Android Nougat：TextureView 不支持显示可绘制背景
Android Nougat: TextureView doesn't support displaying a background drawable
我一直在我的 android 应用程序中使用 TextureView，它运行良好。最近我在 Android 设备上用 Android API 25 (7.1.2) 测试了我的代码。相同的代码现在不起作用并抛出错误 java.lang.UnsupportedOperationException: TextureView doesn't support displaying a background drawable.
我知道 void setBackgroundDrawable (Drawable background) 曾经是 deprecated for a long time，现在肯定已经被删除了。但我什至没有自己设置它。
我正在使用最新的 buildTools 和 SDK。所以，我想知道为什么textureView内部实现还没有更新。
这是相关的堆栈跟踪：
java.lang.UnsupportedOperationException: TextureView doesn't support displaying a background drawable
at android.view.TextureView.setBackgroundDrawable(TextureView.java:315)
at android.view.View.setBackground(View.java:18124)
at android.view.View.<init>(View.java:4573)
at android.view.View.<init>(View.java:4082)
at android.view.TextureView.<init>(TextureView.java:159)
at com.abdulwasaetariq.xyz.ui.customView.AutoFitTextureView.<init>(AutoFitTextureView.java:24)
at com.abdulwasaetariq.xyz.ui.customView.AutoFitTextureView.<init>(AutoFitTextureView.java:20)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
[...]
at java.lang.Thread.run(Thread.java:745)
下面是我如何使用我的（尚未定制的）自定义 TextureView：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.abdulwasaetariq.xyz.ui.activity.MainActivity">
<com.abdulwasaetariq.xyz.ui.customView.AutoFitTextureView
android:id="@+id/texture"
android:layout_width="1080px"
android:layout_height="1080px"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true" />
</RelativeLayout>
这是我的相关 AutoFitTextureView.java: enter code here
public class AutoFitTextureView extends TextureView {
private int mRatioWidth = 0;
private int mRatioHeight = 0;
public AutoFitTextureView(Context context) {
this(context, null);
}
public AutoFitTextureView(Context context, AttributeSet attrs) {
this(context, attrs, 0); //(LINE#20)
}
public AutoFitTextureView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle); //(LINE#24)
}
public void setAspectRatio(int width, int height) {
if (width < 0 || height < 0) {
throw new IllegalArgumentException("Size cannot be negative.");
}
mRatioWidth = width;
mRatioHeight = height;
requestLayout();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
if (0 == mRatioWidth || 0 == mRatioHeight) {
setMeasuredDimension(width, height);
} else {
if (width < height * mRatioWidth / mRatioHeight) {
setMeasuredDimension(width, width * mRatioHeight / mRatioWidth);
} else {
setMeasuredDimension(height * mRatioWidth / mRatioHeight, height);
}
}
}}
因此，如您所见，异常发生在 super() 方法处，这意味着我的自定义 TextureView 不负责此异常。这是一个内部电话。
这是我的 gradle 配置：
apply plugin: 'com.android.application'
android {
compileSdkVersion 25
buildToolsVersion '25.0.2'
defaultConfig {
applicationId "com.abdulwasaetariq.xyz"
minSdkVersion 21
targetSdkVersion 25
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha8'
compile 'com.github.hotchemi:permissionsdispatcher:2.3.2'
annotationProcessor 'com.github.hotchemi:permissionsdispatcher-processor:2.3.2'
}
知道为什么会这样吗？ Android API 25 的任何发行说明，其中讨论了此更改？
以下是 Android 牛轧糖的 View 源代码片段：
/**
* Allow setForeground/setBackground to be called (and ignored) on a textureview,
* without throwing
*/
static boolean sTextureViewIgnoresDrawableSetters = false;
在单参数构造函数中（从所有其他构造函数调用）：
// Prior to N, TextureView would silently ignore calls to setBackground/setForeground.
// On N+, we throw, but that breaks compatibility with apps that use these methods.
sTextureViewIgnoresDrawableSetters = targetSdkVersion <= M;
在抛出异常的 View 构造函数中：
...
switch (attr) {
case com.android.internal.R.styleable.View_background:
background = a.getDrawable(attr);
break;
...
if (background != null) {
setBackground(background); // <--- this is the problematic line, apparently "background" is not null here
}
setBackground的实际定义：
/**
* Set the background to a given Drawable, or remove the background. If the
* background has padding, this View's padding is set to the background's
* padding. However, when a background is removed, this View's padding isn't
* touched. If setting the padding is desired, please use
* {@link #setPadding(int, int, int, int)}.
