CollapsingTitleLayout


Source link: https://gist.github.com/chrisbanes/91ac8a20acfbdc410a68

CollapsingTitleLayout

Java file (14 KB): CollapsingTitleLayout.java

/*  * Copyright 2014 Chris Banes  *  * 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 your.package;  import android.content.Context; import android.content.res.TypedArray; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Rect; import android.os.Build; import android.support.v4.view.ViewCompat; import android.support.v7.widget.Toolbar; import android.text.TextPaint; import android.text.TextUtils; import android.util.AttributeSet; import android.util.DisplayMetrics; import android.util.TypedValue; import android.view.View; import android.view.ViewGroup; import android.view.animation.AnimationUtils; import android.view.animation.Interpolator; import android.widget.FrameLayout;  import app.philm.in.R;  public class CollapsingTitleLayout extends FrameLayout {

// Pre-JB-MR2 doesn't support HW accelerated canvas scaled text so we will workaround it
  // by using our own texture
  private static final boolean USE_SCALING_TEXTURE = Build.VERSION.SDK_INT < 18;

private static final boolean DEBUG_DRAW = false;
  private static final Paint DEBUG_DRAW_PAINT;
  static {

DEBUG_DRAW_PAINT = DEBUG_DRAW ? new Paint() : null;

if (DEBUG_DRAW_PAINT != null) {

 DEBUG_DRAW_PAINT.setAntiAlias(true);

 DEBUG_DRAW_PAINT.setColor(Color.MAGENTA);

}

  
}

private Toolbar mToolbar;
  private View mDummyView;

private float mScrollOffset;

private final Rect mToolbarContentBounds;

private float mExpandedMarginLeft;
  private float mExpandedMarginRight;
  private float mExpandedMarginBottom;

private int mRequestedExpandedTitleTextSize;
  private int mExpandedTitleTextSize;
  private int mCollapsedTitleTextSize;

private float mExpandedTop;
  private float mCollapsedTop;

private String mTitle;
  private String mTitleToDraw;
  private boolean mUseTexture;
  private Bitmap mExpandedTitleTexture;

private float mTextLeft;
  private float mTextRight;
  private float mTextTop;

private float mScale;

private final TextPaint mTextPaint;
  private Paint mTexturePaint;

private Interpolator mTextSizeInterpolator;

public CollapsingTitleLayout(Context context) {

this(context, null);

  
}

public CollapsingTitleLayout(Context context, AttributeSet attrs) {

this(context, attrs, 0);

  
}

public CollapsingTitleLayout(Context context, AttributeSet attrs, int defStyleAttr) {

super(context, attrs, defStyleAttr);

 mTextPaint = new TextPaint();

mTextPaint.setAntiAlias(true);

 TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CollapsingTitleLayout);

 mExpandedMarginLeft = mExpandedMarginRight = mExpandedMarginBottom =

  a.getDimensionPixelSize(R.styleable.CollapsingTitleLayout_expandedMargin, 0);

 final boolean isRtl = ViewCompat.getLayoutDirection(this)

  == ViewCompat.LAYOUT_DIRECTION_RTL;

if (a.hasValue(R.styleable.CollapsingTitleLayout_expandedMarginStart)) {

 final int marginStart = a.getDimensionPixelSize(

R.styleable.CollapsingTitleLayout_expandedMarginStart, 0);

 if (isRtl) {

  mExpandedMarginRight = marginStart;

 
}
 else {

  mExpandedMarginLeft = marginStart;

 
}

}

if (a.hasValue(R.styleable.CollapsingTitleLayout_expandedMarginEnd)) {

 final int marginEnd = a.getDimensionPixelSize(

R.styleable.CollapsingTitleLayout_expandedMarginEnd, 0);

 if (isRtl) {

  mExpandedMarginLeft = marginEnd;

 
}
 else {

  mExpandedMarginRight = marginEnd;

