener(new ValueAnimatorCompat.AnimatorUpdateListener() {
                 @Override
                 public void onAnimationUpdate(ValueAnimatorCompat animator) {
-                    setScrimAlpha(animator.getAnimatedIntValue());
+                    // BEGIN MODIFICATION by dmfs: apply scrim & blending automatically if configured that way
+                    if ((mAutoAnimate & AUTO_ANIMATE_SCRIM) != 0) {
+                        setScrimAlpha(animator.getAnimatedIntValue());
+                    }
+                    if ((mAutoAnimate & AUTO_ANIMATE_TITLE) != 0) {
+                        mCollapsingTextHelper.setBlendRatio(animator.getAnimatedIntValue()/255f);
+                    }
+                    // END MODIFICATION by dmfs
                 }
             });
         } else if (mScrimAnimator.isRunning()) {
@@ -1303,18 +1321,31 @@ public void onOffsetChanged(AppBarLayout layout, int verticalOffset) {
                 }
             }
 
-            // Show or hide the scrims if needed
-            updateScrimVisibility();
+            // BEGIN MODIFICATION by dmfs: apply scrim & blending gradually if configured that way
+            final float expandRatio =  Math.abs(verticalOffset) /
+                    (float) (getHeight() - ViewCompat.getMinimumHeight(CollapsingToolbarLayout.this) - insetTop);
+
+            if ((mAutoAnimate & AUTO_ANIMATE_SCRIM) == 0) {
+                // title blend it not auto-animated
+                setScrimAlpha((int) (expandRatio * 0xff));
+            }
+            else {
+                // Show or hide the scrims if needed
+                updateScrimVisibility();
+            }
 
             if (mStatusBarScrim != null && insetTop > 0) {
                 ViewCompat.postInvalidateOnAnimation(CollapsingToolbarLayout.this);
             }
 
             // Update the collapsing text's fraction
-            final int expandRange = getHeight() - ViewCompat.getMinimumHeight(
-                    CollapsingToolbarLayout.this) - insetTop;
-            mCollapsingTextHelper.setExpansionFraction(
-                    Math.abs(verticalOffset) / (float) expandRange);
+            mCollapsingTextHelper.setExpansionFraction(expandRatio);
+
+            if ((mAutoAnimate & AUTO_ANIMATE_TITLE) == 0) {
+                // title blend it not auto-animated
+                mCollapsingTextHelper.setBlendRatio(expandRatio);
+            }
+            // END MODIFICATION
         }
     }
 }
diff --git a/multiline-collapsingtoolbar/src/main/res/values/collapsing_toolbar_attrs.xml b/multiline-collapsingtoolbar/src/main/res/values/collapsing_toolbar_attrs.xml
index 823cd33..5632163 100644
--- a/multiline-collapsingtoolbar/src/main/res/values/collapsing_toolbar_attrs.xml
+++ b/multiline-collapsingtoolbar/src/main/res/values/collapsing_toolbar_attrs.xml
@@ -3,6 +3,13 @@
 <resources>
     <declare-styleable name="CollapsingToolbarLayoutExtension">
         <attr name="maxLines" format="integer" />
+        <attr name="autoAnimate">
+            <flag name="none" value="0" />
+            <flag name="scrim" value="1" />
+            <flag name="title" value="2" />
+            <flag name="children" value="4" />
+            <flag name="all" value="7" />
+        </attr>
     </declare-styleable>
 </resources>
 <!--END MODIFICATION-->
\ No newline at end of file