*
* @param background The Drawable to use as the background, or null to remove the
* background
*/
public void setBackground(Drawable background) {
//noinspection deprecation
setBackgroundDrawable(background);
}
然后在TextureView中覆盖setBackgroundDrawable：
@Override
public void setBackgroundDrawable(Drawable background) {
if (background != null && !sTextureViewIgnoresDrawableSetters) {
throw new UnsupportedOperationException(
"TextureView doesn't support displaying a background drawable");
}
}
所以你可以从所有这些中拼凑出：
1) 您有一个目标 SDK N (Nougat) - 从您的构建文件中显而易见；
2）来自View的构造函数确定了一个非空背景（我暂时无法解释这部分）。
这就是一个真正的问题。我没有看到您已设法在 xml 中定义可绘制对象，因此覆盖 setBackground 或 setBackgroundDrawable 对我来说似乎是解决问题的最明智的可能性。可能还有另一种解决方法（或者 "suggested usage" 可能是一个更好的术语），您可以设法强制构造函数中的 background 变量保持为空。
如果您查看 API 24 的纹理视图源，您将看到以下内容：
/**
* Subclasses of TextureView cannot do their own rendering
* with the {@link Canvas} object.
*
* @param canvas The Canvas to which the View is rendered.
*/
@Override
public final void draw(Canvas canvas) {
// NOTE: Maintain this carefully (see View#draw)
mPrivateFlags = (mPrivateFlags & ~PFLAG_DIRTY_MASK) | PFLAG_DRAWN;
/* Simplify drawing to guarantee the layer is the only thing drawn - so e.g. no background,
scrolling, or fading edges. This guarantees all drawing is in the layer, so drawing
properties (alpha, layer paint) affect all of the content of a TextureView. */
if (canvas.isHardwareAccelerated()) {
DisplayListCanvas displayListCanvas = (DisplayListCanvas) canvas;
HardwareLayer layer = getHardwareLayer();
if (layer != null) {
applyUpdate();
applyTransformMatrix();
mLayer.setLayerPaint(mLayerPaint); // ensure layer paint is up to date
displayListCanvas.drawHardwareLayer(layer);
}
}
}
draw() 正文中的评论给出了您看到的更改的基本原理。这是我找到的唯一文档。将此与 API 23 中的 TextureView 进行比较：
/**
* Subclasses of TextureView cannot do their own rendering
* with the {@link Canvas} object.
*
* @param canvas The Canvas to which the View is rendered.
*/
@Override
public final void draw(Canvas canvas) {
// NOTE: Maintain this carefully (see View.java)
mPrivateFlags = (mPrivateFlags & ~PFLAG_DIRTY_MASK) | PFLAG_DRAWN;
applyUpdate();
applyTransformMatrix();
}
API 24 还引入了对 "set background" 方法的覆盖，这些方法在 API 23 中没有被覆盖。现在显然不鼓励设置背景，而且是不允许的。如果您看到不受支持的操作异常并且您没有明确设置背景，那么它可能会通过您的样式潜入。尝试在 XML 中设置 android:background="@null" 以强制背景为空以绕过错误。您还可以将以下代码添加到您的自定义视图中，以保留那些支持设置背景的版本的功能：
@Override
public void setBackgroundDrawable(Drawable background) {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N && background != null) {
setBackgroundDrawable(background);
}
}
目前尚不清楚如何替换您因 API 24+ 而失去的功能，或者如果您甚至需要它但只想在您的武器库中拥有后台工具。
顺便提一下，不仅仅是 TextureView：我发现自 API 24.
以来，GridLayout 也不支持显示背景可绘制对象
我试过了：
A) gridLayout.setBackgroundResource(R.drawable.board_960x960px_border_in_bg);
B)
Resources res = getResources();
Drawable drawable = res.getDrawable(R.drawable.board_960x960px_border_in_bg);
gridLayout.setBackground(drawable);
以上似乎都不适用于 API 23.