 
}

}

if (a.hasValue(R.styleable.CollapsingTitleLayout_expandedMarginBottom)) {

 mExpandedMarginBottom = a.getDimensionPixelSize(

R.styleable.CollapsingTitleLayout_expandedMarginBottom, 0);

}

 final int tp = a.getResourceId(R.styleable.CollapsingTitleLayout_android_textAppearance,

  android.R.style.TextAppearance);

setTextAppearance(tp);

 if (a.hasValue(R.styleable.CollapsingTitleLayout_collapsedTextSize)) {

 mCollapsedTitleTextSize = a.getDimensionPixelSize(

R.styleable.CollapsingTitleLayout_collapsedTextSize, 0);

}

 mRequestedExpandedTitleTextSize = a.getDimensionPixelSize(

  R.styleable.CollapsingTitleLayout_expandedTextSize, mCollapsedTitleTextSize);

 final int interpolatorId = a

  .getResourceId(R.styleable.CollapsingTitleLayout_textSizeInterpolator,

 android.R.anim.accelerate_interpolator);

mTextSizeInterpolator = AnimationUtils.loadInterpolator(context, interpolatorId);

 a.recycle();

 mToolbarContentBounds = new Rect();

 setWillNotDraw(false);

  
}

public void setTextAppearance(int resId) {

TypedArray atp = getContext().obtainStyledAttributes(resId,

  R.styleable.CollapsingTextAppearance);

mTextPaint.setColor(atp.getColor(

  R.styleable.CollapsingTextAppearance_android_textColor, Color.WHITE));

mCollapsedTitleTextSize = atp.getDimensionPixelSize(

  R.styleable.CollapsingTextAppearance_android_textSize, 0);

atp.recycle();

 recalculate();

  
}

@Override
  public void addView(View child, int index, ViewGroup.LayoutParams params) {

super.addView(child, index, params);

 if (child instanceof Toolbar) {

 mToolbar = (Toolbar) child;

 mDummyView = new View(getContext());

 mToolbar.addView(mDummyView, LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);

}

  
}

/**

* 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 layout is fully expanded.

* A value of {
@code 1.0
}
 indicates that the layout is fully collapsed.

*/
  public void setScrollOffset(float offset) {

if (offset != mScrollOffset) {

 mScrollOffset = offset;

 calculateOffsets();

}

  
}

private void calculateOffsets() {

final float offset = mScrollOffset;

final float textSizeOffset = mTextSizeInterpolator != null

  ? mTextSizeInterpolator.getInterpolation(mScrollOffset)

  : offset;

 mTextLeft = interpolate(mExpandedMarginLeft, mToolbarContentBounds.left, offset);

mTextTop = interpolate(mExpandedTop, mCollapsedTop, offset);

mTextRight = interpolate(getWidth() - mExpandedMarginRight, mToolbarContentBounds.right, offset);

 setInterpolatedTextSize(

  interpolate(mExpandedTitleTextSize, mCollapsedTitleTextSize, textSizeOffset));

 ViewCompat.postInvalidateOnAnimation(this);

  
}

private void calculateTextBounds() {

final DisplayMetrics metrics = getResources().getDisplayMetrics();

 // We then calculate the collapsed text size, using the same logic

mTextPaint.setTextSize(mCollapsedTitleTextSize);

float textHeight = mTextPaint.descent() - mTextPaint.ascent();

float textOffset = (textHeight / 2) - mTextPaint.descent();

mCollapsedTop = mToolbarContentBounds.centerY() + textOffset;

 // First, let's calculate the expanded text size so that it fit within the bounds

// We make sure this value is at least our minimum text size

mExpandedTitleTextSize = (int) Math.max(mCollapsedTitleTextSize,

  getSingleLineTextSize(mTitle, mTextPaint,

 getWidth() - mExpandedMarginLeft -mExpandedMarginRight, 0f,

 mRequestedExpandedTitleTextSize, 0.5f, metrics));

mExpandedTop = getHeight() - mExpandedMarginBottom;

