工具栏AlphaScrollBehavior CoordinatorLayout [英] ToolbarAlphaScrollBehavior CoordinatorLayout
本文介绍了工具栏AlphaScrollBehavior CoordinatorLayout的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我一直在关注链接在工具栏上实现不透明效果
我的布局文件:
<?xml version="1.0" encoding="utf-8"?>
<layout>
<android.support.design.widget.CoordinatorLayout
android:id="@+id/coordinator_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".ProductDetailActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="@android:color/transparent"
android:theme="@style/AppTheme.AppBarOverlay"
app:elevation="0dp" />
<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content">
.
.
.
</android.support.v4.widget.NestedScrollView>
<android.support.v7.widget.Toolbar
android:id="@+id/prod_detail_toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_behavior="util.ToolbarAlphaScrollBehavior"
/>
</android.support.design.widget.CoordinatorLayout>
</layout>
和班级:
public class ToolbarAlphaScrollBehavior extends CoordinatorLayout.Behavior<android.support.v7.widget.Toolbar> {
private static final String TAG = ToolbarAlphaScrollBehavior.class.getSimpleName();
private ColorDrawable mStatusBarColorDrawable;
private int mStatusBarColor;
private TextView mTitleView;
private boolean searchedForTitleView = false;
private Context context;
public ToolbarAlphaScrollBehavior(Context context, AttributeSet attrs) {
super(context, attrs);
mStatusBarColor = ContextCompat.getColor(context, R.color.colorPrimaryDark);
mStatusBarColor = getColorWithAlpha(0, mStatusBarColor);
mStatusBarColorDrawable = new ColorDrawable(mStatusBarColor);
this.context=context;
}
public static int getColorWithAlpha(float alpha, int baseColor) {
int a = Math.min(255, Math.max(0, (int) (alpha * 255))) << 24;
int rgb = 0x00ffffff & baseColor;
return a + rgb;
}
public ToolbarAlphaScrollBehavior() {
}
@Override
public boolean layoutDependsOn(CoordinatorLayout parent, Toolbar child, View dependency) {
return dependency instanceof AppBarLayout;
}
@Override
public boolean onInterceptTouchEvent(CoordinatorLayout parent, Toolbar child, MotionEvent ev) {
return ev == null || super.onInterceptTouchEvent(parent, child, ev);
}
@Override
public boolean onDependentViewChanged(CoordinatorLayout parent, Toolbar child, View dependency) {
Log.e(TAG, "child "+child.getTitle() );
if (dependency instanceof AppBarLayout) {
float ratio = (float) getCurrentScrollValue(child, dependency) / getTotalScrollRange(child, dependency);
float alpha = 1f - Math.min(1f, Math.max(0f, ratio));
int drawableAlpha = (int) (alpha * 255);
// Log.i("ToolbarAlphaScrollBehavior", "Alpha: " + alpha);
if (Build.VERSION.SDK_INT==Build.VERSION_CODES.LOLLIPOP ||
Build.VERSION.SDK_INT==Build.VERSION_CODES.LOLLIPOP_MR1) {
child.getBackground().setAlpha(drawableAlpha);
} else if (Build.VERSION.SDK_INT==Build.VERSION_CODES.KITKAT) {
ViewGroup toolbarParent = (ViewGroup) child.getParent();
if (toolbarParent.getChildCount() == 2) {
int count = toolbarParent.getChildCount();
for (int i = count - 1; i >= 0; i--) {
toolbarParent.getChildAt(i).getBackground().setAlpha(drawableAlpha);
}
}
} else {
child.getBackground().setAlpha(drawableAlpha);
}
setStatusBarColor(parent, drawableAlpha);
if (mTitleView != null) {
ViewCompat.setAlpha(mTitleView, alpha);
return false;
}
if (!searchedForTitleView) {
TextView textView= new TextView(context);
textView.setText(child.getTitle());
mTitleView = textView;
searchedForTitleView = true;
}
}
return false;
}
private void setStatusBarColor(CoordinatorLayout parent, int alpha) {
ColorDrawable statusBarBackground = (ColorDrawable) parent.getStatusBarBackground();
statusBarBackground.setColor(getColorWithAlpha(alpha, statusBarBackground.getColor()));
parent.setStatusBarBackground(statusBarBackground);
}
private int getCurrentScrollValue(Toolbar child, View dependency) {
return dependency.getBottom() - child.getTop();
}
private float getTotalScrollRange(Toolbar child, View dependency) {
return Math.max(dependency.getHeight(), ((AppBarLayout) dependency).getTotalScrollRange()) - child.getTop();
}
}
但是我遇到了以下错误
Attempt to invoke virtual method 'void android.graphics.drawable.Drawable.setAlpha(int)' on a null object reference
onDependentViewChanged中的孩子为空
我要完成的行为是这样的: Youtube视频./p>
工具栏的开头必须是透明的，并且在滚动时颜色应为 更改为原色
预先感谢...