但是TableLayout的背景即使在API 24岁以上也不会消失，所以我将所有相关代码从GridLayout重写到TableLayout，现在可以了。
当我将 targetSdkVersion 更改为 23 时，我的问题得到了解决。
在您的 TextureView 的 xml 文件中将背景设置为 null。
例如android:background="@null"
适合我。
我一直在我的 android 应用程序中使用 TextureView，它运行良好。最近我在 Android 设备上用 Android API 25 (7.1.2) 测试了我的代码。相同的代码现在不起作用并抛出错误 java.lang.UnsupportedOperationException: TextureView doesn't support displaying a background drawable.
我知道 void setBackgroundDrawable (Drawable background) 曾经是 deprecated for a long time，现在肯定已经被删除了。但我什至没有自己设置它。
我正在使用最新的 buildTools 和 SDK。所以，我想知道为什么textureView内部实现还没有更新。
这是相关的堆栈跟踪：
java.lang.UnsupportedOperationException: TextureView doesn't support displaying a background drawable
at android.view.TextureView.setBackgroundDrawable(TextureView.java:315)
at android.view.View.setBackground(View.java:18124)
at android.view.View.<init>(View.java:4573)
at android.view.View.<init>(View.java:4082)
at android.view.TextureView.<init>(TextureView.java:159)
at com.abdulwasaetariq.xyz.ui.customView.AutoFitTextureView.<init>(AutoFitTextureView.java:24)
at com.abdulwasaetariq.xyz.ui.customView.AutoFitTextureView.<init>(AutoFitTextureView.java:20)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
[...]
at java.lang.Thread.run(Thread.java:745)
下面是我如何使用我的（尚未定制的）自定义 TextureView：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.abdulwasaetariq.xyz.ui.activity.MainActivity">
<com.abdulwasaetariq.xyz.ui.customView.AutoFitTextureView
android:id="@+id/texture"
android:layout_width="1080px"
android:layout_height="1080px"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true" />
</RelativeLayout>
这是我的相关 AutoFitTextureView.java: enter code here
public class AutoFitTextureView extends TextureView {
private int mRatioWidth = 0;
private int mRatioHeight = 0;
public AutoFitTextureView(Context context) {
this(context, null);
}
public AutoFitTextureView(Context context, AttributeSet attrs) {
this(context, attrs, 0); //(LINE#20)
}
public AutoFitTextureView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle); //(LINE#24)
}
public void setAspectRatio(int width, int height) {
if (width < 0 || height < 0) {
throw new IllegalArgumentException("Size cannot be negative.");
}
mRatioWidth = width;
mRatioHeight = height;
requestLayout();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
if (0 == mRatioWidth || 0 == mRatioHeight) {
setMeasuredDimension(width, height);
} else {
if (width < height * mRatioWidth / mRatioHeight) {
setMeasuredDimension(width, width * mRatioHeight / mRatioWidth);
} else {
setMeasuredDimension(height * mRatioWidth / mRatioHeight, height);
}
}
}}
因此，如您所见，异常发生在 super() 方法处，这意味着我的自定义 TextureView 不负责此异常。这是一个内部电话。
这是我的 gradle 配置：
apply plugin: 'com.android.application'
android {
compileSdkVersion 25
buildToolsVersion '25.0.2'
defaultConfig {
applicationId "com.abdulwasaetariq.xyz"
minSdkVersion 21
targetSdkVersion 25
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha8'
compile 'com.github.hotchemi:permissionsdispatcher:2.3.2'
annotationProcessor 'com.github.hotchemi:permissionsdispatcher-processor:2.3.2'
}
知道为什么会这样吗？ Android API 25 的任何发行说明，其中讨论了此更改？
以下是 Android 牛轧糖的 View 源代码片段：
/**
* Allow setForeground/setBackground to be called (and ignored) on a textureview,
* without throwing
*/
static boolean sTextureViewIgnoresDrawableSetters = false;
在单参数构造函数中（从所有其他构造函数调用）：
// Prior to N, TextureView would silently ignore calls to setBackground/setForeground.
// On N+, we throw, but that breaks compatibility with apps that use these methods.
sTextureViewIgnoresDrawableSetters = targetSdkVersion <= M;
在抛出异常的 View 构造函数中：
...
switch (attr) {
case com.android.internal.R.styleable.View_background:
background = a.getDrawable(attr);
break;
...
if (background != null) {
setBackground(background); // <--- this is the problematic line, apparently "background" is not null here
}
setBackground的实际定义：
/**
* Set the background to a given Drawable, or remove the background. If the
* background has padding, this View's padding is set to the background's
* padding. However, when a background is removed, this View's padding isn't
* touched. If setting the padding is desired, please use
* {@link #setPadding(int, int, int, int)}.
