软件平台：Android11

硬件平台：高通

需求由来：项目中支持电磁笔，发现电磁笔接触屏幕的点系统都会显示黑色的鼠标小箭头，需要将这个屏蔽掉；

这种问题从资源名称着手比较好，而且这种全局的资源一般在SystemUI或者Framework的res目录下的概率较大，我们找到了类似鼠标图片资源的文件：pointer_arrow.png，搜索使用该素材的xml如下：

kongbo@kanyun-SA5112M5:~/qcom-android/LINUX/android/frameworks/base/core/res$ grep pointer_arrow -nrw .
./res/drawable/pointer_arrow_icon.xml:3:    android:bitmap="@drawable/pointer_arrow"

进而查找pointer_arrow_icon.xml的加载位置，

kongbo@kanyun-SA5112M5:~/qcom-android/LINUX/android/frameworks/base$ grep pointerIconArrow -nrw .
Binary file ./tools/aapt2/integration-tests/CommandTests/android-28.jar matches
./core/res/res/values/styles.xml:1356:        <item name="pointerIconArrow">@drawable/pointer_arrow_icon</item>
./core/res/res/values/styles.xml:1391:        <item name="pointerIconArrow">@drawable/pointer_arrow_large_icon</item>
./core/res/res/values/attrs.xml:8633:        <attr name="pointerIconArrow" format="reference" />
kongbo@kanyun-SA5112M5:~/qcom-android/LINUX/android/frameworks/base$ grep pointerIconArrow -nr .
Binary file ./tools/aapt2/integration-tests/CommandTests/android-28.jar matches
./config/hiddenapi-greylist-max-o.txt:96158:Lcom/android/internal/R$styleable;->Pointer_pointerIconArrow:I
./core/java/android/view/PointerIcon.java:550:                return com.android.internal.R.styleable.Pointer_pointerIconArrow;
./core/res/res/values/styles.xml:1356:        <item name="pointerIconArrow">@drawable/pointer_arrow_icon</item>
./core/res/res/values/styles.xml:1391:        <item name="pointerIconArrow">@drawable/pointer_arrow_large_icon</item>
./core/res/res/values/attrs.xml:8633:        <attr name="pointerIconArrow" format="reference" />

锁定是在PointerIcon.java中控制显示的，进入到PointerIcon类中详细分析,该类中主要的方法有getNullIcon() 获取空图标 ;getDefaultIcon()获取默认图标;getSystemIcon()获取系统图标等,认真读几遍代码,不难发现获取鼠标的方法最终都会调用到getSystemIcon()这个方法里

   /** * Gets a system pointer icon for the given type.* If typeis not recognized, returns the default pointer icon.** @param context The context.* @param type The pointer icon type.* @return The pointer icon.** @throws IllegalArgumentException if context is null.*/public static PointerIcon getSystemIcon(@NonNull Context context, int type) {if (context == null) {throw new IllegalArgumentException("context must not be null");}   if (true) {                                                                          return gNullIcon;}   if (type == TYPE_NULL) {return gNullIcon;}   if (sDisplayListener == null) {registerDisplayListener(context);}   final int displayId = context.getDisplayId();SparseArray<PointerIcon> systemIcons = gSystemIconsByDisplay.get(displayId);if (systemIcons == null) {systemIcons = new SparseArray<>();gSystemIconsByDisplay.put(displayId, systemIcons);}   PointerIcon icon = systemIcons.get(type);// Reload if not in the same display.if (icon != null) {return icon;}   int typeIndex = getSystemIconTypeIndex(type);if (typeIndex == 0) {typeIndex = getSystemIconTypeIndex(TYPE_DEFAULT);}   int defStyle = sUseLargeIcons ?com.android.internal.R.style.LargePointer : com.android.internal.R.style.Pointer;TypedArray a = context.obtainStyledAttributes(null,com.android.internal.R.styleable.Pointer,0, defStyle);int resourceId = a.getResourceId(typeIndex, -1);

逻辑上，该方法返回空即可，具体改动如下：

index 18d0d7b98a4..c00c3836e92 100644
--- a/core/java/android/view/PointerIcon.java
+++ b/core/java/android/view/PointerIcon.java
@@ -215,6 +215,10 @@ public final class PointerIcon implements Parcelable {throw new IllegalArgumentException("context must not be null");}+        if (true) {
+            return gNullIcon;
+        }
+if (type == TYPE_NULL) {return gNullIcon;}

编译验证即可。