问题

我正在使用绘图工具（paint）在画布上绘制一些文本上方的突出显示框（highlight boxes）。我需要将绘图工具的混合模式（blendmode）设置为multiply。

```java
Paint paint = new Paint();
paint.setColor(Color.YELLOW);
paint.setBlendMode(BlendMode.MULTIPLY);

然而，这会导致崩溃：
java.lang.NoClassDefFoundError: Failed resolution of: Landroid/graphics/BlendMode;

在我的Oneplus 6T上不会发生这种情况，那里它可以正常工作。然而，在我的LG V10上会出现这种崩溃。

有关如何修复这个问题的任何想法吗？

build.gradle:

apply plugin: 'com.android.application';

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.3"

    defaultConfig {
        applicationId "com.example.test"
        minSdkVersion 24
        targetSdkVersion 29
        multiDexEnabled true
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])

    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

    implementation 'com.google.android.material:material:1.3.0-alpha01'

    implementation 'com.github.barteksc:android-pdf-viewer:3.2.0-beta.1'
    implementation 'com.tom_roush:pdfbox-android:1.8.10.1'
    implementation files('libs\\YouTubeAndroidPlayerApi.jar')
}

<details>
<summary>英文:</summary>

I&#39;m using paint to draw highlight boxes on top of some text using a canvas. I need to set the paint blendmode to multiply. 

Paint paint = new Paint();
paint.setColor(Color.YELLOW);
paint.setBlendMode(BlendMode.MULTIPLY);

This however, causes a crash:
**java.lang.NoClassDefFoundError: Failed resolution of: Landroid/graphics/BlendMode;**

It doesn't happen on my Oneplus 6T where it works perfectly. On my LG V10 however, this crash happens.

Any ideas on how to fix this?

**build.gradle:**

apply plugin: 'com.android.application'

android {
compileSdkVersion 29
buildToolsVersion "29.0.3"

defaultConfig {
    applicationId "com.example.test"
    minSdkVersion 24
    targetSdkVersion 29
    multiDexEnabled true
    versionCode 1
    versionName "1.0"

    testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}

buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
}

}

dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])

implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
implementation 'androidx.legacy:legacy-support-v4:1.0.0'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'androidx.test.ext:junit:1.1.1'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

implementation 'com.google.android.material:material:1.3.0-alpha01'

implementation 'com.github.barteksc:android-pdf-viewer:3.2.0-beta.1'
implementation 'com.tom_roush:pdfbox-android:1.8.10.1'
implementation files('libs\\YouTubeAndroidPlayerApi.jar')

}

</details>


# 答案1
**得分**: 1

***已解决***

显然，setBlendMode 要求在 API 级别 29 中引入，这就是它在我运行 Android 7 的 V10 上不起作用的原因。我发现的解决方案是简单地使用较旧的 Paint.setXfermode，并选择 PorterDuff 乘法模式。

```java
Paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.MULTIPLY));

参见：https://developer.android.com/reference/android/graphics/PorterDuff.Mode

Paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.MULTIPLY));