*
* @param background The Drawable to use as the background, or null to remove the
* background
*/
public void setBackground(Drawable background) {
//noinspection deprecation
setBackgroundDrawable(background);
}
然后在TextureView中覆盖setBackgroundDrawable：
@Override
public void setBackgroundDrawable(Drawable background) {
if (background != null && !sTextureViewIgnoresDrawableSetters) {
throw new UnsupportedOperationException(
"TextureView doesn't support displaying a background drawable");
}
}
所以你可以从所有这些中拼凑出：
1) 您有一个目标 SDK N (Nougat) - 从您的构建文件中显而易见；
2）来自View的构造函数确定了一个非空背景（我暂时无法解释这部分）。
这就是一个真正的问题。我没有看到您已设法在 xml 中定义可绘制对象，因此覆盖 setBackground 或 setBackgroundDrawable 对我来说似乎是解决问题的最明智的可能性。可能还有另一种解决方法（或者 "suggested usage" 可能是一个更好的术语），您可以设法强制构造函数中的 background 变量保持为空。
如果您查看 API 24 的纹理视图源，您将看到以下内容：
/**
* Subclasses of TextureView cannot do their own rendering
* with the {@link Canvas} object.
*
* @param canvas The Canvas to which the View is rendered.
*/
@Override
public final void draw(Canvas canvas) {
// NOTE: Maintain this carefully (see View#draw)
mPrivateFlags = (mPrivateFlags & ~PFLAG_DIRTY_MASK) | PFLAG_DRAWN;
/* Simplify drawing to guarantee the layer is the only thing drawn - so e.g. no background,
scrolling, or fading edges. This guarantees all drawing is in the layer, so drawing
properties (alpha, layer paint) affect all of the content of a TextureView. */
if (canvas.isHardwareAccelerated()) {
DisplayListCanvas displayListCanvas = (DisplayListCanvas) canvas;
HardwareLayer layer = getHardwareLayer();
if (layer != null) {
applyUpdate();
applyTransformMatrix();
mLayer.setLayerPaint(mLayerPaint); // ensure layer paint is up to date
displayListCanvas.drawHardwareLayer(layer);
}
}
}
draw() 正文中的评论给出了您看到的更改的基本原理。这是我找到的唯一文档。将此与 API 23 中的 TextureView 进行比较：
/**
* Subclasses of TextureView cannot do their own rendering
* with the {@link Canvas} object.
*
* @param canvas The Canvas to which the View is rendered.
*/
@Override
public final void draw(Canvas canvas) {
// NOTE: Maintain this carefully (see View.java)
mPrivateFlags = (mPrivateFlags & ~PFLAG_DIRTY_MASK) | PFLAG_DRAWN;
applyUpdate();
applyTransformMatrix();
}
API 24 还引入了对 "set background" 方法的覆盖，这些方法在 API 23 中没有被覆盖。现在显然不鼓励设置背景，而且是不允许的。如果您看到不受支持的操作异常并且您没有明确设置背景，那么它可能会通过您的样式潜入。尝试在 XML 中设置 android:background="@null" 以强制背景为空以绕过错误。您还可以将以下代码添加到您的自定义视图中，以保留那些支持设置背景的版本的功能：
@Override
public void setBackgroundDrawable(Drawable background) {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N && background != null) {
setBackgroundDrawable(background);
}
}
目前尚不清楚如何替换您因 API 24+ 而失去的功能，或者如果您甚至需要它但只想在您的武器库中拥有后台工具。
顺便提一下，不仅仅是 TextureView：我发现自 API 24.
以来，GridLayout 也不支持显示背景可绘制对象我试过了：
A) gridLayout.setBackgroundResource(R.drawable.board_960x960px_border_in_bg);
B)
Resources res = getResources();
Drawable drawable = res.getDrawable(R.drawable.board_960x960px_border_in_bg);
gridLayout.setBackground(drawable);
以上似乎都不适用于 API 23.
但是TableLayout的背景即使在API 24岁以上也不会消失，所以我将所有相关代码从GridLayout重写到TableLayout，现在可以了。
当我将 targetSdkVersion 更改为 23 时，我的问题得到了解决。
在您的 TextureView 的 xml 文件中将背景设置为 null。
例如android:background="@null"
适合我。