解决方案
我做了我需要的一切并得到了-但是工具栏在KitKat上始终是透明的.
链接:透明工具栏
Hi I've been following this link to accomplish the opacity effect on the toolbar
My Layout File :
<?xml version="1.0" encoding="utf-8"?>
<layout>
<android.support.design.widget.CoordinatorLayout
android:id="@+id/coordinator_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".ProductDetailActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="@android:color/transparent"
android:theme="@style/AppTheme.AppBarOverlay"
app:elevation="0dp" />
<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content">
.
.
.
</android.support.v4.widget.NestedScrollView>
<android.support.v7.widget.Toolbar
android:id="@+id/prod_detail_toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_behavior="util.ToolbarAlphaScrollBehavior"
/>
</android.support.design.widget.CoordinatorLayout>
</layout>
And The Class :
public class ToolbarAlphaScrollBehavior extends CoordinatorLayout.Behavior<android.support.v7.widget.Toolbar> {
private static final String TAG = ToolbarAlphaScrollBehavior.class.getSimpleName();
private ColorDrawable mStatusBarColorDrawable;
private int mStatusBarColor;
private TextView mTitleView;
private boolean searchedForTitleView = false;
private Context context;
public ToolbarAlphaScrollBehavior(Context context, AttributeSet attrs) {
super(context, attrs);
mStatusBarColor = ContextCompat.getColor(context, R.color.colorPrimaryDark);
mStatusBarColor = getColorWithAlpha(0, mStatusBarColor);
mStatusBarColorDrawable = new ColorDrawable(mStatusBarColor);
this.context=context;
}
public static int getColorWithAlpha(float alpha, int baseColor) {
int a = Math.min(255, Math.max(0, (int) (alpha * 255))) << 24;
int rgb = 0x00ffffff & baseColor;
return a + rgb;
}
public ToolbarAlphaScrollBehavior() {
}
@Override
public boolean layoutDependsOn(CoordinatorLayout parent, Toolbar child, View dependency) {
return dependency instanceof AppBarLayout;
}
@Override
public boolean onInterceptTouchEvent(CoordinatorLayout parent, Toolbar child, MotionEvent ev) {
return ev == null || super.onInterceptTouchEvent(parent, child, ev);
}
@Override
public boolean onDependentViewChanged(CoordinatorLayout parent, Toolbar child, View dependency) {
Log.e(TAG, "child "+child.getTitle() );
if (dependency instanceof AppBarLayout) {
float ratio = (float) getCurrentScrollValue(child, dependency) / getTotalScrollRange(child, dependency);
float alpha = 1f - Math.min(1f, Math.max(0f, ratio));
int drawableAlpha = (int) (alpha * 255);
// Log.i("ToolbarAlphaScrollBehavior", "Alpha: " + alpha);
if (Build.VERSION.SDK_INT==Build.VERSION_CODES.LOLLIPOP ||
Build.VERSION.SDK_INT==Build.VERSION_CODES.LOLLIPOP_MR1) {
child.getBackground().setAlpha(drawableAlpha);
} else if (Build.VERSION.SDK_INT==Build.VERSION_CODES.KITKAT) {
ViewGroup toolbarParent = (ViewGroup) child.getParent();
if (toolbarParent.getChildCount() == 2) {
int count = toolbarParent.getChildCount();
for (int i = count - 1; i >= 0; i--) {
toolbarParent.getChildAt(i).getBackground().setAlpha(drawableAlpha);
}
}
} else {
child.getBackground().setAlpha(drawableAlpha);
}
setStatusBarColor(parent, drawableAlpha);
if (mTitleView != null) {
ViewCompat.setAlpha(mTitleView, alpha);
return false;
}
if (!searchedForTitleView) {
TextView textView= new TextView(context);
textView.setText(child.getTitle());
mTitleView = textView;
searchedForTitleView = true;
}
}
return false;
}
private void setStatusBarColor(CoordinatorLayout parent, int alpha) {
ColorDrawable statusBarBackground = (ColorDrawable) parent.getStatusBarBackground();
statusBarBackground.setColor(getColorWithAlpha(alpha, statusBarBackground.getColor()));
parent.setStatusBarBackground(statusBarBackground);
}
private int getCurrentScrollValue(Toolbar child, View dependency) {
return dependency.getBottom() - child.getTop();
}
private float getTotalScrollRange(Toolbar child, View dependency) {
return Math.max(dependency.getHeight(), ((AppBarLayout) dependency).getTotalScrollRange()) - child.getTop();
}
}
But i am getting the following error
Attempt to invoke virtual method 'void android.graphics.drawable.Drawable.setAlpha(int)' on a null object reference
The child in onDependentViewChanged is null
The behavior i am trying to accomplish is this one : Youtube video.
The toolbar must be transparent in the beginning and on scroll the color should change to the primary color
Thanks in Advance...
解决方案
I did everything I needed and got this - but the toolbar is always transparent on KitKat .
link: Transparent toolbar
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