 // The bounds have changed so we need to clear the texture

clearTexture();

  
}

@Override
  public void draw(Canvas canvas) {

final int saveCount = canvas.save();

 final int toolbarHeight = mToolbar.getHeight();

canvas.clipRect(0, 0, canvas.getWidth(),

  interpolate(canvas.getHeight(), toolbarHeight, mScrollOffset));

 // Now call super and let it draw the background, etc

super.draw(canvas);

 if (mTitleToDraw != null) {

 float x = mTextLeft;

 float y = mTextTop;

  final float ascent = mTextPaint.ascent() * mScale;

 final float descent = mTextPaint.descent() * mScale;

 final float h = descent - ascent;

  if (DEBUG_DRAW) {

  // Just a debug tool, which drawn a Magneta rect in the text bounds

  canvas.drawRect(mTextLeft,

 y - h + descent,

 mTextRight,

 y + descent,

 DEBUG_DRAW_PAINT);

 
}

  if (mUseTexture) {

  y = y - h + descent;

 
}

  if (mScale != 1f) {

  canvas.scale(mScale, mScale, x, y);

 
}

  if (mUseTexture && mExpandedTitleTexture != null) {

  // If we should use a texture, draw it instead of text

  canvas.drawBitmap(mExpandedTitleTexture, x, y, mTexturePaint);

 
}
 else {

  canvas.drawText(mTitleToDraw, x, y, mTextPaint);

 
}

}

 canvas.restoreToCount(saveCount);

  
}

private void setInterpolatedTextSize(final float textSize) {

if (mTitle == null) return;

 if (isClose(textSize, mCollapsedTitleTextSize) || isClose(textSize, mExpandedTitleTextSize)

  || mTitleToDraw == null) {

 // If the text size is 'close' to being a decimal, then we use this as a sync-point.

 // We disable our manual scaling and set the paint's text size.

 mTextPaint.setTextSize(textSize);

 mScale = 1f;

  // We also use this as an opportunity to ellipsize the string

 final CharSequence title = TextUtils.ellipsize(mTitle, mTextPaint,

mTextRight - mTextLeft,

TextUtils.TruncateAt.END);

 if (title != mTitleToDraw) {

  // If the title has changed, turn it into a string

  mTitleToDraw = title.toString();

 
}

  if (USE_SCALING_TEXTURE && isClose(textSize, mExpandedTitleTextSize)) {

  ensureExpandedTexture();

 
}

 mUseTexture = false;

}
 else {

 // We're not close to a decimal so use our canvas scaling method

 if (mExpandedTitleTexture != null) {

  mScale = textSize / mExpandedTitleTextSize;

 
}
 else {

  mScale = textSize / mTextPaint.getTextSize();

 
}

  mUseTexture = USE_SCALING_TEXTURE;

}

 ViewCompat.postInvalidateOnAnimation(this);

  
}

private void ensureExpandedTexture() {

if (mExpandedTitleTexture != null) return;

 int w = (int) (getWidth() - mExpandedMarginLeft - mExpandedMarginRight);

int h = (int) (mTextPaint.descent() - mTextPaint.ascent());

 mExpandedTitleTexture = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);

 Canvas c = new Canvas(mExpandedTitleTexture);

c.drawText(mTitleToDraw, 0, h - mTextPaint.descent(), mTextPaint);

 if (mTexturePaint == null) {

 // Make sure we have a paint

 mTexturePaint = new Paint();

 mTexturePaint.setAntiAlias(true);

 mTexturePaint.setFilterBitmap(true);

}

  
}

@Override
  protected void onLayout(boolean changed, int left, int top, int right, int bottom) {

super.onLayout(changed, left, top, right, bottom);

 mToolbarContentBounds.left = mDummyView.getLeft();

mToolbarContentBounds.top = mDummyView.getTop();

mToolbarContentBounds.right = mDummyView.getRight();

mToolbarContentBounds.bottom = mDummyView.getBottom();

 if (changed && mTitle != null) {

 // If we've changed and we have a title, re-calculate everything!

 recalculate();

}

  
}

private void recalculate() {

if (getHeight() > 0) {

 calculateTextBounds();

 calculateOffsets();

}

  
}

/**

* Set the title to display

*

* @param title

*/
  public void setTitle(String title) {

if (title == null || !title.equals(mTitle)) {

 mTitle = title;

  clearTexture();

  if (getHeight() > 0) {

  // If we've already been laid out, calculate everything now otherwise we'll wait

  // until a layout

  recalculate();

 
}

}

  
}

private void clearTexture() {

if (mExpandedTitleTexture != null) {

 mExpandedTitleTexture.recycle();

 mExpandedTitleTexture = null;

}

  
}

/**

* Recursive binary search to find the best size for the text

*

* Adapted from https://github.com/grantland/android-autofittextview

*/
  private static float getSingleLineTextSize(String text, TextPaint paint, float targetWidth,

 float low, float high, float precision, DisplayMetrics metrics) {

final float mid = (low + high) / 2.0f;

 paint.setTextSize(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX, mid, metrics));

final float maxLineWidth = paint.measureText(text);

 if ((high - low) < precision) {

 return low;

}
 else if (maxLineWidth > targetWidth) {

 return getSingleLineTextSize(text, paint, targetWidth, low, mid, precision, metrics);

}
 else if (maxLineWidth < targetWidth) {

 return getSingleLineTextSize(text, paint, targetWidth, mid, high, precision, metrics);

}
 else {

 return mid;

}

  
}

/**

* Returns true if {
@code value
}
 is 'close' to it's closest decimal value. Close is currently

* defined as it's difference being < 0.01.

*/
  private static boolean isClose(float value, float targetValue) {

return Math.abs(value - targetValue) < 0.01f;
  
}

/**

* Interpolate between {
@code startValue
}
 and {
@code endValue
}
, using {
@code progress
}
.

*/
  private static float interpolate(float startValue, float endValue, float progress) {

return startValue + ((endValue - startValue) * progress);

  
}
 
}

XML file (1 KB): attrs.xml

<?xml version="1.0" encoding="utf-8"?> <!--
~ Copyright 2014 Chris Banes
~
~ 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.
-->  <resources>

<declare-styleable name="CollapsingTitleLayout">

<attr name="expandedMargin" format="reference|dimension" />

<attr name="expandedMarginStart" format="reference|dimension" />

<attr name="expandedMarginBottom" format="reference|dimension" />

<attr name="expandedMarginEnd" format="reference|dimension" />

<attr name="expandedTextSize" format="reference|dimension" />

<attr name="collapsedTextSize" format="reference|dimension" />

<attr name="android:textAppearance" />

<attr name="textSizeInterpolator" format="reference" />
  </declare-styleable>

<declare-styleable name="CollapsingTextAppearance">

<attr name="android:textSize" />

<attr name="android:textColor" />
  </declare-styleable>  </resources>

XML file (1 KB): example_layout.xml

<?xml version="1.0" encoding="utf-8"?>  <!--
~ Copyright 2014 Chris Banes
~
~ 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.
-->  <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"

 xmlns:app="http://schemas.android.com/apk/res-auto"

 android:layout_height="match_parent"

 android:layout_width="match_parent">

<!-- Your content, maybe a ListView? -->

<app.philm.in.view.CollapsingTitleLayout

android:id="@+id/backdrop_toolbar"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:textAppearance="@style/TextAppearance.AppCompat.Widget.ActionBar.Title.Inverse"

app:expandedTextSize="40dp"

app:expandedMargin="16dp">

 <android.support.v7.widget.Toolbar

 android:id="@+id/toolbar"

 android:layout_height="?attr/actionBarSize"

 android:layout_width="match_parent" />

</app.philm.in.view.CollapsingTitleLayout>  </FrameLayout>

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